Tesi sul tema "Effect of temperature on food crops"
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Phillips, Lisa Elaine. "The effect of low temperature on Salmonella". Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286534.
Testo completoWalden, Ronald Francis. "Influences of supraoptimal root-zone temperature on the medium solution and growth of woody nursery crops". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/39733.
Testo completoJames, Neil Anthony. "Evaluating the effect of temperature on the planktonic food-web". Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.511064.
Testo completoPatana-anake, Pakanat. "The Effect of Temperature, pH, and Food additives on Tomato Product Volatile Levels". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397135614.
Testo completoTyrer, Helen Linsey. "The effect of storage temperature on the measured predicted shelf life of chilled prepared foods". Thesis, Manchester Metropolitan University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266441.
Testo completoBozkurt, Murat. "Effect Of Different Wheat Varieties On Pasta Quality". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614874/index.pdf.
Testo completoesit 1252, Ege 88, Firat 93, Fuatbey 2000, Burgos, Kiziltan 91, Sariç
anak 98, Svevo and Zenith durum wheat varieties were used in this study. Semolina and pasta have been produced in an industrial plant under constant process conditions from these varieties. In general, pasta quality is determined by three main factors, the raw materials, the production recipe and the production process. In this study, the production recipe and the production process were fixed and only durum wheat varieties were variable. So, the effects coming from the production recipe and the production process on pasta quality were eliminated. Physical, chemical and sensory properties of these pasta were determined and the effect of different durum wheat varieties on pasta quality has been investigated to give a clear idea to the Turkish pasta industry about the most commonly grown durum wheat varieties in Turkey, hoping that Turkish pasta in domestic and international Markets will continue to grow with the help of clear understanding about the quality characteristics of the durum wheat they are using. v The important criteria of acceptability of pasta products is its cooking quality and cooking quality of pasta products is of importance to consumers and also to wheat producers, breeders and manufacturers. The pasta samples produced from Svevo, Zenith and Firat 93 varieties got the higher scores than others in pasta cooking quality while those produced from Sariç
anak 98, Ç
esit 1252, Kiziltan 91, and Fuatbey 2000 durum wheat were evaluated as relatively low. The main reasons of cooking quality differences can be interpreted as a result of the difference in protein quantity and quality of the varieties. The bright yellow color of pasta products, rather than cooking behavior taste, is reported to be one of the most important considerations in assessing durum wheat quality. In this study, the pasta samples produced from Svevo, Zenith and Burgos varieties got the higher scores than others in pasta color (yellowness) while that produced from Firat 93 had the lowest yellow color. The main reasons of yellow color differences can be interpreted as a result of the differences in carotenoid pigments, lipoxygenase and peroxidase enzymes contents of the varieties.
Kong, Emily S. "EFFECT OF pH AND TEMPERATURE ON THE BINDING INTERACTIONS OF CAFFEINE AND CHLOROGENIC ACID WITH SODIUM CASEINATE". DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/947.
Testo completoHan, Yafei. "Effect of fruit types and temperature on formation of volatiles in the lipoxygenase (LOX) pathway". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430955718.
Testo completoKabbara, Salam. "EFFECT OF COOKING TIME AND TEMPERATURE ON HARDNESS AND ANTI-NUTRITIONAL FACTORS OF TEPARY BEAN". Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275284.
Testo completoSandhi, Arifin. "ARSENIC REMOVAL BY PHYTOFILTRATION AND SILICON TREATMENT : A POTENTIAL SOLUTION FOR LOWERING ARSENIC CONCENTRATIONS IN FOOD CROPS". Doctoral thesis, KTH, Mark- och vattenteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203995.
Testo completoQC 20170323
Aykas, Didem P. "The Effect of Temperature, Lecithin Content, Voltage, Resistivity, Viscosity, and Surface Tension on Droplets/cm² During Electrostatic Spraying of Oil". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1330588156.
Testo completoAkpolat, Hacer. "The Effect of pH and Temperature on Cabbage Volatiles during Storage". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1427734475.
Testo completoGandy, April Lynne. "THE EFFECT OF PASTEURIZATION TEMPERATURE ON CONSUMER ACCEPTABILITY, SENSORY CHARACTERISTICS, VOLATILE COMPOUND COMPOSITION, AND SHELF-LIFE OF FLUID MILK". MSSTATE, 2007. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07022007-162142/.
Testo completoKim, Lesley Yu-Jung. "Effect of increased temperature and decreased food quality on metabolism and growth of an algivorous cichlid, Tropheus duboisi and effect of food habit on the field metabolism of African Cichlids". Wright State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=wright1409625207.
Testo completoBangcuyo, Ronald G. "Lingual tactile sensitivity: Effect of age, gender, fungiform papillae density, and temperature". The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1436390197.
Testo completoKhan, Md Imran Hossen. "Fundamental understanding of cellular water distribution and transport in plant-based food material during drying". Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/121217/1/Md%20Imran%20Hossen_Khan_Thesis.pdf.
Testo completoSingh, Amandeep. "Effect of temperature/ethanol on the secondary structure of bovine Apo Alpha-Lactalbumin investigated by FTIR/2D IR correlation spectoscropy". Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123309.
Testo completoÉtant donné leur valeur nutritive et leurs multiples propriétés fonctionnelles, les protéines du lactosérum jouent un rôle crucial dans la fabrication de denrées alimentaires. L'α-lactalbumine (α-LA) est la plus abondante protéine parmi celles du lactosérum bovin et la seconde plus abondante protéine parmi celles du lactosérum humain. L'α-LA , une protéine acide (pI 4-5) à faible poids moléculaire (14.2 kDa) produite dans les glandes mammaires, joue un rôle important dans la biosynthèse du lactose. Composés des complexes d' α-LA et d'acide oléique, le BAMLET/HAMLET (bovine/human alpha-lactalbumin made lethal to tumor cells) a démontré des effets cytotoxiques sur les cellules tumorales, tout en laissant les cellules saines indemnes. On rapporte que les complexes de type BAMLET peuvent être préparées en chauffant une solution d'apo (décalcifiée) α-LA bovine dans un tampon de phosphate de sodium à laquelle on ajoute une solution d'acide oléique dissoute dans de l'alcool éthylique. Cependant, la possibilité que la présence d'alcool éthylique facilite la complexation de l'acide oleique acid à l'α-LA en influençant la dénaturation thermique de la protéine n'a pas été évaluée. Dans la présente étude, les effets combinés de l'alcool éthylique et de la température sur la structure secondaire de l'apo α-LA bovine furent examinés par spectrométrie infrarouge à transformée de Fourier opérant à température variable (VT-FTIR) en combinaison avec une autodéconvolution de Fourier (technique d'amélioration de la résolution) et de spectroscopie à corrélation croisée en deux dimensions (2D CCS). À la température de la pièce, une augmentation de la concentration en alcool éthylique d'environ 2.5% à 33% w/v donna lieu à une augmentation des structures en hélices alpha et à feuillets bêta, aux dépends d'hélices et coudes 310. Ces résultats sont conformes à ceux de plusieurs études fluoroscopiques et protéolytiques de l'α-LA préalables, montrant un effet semblable de l'alcool éthylique sur la structure secondaire de l'α-LA. Soumettant l'apo α-LA bovine à un cycle de chauffage-refroidissement entre des extrêmes de 25°C et 95°C, en présence de différentes concentrations d'alcool éthylique, s'avéra modifier la structure secondaire de la protéine. A toutes concentrations d'alcool éthylique, les hélices alpha et 310 de la structure secondaire de l'apo α-LA bovine furent perdues lorsque la protéine fut chauffée. La séquence des altérations de la structure secondaire durant les cycles de chauffage-refroidissement fut suivie par 2D CCS. Les résultats démontrèrent que ce fut seulement en la présence d'une concentration de 20% ou plus d'alcool éthylique que la protéine se replia durant le refroidissement, en suivant une séquence inverse à celle de son dépliement durant le réchauffement. Globalement, la présente étude confirma la dénaturation thermale réversible de l'apo-α-LA bovine comme étant induite par l'alcool éthylique.
Dixon, Mark Geoffrey. "The effect of temperature and photoperiod on the digestive physiology of the South African abalone Haliotis midae". Thesis, Rhodes University, 1992. http://hdl.handle.net/10962/d1005120.
Testo completoParin, Harika. "Effect Of Pretreatment And Air Temperature On The Drying Rate, Rehydration Capacity And Color Of Artichoke". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605458/index.pdf.
Testo completoC using an air inlet velocity of 8.1 m/s. The sample to be dried was pretreated either by keeping it in distilled water or 1% (w/v) ascorbic acid or sodium bisulfite solutions for 30 minutes at the corresponding drying temperatures. Further, for comparison, the use of citric acid solution, increasing the concentrations of the solutions, reducing the pretreatment time, effect of degree of trimming and halving the samples were investigated. The experimental drying rate data were treated to estimate the effective diffusivities and the effect of temperature together with the activation energy according to an Arrhenius type relation. For the product quality, rehydration capacity of the dried samples in water at 20°
C as well as their color were determined. As expected, the rate results indicated an increase in the drying rate hence the effective diffusivity with temperature for the distilled water and ascorbic acid pretreated samples. However, a reduction in the rate at the high drying temperature when sodium bisulfite solution used was attributed to the clogging of the pores by the precipitated solid due to rapid evaporation at the surface. Similarly, rehydration capacity and color of the water treated samples were enhanced with temperature where with the solution treated ones a reverse effect was observed. It is also found that the rehydration data could be well represented by Peleg equation. Further, when citric acid solution was used for pretreatment, the results were quite identical to those of ascorbic acid. Also, increasing the ascorbic acid concentration to 2% (w/v) improved color whereas decreasing the dipping time increased discoloration. Finally, as an important parameter, the degree of trimming of the hearts proved to be highly effective on the rate and the other studied parameters as well as the post harvest and storage time.
Pfunde, Cleopatra Nyaradzo. "Parent characterization of quality protein maize (Zea mays L.) and combining ability for tolerance to drought stress". Thesis, University of Fort Hare, 2012. http://hdl.handle.net/10353/d1007536.
Testo completoShikwambana, Kingsly. "Effect of harvest time, post-harvest storage and ripening temperature on fruit quality of reed avocado cultivar". Thesis, University of Limpopo, 2016. http://hdl.handle.net/10386/2049.
Testo completo‘Reed’ avocado is a late season cultivar introduced to South Africa from California. The cultivar has shown good adaptation and produces quality fruit with export potential. Its pre-harvest adaptation and production aspects have been researched and documented. However, the effect of harvest time, post-harvest storage and ripening temperature has not been comprehensively studied on this newly introduced ‘Reed’ avocado cultivar. Therefore, the aim of this work was to investigate the effect of different harvest time, post-harvest storage and ripening temperature on the quality of late season ‘Reed’ avocado fruit. Matured ‘Reed’ avocado fruit were harvested based on moisture content indexing in December (2015) and January (2016). The experiment was carried out in a factorial, arranged in a completely randomised design (CRD) with three replicates. Treatment factors were: 2 x harvest time (mid-and late), 2 x post-harvest storage (2.0 and 5.5°C), 3 x ripening temperature (16, 21 and 25°C) and 5 x ripening day (0, 2, 4, 6 and 8). Fruit were stored at 2.0 and 5.5°C for 28 days, thereafter, ripened at 16, 21 and 25°C until fully ripe. During ripening, fruit were evaluated for weight loss, skin colour, firmness, respiration rate, physiological and pathological disorders. Mid-harvest fruit had higher moisture content when compared with late harvest fruit. However, harvest time, post-harvest storage, ripening temperature and ripening time (days) significantly influenced fruit weight loss, firmness, respiration rate, ripening percentage of ‘Reed’ avocado fruit during ripening. Moreover, fruit firmness decreased faster at higher temperatures (25 and 21°C) with fruit ripening within 4 and 6 days, respectively. In addition, ripening at a lower temperature (16°C) was slower with fruit fully ripened within 8 days after withdrawal from cold storage at both harvest times. ‘Reed’ avocado fruit respiration rate followed a climacteric pattern, however, significantly higher rate at higher temperature (25°C) when compared with lower temperature (16°C) after withdrawal from cold storage during both harvest times. Interestingly, mid-harvest fruit showed high electrolyte damage after withdrawal from 2.0°C when compared with late harvest fruit at the same temperature. Furthermore, mid-harvest fruit stored at 2.0ºC and ripened at 21°C showed higher chilling injury when compared with fruit ripened at 16 and 25°C. High electrolyte leakage positively correlated (R2 = 0.242) with high chilling damage for xiv mid-harvest fruit stored 5.5°C. Treatment factors had a significant effect (P < 0.05) on lightness (L *) and hue angle (h ) but no significant effect (P > 0.05) on chroma (C *) and eye colour of ‘Reed’ avocado fruit during ripening, irrespective of harvest time. Overall results showed a visual change in ‘Reed’ avocado skin colour, with eye colour changing from green to bright yellow. Furthermore, late harvest fruit showed high post-harvest pathological diseases after removal from high temperature (5.5°C) when compared with mid-harvest fruit stored at low storage temperature (2.0°C). Ripening at a higher temperature (21 and 25°C) resulted in higher incidence of stem-end rot and body rot when compared with lower temperature (16°C) for both harvest times. Late harvest fruit showed a higher incidence of vascular browning at higher ripening temperatures (21 and 25°C) when compared with lower temperature (16°C) after withdrawal from cold storage. Moreover, overall results showed that harvest time, post-harvest storage and the ripening temperature had a profound influence on the quality of ‘Reed’ avocado fruit. In conclusion, ‘Reed’ avocado fruit can be harvested during mid- or late season and stored at recommended low temperature (2.0ºC); and thereafter, ripened at either 16 or 21ºC. In addition, future studies should focus on identifying pre-harvest practices that promote higher post-harvest fruit quality for ‘Reed’ avocado fruit under South African production environment. Keywords: ‘Reed’ avocado fruit; firmness; electrolyte leakage; respiration rate; stem-end rot; body rot; vascular browning
Erwee, Anton. "Development of technology for the production of stable high moisture dried fruit". Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53365.
Testo completoENGLISH ABSTRACT: Dried fruit is a well-known food product that has been produced for many years. The product characteristics have remained constant throughout this time with a moisture content of ca. 18 - 26% (mlm). However, in recent times there has been a definite trend towards a fmal dried fruit product in the intermediate moisture range with a moisture content of ca. 36%. The high water activity (aw) of the product (ca. 0.85) makes the product susceptible to microbiological spoilage and the product therefore requires a subsequent pasteurisation step to ensure a safe product. A further consequence of the increased moisture content, higher aw and the temperature of the pasteurisation step, is the increased rate of non-enzymatic browning reactions. Currently the shelf life is only 15 weeks while a minimum shelf life of 30 weeks is required to enable product export. Moisture sorption isotherms may be used to depict the relationship between moisture content and aw. Moisture sorption isotherms were thus determined for Royal type apricots and nectarines at 25° and 40°C. Samples, equilibrated at relative humidities in the range of 11-97%, were obtained using saturated salt solutions and a static gravimetric method. Isotherms were found to be of type I, typical of dried fruit. Six mathematical models namely; BET, GAB, Iglesias and Chirife, Halsey, Henderson, and Chung and Pfost, were fitted to experimental data. The GAB model predicted the aw of both apricots and nectarines the best at 25° and 40°C with the Henderson equation second best in all instances. The binding energy, as a function of moisture content, was calculated to determine energy requirements for drying. At low moisture contents « 20%) an increase of energy was required for drying. Discolouration of macerated dried Royal type apricots and nectarines during accelerated storage as affected by moisture (32, 36, and 40%, mlm) and sulphur dioxide (S02) content (2500, 3000 and 3300 mg.kg" for apricots; 1800, 2200 and 2600 mg.kg" for nectarines) was investigated. The macerated samples were stored at 30°, 40°, 50° and 60°C. Colour was quantified in terms of the L* value of the CIELab system (used throughout the study). Moisture and S02 contents affected both the initial fruit colour and the rate of discolouration. The highest L* values, i.e. lightest fruit colour, were obtained for fruit at 40% moisture content and the highest S02 levels. Increasing storage temperature accelerated the loss of moisture and S02. The influence of a 10°C increase in storage temperature on the rate of browning and thus shelf life was described in terms of the QIO value. QIO and aw values of apricots ranged from 1.96 - 2.47 and 0.833 - 0.890, respectively, while QIO values of 1.50 - 4.61 and aw values ofO.844 to 0.890 were obtained for nectarines. Discolouration of dried nectarine halves during accelerated storage at 40°C as affected by rehydration method, moisture content, packaging atmosphere and pasteurisation method, was investigated. The fruit halves were rehydrated using three different methods to obtain moisture contents of 36 and 40%, respectively. Dry heat and steam pasteurisation techniques were used to render a microbiologically safe product. Commercial packaging material was used and the atmosphere was modified with CO2 to lower the O2 concentration in the headspace. A two-step rehydration at 45°C, steam pasteurisation at 90°C for 150 minutes and packaging under a high CO2 atmosphere rendered a product with the best colour retention under accelerated storage conditions of 40°C for eight weeks. To confirm the results obtained with accelerated storage at temperatures that the product would normally be retailed at, shelf life tests were also performed at 5° and 25°C. Discolouration of whole dried Royal type apricot and nectarine halves as affected by rehydration method, moisture content, packaging atmosphere and pasteurisation method was investigated. The methodology for rehydrating, pasteurising and packaging the high moisture dried fruit developed in this study was compared against the standard method used by the industry. The new processing method increased shelf life. Samples were stored for a period of 30 weeks and were tested every five weeks to determine CO2 concentration in headspace, colour retention and S02 concentration of the fruit. Both apricots and nectarines achieved a shelf life of 30 weeks at both storage temperatures and an extrapolated shelf life of 89 weeks at 5°C, but only 32 weeks at 25°C.
AFRIKAANSE OPSOMMING: Droë vrugte is 'n welbekende voedselproduk en word reeds vir baie jare vervaardig. Die produkeienskappe het konstant gebly gedurende hierdie tydperk met 'n produkvoginhoud van ca. 18 - 26% (mlm). Daar is egter 'n tendens die afgelope tyd na 'n finale produk in die intermediêre voggebied met 'n voginhoud van ca. 36% en 'n water aktiwiteit (aw) van ca. 0.85. Hierdie verandering in voginhoud en aw maak die produk vatbaar vir mikrobiologiese bederf, en gevolglik word pasteurisasie benodig om dit te preserveer. 'n Verdere gevolg van die verhoogde voginhoud en aw en die hoë temperature van pasteurisasie, is die verhoogde tempo van nieensiematiese verbruiningsreaksies. Huidig is die produk se rakleeftyd 15 weke terwyl 'n minimum van 30 weke benodig word om hierdie produk suksesvol uit te voer. Vogsorpsie-isoterme kan gebruik word om die verwantskap tussen voginhoud en aw uit te beeld. Vogsorpsie-isoterme van Royal tipe applekose en nektariens is gevolglik bepaal by 25° en 40°C. Monsters, geëkwilibreer by relatiewe humiditeite van 11 - 97%, is verkry deur gebruik te maak van versadigde soutoplossings en 'n statiese gravimetriese metode. Tipe I isoterme, wat tipies van droëvrugte is, is verkry. Ses wiskundige modelle naamlik; BET, GAB, Iglesias en Chirife, Halsey, Henderson, en Chung en Pfost, is gepas op die data. Die GAB model het die aw van beide appelkose en nektariens by 25° en 40°C die beste voorspel en die Henderson model die tweede beste in al die gevalle. Die bindingsenergie as 'n funksie van voginhoud is bereken om die energie vereistes van droging te bepaal. By lae voginhoude (<20%) is 'n skerp styging in benodigde energie waargeneem. Die verkleuring van gemaalde gedroogde Royal tipe appelkose en nektariens gedurende versnelde opberging en die invloed van voginhoud (32, 36, en 40%, mlm) en swaweldioksied (S02) konsentrasie (2500, 3000 en 3300 mg.kg' vir appelkose; 1800, 2200 en 2600 mg.kg" vir nektariens) is ondersoek. Die gemaalde monsters is gestoor by 30°, 40°, 50° en 60°C. Kleur is gekwantifiseer in terme van L* waardes van die CIELab sisteem (ook gebruik vir daaropvolgende ondersoeke). Vog en S02 het albei die aanvanklike kleur asook die tempo van verbruining beïnvloed. Die hoogste L* waardes, d.i. die ligste kleur, is verkry vir die monsters met 40% voginhoud en die hoogte S02 vlakke. Verhoogde temperature tydens opberging het aanleiding gegee tot verhoogde verliese van vog en S02. Die invloed van 'n 10°C verhoging in opbergingstemperatuur op die tempo van verbruining en dus rakleeftyd, word beskryf in terme van QIO waardes. QIO en aw waardes van die appelkose het gestrek van 1.96 - 2.47 en 0.833 - 0.890, onderskeidelik, terwyl QIO waardes van 1.50 - 4.61 en aw waardes van 0.844 tot 0.890 verkry is vir die nektariens. Verkleuring van gedroogde nektarien halwes gedurende versnelde opberging by 40°C en die invloed van rehidrasie metode, voginhoud, verpakkingsatmosfeer en pasteurisasiemetode is ondersoek. Die vrughalwes is gerehidreer deur middel van drie metodes om die voginhoud te verhoog tot 36 en 40%, onderskeidelik. Droë hitte en stoompasteurisasie metodes is gebruik om 'n mikrobiologiese veilige produk daar te stel. Kommersiële verpakkingsmateriaal is gebruik en die CO2 konsentrasie van die atmosfeer in die verpakking is verhoog om die invloed daarvan te bepaal. 'n Twee-stap-rehidrasie by 45°C, stoompasteurisasie by 90°C vir 150 minute en 'n hoë C02 atmofeer het aanleiding gegee tot die monster met die beste kleurbehoud tydens versnelde opberging by 40°C vir agt weke. Om die resultate, verkry met die versnelde rakleeftyd studie, te bevestig by temperature waarby die produk normaalweg blootgestel sal word tydens kleinhandel, is 'n rakleeftyd studie uitgevoer by 5° en 25°C. Verkleuring van heel gedroogde Royal tipe appelkoos en nektarien halwes, die invloed van rehidrasie metode, voginhoud, verpakkingsatmosfeer en pasteurisasiemetode is ondersoek. Die metodiek vir die rehidrasie, pasteurisasie en verpakking van hoë vog droëvrugte ontwikkel in hierdie studie, is getoets teen die standaardmetode wat deur die industrie gebruik word. Die nuwe prosesseringsmetode het aanleiding gegee tot 'n langer rakleeftyd. Monsters is opgeberg vir 'n tydperk van 30 weke om die rakleeftyd te bepaal. Die CO2 konsentrasie in die pakkie, kleurbehoud en S02 konsentrasie van die vrugte is elke vyf weke getoets. Beide appelkose en nektariens het 'n rakleeftyd van 30 weke by albei opbergingstemperature behaal, terwyl 'n ekstra-gepoleerde rakleeftyd van 89 weke by 5°C en 32 weke by 25°C behaal is.
Kritzinger, Madeleine. "Evaluation of hot water and hot air heat shock treatments on South African avocados to minimise the occurrence of chilling injury". Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52835.
Testo completoENGLISH ABSTRACT: The South African avocado fruit industry is export driven and the successful storage of fruits for extended periods is, therefore, essential. It was recorded that 7.7 million cartons were exported during the 1995 season. The shipping of the avocados takes approximately 15 days and the fruits are being stored at low temperatures to minimise the possibility of fruits softening. Unfortunately low temperature storage results in chilling injury. A possible method to increase avocado resistance to chilling injury is to administer a heat shock treatment. In this way the fruits are protected from chilling injury by inducing the formation of so-called heat-shock proteins which render the cell membranes more resistant to chilling injury. The objective of this study was to evaluate different heat shock treatment protocols as a method of preventing or minimising chilling injury and to extend the shelf-life of avocado fruits while exporting at the lowest possible temperature. Examining the effect of different temperatures and exposure times on the quality of the different avocado cultivars pursued this. The exterior chilling injury on each fruit was quantified and the firmness and internal quality parameters evaluated. A total of 32 Experimental Studies were conducted. The results showed that the Hot Water Heat shock Treatment (HWHST) worked effectively for the South African 'Fuerte' cultivar between 40° and 42°C for exposure times of between 20 and 30 min. The 'Edranol' cultivar also showed promising results between 40° and 42°C for exposure time of between 8 and 22 min. The HWHST was not effective on the South African 'Hass' cultivar. The 'Ryan' cultivar with its thick skin made this cultivar less susceptible to chilling injury and therefore HWHST would be unnecessary. The 'Pinkerton' cultivar had a lot of factors that influenced the results. Therefore, more research needed to be done on the 'Pinkerton' cultivar, before any conclusions could be obtained from this cultivar, although it showed potential. Hot air treatment worked fairly well, but unfortunately the long exposure time needed made this treatment unpractical. Throughout the whole study the importance of maturity surfaced as a major role in all the aspects of post harvest quality.
AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse avokado vrugtebedryf is hoofsaaklik gerig op die uitvoermark en daarom is dit belangrik dat die vrugte vir 'n bepaalde tyd suksesvolopgeberg kan word. Die sensus opname gedurende die 1995 seisoen het getoon dat 7.7 miljoen bokse avokados uitgevoer is. Die avokados word vir ongeveer 15 dae per boot vervoer, wat kan lei tot vrugte wat sag word. Om dit te verhoed, word die vrugte by lae temperature opgeberg. Ongelukkig veroorsaak lae opbergingstemperature koueskade. 'n Moontlike metode om avokados te beskerm teen lae temperature en koueskade te verminder, is om 'n hitteskok behandeling toe te pas. Op hierdie manier word die vrugte beskerm teen koueskade deur die vorming van sogenaamde hitteskok proteïene wat die selwande meer bestand maak teen koueskade. Die doel van hierdie studie was om die verskillende hitteskok behandelings protokols te evalueer as 'n metode van beskerming of vermindering van koueskade en om sodoende die rakleeftyd van avocados te verleng as die vrugte by lae temperature uitgevoer word. Eksperimente is uitgevoer om die effek van verskillende temperature en blootstellingstye op die kwaliteit van die verskillende avokado kultivars te bepaal. Die koueskade op die oppervlakte van elke vrug is bepaal en die fermheid en interne kwaliteit parameters is geëvalueer. In totaal is daar altesaam 32 Eksperimentele Studies gedoen. Die resultate het gewys dat die Warm Water Hitteskok Behandeling (WWHB) effektief was op die Suid-Afrikaanse 'Fuerte' kultivar by temperature tussen 40° en 42°C en by blootstellingstye van tussen 20 en 30 min. Belowende resultate is ook met die 'Edranol' kultivar by temperature tussen 40° en 42°C met blootstellingtye van tussen 8 en 22 min behaal. Die WWHB was oneffektief vir die Suid-Afrikaanse 'Hass' kultivar. Die 'Ryan' kultivar se dik skil het hierdie kultivar minder vatbaar gemaak vir koueskade en daarom was 'n WWHB onnodig gewees. By die 'Pinkerton' kultivar kon daar nog nie 'n gevolgtrekking gemaak word nie, aangesien daar nog baie faktore is wat ondersoek moet word, alhoewel die kultivar baie potentiaal getoon het. Warm lug behandeling het potensiaal gehad, maar die lang blootstellingstye het hierdie behandeling onprakties gemaak. Gedurende die hele studie is daar klem gelê op die rypheisgraad van die vrugte wat na vore gekom het as 'n belangrike faktor wat 'n hoofrol speel in al die aspekte van die na-oes kwaliteit.
Milham, Paul J. "The behaviour of cadmium in soil". Thesis, View thesis, 2008. http://handle.uws.edu.au:8081/1959.7/39519.
Testo completoLinton, Richard Howard. "Use of the Gompertz equation to model non-linear survival curves and predict temperature, pH, and sodium chloride effects for Listeria monocytogenes Scott A". Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-164544/.
Testo completoBotha, Sune St Clair. "The effects of hot-deboning on the physical quality characteristics of ostrich (Struthio camelus) Muscularis gastrocnemius, pars interna and Muscularis iliofibularis". Thesis, Stellenbosch : University of Stellenbosch, 2005. http://hdl.handle.net/10019.1/1513.
Testo completoThe aim of this study was to investigate the effects of hot-deboning (1 h post-mortem) on the shelf-life and the physical meat quality characteristics, including tenderness, pH, purge (%), cooking loss (%), and raw meat colour of vacuum packed ostrich (Struthio camelus var. domesticus) meat cuts from the M. gastrocnemius, pars interna and the M. iliofibularis during post-mortem refrigerated aging for respectively 21 d at 4ºC and 42 d at -3º to 0ºC.
Di-tanno, Marilisa Flavia Pereira. "Influência da tempertura, tempo e concentração de pectinase na textura, rendimento e características físico-químicas da mandioca (Manihot esculenta C.) durante fermentação". Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/11/11141/tde-03072002-174015/.
Testo completo"Retting" is a natural fermentation of cassava roots for the production of puba, a traditional food in the North and Northeast of Brazil. Besides the lactic fermentation, the combined action of the endogenous pectin-methyl-esterase and depolymeryzyng enzymes, causes a softening of the roots which is important for its complete disintegration. However, the recognition of the end point of fermentation and the conditions that lead to good quality puba are not completely understood. The objective of this work was to study the influence of the temperature and enzyme concentration on the yield and texture, aiming at associating these parameters to detect the end point of fermentation. The physicochemical properties of the puba flour were also determined. About 1Kg of peeled roots and 2 liters of water were placed in plastic containers. One or two milliliters of commercial pectinase from Aspergillus aculeatus were added / Kg root, in separate treatments. In the control treatment no enzyme was added. Samples were incubated at 25, 30 and 35ºC and portions removed after 48, 72 and 96 hours for the determination of pH, texture, yield and dry matter. Fibers, starch, total soluble sugars and amylose were determined in the flour of the dried puba. The highest yield of 77% was obtained after 72 hours for the treatment at 25ºC with 2mL of enzyme/kg of root, when the texture values decreased from 18.62lbf/g (raw material) to 3.92lbf/g (retted root). A high yield of 75.7% was also observed in same period, for the natural fermentation at 35ºC, when texture values of 2.50lbf/g were reached. The relation between texture and yield was significant for a temperature of 30ºC and a period of 72 hours. The association between the texture and yield data suggests that when the texture reaches values of the order of 4lbf/g, the yields are higher, indicating the end of the process. The yields were lower when texture values were close to 2.30lbf/g, usually achieved for long fermentations and higher enzyme concentrations.
Makambila, Casimir. "Etude de l'anthracnose du manioc (manihot esculenta crantz) et son agent pathogene colletotrichum gloeosporioides penz f. Sp. Manihotis henn". Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF2E385.
Testo completoMbande, Sekiwe. "Fishes in the Mngazi and Mngazana estuaries, with particular emphasis on the community structure and primary carbon sources". Thesis, Rhodes University, 2004. http://hdl.handle.net/10962/d1005386.
Testo completoSigrist, José Maria Monteiro. "Estudos fisiológicos e tecnológicos de couve-flor e rúcula minimamente processadas". Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-03042003-155537/.
Testo completoThis work aimed at evaluating the effects of temperature on the metabolism of minimally processed and intact cauliflowers and salad rockets, and of different packaging materials on the quality of cauliflower florets and loose salad rocket minimally processed leaves. In the first experiment, intact cauliflowers, florets, intact salad rockets and loose salad rocket leaves were held at 1º, 5º and 11ºC and their respiration rates, ethylene production and temperature quotients (Q10) determined. In the second experiment, the florets were packed in low density polyethylene film (PEBD), co-extruded polyolefins (PD 941 and Clysar AFG) and in 12 and 20 mm polyvinyl chloride (PVC) overwrapping expanded polystyrene trays, and maintained at 5ºC/85-95% relative humidity for 14 days. In the third experiment, loose salad rocket leaves were held under the same conditions in bags of low density polyethylene film (PEBD), laminated polypropylene/polyethylene film (PP/PE), co-extruded polyolefins, PD 900 and Clysar HP and in expanded polystyrene trays overwrapped with 20 mm polyvinyl chloride (PVC). In the second and third experiments, physical, chemical, physical-chemical, microbiological and sensory analyses were performed. The respiration rates of both intact and fresh-cut cauliflowers declined over the 16-day period and were significantly the same at all temperatures studied. At 1º and 5ºC the respiration rates were the same but differed from those (cauliflower and florets) at 11ºC. From 1º to 11ºC, the Q10 for the cauliflowers was 2.2 and for the florets, 2.1. In contrast, the intact and fresh-cut salad rocket respiration rates were the same at 1º and 5ºC. At 11ºC, the fresh-cut salad rocket showed higher respiration rates than the intact ones as from the 4 th day. By the end of the experiment (14 th and 16 th days) the respiration rates of the fresh-cut salad rockets were twice those of the intact salad rockets, whose Q10 was about 3.45 from 1° to 11°C as compared to 5.74 for the fresh cut product. No ethylene production was detected by any sample at any temperature. The packaging materials had little or no effect on pH, titratable acidity, soluble solids, luminosity, chroma, hue and firmness of the florets at 5ºC. PD 941 seemed to be the best packaging for florets, maintaining the atmosphere closest to that recommended for intact cauliflower (2-3%O2, CO2 < 5%), showing the lowest vitamin C losses and the best scores for several of the quality attributes. In general, all the packaging materials kept the yeast and mold counts low and the total coliform counts far below the maximum values permitted by the Brazilian Legislation, during 14 days at 5ºC, except for fresh-cut salad rocket leaves, which presented 10 5 CFU/g total coliforms by the 10 th day, being inappropriate for consumption. For 10 day periods, PEBD and PP/PE were the best packaging materials for green color and vitamin C retention, higher soluble solids, firmness, lack of off-odors, overall quality, decay and shriveling. The modified atmosphere generated inside these packaging materials (5-7% O2, 10-15% CO2) seemed the best for maintaining the quality of fresh-cut salad rockets held at 5ºC.
Nevhulaudzi, Thalukanyo. "Interactive effects of Bacillus subtilis and elevated temperature on germination, growth and grain quality of cowpea irrigated with acid mine drainage". Diss., 2019. http://hdl.handle.net/10500/26149.
Testo completoEnvironmental Sciences
M. Sc. (Environmental Sciences)
Chandler, Robert Edward. "The effect of temperature and water activity on microbial growth rate and food spoilage". Thesis, 1988. https://eprints.utas.edu.au/18938/1/whole_ChandlerRobertEdward1988_thesis.pdf.
Testo completoNgomane, Dambuza. "Moderation of growth and sucrose flux in sugarcane by temperature". Thesis, 2005. http://hdl.handle.net/10413/4490.
Testo completoThesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
KILLI, HAWORTH DILEK. "The responses of crop and tree species to future elevated [CO2], temperature and drought stress". Doctoral thesis, 2017. http://hdl.handle.net/2158/1081327.
Testo completoKhoo, Khar Yean. "Predictive modelling and experimental studies of thermal inactivation of bacteria as affected by combined temperature and pH in liquid". Thesis, 2006. http://hdl.handle.net/2440/37994.
Testo completoThesis (Ph.D.)--School of Chemical Engineering, 2006.
Khoo, Khar Yean. "Predictive modelling and experimental studies of thermal inactivation of bacteria as affected by combined temperature and pH in liquid". 2006. http://hdl.handle.net/2440/37994.
Testo completoThesis (Ph.D.)--School of Chemical Engineering, 2006.
Lin, Chi-An, e 林祈安. "Effect of novel MAP on inhibiting microbial growth in Chinese ready-to-eat food products at ambient temperature". Thesis, 2001. http://ndltd.ncl.edu.tw/handle/80552050692442036355.
Testo completo輔仁大學
食品營養學系
89
Ready-to-eat products stored at ambient temperature (25oC or up) were studied in this study, and the inhibitory effect on microbial growth and the retention of quality by modified atmosphere packaging (MAP) were investigated. MAP model system was constructed to assess the inhibitory effect on microbial growth at ambient temperature, and the effectiveness associated with ethanol or limonene was also achieved. Subsequently, the modified atmosphere environment was applied to ready-to-eat food. More than 200 colonies were observed from the control stored at 37℃, 48hr in the model study; however, less microbial growth was noticed under 30-40% CO2 environment. MAP (CO2:O2:N2=30:5:65) incorporated with ethanol vapor functioned inhibiting E. coli growth, and the effectiveness related to the amount of ethanol vapor. Sushi packed under modified atmosphere containing 0.05% ethanol vapor was found no increase in cell number after 2 days, either at 18 or 25oC. Use of limonene associated with MA also performed inhibiting microbial growth; however the efficiency was not as good as ethanol vapor. In the study of noodle salad, cells were found increasing sharply in all packaged products at 25oC after 24hr. Apparently, MA incorporated with ethanol vapor is effective on inhibiting microbial growth in certain ready-to-eat food stored at ambient temperature, thus the extension of shelf life is achieved.
MacPherson, Margaret Jeanette. "Effect of Salinity, Photoperiod, Temperature, and Restricted Food Intake on Growth and Incidence of Sexual Maturation of Labrador Arctic charr (Salvelinus alpinus)". 2012. http://hdl.handle.net/10222/15524.
Testo completoKumari, Savitri. "Effect of Temperature and Storage on Free and Encapsulated Lactobacillus Acidophilus NCIM 2660 and Lactobacillus Bulgaricus NCIM 2056 in Different Food Matrix". Thesis, 2015. http://ethesis.nitrkl.ac.in/7269/1/2015_Effect_Kumari.pdf.
Testo completoBally, Ian S. E. "The effect of preharvest nutrition and crop load on fruit quality and postharvest disease in mango (mangifera indica l.)". Thesis, 2007. http://era.daf.qld.gov.au/id/eprint/7956/.
Testo completoBeaupre, Steven John. "The effect of ambient temperature, food type, and meal size on post-feeding oxygen consumption and specific dynamic action in captive Dipsosaurus dorsalis". 1987. http://catalog.hathitrust.org/api/volumes/oclc/16919370.html.
Testo completoTypescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 29-38).
Yadav, Rina. "Effect of Encapsulation on Survival of Lactobacillus Fermentum NCIM 2156 and Lactobacillus Plantarum NCIM 2083 under Temperature Stress and Storage in Food Matrix". Thesis, 2015. http://ethesis.nitrkl.ac.in/7242/1/2015_Effect_Yadav.pdf.
Testo completoMilham, Paul J., University of Western Sydney, College of Health and Science e Centre for Plant and Food Science. "The behaviour of cadmium in soil". 2008. http://handle.uws.edu.au:8081/1959.7/39519.
Testo completoDoctor of Philosophy (PhD)
Vilakazi, Busisiwe. "The effect of water stress and storage conditions on seed quality of chickpea genotypes characterized by differences in seed size and coat colour". Diss., 2018. http://hdl.handle.net/11602/1086.
Testo completoDepartment of Plant Production
Chickpea (Cicer arietinum L.) is an excellent utilizer of residual soil moisture in agricultural ecosystems. However, its seed quality and hence reproduction is constrained by water stress, seed size and storage conditions. This study was carried out at the University of KwaZulu- Natal (UKZN), Pietermaritzburg Campus. It was conducted to evaluate the performance of chickpea genotypes (Desi-K, Saina-K and ICCV-K) with different seed sizes on seedling emergence (i), seed ageing effect on seed quality and imbibition of genotypes produced under water stressed and non-stressed conditions (ii), and (iii) the effect of water stress during seed development on sugars and protein accumulation, germination and seed vigour. Pot experiments were conducted under glasshouse / tunnel conditions at the Controlled Environment Facilities (CEF). The experiment for objective 1 was laid out as a single factor in completely randomized design (CRD). Data on emergence rate, final hypocotyl and complete emergence was collected. The small seeded Desi-K showed higher and faster emergence compared to medium sized Saina-K and large seeded ICCV-K. In the experiment of the second objective, seeds of the three genotypes were first obtained by production under water stressed and non-stressed growing conditions. They were then aged for 0, 1, 3, 5, or 7 days at 41 ºC and 100% relative humidity to form a 2 x 3 x 5 (water levels x genotypes x ageing) factorial design. Data was collected on germination percentage (GP), mean germination time (MGT), electrical conductivity (EC), tetrazolium chloride test (TZ) and imbibition weight. Seed ageing caused progressive loss of seed viability and vigour in all genotypes, which resulted in lower GP, delayed MGT, reduced TZ staining, cell death and high solute leakage from the seeds produced under the two water regimes. However, the effect was more severe under water stressed conditions. In the experiment for objective 3, seeds of all three genotypes were larger when grown under non-stressed condition compared to those under water stressed condition. These larger seeds had higher seed viability and germination percentage but lower electrical conductivity and mean germination time. Stressed seeds had higher soluble sugars than non-stressed seeds. It was deduced that irrigation during seed development reduces the final sugars and protein content but increases the seed size and physiological quality parameters allied to production of chickpea. Therefore, water provision to chickpea crop is critical during seed development.
NRF
Ryalls, James M. "The impacts of climate change and belowground herbivory on aphids via primary metabolites". Thesis, 2016. http://hdl.handle.net/1959.7/uws:37585.
Testo completoLosee, James P. "Trophically transmitted parasites as ecosystem indicators : relationships among parasite community structure, juvenile salmon diet composition, and ocean conditions". Thesis, 2012. http://hdl.handle.net/1957/29897.
Testo completoGraduation date: 2012