Dissertationen zum Thema „Macadamia nuts“

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The South African macadamia industry is centred in the sub-tropical regions of South Africa with 40% of the plantings in the Lowveld. Growers receive higher pay-outs for high kernel recovery and unblemished (not discoloured) whole kernels. It is known that the same cultivar in the Lowveld region, produces nuts that differ in kernel recovery, whole kernel recovery and kernel discolouration. Therefore to develop optimal management strategies to maximize productivity and profitability of macadamias, factors that influence kernel recovery, whole kernel recovery and kernel discolouration needed to be investigated. The fruit structures are formed the first 90 days after anthesis and the fruit continues to grow until 12 to 15 weeks after anthesis until the shell hardens. Climate, soil moisture, cross-pollination and nutrition influence this process which determines the shell thickness and kernel size which in turn both determine kernel recovery. A large set of historical data from different regions were used to establish and isolate possible factors involved in kernel recovery, whole kernel recovery and kernel discolouration. These differed between the six regions over two seasons. High kernel recovery was associated with high orchard altitude, good cross-pollination, high crop load (high yield), early season harvesting and processing of nut-in-shell (NIS), high leaf boron concentrations in Nov., water management using deficit irrigation and low daily maximum relative humidity during the nut growth stage (Oct. to middle Jan.). High whole kernel recovery was associated with high kernel recovery, early season harvesting and processing of NIS, Bungay curing system of NIS compared to ambient air, low vapour pressure deficit during the nut maturation period (middle Jan. to harvest), elevated leaf boron and copper concentrations and low manganese leaf concentrations in Nov. High crop load, no cross pollination, low leaf nitrogen and zinc and high leaf potassium concentrations in Nov. were associated with low kernel discolouration. In order to develop possible orchard practices that increase kernel recovery, whole kernel recovery and decrease kernel discolouration, two irrigation trials and one kaolin trial were conducted. In the two irrigation trials, water stress was induced over two growing seasons (2011-2013) by applying different levels of irrigation at different phenological stages. Kernel recovery was not affected by any of the treatments, but water stress could not be applied continuously due to frequent high rainfall. Moderate water stress did not influence yield, only trees that were over watered during a drier premature nut drop stage during the 2011/12 season increased yield, although it could not be repeated the following season during a wetter premature nut drop stage. In the kaolin trial, the efficacy of kaolin foliar application was evaluated to reduce heat stress. Kaolin applications did not affect kernel recovery, nut yield or quality. Temperature during the study was not continuously high (>30 ⁰C), thus heat stress could not be mitigated. We did however establish that up to five layers of foliar applied kaolin did not significantly reduce individual leaf photosynthesis.
AFRIKAANSE OPSOMMING: Die makadamia-industrie in Suid-Afrika, is gesentreer in die sub-tropiese streke van die land met 40% van die aanplantings in die Laeveld. Produsente ontvang hoër uitbetalings vir neute wat 'n hoë uitkraak (kernherwinning) persentasie lewer asook ongeskonde (nie verkleurde), heel-kern neute. Daar is gevind dat dieselfde kultivar verskil ten opsigte van kernherwinning, heel-kernherwinning en kernverkleuring in die Laeveld. Om 'n optimale bestuurstrategie te ontwikkel en so maksimale opbrengs en wins te verkry, moes die faktore wat kernherwinning, heel-kernherwinning en kernverkleuring beïnvloed ondersoek word. Die eerste 90 dae na blom word die vrugstrukture gevorm en vrugte groei tot en met 12 tot 15 weke na volblom totdat die dop verhard. Klimaat, grondvog, kruisbestuiwing en voedingstowwe beïnvloed die prosesse wat dopdikte en kerngrootte beïnvloed en wat beide kernherwinning bepaal. 'n Groot stel historiese data vanaf verskillende streke is gebruik om die moontlike faktore wat kernherwinning, heel-kernherwinning en kernverkleuring beïnvloed te bepaal. Hierdie aspekte het verskil in die ses streke oor twee seisoene. Hoë kernherwinning was geassosieer met hoër liggende boorde (hoogte bo see spieël), goeie kruisbestuiwing, hoë oeslading, vroeë seisoen oes en prosessering van neut-in-dop, hoë boor blaarkonsentrasie in Nov., waterbestuur met onthoudingsbesproeïng en lae daaglikse maksimum relatiewe humiditeit gedurende die neut-groei-stadium (Okt. tot middel Jan.). Hoë heel-kernherwinning was geassosieer met hoë kernherwinning, vroeë seisoen oes en prosessering van neut-in-dop, Bungay droging, lae waterdampdruk tekort gedurende die neut-rypwording stadium (Jan. tot oes), hoë boor en koper blaarkonsentrasies en lae mangaan blaarkonsentrasie in Nov. Hoë oeslading, geen kruisbestuiwing, lae stikstof, sink en hoë kalium blaarkonsentrasies in Nov. was geassosieer met lae kernverkleuring. Twee besproeïngsproewe en een kaolienproef is uitgevoer om moontlike boord praktyke te ontwikkel wat kernherwinning en heel-kernherwinning verhoog en kernverkleuring verlaag. In die twee besproeïngsproewe is watertekorte aangewend oor twee seisoene (2011-2013) deur verskillende hoeveelhede te besproei gedurende verskillende fenologiese stadiums. Kernherwinning was nie geaffekteer deur die behandelings nie, maar dit moet ingedagte gehou word dat watertekorte nie deurlopend toegepas kon word nie as gevolg van hoë reënval. Gematigde watertekorte het nie die opbrengs beïnvloed nie, slegs bome wat oor-besproei was in ’n droeër voor-rypwording-neut-val stadium in die 2011/12 seisoen het 'n verhoging in opbrengs getoon, maar dit kon nie herhaal word die daaropvolgende natter seisoen nie. In die kaolienproef, is die gebruik van kaolien blaarbespuiting geëvalueer om hitte stress te verminder. Kaolienbespuitings het geen effek op kernherwinning, neut opbrengs of neutkwaliteit gehad nie. Temperature gedurende die studie was nie deurlopend hoog nie (>30 0C) en dus kon hitte stress nie gemanipuleer word nie. Daar is wel vasgestel dat tot vyf lae kaolien nie enkel-blaar fotosintese verminder het nie.

Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.

Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.
Master of Science (Hons) (Food Science and Nutrition)

One of the top priorities of the South African government is to maintain and enhance economic growth. The South African government is seeking to achieve this by implementing export-led growth policies. In many exporting economies. resources are scarce and often export promotion institutions face the double allocation problem. The double allocation problem implies that export promotion institutions face the difficulty of having to allocate scarce resources efficiently (Cuyvers. De Pelsmaker. Rayp & Roozen. 1995). The apportionment of financial resources is among several export promotion instruments that can be used to attain export success. In 2005. the Department of Trade and Industry (the dti). as the trade promotion organisation in South Africa. expressed the need for a scientific study on• the realistic export opportunities in products and markets. This would enable decision-makers to scientifically justify the allocation of public resources to promote products with the highest potential earnings. A Decision Support Model (DSM) designed by Cuyvers (1995) was applied to the South African economy (in a study done by Viviers & Pearson (2007)) to identify priority products with high export potential in new and I or existing markets. The DSM identified the product group,. under the Standard International Trade Classification (SITC). SITC 0577 as the twenty-second product with the most realistic export opportunities. SITC 0577 was identified as having thirty-six potential export destinations. This study evaluated each of the fifteen product categories corresponding to SITC 0577 on an HS level. to determine the product with the most potential for export success for the South African economy. This was achieved by employing a quantitative approach to construct a composite index. The composite export potential index comprised three sub indices: South Africa's export performance index. the world markets index and the production index. Based on an export potential index score of 4.16. macadamia nuts, classified under nuts not else specified (nes). were identified as the product with the highest potential for export success. Once the product with the highest export potential had been identified. trade and market access statistics were analysed to determine a target market with the highest import potential for South African macadamia nuts. Germany was selected from a group potential target markets as the target market for South African macadamia nuts based on an analysis of market size, growth trends, share in the world market trade, and market accessibility. Thereafter, a survey was conducted through unstructured telephone interviews and from secondary sources of information. The survey determined the market entry requirements, consumption trends and price information for South African exporters of macadamia nuts to Germany. This information was compiled into a market profile to provide exporters of macadamia nuts with essential market information on the German market.
Thesis (M.Com. (International Commerce))--North-West University, Potchefstroom Campus, 2010.

Orientador: Antonio Marsaioli Junior
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-05T01:14:32Z (GMT). No. of bitstreams: 1 Silva_FlavioAlvesda_D.pdf: 2135599 bytes, checksum: 1cb50b2bea2c0d7059788a4f01434a15 (MD5) Previous issue date: 2005
Doutorado
Doutor em Engenharia de Alimentos

The drying of agricultural food crops is an essential process in ensuring the safe and reliable delivery of produce to consumers. This is no less true for cultivated nuts, grains and seeds, which have a certain vulnerability to degradation under moist conditions. The macadamia nut is particularly susceptible to this issue, due to its high oil content and markedly slow drying characteristics, providing rancidity and disease with an opportunity to spoil the produce. In recent decades, the design of efficient industrial drying schemes has become a large focus for researchers, with many studies aiming to better describe the underlying physical processes in food drying. This dissertation details the design and implementation of a fundamental model and accompanying simulation for the drying of nut-in-shell macadamias, intended to aid a future control system design study. Research is given toward the macadamia industry, as well as some of the relevant physical properties of the nut. An extensive review is given on modelling, with particular importance placed on techniques used for the deep-bed drying of nuts, grains and seeds. Control system architecture is briefly discussed, but is not the primary focus of this report. Verification of work done by prior researchers is carried out, before then deriving a comprehensive deep-bed drying model for macadamias. Crucial aspects toward how such a model is adapted into a MATLAB simulation is given, without intending to become an extensive review on software design. A robust and thorough model verification procedure is conducted, to prove that the final simulation does indeed successfully suit the purposes of control system design.

Saturated steam (SS) and propylene oxide (PPO) fumigation are two common methods to improve microbiological quality and safety of tree nuts. Validation of these processes is needed to ensure adequate control of bacterial pathogens. Since pathogens cannot be studied in food processing environments, surrogates with resistance comparable to the pathogens needed to be identified. The objective was to investigate the suitability of Enterococcus faecium, Pediococcus acidilactici, and Staphylococcus carnosus as surrogate bacteria for Salmonella spp. on whole cashews and macadamia nuts, processed with SS or PPO. Whole cashews and macadamia nuts were co-inoculated with a cocktail of Salmonella enterica and one of the three potential surrogates. Nuts were dried to original aw, packaged in poly-woven bags (2.3 kg) and commercially processed using vacuum assisted steam at 80 ͦ C or PPO fumigation. Salmonella and the potential surrogates were enumerated by serial dilution, and plated onto TSA with overlay of XLT-4 (Salmonella) or media selective for the potential surrogates. Mean log reductions (CFU/g) of Salmonella and each potential surrogate were compared using a paired T-test. SS results: reduction of Salmonella (6.0 ± 0.14) was significantly larger than E. faecium (4.3± 0.12), or P. acidilactici (3.7± 0.14) on whole cashews. Salmonella (5.9 ± 0.18) was significantly larger than P. acidilactici (4.4± 0.18) on whole macadamia nuts. PPO results: reduction of Salmonella (7.3 ± 0.19) was significantly greater than E. faecium (6.4± 0.31), or P. acidilactici (6.3± 0.33) on whole macadamia nuts. Reduction of Salmonella was significantly greater than E. faecium and P. acidilactici reduction on cashews. P. acidilactici may be considered a surrogate for Salmonella reduction on whole macadamia nuts and whole cashews processed using SS at 80 ͦ C. E. faecium and P. acidilactici may be considered surrogates for Salmonella reduction on whole macadamia nuts and whole cashews processed using PPO. Reduction of St. carnosus exceeded that of Salmonella indicating it is not a suitable surrogate for Salmonella using either processing intervention.
Master of Science in Life Sciences

A new European labeling directive (2003/89/EC) states that certain foods and products derived thereof must always be declared. Among the tree nuts specified is Macadamia nut (Macadamia spp.). During the last few years, cases of IgE-allergic reactions, even severe anaphylaxes, have been reported. Reliable methods for the detection of this nut are needed.

Protein from Macadamia nuts was isolated. Polyacrylamide gel electrophoresis in SDS revealed two main protein bands of about 20 and 50kDa. These protein bands were cut and extracted from the gel and rabbits were immunized with each protein.

Immunoblotting showed dominant reactivity with the respective antigens. The antisera were further tested for specificity in immunodiffusion and in rocket immunoelectrophoresis.

In addition, a specific DNA-method was developed, based on Real-Time PCR using Macadamia vicilin as target sequence. Two different primer pairs were tested. Specificity was tested against potentially related nuts. Optimisation of primer and probe concentrations was performed. The limit of detection was 2-4 pg DNA, corresponding to a macadamia nut concentration of 50 to 100 μg per g. In a background of soybean DNA, down to 0,01 % macadamia DNA could be detected.

Made available in DSpace on 2014-06-11T19:31:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-16Bitstream added on 2014-06-13T20:42:07Z : No. of bitstreams: 1 piza_plbt_dr_botfca.pdf: 576119 bytes, checksum: e10fb2efd0d10e64fe9dc7061c5a81e8 (MD5)
A pós-colheita da noz macadâmia é uma das etapas mais críticas de sua cadeia produtiva, as baixas produtividades nos primeiros anos de vida dos pomares não permitem que os agricultores realizem grandes investimentos neste período, iniciando, assim, um processo de improvisações que se perpetuará ao longo do tempo. Este trabalho teve como principal objetivo melhorar o rendimento operacional de um processo de pré-limpeza de macadâmia, desenvolvendo, a partir de um sistema existente, uma nova unidade, com capacidade de receber e processar, no mínimo, 8.000 kg de produto por dia. O experimento foi realizado em uma fazenda situada no município de Dois Córregos, Estado de São Paulo, nas safras de 2003, 2004 e 2005. A partir do processo existente foram desenvolvidas 3 novas unidades. As duas primeiras apresentaram aumentos na produtividade e reduções nos custos operacionais, entretanto, não atenderam as condições de recebimento e processamento. A terceira unidade, representou a somatória dos conhecimentos obtidos nas análises anteriores, e, atendeu os objetivos propostos no presente trabalho. A análise econômica dos custos para migrar do processo existente para a unidade de melhor rendimento mostrou que, os investimentos em equipamentos e automação foram pagos em aproximadamente 50 dias de processamento.
The macadamia nut post-harvest is one of the most critical stages of the productive chain, the low orchards productivity in the first life years does not allow farmers much investments in this period, initiating, thus, a process of improvisations that will be perpetuated trough the years. This work had as main objective to improve the efficiency of a cleaning macadamia process. It was developed a new unit based as an existing system with capable to process, at least, 8,000 kg of product per day. The experiments were carried out in a farm situated in Dois Córregos city, São Paulo, during harvest season of 2003, 2004 and 2005. From the existing process three new units were developed. The first two ones shoud increases in productivity and reductions in operational costs, however, it did not attend the necessities of receiving and processing. The third unit, represented incorporation of the knowledge obtained in the previous analyses, and, fulfilled the objectives of this work. The costs analysis to go from the existing process to the better income unit, showed that, the investments in equipment and automation had been paid in approximately 50 processing days.

Resumo: A pós-colheita da noz macadâmia é uma das etapas mais críticas de sua cadeia produtiva, as baixas produtividades nos primeiros anos de vida dos pomares não permitem que os agricultores realizem grandes investimentos neste período, iniciando, assim, um processo de improvisações que se perpetuará ao longo do tempo. Este trabalho teve como principal objetivo melhorar o rendimento operacional de um processo de pré-limpeza de macadâmia, desenvolvendo, a partir de um sistema existente, uma nova unidade, com capacidade de receber e processar, no mínimo, 8.000 kg de produto por dia. O experimento foi realizado em uma fazenda situada no município de Dois Córregos, Estado de São Paulo, nas safras de 2003, 2004 e 2005. A partir do processo existente foram desenvolvidas 3 novas unidades. As duas primeiras apresentaram aumentos na produtividade e reduções nos custos operacionais, entretanto, não atenderam as condições de recebimento e processamento. A terceira unidade, representou a somatória dos conhecimentos obtidos nas análises anteriores, e, atendeu os objetivos propostos no presente trabalho. A análise econômica dos custos para migrar do processo existente para a unidade de melhor rendimento mostrou que, os investimentos em equipamentos e automação foram pagos em aproximadamente 50 dias de processamento.
Abstract: The macadamia nut post-harvest is one of the most critical stages of the productive chain, the low orchards productivity in the first life years does not allow farmers much investments in this period, initiating, thus, a process of improvisations that will be perpetuated trough the years. This work had as main objective to improve the efficiency of a cleaning macadamia process. It was developed a new unit based as an existing system with capable to process, at least, 8,000 kg of product per day. The experiments were carried out in a farm situated in Dois Córregos city, São Paulo, during harvest season of 2003, 2004 and 2005. From the existing process three new units were developed. The first two ones shoud increases in productivity and reductions in operational costs, however, it did not attend the necessities of receiving and processing. The third unit, represented incorporation of the knowledge obtained in the previous analyses, and, fulfilled the objectives of this work. The costs analysis to go from the existing process to the better income unit, showed that, the investments in equipment and automation had been paid in approximately 50 processing days.
Orientador: Widsney Alves Ferreira
Coorientador: Marco Antonio Martin Biaggioni
Banca: José Armando Xavier
Banca: Antonio Carlos de O. Ferraz
Banca: João Domingos Biagi
Banca: Clovis Isberto Biscegli
Doutor

M. Tech. (Chemistry, Faculty of Applied and Computer Science), Vaal University of Technology
The abundance of agricultural waste materials has led to its use as adsorbents for trace metal adsorption. The raw Macadamia nutshell (RMN) powder was treated with a hydrochloric acid solution to obtain acid modified Macadamia nutshells (AMM), and with sodium hydroxide solution to obtain base modified Macadamia nutshells (BMM). Then, the AMM and BMM materials were grafted with 0.5 M, 1 M, and 2 M acrylic acid. The different AMM grafted materials were labelled 0.5 GAM, 1 GAM and 2 GAM representing the different grafting ratios. The same naming order was followed for the BMM grafted materials, that is, 0.5 GBM, 1 GBM and 2 GBM corresponding to different concentrations used. The prepared Macadamia based adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), carbon, hydrogen, nitrogen and sulphur (CHNS) analysis, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis. The determination of surface properties such as the point of zero charge (pHPZC), bulk density and the surface negative charge was accomplished with appropriate wet chemistry methods. The adsorption of selected trace metals (Cu(II), Cd(II), Co(II), and Cr(VI)) was done in batch experiments. Atomic absorption spectroscopy (AAS) was used for the determination of metal ions concentrations and total Cr. The ultraviolet-visible (UV–Vis) spectroscopy was used for the determination of Cr(VI) concentration remaining in solution after adsorption. The RMN, AMM, and BMM adsorbents showed potential in removing more than 45% Cu(II) ions, but less than 30% for both Cd(II) and Co(II) ions. However, more than 90% removal of Cr(VI) ions was achieved with the same adsorbents. Consequently, only the adsorption of Cr(VI) was further investigated in the study due to the higher removal efficiency displayed by the Macadamia based biosorbents. The optimum adsorption conditions for the RMN, AMM, and BMM materials were found to be pH 2, 100 mg/L initial concentration of Cr(VI), 600 min contact time and 0.2 g adsorbent mass. The ideal conditions for the 0.5 GAM and 0.5 GBM were found to be pH 2, 25 mg/L initial concentration of Cr(VI), 180 min contact time, and 0.15 g adsorbent mass. The optimum temperature was found to be 40℃ for all materials. A volume of 20 mL was used for all batch experiments. The RMN, AMM, BMM, 0.5 GBM, and 0.5 GAM adsorption mechanisms were better described by the Langmuir isotherm which predicted a monolayer sorption process. The kinetic data fitted better to the pseudo second-order rate model which signified a chemisorption type of interaction. The thermodynamic parameters showed that the adsorption reaction was feasible, spontaneous and endothermic. The Macadamia based materials showed greater potential as adsorbents for the adsorption of Cr(VI) ions from aqueous solution compared to the other selected trace metal ions [Cd(II), Cu(II) and Co(II)].

Plasma gasification experiments were conducted on sucrose and crushed macadamia nutshells. The pilot-scale plasma gasification system used comprises a 15 kW DC plasma torch fitted to a 5 L gasification reactor. The DC plasma torch has an efficiency of ~30 % with most of the energy lost in the torch anode. For the macadamia nutshells, the plasma input-power was set at 9, 11 and 14 kW. At each power input setting, four different feed rates were investigated, namely 0.5, 0.7, 1.04 and 1.14 kg/h. It was observed that as the power increases, conversion increases from 48 % at 9 kW to higher than 80 % at 14 kW. It was also observed that higher mass feed rates increase the conversion. The lower heating values of the syngas produced during gasification increased with higher power inputs and higher feed rates. At a feed rate of 1 kg/h, the maximum calorific power value was 3.45 kW, at a torch setting of 14 kW. The highest power values obtained was slightly more than 4 kW. The effect of equivalence ratio (ER) was evaluated on the plasma gasification of sucrose. ER values of 1 and 2 were investigated. With an ER of 1, the CO/H2 ratio was 1.8 and the CO/CO2 ratio was 109. With an ER of 2, the CO/H2 ratio was 1.73, and the CO/CO2 ratio 18. As expected, an increase in ER enhances the formation of CO2. A low ER thus results in higher syngas quality. At equivalent conditions the homogenous, crystalline sucrose yielded a CO/CO2 ratio of 109, significantly higher than the 29 for plasma gasification of the macadamia nut shells. A contributing factor to having better quality syngas, was the smaller the average particle diameter of the sucrose, 0.4 mm, compared to the 10 mm of the crushed macadamia nut shells was. Another contributing factor could be that the available carbon in the macadamia nut shells structure are more strongly bonded than in sucrose. For additional insight, kinetic data for the pyrolysis of sucrose, fructose and glucose were obtained using a TGA-FTIR hyphenated system, at much lower heating rates than anticipated in plasma system, and TGA-DTG experiments on macadamia nut shells. Dynamic studies were performed on sucrose, fructose and glucose at heating rates of 5, 10, 15, 20 and 50 °C/min in an atmosphere of nitrogen flowing at 50 mL/min, and for the macadamia shell at heating rates of 5, 10 and 20 °C/min in an atmosphere of nitrogen flowing at 50 mL/min. The sugars yielded 80 % to 85 % conversion into gaseous products, while the conversion of the shells approached 90 %; the residue was biochar. The FTIR spectra showed the major products that form from the pyrolysis of sugars to be CO2, H2O, along with large quantities C-H-O-containing compounds, amongst them C5H4O2 and C6H6O3. The latter two compounds are probably condensible.
Dissertation (MEng)--University of Pretoria, 2020.
Chemical Engineering
MEng
Unrestricted

A macadâmia (Macadamia integrifolia Maiden & Betche) é uma nogueira arbórea originária das florestas tropicais australianas. Sua distribuição natural ocorre por quase toda a costa leste da Austrália. No Brasil, foi introduzida em 1931, mas sua expansão aconteceu a partir da década de 70. As variedades comerciais são originadas de duas espécies, Macadamia integrifolia e M. tetraphylla, e seus híbridos. As informações sobre pedigree são geralmente incompletas e a identificação das variedades algumas vezes não é clara. O uso de técnicas moleculares auxilia em diversas fases dos programas de melhoramento, inclusive na caracterização do material genético e seleção de parentais envolvidos nos cruzamentos. A partir do uso de técnicas moleculares (microssatélites e diversity array technology), as 28 variedades que compõe o germoplasma brasileiro foram genotipadas com a finalidade de investigar a estrutura e a divergência genética entre estas. Foram utilizados 29 primers flanqueadores de locos microssatélites e 462 marcas de diversity array technology. A análise pelo programa Structure apresentou a formação de duas subpopulações: uma com a maioria das variedades desenvolvidas no Havaí/USA e Brasil, e outra composta pelas variedades desenvolvidas na Austrália e três variedades brasileiras. A análise da diversidade genética detectou valores medianos de heterozigosidade para o conjunto de variedades ( = 0,46 e = 0,43), com indicação de um pequeno excesso de homozigoto em relação ao esperado sob Equilíbrio de Hardy-Weinberg. A estimativa do índice de fixação (F = 0,067) para o conjunto de subpopulações apresentou grande variação, porém na média, foi baixo e não diferente de zero. Os resultados também mostram que a maior parte da diversidade genética do germoplasma está dentro de subpopulações ( q = 0,041). O índice de fixação devido ao sistema reprodutivo também variou entre os locos analisados, mas na média foi igualmente baixo e não diferente de zero ( f = 0,027). Os valores das Distâncias de Jaccard variaram entre 0,00 e 0,787 enquanto que as Distâncias de Roger Modificada variaram entre 0,227 e 0,671. O dendrograma UPGMA formado pelas Distâncias de Jaccard formou três grupos enquanto que pelas Distâncias de Roger Modificada formou dois grupos, sendo possível distinguir somente o grupo externo formado pelas duas espécies de grevílea. A falta de divergência entre alguns pares de variedades foi inesperada, assim como o não agrupamento entre variedades identificadas com o mesmo nome ou que apresentam histórico de parentesco. Da mesma forma, as duas subpopulações discriminadas pelo programa Structure não formaram agrupamento específico em ambos os dendrogramas. Os resultados das análises dos Componentes Principais foram coerentes aos obtidos nos dendrogramas formando os mesmos agrupamentos.
Macadamia (Macadamia integrifolia Maiden and Betche) is a nut crop tree widespread across eastern Australia. Although has been introduced in Brazil in 1931, just in the past 20 years its cultivated area has expanded more significantly. Commercial varieties are originated from Macadamia integrifolia and M. tetraphylla, as well as its hybrids. The information on pedigree is generally incomplete and the identification of varieties is sometimes not so clear. Molecular techniques could provide genetic information useful for breeding programs, such as, the kinship (relatedness) between individuals. Molecular techniques (microsatellites and diversity array technology) was used to genotype all 28 varieties that composes Brazils germoplasma with the purpose to investigate the structure and the genetic divergence between these varieties. Twenty nine microsatellites locus and 462 markers of diversity array was used. Analysis using the Structure software showed evidence of two subpopulations: one with the majority of the varieties developed in the Hawaii/USA and Brazil, and another with varieties developed in Australia and three in Brazil. The analysis of genetic diversity detected medium values of heterozigosis ( = 0.46 and = 0.43), with indication of a small excess of homozygotes in relation the expected value under Hardy- Weinberg equilibrium. The estimate of inbreeding coefficient showed great variation (from - 0.522 to 0.558), however in the average (F = 0.067) it was low and statistically not different from zero. The results also showed that most of the genetic diversity is within subpopulations ( q = 0.041). The inbreeding due to the reproductive system varied between analyzed loci, but on average it was low and statistically not different from zero ( f = 0.027). Values of Jaccard distances ranged from 0 to 0.787, whereas the modified Rogers distances ranged from 0.227 to 0.671. UPGMA Cluster analysis from Jaccard distances formed three groups, whereas modified Rogers distances of formed two groups. In the latter, it is possible to distinguish only the external group formed by the two species from Grevilea spp. For some varieties that we expected to be clustered together were unexpected assigned to different clusters. On the other hand, for some varieties that we expected to be placed in different clusters were unexpected clustered together. Unexpected, the two subpopulations discriminated in the analysis (Structure) did not form specific groups when using both Jaccard and modified Rogers distances. The results of Principal Coordinate Analysis were coherent with the UPGMA analyses.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-04-04T10:15:18Z No. of bitstreams: 2 Dissertação - André Luiz Borges Machado - 2017.pdf: 4018960 bytes, checksum: 0f752eee89eafe0cb8606742dc6901b7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)
Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-04-04T10:15:52Z (GMT) No. of bitstreams: 2 Dissertação - André Luiz Borges Machado - 2017.pdf: 4018960 bytes, checksum: 0f752eee89eafe0cb8606742dc6901b7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5)
Made available in DSpace on 2017-04-04T10:15:52Z (GMT). No. of bitstreams: 2 Dissertação - André Luiz Borges Machado - 2017.pdf: 4018960 bytes, checksum: 0f752eee89eafe0cb8606742dc6901b7 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-02-23
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Brazil nut (Bertholletia excelsa) and Macadamia (Macadamia integrifolia) are rich feeds with excellent nutrients with higher quality. The main form of consumption of these nuts and almonds are in natura, but there are products which can be elaborated using these raw materials with high nutritional value and pleasant flavor. Water-soluble extracts are an alternative to consume them, which consist of fluid food of plant origin, that can be produced by nuts, oleaginous and even some grasses and they have great commercial appeal since they are free of animal’s fats, “lac free” (free of lactose) and have high rate of minerals. Thus, this research aimed to determine the best formulation, to accompany physical and microbiological stability, proximal composition, to estimate the shelf life and to determine the rheological behavior of a water-soluble extract made of Brazil nut and Macadamia. For the construction of mathematical models, with the purpose of knowing the effect of the variation of water, Brazil nut and Macadamia concentrations, basic components in the elaboration of the product on the proximal composition and physical aspects such as pH, titratable acidity and colorimetry, a simplex centroid design for mixtures was used and provided quadratic and cubic models showing excellent adjustment of experimental data. The Global Acceptance and Purchase Intention tests were performed for each experiment proposed by simplex centroid design and the Tukey test was used in order to determine the best proportion among the components of the ternary mixture. The formulation of water-soluble extract composed of 70% (w/w) water, 15% (w / w) Brazilian nut and 15% (w/w) Macadamia was considered to be the most preferred by tasters submitted to the sensory evaluations. In order to improve the product’s flavor, 10% (w/v) of sugar, expressed as sucrose, was added and the concentration of preservatives citric acid, potassium sorbate and sodium benzoate was reduced. The product was processed technologically under hygienic conditions and filled in 220 ml transparent glass bottles, hermetically sealed with metal crown cork, pasteurized at 80 °C/25 min, stored under refrigeration at 4 ° C and had its stability evaluated during 28 days. Growth of Thermotolerant Coliforms, Positive Coagulase Staphylococci, Salmonella sp, Molds and Yeasts during the evaluation period was not detected. There was a significant variation (p < 0.05) in pH in the first two weeks of storage, and remained without significant variation (p > 0.05) for the other weeks analyzed. The acidity remained constant throughout the lifetime. The product showed a yellowish-white color throughout the study, determined by the coordinates of the colorimetry. Sensory analysis scores for odor, color, taste and global impression averaged around 6, thus, concluding that the product has a 28 days of shelf life. The rheological profile of the beverage was evaluated at three different temperatures, at 25 °C (room temperature), at 45 °C (temperature of the disintegration stage of Brazil nut and Macadamia with water in blender), and at 80 °C, (pasteurization temperature). The Ostwald-de-Waele model was considered the best to describe the beverage flow and since the calculated flow rate of the model, was less than 1 at the temperatures studied, it had concluded that the beverage behaved as a fluid Non-Newtonian pseudoplastic. The apparent viscosity curves of the mixed drink were plotted and showed that the apparent viscosity decreased significantly (p < 0.05) with the increasing of temperature.
A Castanha-do-Brasil (Bertholletia excelsa) e a Macadâmia (Macadamia integrifolia) são alimentos ricos em nutrientes de excelente qualidade. A principal forma de consumo de nozes e amêndoas é in natura, porém existem produtos que podem ser elaborados a partir destas matérias-primas com alto valor nutricional e também de sabor agradável. Uma alternativa ao consumo desses alimentos são os extratos hidrossolúveis, que consistem em alimentos fluidos de origem vegetal que podem ser produzidos a partir de castanhas, oleaginosas e até mesmo algumas gramíneas e possuem grande apelo comercial, uma vez que são isentos de gorduras animais, não possuem lactose e apresentam alto teor de minerais. Sendo assim, esta pesquisa objetivou determinar a melhor formulação, acompanhar a estabilidade física e microbiológica, composição proximal, estimar a vida útil e determinar o comportamento reológico de um extrato hidrossolúvel a base de Castanha-do-Brasil e Macadâmia. Para a construção de modelos matemáticos, com a finalidade de se conhecer o efeito da variação das concentrações de água, Castanha-do-Brasil e Macadâmia, dos componentes básicos na elaboração do produto sobre a composição proximal e aspectos físicos como pH, acidez titulável e colorimetria, utilizou-se o planejamento experimental para misturas tipo simplex centroide que forneceu modelos quadráticos e cúbicos com excelente ajuste frente aos dados experimentais. Os Testes de Aceitação Global e Intenção de Compra foram realizados para cada experimento proposto pelo planejamento simplex centroide e o teste de Tukey foi utilizado a fim de determinar a melhor proporção entre os componentes da mistura ternária. A formulação de extrato hidrossolúvel composta por 70% (p/p) de água, 15% (p/p) de Castanha-do-Brasil e 15% (p/p) de Macadâmia, foi considerada como a mais preferida pelos provadores submetidos as avaliações sensoriais. Com a finalidade de melhorar o sabor do produto, adicionou-se 10% (p/v) de açúcar, expressos em sacarose, e reduziu-se a concentração dos conservantes ácido cítrico, sorbato de potássio e benzoato de sódio. O produto foi processado tecnologicamente sob condições higiênicas, sendo envasado em garrafas de vidro transparente de 220 mL, fechado hermeticamente com tampas metálicas do tipo coroa, pasteurizado a 80 °C/25 min, armazenado sob refrigeração a 4 °C e teve sua estabilidade avaliada por 28 dias. Não foi detectado o crescimento de Coliformes Termotolerantes, Estafilococos Coagulase Positiva, Salmonella sp, Bolores e Leveduras durante o período de avaliação. Houve variação significativa (p < 0,05) do pH nas duas primeiras semanas de estocagem, estabilizando-se para as demais semanas analisadas. A acidez se manteve constante durante todo o período de vida útil. O produto apresentou coloração branco-amarelada durante todo o estudo, determinada pelas coordenadas da colorimetria. As notas das análises sensoriais para Odor, Cor, Sabor e Impressão Global tiveram média em torno de 6, concluindo assim que o produto tem vida útil de, pelo menos, 28 dias. Foi avaliado o perfil reológico da bebida em três temperaturas distintas, a 25 ºC (temperatura ambiente), a 45 ºC, (temperatura da etapa de desintegração da Castanha-do-Brasil e Macadâmia com a água em liquidificador), e a 80 ºC, (temperatura de pasteurização). O modelo de Ostwald-de-Waele foi considerado o melhor para descrever o escoamento da bebida e uma vez que o índice de escoamento calculado do modelo foi menor que 1, nas temperaturas estudadas, conclui-se que a bebida comportou-se como um fluido não newtoniano pseudoplástico. As curvas de viscosidade aparente da bebida mista foram plotadas e mostram que a viscosidade aparente diminuiu significativamente (p < 0,05) com o aumento da temperatura.

As embalagens ativas têm ganhado destaque no mercado mundial, pois possibilitam a interação do alimento com o material da embalagem, permitindo a incorporação de compostos ativos. Dentre os compostos ativos, o extrato etanólico de cúrcuma (EEC) tem chamado atenção, devido suas propriedades antioxidante, antimicrobiana, dentre outras. Assim, os objetivos deste trabalho foram desenvolvimento, caracterização e aplicação de filmes à base de gelatina aditivados com EEC. Os filmes foram produzidos pela técnica de casting (2 g de gelatina/100 g de solução filmogênica (SF), 30 g de sorbitol/100 g de gelatina) e o EEC foi incorporado na SF, nas concentrações de 0, 5, 50, 100, 150 e 200 g EEC/100 g de gelatina. Os filmes foram caracterizados em relação às propriedades mecânicas, conteúdo de água, matéria solúvel, permeabilidade ao vapor de água, parâmetros de cor, opacidade, brilho, microestrutura, espectroscopia de infravermelho com transformada de Fourier (FTIR), barreira UV/Vis, transparência, teor de curcumina, atividade antioxidante e atividade antimicrobiana. O filme com os melhores resultados para as propriedades mecânicas, barreira UV/Vis e atividade antioxidante foi utilizado para embalar noz macadâmia e, as propriedades da noz foram avaliadas em função do tempo de estocagem. A incorporação do EEC melhorou as propriedades mecânicas dos filmes, a tensão de ruptura aumentou de 27,7 MPa (filme controle) para 35,1 MPa (filme com 200 g de EEC/100 g de gelatina) e a elongação na ruptura aumentou de 22,3 % (filme controle) para 36,5 % (filme com 200 g de EEC/100 g de gelatina). O conteúdo de água não foi influenciado pela adição do EEC, porém a matéria solúvel reduziu em relação ao filme controle. A permeabilidade ao vapor de água também reduziu em média 24,1 % para os filmes aditivados. Os parâmetros de cor, opacidade e brilho foram afetados pela incorporação do EEC. As análises de microestrutura indicaram alterações na rugosidade da superfície e um aumento na rugosidade da estrutura interna, em função do aumento da concentração de EEC nos filmes. A análise de FTIR mostrou deslocame ntos dos picos associados às amidas A, I e II para os filmes aditivados. Os filmes com EEC apresentaram reduzida transmitância na região UV/Vis e aumento da transparência. O teor de curcumina aumentou linearmente (y=0,6115x+6,6629, R2=0,9817) com o aumento da concentração do extrato. A capacidade antioxidante aumentou em função do aumento da concentração do EEC e a atividade antimicrobiana (Staphylococcus aureus) foi verificada para concentrações acima de 5 g de EEC/100 g de gelatina. Assim, o filme com concentração de EEC de 200 g de EEC/100 g de gelatina foi utilizado para embalar noz macadâmia. Em relação ao conteúdo de água da noz macadâmia foram observadas diferenças significativas em função do tipo de filme utilizado (com e sem ad ição de EEC) nos primeiros 30 dias de estocagem. Entretanto, para a atividade de água não foram observadas diferenças. Após 60 dias a dureza da noz macadâmia embalada com o filme aditivado foi superior e as substâncias reativas (ácido tiobarbitúrico) fora m inferiores. Pode-se concluir que é possível a utilização desse sistema como embalagem ativa para a noz macadâmia.
Active packaging has been receiving growing attention in the world market because it allows interaction between food and packaging material, thus enabling the incorporation of active compounds. Among active compounds, curcuma ethanol extract (CEE) has been highlighted mainly because its antioxidant and antimicrobial properties. The objectives of this study were the development, characterization and application of gelatin-based films added with CEE. The films were produced by casting technique (2 g gelatin/100 g filmogenic solution (FS), 30 g sorbitol/100 g gelatin) and CEE was added to FS at 6 concentrations (0, 5, 50, 100, 150 and 200 g CEE/100 g gelatin). The films were characterized regarding mechanical properties, water content, soluble matter, water vapor permeability, color parameters, opacity, gloss, microstructure, Fourier transform infrared spectroscopy (FTIR), light transmission, transparency, curcumin content, antioxidant activity, and antimicrobial activity. The film with the best results concerning mechanical properties, light transmission and antioxidant activity was selected to package macadamia nut, whose properties were evaluated during the storage time. The addition of CEE improved mechanical properties of the films: tensile strength increased fro m 27.7 MPa (control film) to 35.1 MPa (film with 200 g CEE/100 g gelatin) and the elongation at break increased from 22.3 % (control film) to 36.5 % (film with 200 g CEE/100 g gelatin). Water content was not affected by the addition of CEE, however soluble matter reduced compared to control film. The water vapor permeability for added films also reduced on average 24.1 %. Color parameters, opacity and gloss were affected by the incorporation of CEE. Microstructure analysis indicated changes in surface roughness and increase in roughness regarding the internal structure due to the growing concentration of CEE in the films. FTIR analysis showed peaks displacements associated to amides A, I and II for the added films. Films added CEE showed reduced transmittance for the UV/Vis region and increased transparency. The curcumin content increased linearly (y=0.6115x+6.6629, R2=0.9817) with increasing extract concentration. The antioxidant capacity increased was improved with the increase of extract concentration and antimicrobial activity (Staphylococcus aureus) was verified at concentrations above 5g CEE/100g gelatin. Thus, the film with CEE concentration of 200 g CEE/100 g gelatin was used for macadamia nut packaging. Regarding water content in the macadamia nut, significant differences in the first 30 day of storage were found according to the film (with or without CEE). However, no significant difference concerning water activity was found. After 60 days of storage nuts packaged with added film had their hardness increased and lower reactive substances (thiobarbituric acid). It can be concluded that the utilization of this system as active packaging for macadamia nut is possible.

M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology.
Activated carbons have been produced from various carbonaceous source materials including nutshells, peat, wood, coir, lignite, coal and petroleum pitch and the produced carbons have been used for adsorption of inorganic and organic compounds from numerous matrices. Activated carbons are characterized by large surface area and high degree of microporosity. The ability of activated carbon to adsorb gold from solutions, which is present in very low concentrations while loading to fairly high concentrations, has made it an attractive material for the concentration of gold from dilute solutions. Consequently, the use of activated carbons for the recovery of gold from cyanide-leached liquors has gained wide acceptance in the mining industry. However, the price of commercially prepared carbons, the time taken for them to arrive, the breakage of the carbon during transportation and the interest in utilization of various local wastes for the generation of adsorbents has led to a search of more cost effective and time friendly source for the activated carbons. The focus of this research was to conduct a study in which a comparison was conducted between untreated coconut shell derived activated carbon (CAC) and Macadamia nutshell derived activated carbon (MAC) for the adsorption of gold. These activated carbons were modified with HNO3 and H3PO4 to increase their surface adsorption properties. This was done in order to explore if these activated carbons prepared from Macadamia shells could be an attractive alternative or a complementary supplement to the coconut shell based carbons that are currently being used in the gold extraction industry. The modification of the commercially prepared Macadamia activated carbons was done with 3 different concentrations for both nitric acid and phosphoric acid. The modified activated carbons were labelled MACP20%, MACP40% and MACP60%, to signify the materials prepared from 20% (v/v) H3PO4, 40% (v/v) H3PO4 and 60% (v/v) H3PO4 , respectively . Same labelling was used for 20% (v/v) HNO3, 40% (v/v) HNO3 and 55% (v/v) HNO3 modifications to correspond to MACN20%, MACN40% and MACN55%, respectively. Also, untreated coconut shell derived activated carbon (CAC) and Macadamia nutshell derived activated carbon (MAC) were investigated for gold adsorption for comparison purposes. All the activated carbons prepared in the iii | P a g e study were characterized with Brunauer-Emmet-Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Thermo gravimetric analysis (TGA), elemental analysis (EL) and X-ray diffraction spectroscopy (XRD). The physical properties of the activated carbons were done by determining attrition, ash content, volatile matter, and moisture content of all the activated carbons. Various parameters that affect selective adsorption such as the effect of initial concentration, time, agitation speed, interfering species, and dose of the adsorbent were investigated. Optimal parameters for gold ion adsorption were as follows: solution pH, 10; contact time, 6 h; agitation speed 150 rpm; sorbent amount 4 g and 5.5 ppm for initial concentration of gold. The observed selectivity order was not the same for all the adsorbents but the adsorption of gold was found to be mostly influenced by the presence of nickel and least influenced by copper. The MACP60% was found to be the most effective from the three concentrations investigated for the phosphoric acid modified activated carbons yet proved to have lower adsorption capabilities compared to CAC. The MACN55% was found to be the most efficient and displayed similar adsorption capabilities to those of CAC.

Department of Ecology and Resource Management
PhDENV
The main aim of the research was to contribute means for converting conventional, high-input production systems to more sustainable ecological systems, thereby improving the sustainability of macadamia production and ultimately contributing to food security. This was achieved by a) investigating the potential use of cover crops and compost to enhance soil quality in macadamia orchards and b) investigating the potential use of use of cover crops and orchard heterogeneity to control stinkbug pests that target macadamia crops. Field experiments were conducted in three phases: phase one tested the potential of six cover crops for crop protection (as trap crops) and simultaneously for soil restoration or fertility enhancement purposes in macadamia orchards. Phase two repeated the trials of phase one (both soil restoration and trap crops) but with modifications to both categories. Soil restoration treatments were conducted with trees which were growing in what appeared to be healthy soils, and then repeated with trees in the same orchard where the topsoil had been degraded (totally removed) by agricultural operations. The third phase repeated the trap crop trials only, but this time on three different study areas (all commercial farms) with the single cover crop which performed the best as a trap crop during phase two. Trials were modified from the first to the last phase to overcome practical implementation problems encountered along the way and to adapt to local conditions experienced in the commercial macadamia farming systems which served as research sites. Diversity of natural orchard vegetation was enhanced in phase three to improve conditions for natural predators as part of the trap crop treatments in the last phase and cover crops were finally first composted and then returned to the root zones of the macadamia trees as part of the soil quality enhancement treatments in the second phase. The results from the trap crop trials shows a significant effect of trap crops combined with increased orchard diversity in reducing unsound kernel percentages caused by stinkbug pests and demonstrate that trap crops combined with an increase in orchard diversity could be utilized in macadamia orchards as a more sustainable alternative to inorganic pesticides against the stinkbug complex. The most notable changes in the soil that took place with soil quality enhancement treatments were the significant increases in soil phosphorous content and pH which resulted not in an improvement in soil quality in terms of these two indicators but revealed an important issue about the use of compost containing animal manure originating from dairies or feedlots. In summary however, it was clear that although not all the soil quality indicators that were employed to assess changes in the soil with compost treatments improved significantly, a holistic consideration of all indicators portrays an overall improvement which was particularly significant in the degraded soil plots where the topsoil had been removed by prior agricultural activities.
NRF

Thesis (Ph. D.)--Florida State University, 2008.
Advisor: Bahram Arjmandi, Florida State University, College of Human Sciences, Dept. of Nutrition, Food and Exercise Sciences. Title and description from dissertation home page (viewed Oct. 3, 2008). Document formatted into pages; contains xiv, 166 pages. Includes bibliographical references.

The global macadamia nut industry is fast developing at present. South Africa is currently the third largest global producer. There are many contributing factors influencing the increased demand for macadamia nuts. The most important factor would probably be the nutritional value provided by the nuts. It is important for the macadamia nut industry to demonstrate strong leadership in order to ensure that the growers and the industry develop ahead of the markets and retain a competitive edge as the industry develops. In agricultural terms the investment into a macadamia farm is significant.Developing a farm with a long gestation period and high capital input cost requires a significant commitment from a grower. The risk associated with error is potentially very high and may have serious financial repercussions to the growers and their long term sustainability. Strong leadership and innovation practices within the industry should be a continuous improvement process in order to challenge and enhance current practices within the industryand to mitigate risks associated with the industry as a whole. The purpose of this research was to understand the perceptions of growers and the macadamia nut industry regarding the role of leadership and innovative behaviour to support increased growth and sustainability of growers and the industry alike.
Graduate School of Business Leadership
(M.B.A.)

M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology.
Agricultural waste such as Macadamia nutshells are currently receiving more attention for removal of hexavalent chromium (Cr(VI)). However, they have low adsorption capabilities when used in their raw form. In this study, the efficiency of using Macadamia nutshell powder modified with different concentrations of hydrogen peroxide, grafted with 1,5’-diphenylcarbizide (DPC) for the removal of hexavalent chromium from aqueous solution was explored. The effects of various parameters controlling adsorption of Cr(VI) onto Macadamia adsorbents such as initial concentration, contact time, adsorbent concentration and pH were investigated. The optimal operating parameters for Macadamia nutshells treated with hydrogen peroxide (MHP) adsorbents were determined to be 75 mg/L, 3 h, 0.1 g and pH 1. The optimal operating parameters for Macadamia nutshells treated with hydrogen peroxide and grafted with 1,5’-diphenylcarbizide (MHPD) were determined to be 150 mg/L, 1 h, 0.1 g and pH 3. Fourier transform infrared (FTIR) spectroscopy of the adsorbents revealed that treated MHP showed amino groups attached to the adsorbents. Thermogravimetric analysis (TGA) revealed that the grafted material lowered the thermal stability from 180◦C to 300◦C due to volatile nature of DPC. The surface of the MHPD materials was rough due to grafting. The results showed that the 1,5’-diphenylcarbazide treatment improved the removal efficiency of Cr(VI).

PhD (AGR) (Animal Science)
Department of Animal Science
Horticultural by-products such as seed and nut oil residues have the potential to replace conventional protein and energy sources in diets for ruminants. The objective of the study was to evaluate the nutritive value of Macadamia oil cake and Baobab seed cake as nutrient supplements for feedlot animals. Several experiments were carried-out to evaluate the nutritive value of Macadamia oil cake and Baobab seed cake as feed for ruminants. The nutrient composition of the cakes were determined using both proximate and modern methods of analysis of feeds and a t-test was used to compare the means of Macadamia oil cake and Baobab seed cake. The in sacco technique was used to determine the rumen degradability parameters of dry matter, crude protein and Amino acids of the cakes. This experiment was conducted using a completely randomized design. A three step-in vitro technique was used to conduct a post ruminal digestibility trial and the study was arranged in a completely randomized design. An apparent digestibility trial was conducted using metabolism cages and fecal bags to avoid the mixing of urine and faeces and the experiment was carried out as a completely randomized design arranged in a 2 x 2 factorial. A growth trial was conducted using a completely randomized block design arranged in a 2x2 factorial with two protein supplements and two inclusion levels as factors and blocked by sex of the lambs. The two cakes had similar (P>0.05) dry matter, fat, hemicellulose and gross energy contents. Baobab seed cake had significantly (P<0.05) higher ash, crude protein, acid detergent lignin and nitrogen free extract than macadamia oil cake. Macadamia oil cake had significantly (P<0.05) higher crude fiber, acid detergent fiber, neutral detergent fiber and cellulose concentrations. Baobab seed cake had significantly (P<0.05) higher calcium, magnesium, potassium, phosphorus (macroelements), zinc, and copper than macadamia oil cake. Macadamia oil cake was significantly (P<0.05) higher in manganese and iron contents than Baobab seed cake. Sodium content was not significantly (P>0.05) different between the two cakes. Baobab seed cake had more (Tryptophan, Cysteine, Arginine, Aspartic acid, Glutamic acid, Valine, Phenylalanine, Isoleucine, Leucine) Amino acids which were significantly (P<0.05) higher in quantity than macadamia oil cake with the two cakes having similar (P>0.05) remaining Amino acids contents. Generally Macadamia oil cake had more (P<0.05) saturated and mono-unsaturated fatty acids than Baobab seed cake whereas Baobab seed cake had more (P<0.05) poly-unsaturated fatty acids. v The in sacco rumen degradability characteristics of baobab seed cake and macadamia oil cake were estimated for dry matter and crude protein of the cakes. Macadamia oil cake had significantly (P<0.01) higher a value for dry matter than boabab seed cake. Baoaba seed cake had significantly (P<0.01) higher a value for crude protein than macadamia oil cake. the b, c, and a+b values for dry matter of both Baobab seed cake and Macadamia oil cake were not significantly (P>0.05) different form each other. However, the potential degradability (a+b) value for crude protein of baobab seed cake was significantly (P<0.01) higher than that of macadamia oil cake. The b and c constants of the two cakes for crude protein were not significantly (P>0.05) different from each other. The ED (Effective degradability) values calculated at three outflow rates (0.02, 0.05, 0.08) were estimated for dry matter and crude protein of Baobab seed cake and macadamia oil cake. The ED of the two cakes calculated at 0.02 outflow rate did not significantly (P>0.05) differ from each other. However, baobab seed cake had significantly (P<0.05) higher ED value at outflow rate of 0.05 whereas macadamia oil cake had significantly (P<0.05) higher ED value calculated at outflow rate of 0.08. The ED values of baobab seed cake for crude protein calculated at the three outflow rate were significantly (P<0.01) higher than those of macadamia oil cake. The two cakes did not significantly (P>0.05) differ in dry matter ruminal degradability but baobab seed cake had significantly (P<0.05) higher ruminal crude protein disappearance from 16 to 72 hours of incubation than macadamia oil cake. The in situ Amino acid degradation was determined on 0, 12, 16, 24, and 48 hour of ruminal incubation of the cakes’ samples and generally they were significant (P<0.05) differences for both cakes according to different incubation periods. The 3-step in vitro digestibility trial revealed that baobab seed cake had significantly (P<0.05) higher dry matter, crude protein and Amino acids digestibility values than macadamia oil cake. Apparent digestibility study revealed that nutrient intake, faecal and urine outputs, and digestibility of nutrients were not significantly (P>0.05) different between baobab seed cake and macadamia oil cake. However, lambs on 10% macadamia cake having retained significantly (P<0.05) more nitrogen than the lambs on 15% macadamia oil cake, 10% and 15% baobab seed cakes diets. However, the inclusion of either baobab seed cake or macadamia oil cake at 10% or 15% in the diets of lambs did not significantly (P>0.05) affect the DOMR, microbial protein yield and purine derivates output. For the growth trial the lambs were offered four diets formulated to contain 10% MOC (control), 15% MOC, 10 BSC and 15% BSC. The inclusion of 15% MOC and 10% BSC in the diets of lambs did not significantly (P>0.05) affect their final body weight, total weight gain, average daily feed intake, average daily weight gain, warm and cold carcass masses between these two vi groups. The inclusion of 10% MOC and 15% BSC in the diets of lambs did not significantly affect average daily feed intake and animal performance between these two groups. However, lambs on 10% MOC and 15% BSC had significantly (P<0.05) higher average daily feed intake and animal performance compared to lambs on 15% MOC diet. The feed conversion efficiency and of the lambs in the four diets were not significantly (P>0.05) different. The dressing percentage, carcass length, neck weight, fat thickness, body weight thickness and rib eye area of the carcasses of lambs in this trial did not differ significantly (P>0.05) except for spleen and skin with lambs on 10% BSC diets having the least skin weight and lambs on 10% MOC diet having heaver spleens. Generally BSC had higher (P<0.05) nutrient content than MOC. BSC and MOC were highly degradable in the rumen whereas BSC was higly digestible post-ruminally compared to MOC. The diets of fattening lambs formulated to include 10% or 15% of BSC or MOC as protein supplements did not affect the apparent digestibility of the diets. Macadamia oil cake can be incomporated in the diet of finishing lambs as a protein supplement at 10% inclusion level without compromising the growth and carcass characteristics of the lambs. Baobab seed cake as a protein supplement can be included in the diet of finishing lambs at up to 15% inclusion level without deleteriously compromising on the growth and carcass characteristics of the animals. ______________________________________
NRF

PhD (Zoology)
Department of Zoology
Ecosystem services and disservices are important features in agro-ecosystems and both can have relevant economic impacts on farmers. While there has been much research on the value of ecosystem services, especially that of pest control by bats and birds, ecosystem disservices are often overlooked or estimated separately. Both, services and disservices, however, change with landscape and may be supported by natural vegetation. It is hence inevitable to assess them together to uncover their relative value and importance. Habitat loss and fragmentation are major threats to biodiversity and ecosystem services. Agricultural intensification can cause habitat loss and can negatively affect natural ecosystems and their services. However, the removal of natural vegetation can also reduce ecosystem disservices that origin from natural areas. This study focused on the economic trade-off between biocontrol by bats and birds and crop raiding by vervet monkeys in South African macadamia orchards, using vertebrate exclusion experiments. Crop quality and yield were assessed and extrapolated to income values. The study furthermore focused in more detail on the impact of orchard edge habitat and farm management on bats as ecosystem service providers as well as the arthropod community, which can provide both services (pollination, biocontrol) as well as disservices (crop damage). The macadamia industry is highly profitable and plantings are expanding worldwide. South Africa is currently the largest macadamia producer in the world and the study area, Levubu, holds some of the oldest macadamia plantings in the country. The subtropical climate and high annual rainfall make this area an intensively farmed landscape. Levubu lies at the foothills of the Soutpansberg, a centre of biodiversity and patches of natural vegetation wind through orchards of macadamia, avocado, banana and timber. Insect pest pressure is high in the macadamia industry, with several stink bug species (Hemiptera) and two moth species (Lepidoptera) accounting for most of the damage to the crop. Chapter One provides a detailed overlook over the South African macadamia industry, describes the major pest insect species and their impact on the crop and highlights the role of ecosystem services and disservices and the potential importance of remaining natural areas. Over three consecutive seasons, between September 2015 and May 2018, bats, birds and monkeys were excluded, using cages with nets, from a total of 96 macadamia trees. Four treatments were applied (Full, Day, Night, Control) to distinguish between effects of the different functional groups. Exclusions took place at orchard edges with natural or human-modified edge habitat to assess the impact of vicinity to natural vegetation on pest control and crop raiding. Results presented in Chapter Two showed that biocontrol by bats and birds was stronger near natural vegetation and significantly impacted crop quality as well as yield. Effects of bats and birds were still significant at human-modified edges, whereas crop raiding by monkeys is limited to the natural orchard edges. The economic impact analysis shows that the benefits of biocontrol through bats and birds outweighed the income losses due to crop-raiding monkeys. The value of bats and birds was as high as USD 5000 per hectare per year through prevented insect damage and a 60% crop increase. Crop-raiding affected the yield, which dropped by about 26% and resulted in losses of about USD 1500 per hectare. These results highlight the importance of integrating natural areas into agricultural landscapes, even if they incur the risk of being disadvantageous. Farmers need to be made aware of the enormous economic benefits. Effective crop raiding mitigation strategies still need to be researched to avoid negative association with natural areas. These can, however, possibly also limit access for biocntrol agents, like bats and birds and thereby reduce their economic impact. Especially the removal of natural areas or establishment of buffer zones of unpalatable crops between agricultural land and forests is not advisable. Integrative research in agro-ecosystems on trade-offs between a variety of ecosystem services and disservices is necessary in future, rather than assessing them separately. The bat community on macadamia farms was monitored monthly and compared between orchard edges. Stationary bat detectors were placed at each set of exclosures for two consecutive nights a month, automatically recording from sunset to sunrise. Recorded bat calls were identified manually to species level and activity converted to Miller’s activity index, which counts the number of active minutes per species per night. We analysed the activity per feeding guild over season and landscape setting, estimated species richness and diversity (Hill’s numbers) and species turnover between farms, season and landscape setting, using diversity partitioning. The bat community was mostly influenced by seasonality with season turn-over accounting for 21% of total bat diversity (21.25 species). Edge habitat on the other hand only accounted for 5%. We found higher species richness and activity in the high season compared to the low. While there was no difference in diversity in the high season between the two orchard edge types, species diversity at the human-modified edge was lower than in the natural during the low season. Natural habitat might therefore be more important in the low season, while its effect is overwritten by high food availability during the high season. Clutter-edge species furthermore were more active at the natural orchard edges than open-air feeders, which were in turn more active at human-modified edges. Both activities dropped significantly during the low season. Chapter Three concludes that the macadamia landscape is able to support a high bat species diversity, which is affected by seasonal differences, probably due to food availability. Natural areas are important to be maintained to support sensitive species, relying on clutter habitat and natural roosts. Habitat features as well as farm management can also influence arthropod communities. Visual observations took place each month for 20 minutes per tree. Observations were counted and identified to at least order level. Chapter Four concentrates on the impact of orchard edge habitat and insecticide treatment on honey bees (83% of Hymenoptera observations) abundance. Honey bees were the only taxon significantly responding to both variables, with higher abundance close to natural areas and increasing abundance with increasing time since pesticide application. Honey bees furthermore seemed to recover slightly quicker from population crashes after insecticide treatments at natural edges than they did at human-modified edges. Hymenoptera can be highly beneficial to macadamia farmers, as farmers are heavily relying on pollination by honey bees and parasitoids are known to feed on major macadamia pest insect species. These ecosystem service providers were mostly affected by habitat and management practices, which may compromise their ecosystem service provision. Although commercial bee hives are exposed throughout macadamia orchards, they do not appear to fully replace the pollination and biocontrol services provided by feral species, which can be enhanced through resource supplementation by patches of nearby natural vegetation. Chapter Five concludes with emphasizing the general importance of natural vegetation in landscape planning of agricultural areas. This study proved confidently that benefits through ecosystem services largely outweigh negative impacts of ecosystem disservices, both stemming from these natural areas. Through the inclusion, maintenance and restoration of such patches of natural vegetation, farmers can potentially increase the value and effectiveness of biocontrol by bats and birds or other services. Seasonality largely determined bat species diversity, and a general high species diversity was observed in the macadamia landscape, possibly due to a certain degree of landscape heterogeneity and high food availability. Activity patterns of clutter-edge and open-air feeding bats varied with edge habitat, while clutter-dependent bat species
NRF

M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology.
In this study, analytical method for determining the chlorinated phenols in water was developed using High Performance Liquid Chromatography. The following four compounds which are 2, 4, 6- Trichlorophenol (2, 4, 6 TCP), 3-chlorophenol (3CP), 2, 4- Dichlorophenol (2, 4 DCP) and 4-chloro-3-methylphenol (4C3MP) were identified and quantified with a High Performance Liquid Chromatography (HPLC). The validation parameters tested were,: linearity, trueness, precision, detection limit of quantitation, sensitivity, specificity, selectivity. The linear calibration ranges of five standard solution from 1-10 ppm. The linearity ranges between 0.9298-0.9813. The activated carbon based on the waste macadamia nutshell activated carbon (MAC) was investigated for its potential uses as an adsorbent for chlorinated phenols removal and compared with grafted macadamia nutshell activated carbon (GMAC). The adsorbent was characterized with Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM) and thermo gravimetric analysis (TGA). The parameters such as pH, temperature, contact time, concentration and adsorbent were investigated by adsorption technique. The strata C18E has been used before for the same reason and therefore the research was based on mimic the functional group of solid phase extraction (SPE) into macadamia activated carbon (MAC). The functional groups in SPE C18E are benzene and octadecyl. MAC was grafted with strata C18E functional groups to compare its potential with the SPE. The pseudo-first-order and pseudo-second-order kinetic models were applied to verify the experimental data. The pseudo-second order exhibited the best fit for the kinetic studies for MAC adsorption. Chemical removal of chlorinated phenols from wastewater is necessary to reduce harmful products on the environment and human health. Chlorinated phenols have been previously listed as some of the highest priority contaminants and as well as mainly important capability carcinogenic toxins released from chemical plants. Their availability in water supplies was perceived by their bad taste and smell. The acceptable chlorinated phenols concentration in portable water is 1 (mg/l) base on the approval of world health organization. The permanent checking of chlorinated phenols in environmental samples has a greater significance and stresses highly effectiveness, common selectively and great sensitively methods. The maximum uptake of Phenol using weighed mass of MAC was found to be 78 % and for GMAC was 84% for both 2,4,6TCP. t=250 min, pH=5, Co=1mg/l, T = 25 oC and m = 0.3 g/l were the optimum condition for Phenol-MAC system and GMAC system. Over all analysis of equilibrium model analysis indicates the fitness of Langmuir isotherm model to Phenol MAC adsorption system, suggesting a monolayer adsorption of phenol on the surface of MAC. Phenol adsorption capacity of MAC was found to be decreasing with increase in temperature suggesting that the adsorption process was exothermic in nature, which was further supported by the negative values of change in enthalpy. Characterization of MAC and GMAC confirmed the mesoporous texture, highly carbonaceous nature and a higher effective surface area of 912 m2/g. The highest phenol uptake capacity of GMAC was found to be 8.0049 mg/g. The optimal conditions for various process parameters are t = 250 min, pH=5, Co=1mg/l, T = 25 oC and m = 0.3 g/l were the optimum condition for Phenol-GMAC system. Like Phenol-MAC system, the kinetics studies confirmed that Phenol-GMAC adsorption system can be described by pseudo- second-order kinetics model. Equilibrium model analysis indicates the fitness of Langmuir isotherm model to Phenol-MAC adsorption system, suggesting a monolayer adsorption of phenol on the surface of GMAC. Phenol adsorption capacity of GMAC was found to be decreasing with increase in temperature suggesting that the adsorption process was exothermic in nature, which was further supported by the negative values of change in enthalpy. The negative values of Gibb’s free energy suggested that adsorption of phenol onto GMAC was a spontaneous process.

M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology.
Persisting challenges associated with remediation of heavy metals from aqueous media have stirred the need for enhancement of current technologies. Cellulosic agro waste materials (AWM) as well as ion-imprinted polymers (IIP) have received ardent attention from researchers. These materials are often employed in the following industries: water and wastewater treatment, medical, pharmaceutical and packaging. Applications in water and wastewater treatment have gained significant interest due to desirable features they possess. In the case of AWM, these features include a tuneable surface area and poor porosity, basic surface functional groups and chemical stability. Some desired features in IIP include adsorption sites compatible for the ion imprint obtained after leaching with suitable reagents, rigidity and reusability. The efficacy of employing AWM and IIP for the remediation of toxic chromium from aqueous solution was explored. The current study is made up of part A and B. In part A, Macadamia nutshell powder was treated using HNO3, NaOH, as well as Fenton’s reagent. The three materials underwent a new modification which involved reacting treated adsorbents with cetyltrimethylammonium chloride (CTAC), followed by immobilization of 1,5' diphenylcarbazide (DPC) ligand. The adsorbents were ultimately washed, dried and stored for Cr(VI) batch adsorption experiments. Part B involved a synthesis of IIP and their non-imprinted polymer counterpart (NIP) for Cr(VI) sequestration in aqueous solution. This was done by precipitation polymerization of functional monomers, crosslinker and DPC-Cr(VI) complex as a template. Non-imprinted polymers were fashioned in a manner like that of IIP but with the exclusion of Cr(VI) ion template. Characterizations of the adsorbents were done using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and carbon, hydrogen, nitrogen and sulphur (CHNS) analyzer. Batch adsorption experiments were done and parameters such as solution pH, adsorbent dosage, initial Cr(VI) concentration and contact time were optimized. Working solutions were analyzed using ultraviolet-visible (UV-Vis) and atomic absorption (AA) spectroscopy. Adsorption parameters found to be optimum for DPC immobilized cellulosic adsorbents were pH 1.4, adsorbent mass of 0.1 g, 100 mg/L initial concentration and 125 minutes of contact time. The adsorption parameters determined to be optimum for IIP and NIP were pH 2.6, 0.2 g adsorbent mass, 80 mg/L initial concentration and 240 minutes of contact time. Reusability studies demonstrated the potential of adsorbents to remove Cr(VI) ions from aqueous media after successive adsorption-desorption cycles. Selectivity studies indicated that DPC immobilized adsorbents as well as IIP were able to selectively adsorb Cr(VI) ions from aqueous media in the presence of Zn(II), Cu(II), Co(II) and NI(II) ions. Kinetic models revealed that DPC immobilized cellulosic adsorbents and synthetic IIP were most fitting for pseudo-second order and pseudo first order, respectively. On the other hand, adsorption isotherm studies demonstrated that DPC immobilized cellulosic adsorbents and synthetic polymers were best fit for Freundlich and Langmuir adsorption isotherm, respectively.

The current research was done to evaluate the nutritive values and the ruminal degradation of dry matter (DM) and crude protein (CP) from three non-conventional oil cakes, viz: amarula (Sclerocarya birrea) (AOC), macadamia (Integrifolia) (MOC) and baobab (Adansonia digitate L.) (BOC). The oil cakes were collected from biodiesel producers in Limpopo Province, transported to the ARC-Animal Production campus, where proximate and ruminal nutrient degradation analysis were conducted. Triplicates samples from each oil cake were analyzed for the nutritive values, mineral and amino acids contents. Three rumen cannulated mid-lactating (days in milk; DIM: 180±5) Holstein cows weighing 667±43 kg body weight were allocated to determine the in situ ruminal dry matter (DM) and crude protein (CP) degradation. The cows were offered a totally mixed ration (TMR) (60 concentrate: 40 forage ratio) that was compounded according to their daily nutrient requirements, and were milking was done twice per day at 12 hrs intervals. The three oil cake samples were ground using a 2-mm screen after which sub-samples (6.5 g) were put in 10 x 20 cm; 50 μm pore size polyester bags to achieve 15 mg/cm² (ratio of the sample size to surface area). The bags were then fistulated in each cow’s rumen in triplicate for a period of 2, 4, 8, 16, 24, or 48 hrs. After being incubated, the bags were removed from the rumen and washed with cold (4°C) water in 20-L buckets. Following immersing in cold water, the bags were machine washed until clean water was obtained. The bags were then dried at 60 °C in an oven for 48 hrs. The dried bags were individually weighed, and the content of each bag were removed and stored into glass vial until analysis. The remaining two duplicate sets of each sample were rinsed using cold water in order to determine solubility at 0 hrs. The AOC had higher (P<0.05) ether extract (EE) and CP content than both BOC and MOC. Macadamia oilcake (MOC) and BOC had higher (P<0.05) fractions of fibre (NDF, ADF and ADL) compared to the AOC. The AOC had greater (P<0.05) content of essential amino acids than in the BOC and MOC. Additionally, AOC had a high (P<0.05) phosphorus, but low calcium and potassium concentration. While AOC had high effective degradability of DM, it also had high water soluble as well as DM and CP rapidly degradable fractions. Effective degradation of CP was higher in AOC and BOC than in MOC. However, BOC had a high insoluble but degradable fraction of CP. Further work to determine the toxicology of these non-conventional oil cakes and animal feeding experiments is needed
Agriculture and  Animal Health
MSc. Agriculture

MSCAGR (Plant Production)
Department of Plant Production
Poor soil fertility caused by inadequate supply of nutrients on soil is one of the major constraints limiting crop production especially in the Vhembe District Municipality, Limpopo, South Africa. Therefore, management practices such as application of organic manure to minimize soil infertility is considered as good practice for smallholder farmers. This study aimed at evaluating the effect of macadamia husk compost on selected soil properties as well as the growth and yield of Chinese cabbage on sandy loam soil. A field experiment was carried out during 2018 and 2019 winter season at the Agricultural Research Council (ARC) research farm in Levubu. The experiment was laid out in a randomized complete block design (RCBD) with 4 treatments (control (zero)), inorganic fertilizer (100:60:60 NPK Kg ha-1) and compost at 15t ha-1 & 30t ha-1 replicated 3 times. Soil was analyzed before planting and after harvesting to determine the influence of applied compost on selected physical properties (soil bulk density and water holding capacity) and chemical properties (soil pH, soil organic matter, soil organic C, EC, total N, P, K, Ca, Mg, Na, Al, Zn and Mn). Number of leaves, fresh mass, dry mass and leaf area was collected at three harvests interval (28, 46 and 74 days after transplanting). After each harvest period, leaves were analysed for nutrient content (N, P, K, Ca, Mg, Zn, Cu, Mn and B). During the final harvest crops were uprooted and root biomass (fresh mass, dry mass and root length) were recorded. Analysis of variance (ANOVA) were conducted on all data using Genstat package 18th addition. Differences between treatment means were separated using the least significant differences (LSD) procedure and correlations analysis was determined using Pearson’s simple correlation coefficient. Macadamia husk compost application had a significant effect on soil bulk density and water holding capacity. Addition of macadamia husk compost significantly increased soil pH, OC, N, C: N K, P, Mg, Ca, Na, Al, Zn, Ca and Mn. In contrast, addition of macadamia husk compost had no effect on soil EC. Yield components (number of leaves, fresh mass, dry mass), root biomass, root length and leaf area increased with application of macadamia husk compost. Yield components, root biomass, root length and leaf area were significantly affected (p<0.01) by harvesting time. Yield components in the second cropping season was greater than yield components in the first season. Macadamia husk compost application showed no significant effect on leaf nutrient content of Chinese cabbage. However, leaf nutrient content was affected by harvesting time. It is evident from the results of this study that macadamia husk compost affects soil fertility and plant production. The results suggest that macadamia husk compost has a potential to be used as a reliable fertilizer by famers especially smallholder farmers who struggle to buy inorganic fertilizer because they are expensive. Since this study was conducted over two seasons and compost effect tend to be long term, further research is needed on application of macadamia husk compost on soil properties and yield of other crops over wide range of soils.
NRF