Dissertationen: „Starch“

1

Jiang, Hongxin. „Resistant-starch formation in high-amylose maize starch“. [Ames, Iowa : Iowa State University], 2010. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3403807.

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2

Thorburn, Patricia Jane. „Effect of non-starch hydrocolloids on starch processing“. Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423624.

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3

Hardy, Jeffrey J. E. „Starch, and modified starches as support materials and catalysts“. Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341483.

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4

Simpson, David Bradley Brook. „Starch 1500“. Thesis, University of Bath, 2000. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760736.

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5

Song, Delong. „Starch crosslinking for cellulose fiber modification and starch nanoparticle formation“. Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39524.

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As a low cost natural polymer, starch is widely used in paper, food, adhesive, and many other industries. In order to improve the performance of starch, crosslinking is often conducted either in the processes of starch modification or during the application processes. Many crosslinkers have been developed in the past for crosslinking starch. Ammonium zirconium carbonate (AZC) is one of the common crosslinkers for crosslinking starch in aqueous solutions, having been widely used as a starch crosslinking agent in paper surface coating for more than 20 years. However, the mechanisms of starch crosslinking with AZC have not been well studied. In order to optimize the crosslinking chemistry of starch and find new paths for the utilization of starch in papermaking, a better understanding of the starch crosslinking mechanism is necessary. This thesis focuses on the fundamental study of starch crosslinking in an aqueous solution and its applications in fiber surface grafting, filler modification, and starch nanoparticle formation. Particularly, the thesis contains three major parts: (1) Mechanism study of starch crosslinking induced by AZC: In this thesis, the crosslinking (or gelation) kinetics of starch/AZC blends were investigated by using rheological measurements. The evolution of viscoelastic properties of AZC solutions and the AZC-starch blends was characterized. It was found that for both AZC self-crosslinking and AZC-starch co-crosslinking, the initial bond formation rate and the gel strength had a strong power law relationship with the concentrations of both AZC and starch. It is suggested that the development of the crosslinking network is highly dependent on the AZC concentration, while the starch concentration effect is less significant. It was determined that the activation energy of AZC self-crosslinking was approximately 145-151 kJ/mol, while the activation energy of AZC-starch co-crosslinking was 139 kJ/mol. (2) Fiber and filler modifications with starch and crosslinkers: Besides reacting with starch, AZC can react with cellulose which also contains hydroxyl groups. Theoretically, it is possible to use AZC as a crosslinker / coupling agent to graft starch onto cellulose fibers. It is believed that the grafted starch on fiber surfaces can improve the fiber bonding capability. In this thesis, a facile method to graft starch onto cellulose fiber surfaces through the hydrogen bond formation among cellulose, starch and AZC was developed. Compared with the paper sheets made of fibers with an industry refining level (420 ml CSF), the paper sheets made of fibers with a much lower refining degree but with grafted starch showed higher paper strengths, including the tensile strength, stiffness and z direction tensile; meanwhile, a faster drainage rate during web formation could also be achieved. Not only can the fiber-fiber bonding be improved by grafting starch onto fiber surfaces, but the filler-fiber bonding can also be improved if starch can be effectively coated on the filler surface. This concept has been supported by the early studies. In this thesis, the effects of the crosslinking of starch in the filler modification for the papermaking application were also studied. (3) Mechanism of starch nanoparticle formation during extrusion with crosslinkers: It was reported that starch crosslinking could facilitate the reduction of starch particle size during reactive extrusion. However, the mechanism of the particle size reduction by starch crosslinking was not illustrated. The reason that the crosslinking can cause the particle size reduction of starch during extrusion is fundamentally interesting. In this thesis, the mechanism of starch particle size reduction during extrusion with and without crosslinkers was investigated by identifying the contributions of thermal and mechanical effects. The effects of extrusion conditions, including temperature, screw speed, torque, starch water content and crosslinker addition, on the particle size were studied. It was found that the addition of crosslinkers could significantly increase the shear force (torque), and consequently facilitate the reduction of the particle size. The results indicate that for extrusion without a crosslinker, the starch particle size decreased with the increase of temperature. At 100 degree Celsius, the starch particles with a size of 300 nm could be obtained. With the addition of appropriate crosslinkers (glyoxal), the starch particle size could be reduced to around 160 nm, even at a lower extrusion temperature of 75 degree Celsius .

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6

BenBrahim, Andrea. „Characterisation of starch and starch-poly #epsilon#-caprolactone biocompostable composites“. Thesis, University of York, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273819.

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7

Song, Lin. „Chemical Modification of Starch and Preparation of Starch-Based Nanocomposites“. University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1275581955.

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8

Kant, Avinash. „Starch-aroma interactions“. Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403302.

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9

Kaidaniuk, Denys. „Starch bioplastic production“. Thesis, National Aviation University, 2021. https://er.nau.edu.ua/handle/NAU/50627.

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1. Tang H., Ando H., Watanabe K. et al. Fine structures of amylose and amylopectin from large, medium and small waxy barley starch granules. Cereal Chemistry. 2001. Vol. 78. P. 111–115.
Plastic production is a necessity for humanity today. It is impossible to imagine an industry without it, whether it is the production of children's toys or the production of test tubes. However, the issue of environmental pollution is growing in direct proportion to the increase in plastic production. For example, mankind has created about 380 tons of plastic in 2018, of which only a small part was disposed of. Therefore, the issue of alternatives to plastics that are tolerant of the environment and human health is only gaining momentum. The main task of this work is to create a viable bioplastic from starch that can compete in the market with the usual sample. In fact, starch has long been used in this industry, this polysaccharide is a successful raw material for plastic production due to its properties, which are provided by its components: amylase and amylopectin, amylase in turn responsible for stickiness and water absorption, and amylopectin for strength. Виробництво пластику - це необхідність для людства сьогодні. Неможливо уявити собі індустрію без нього, незалежно від того, чи є це виробництво дитячих іграшок чи виробництво пробірок. Однак питання забруднення навколишнього середовища зростає прямо пропорційно збільшенню виробництва пластмас. Наприклад, людство виробило близько 380 тонн пластмаси у 2018 році, з якої була використана лише невелика частина. Тому питання альтернатив пластмас, які є толерантними до навколишнього середовища та здоров'я людини, отримує лише імпульс. Основним завданням цієї роботи є створення стійкого біопластику з крохмалю, який може конкурувати на ринку зі звичайним зразком. Фактично, крохмаль давно використовується в цій галузі, цей полісахарид є успішною сировиною для виробництва пластмас завдяки своїм властивостям, які забезпечуються його компонентами: амілаза та амілопектин, амілаза, яка відповідає за липкість та поглинання води, а також амілопектин для міцності.

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10

Cunin, Dalvand Catherine. „Investigations on starch and starch-emulsifier interactions in durum wheat pasta /“. [S.l.] : [s.n.], 1995. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=11389.

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11

Lengstrand, Anna. „Molecular Characterizing of Starch and Starch Based Materials in Food Packaging“. Thesis, University of Kalmar, School of Pure and Applied Natural Sciences, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-2949.

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12

Mira, Isabel. „Interactions between surfactants and starch : from starch granules to amylose solutions“. Doctoral thesis, Stockholm : Chemical Science and Engieering, KTH : Ytkemiska institutet, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4123.

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13

Clarke, Belinda. „The rate of starch synthesis as a determinant of starch composition“. Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267540.

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14

Martinet, Cecile. „Ageing of starch and starch-sugar systems in the glassy state“. Thesis, University of Nottingham, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342043.

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15

Andersson, Lena. „Studies on starch structure and the differential properties of starch branching enzymes /“. Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 2001. http://epsilon.slu.se/avh/2001/91-576-5834-X.pdf.

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16

Svensson, Erik. „Crystalline properties of starch“. Lund : Lund University, 1996. http://books.google.com/books?id=VOdqAAAAMAAJ.

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17

Prentice, Robert D. M. „Studies on barley starch“. Thesis, Heriot-Watt University, 1991. http://hdl.handle.net/10399/866.

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18

Entwistle, Tina Gail. „Synthesis of storage starch“. Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316826.

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19

Van, der Merwe Belinda. „Maize porridge starch digestibility“. Diss., University of Pretoria, 1999. http://hdl.handle.net/2263/23282.

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20

Alvani, Kamran. „Amylolysis of potato starch“. Thesis, Glasgow Caledonian University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493923.

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Hydrolysis of native starch by α-amylase is a complicated process which is highly affected by compositional and architectural properties of starch granules that affect accessibility of enzymes to the interior of the granule. In view of the paucity of knowledge in this area regarding the control of amylolysis, the following study was undertaken using different potato starches (grown under the same conditions). The focus was to understand how cultivar specific variation regulated hydrolysis with a-amylase. The composition of the starches was determined using classical chemistry techniques while structural aspects were determined by specific physical techniques including differential scanning calorimetry (DSC), particle sizing (Coulter conter), high performance size exclusion chromatography (HPSEC) and nuclear magnetic resonance (NMR). Different amylase enzymes were employed (fungal and pancreatic) and possible inhibition of activity of the enzymes was studied.

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21

Moura, Ricardo Acioli. „The effect of physical aging, starch particle size, and starch oxidation on thermal-mechanical properties of poly(lactic acid)/starch composites“. Diss., Manhattan, Kan. : Kansas State University, 2006. http://hdl.handle.net/2097/169.

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22

Lin, Qiaohui. „Study on the regulatory function of starch synthase III in maize starch metabolism“. [Ames, Iowa : Iowa State University], 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1472094.

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23

Nath, de Oliveira Daniela. „Thermal properties of starch from transgenic isolines of wheat differing in starch surface components“. Thesis, Kansas State University, 2010. http://hdl.handle.net/2097/4319.

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Master of Science
Department of Grain Science and Industry
Jon M. Faubion
Endosperm texture is an important characteristic in determining wheat processing and end-use. The presence of puroindoline proteins on the starch surface is the biochemical marker for wheat hardness. Near-isogenic samples over expressing puroindolines have been used to assess the effect of wheat hardness on final product characteristics. The objective of this study was to determine differences among starch isolated from near-isogenic samples and to investigate the role starch surface components play in pasting. The use of near-isogenic samples over expressing puroindolines combined with the use of two methods of starch isolation (batter and dough) was an effective means to create samples with varied amounts of surface components. Starch thermal properties were characterized and surface proteins and lipids were quantified. Starch isolated from hard wheat cultivars presented more similarities with starch isolated from its soft near-isogenic line when a dough method was used than when a batter method was used. Starch from soft experimental lines isolated using a batter method showed increased MVA peak viscosity, breakdown and swelling power. Increased levels of LysoPC in starch isolated from hard wheat cultivars or soft experimental lines by dough method could have complexed with amylose and restricted granule swelling. Thereby, decreasing peak viscosity, breakdown and swelling power.

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24

Grewal, Navneet Kaur. „Structural changes induced in waxy maize starch and normal wheat starch by maltogenic amylases“. Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/18145.

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Master of Science
Department of Grain Science and Industry
Yong Cheng Shi
Maltogenic amylases are widely being used as an antistaling agent in baking industry. However, their action on starch in granular, swelled and dispersed forms, important components formed during bread baking, is largely unknown. Actions of two maltogenic amylases- A and -B on waxy maize starch (WMS) (100% amylopectin) and normal wheat starch (NWS) (~25% amylose) were studied and compared. For any given starch type, starch form, and hydrolysis time, maltogenic amylase-B hydrolyzed both starches more than maltogenic amylase-A as seen through sugar profile analysis indicating its higher degree of multiple attack action (DMA). Their action on non reducing ends blocked compound, p nitrophenol maltoheptaoside, confirmed their endo action. Maltogenic amylase-B showed a higher endo to total enzyme activity ratio than maltogenic amylase-A at any given enzyme weight. Greater MW reduction of dispersed starches by maltogenic amylase-B indicates its higher level of inner chain attack (LICA). Interestingly, MW distributions profiles of swelled starch hydrolysates did not show significant differences irrespective of swelling temperatures. Both enzymes showed differences in oligosaccharides compositions in dispersed and swelled starches’ reaction mixtures with sugars of degree of polymerization (DP) > 2 being degraded to glucose and maltose during later stages. For granular starches, enzymes followed a random pattern of formation and degradation of sugars with DP >2. MW distributions of hydrolyzed granular starches did not show significant shift until at the end of 24h when a low MW peak was observed. Morphological study of granular starches showed that maltogenic amylase-A mainly caused pinholes on WMS while maltogenic amylase-B caused surface corrosion with fewer pinholes. For NWS, both enzymes degraded A granules with deep cavities formation during later stages. A decrease in crystallinity of granular starches means that enzymes were able to hydrolyze both amorphous and crystalline regions. These results indicate that maltogenic amylase-B with a high LICA and high DMA possesses a better starch binding domain which can decrease the starch MW without affecting bread resilience. Strucuture of maltogenic amylase-A modified amylopectin (AP) in relation to its retrogradation was also studied. AP retrogradation was completely inhibited at % DH ≥ 20. MW and chain length distributions of debranched residual AP indicated with increase in % DH, a high proportion of unit chains with DP ≤ 9 and low proportion of unit chains with DP ≥ 17 were formed. Higher proportion of short outer AP chains which cannot participate in double helices formation supports the decrease and eventually complete inhibition of retrogradation. Thus, maltogenic amylase-A can play a very powerful role in inhibiting starch retrogradation even at limited DH (%).

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25

Sommerville, Marion Don. „The effects of non-starch polysaccharides on the hydrolysis, gelatinisation and retrogradation of starch“. Thesis, Glasgow Caledonian University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311801.

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26

Boatwright, Mark Daniel. „Infrared microspectroscopic chemical imaging applied to individual starch granules and starch dominant solid mixtures“. Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14172.

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Master of Science
Department of Grain Science and Industry
D.L. Wetzel
Chemical imaging enables displaying the distribution of different substances within a field of view based on their fundamental vibrational frequencies. Mid-IR bands are generally strong and feature direct correlation to chemical structure, while near IR spectra consist of overtones and combinations of mid-IR bands. Recently, mid-IR microspectroscopy has enabled determination of the relative substitution of hydroxyl groups with the modifying agent for individual waxy maize starch granules by using synchrotron source. The brightness and non-divergence of the synchrotron source and confocal masking enabled obtaining individual spectra with 5 [mu]m[superscript]2 masking and 1 [mu]m raster scanned steps. Each 1 [mu]m step results from the coaddition of hundreds of scans and lengthy data collection is required to produce data. The recent breakthrough at the Synchrotron Research Center uses a multi-beam synchrotron source combined with a focal plane array microspectrometer. This major improvement in localized detection of the modifying agent within single waxy maize starch granules is the increased efficiency of focal plane array detection and an effective spatial resolution of 0.54 [mu]m. Mixtures of granular solids represent an analytical challenge due to the range of heterogeneity and homogeneity within samples. Near IR imaging provides deeper sample penetration allowing for solid mixture analysis. However, the broad, overlapping bands present in the near IR necessitates statistical data treatment. This requires imaging specimens representative of the individual components to create spectral libraries for classification of each component. Partial least squares analysis then allows characterization and subsequent pixel analysis provides quantitative results. The primary break system for wheat milling was studied as it is key in releasing endosperm to be further ground into fine flour in subsequent processes. The mass balance of endosperm throughout individual unit processes was determined by obtaining flow rates of incoming and outgoing millstreams and calculating endosperm content through pixel identification. The feed milling industry requires the use of a tracer to determine adequate mixing and mix uniformity to limit the time and energy in processing. Near IR imaging allows individual components of a formula feed to serve as a self-tracer, eliminating the need of an inorganic tracer.

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27

Adam, Ibrahim Khalil. „Starch-based bioethanol process innovation“. Thesis, University of Leeds, 2013. http://etheses.whiterose.ac.uk/5744/.

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Starch liquefaction and saccharification are key processing steps in the bioethanol industry. The rate-limiting α-amylase plays an important role due to its endo-glycosidic activity. Work carried out in this thesis on barley α-amylase focused on ER retention to boost recombinant protein expression in planta and purification of the protein to facilitate a cascade refinery approach allowing other high value proteins to be co-produced together with starch for bioethanol production. Results obtained generated evidence for context-dependence of the ER retention motif HDEL, the existence of an HDEL-independent ER retention mechanism and quantitative data showing toxicity or detrimental effects of HDEL overdose. Results also revealed an effect of peptide tags on N-linked glycosylation as well as evidence that expression levels and systems can strongly affect glycosylation of proteins in the secretory pathway. Furthermore, α-amylase endo-glycosidic action on long glucan chains was shown not to be rate limiting in starch saccharification but the presence of short oligomers and their susceptibility to hydrolysis by fungal amyloglucosidase must be considered next. Interestingly, starch saccharification using acid hydrolysis was more efficient compared to enzyme catalysed hydrolysis. In order to optimise the saccharification process further, the research centred on exploring enzymes with raw-starch digesting properties at low temperature and increased specificity for low molecular weight oligosaccharides. Therefore, an alpha amylase-like gene was identified in ripening plantain (Musa acuminata × balbisiana) using degenerate primers. The gene encodes a putative protein product with close homology to chloroplast α-amylases from Ricinus communis, and Arabidopsis thaliana (AtAMY3).

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28

Ponstein, Anne Silene. „Starch synthesis in potato tubers“. [S.l. : [Groningen : s.n.] ; University Library Groningen] [Host], 1990. http://irs.ub.rug.nl/ppn/291023398.

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29

Boren, Mats. „Proteomics of barley starch granules /“. Uppsala : Dept. of Plantbiology and Forest Genetics, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005107.pdf.

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30

Koch, Kristine. „Methods for studying starch characteristics /“. Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5487-5.pdf.

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31

Sweetlove, Lee. „The control of starch synthesis“. Thesis, University of Cambridge, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264287.

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32

Livings, Simon John. „Physical properties of starch wafers“. Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321480.

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33

Chan, Sze-ming Almen, und 陳詩明. „The characterization of amaranthus starch“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B3122717X.

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34

Laurens, Lieve M. L. „Starch metabolism in maize leaves“. Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433600.

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35

Trethewey, Richard N. „The metabolism of transitory starch“. Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318206.

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36

Sanderson, James Stuart. „Physical aspects of starch biodiversity“. Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619816.

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37

Bryce, D. J. „The thermal degradation of starch“. Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/18062.

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38

Lauro, Marianna. „[Alpha]-amylolysis of barley starch /“. Espoo [Finland] : Technical Research Centre of Finland, 2001. http://www.vtt.fi/inf/pdf/publications/2001/P433.pdf.

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39

Gilfillan, William N. „Developing starch-based polymer composites“. Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/86612/6/William_Gilfillan_Thesis.pdf.

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This project aim was to replace petroleum-based plastic packaging materials that pollute the environment, with biodegradable starch-based polymer composites. It was demonstrated that untreated sugar cane bagasse microfibres and unbleached nanofibres significantly improved the physical, mechanical and chemical properties of starch films, while thermal extrusion of starch with alcohol improved the stiffness and the addition of aconitic acid cross-linked the film making it moisture resistant and extensible.

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40

Bai, Yanjie. „Preparation and structure of Octenyl succinic anhydride modified waxy maize starch, microporous starch and maltodextrin“. Thesis, Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/948.

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41

Newton, Jennifer. „The role of non-starch polymers on starch availability in zea mays and triticum aestivum“. Thesis, Heriot-Watt University, 1995. http://hdl.handle.net/10399/1326.

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42

Hasjim, Jovin. „Enzyme digestibility of starch and methods to produce enzyme-resistant starch to improve human health“. [Ames, Iowa : Iowa State University], 2009.

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43

Sang, Yijun. „Cross-linked resistant starch from high-amylose corn starch, and structures of phosphate esters in cross-linked resistant wheat starch determined by ³¹P NMR spectroscopy /“. Search for this dissertation online, 2004. http://wwwlib.umi.com/cr/ksu/main.

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44

Abubakar, Hafiz. „Gelatinization behaviour of Nigerian sorghum starch : a comparative study with wheat and maize starches“. Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317318.

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45

Blazek, Jaroslav. „Role of amylose in structure-function relationship in starches from Australian wheat varieties“. Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/4023.

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In this thesis, a set of wheat varieties (Triticum aestivum L.) produced by the Value Added Wheat Cooperative Research Centre with lower swelling power as compared to commercial Australian wheat varieties were studied to enhance our understanding of the role of amylose in starch functionality. These starches originated from a heterogeneous genetic background and had a narrow range of elevated amylose content (35 to 43%) linked with diverse functional properties. Small-angle X-ray scattering together with complementary techniques of differential scanning calorimetry and X-ray diffraction have been employed to investigate the features of starch granular structure at the nanometer scale. Starch chemical structure was characterized in terms of amylose content and amylopectin chain length distribution. Starch functionality was studied by a series of swelling, pasting and enzymic digestion methods. This study showed that swelling power of flour is a simple test that reflects a number of industrially relevant characteristics of starch, and therefore can be used as an indicator of amylose content and pasting properties of starch. In contrast to waxy starches and starches with normal amylose content, wheat starches with increased amylose content displayed characteristic pasting properties that featured decreasing peak, breakdown and final viscosities with increasing amylose contents. Existence of a threshold value in amylose content, above which final viscosity of starch paste does not further increase with increasing amylose content, was proposed. Variability in amylopectin chain length distribution was shown to have an additional effect on the swelling and pasting properties of the starches. On the molecular level, increased amylose content was correlated with increased repeat spacing of the lamellae present in the semicrystalline growth rings. In agreement with current understanding of starch synthesis, amylose was shown to accumulate in both crystalline and amorphous parts of the lamella. Using waxy starch as a distinctive comparison with the other samples confirmed general trend of increasing amylose content being linked with the accumulation of defects within crystalline lamellae. Amylose content was shown to directly influence the architecture of semicrystalline lamellae, whereas thermodynamic and functional properties were proposed to be brought about by the interplay of amylose content and amylopectin architecture. Subjecting starch granules with varying amylose content to pancreatic α-amylase showed differences in their digestion patterns. Pancreatic α-amylase preferentially attacked amorphous regions of waxy starch granules, whereas these regions for initial preferential hydrolysis gradually diminished with increasing amylose content. Observed variations in the extent of enzymic digestion were concluded to be primarily determined by the level of swelling of amorphous growth rings, which can also explain observed morphologies of partly digested granules with varying amylose content. It was confirmed that access to the granular components is not a function of the extent of crystallinity but rather the spatial positioning of the crystalline regions within the granule. Digestion kinetics is governed by factors intrinsic to starch granules, whereas influence of enzyme type was shown to be critical in determining the absolute rate of hydrolysis. Wheat starches with increased amylose content offer the potential to be used as slow digestible starch, mostly in their granular form or when complexed with lipids. Differences among varieties largely diminished when starches were gelatinized or allowed to retrograde demonstrating the importance of granular structure on starch hydrolysis. Wheat varieties used in this study displayed widely differing pasting properties in a Rapid Visco Analyser (RVA) and textural characteristics of the respective retrograded starch gels. Varietal differences in starch chemical composition among wheat varieties were shown to have significant effect on the extent of the response of starch viscoelastic characteristics to the addition of monopalmitin. Amylose content was positively correlated with the increase in final viscosity, which was attributed to the presence of more amylose in non-aggregated state contributing to higher apparent viscosity of the starch paste. Comparison of stored gels obtained from amylose-rich starches with gel prepared from waxy wheat varieties confirmed the critical role of amylose on the formation of starch network and thus providing the strength of the gel. Lack of correlation between textural properties of stored gels with amylose content or rheological characteristics measured by the RVA indicated that subtle differences in starch structure may have far-reaching consequences in relation to the strength of the gels, although these differences may have only limited effect on pasting properties in the RVA Viscoelastic properties of starch paste prepared from commercial wheat starch were significantly altered depending on the chain length and saturation of the fatty acid of the monoglyceride added during repeated heating and cooling in the Rapid Visco Analyser. Varying effects of different monoglycerides on the paste viscosity were attributed to different complexation abilities of these lipids with starch. It was proposed that stability and structure of the starch-lipid complexes formed affect the viscosity trace of the paste subjected to multiple heating and cooling. Our study indicated that differing monoglycerides in combination with the number of heat-cool cycles can be used to induce form I or form II starch-lipid complexes and thus manipulate paste rheology, gel structure and resistant starch content.

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46

Blazek, Jaroslav. „Role of amylose in structure-function relationship in starches from Australian wheat varieties“. University of Sydney, 2008. http://hdl.handle.net/2123/4023.

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Doctor of Philosophy
In this thesis, a set of wheat varieties (Triticum aestivum L.) produced by the Value Added Wheat Cooperative Research Centre with lower swelling power as compared to commercial Australian wheat varieties were studied to enhance our understanding of the role of amylose in starch functionality. These starches originated from a heterogeneous genetic background and had a narrow range of elevated amylose content (35 to 43%) linked with diverse functional properties. Small-angle X-ray scattering together with complementary techniques of differential scanning calorimetry and X-ray diffraction have been employed to investigate the features of starch granular structure at the nanometer scale. Starch chemical structure was characterized in terms of amylose content and amylopectin chain length distribution. Starch functionality was studied by a series of swelling, pasting and enzymic digestion methods. This study showed that swelling power of flour is a simple test that reflects a number of industrially relevant characteristics of starch, and therefore can be used as an indicator of amylose content and pasting properties of starch. In contrast to waxy starches and starches with normal amylose content, wheat starches with increased amylose content displayed characteristic pasting properties that featured decreasing peak, breakdown and final viscosities with increasing amylose contents. Existence of a threshold value in amylose content, above which final viscosity of starch paste does not further increase with increasing amylose content, was proposed. Variability in amylopectin chain length distribution was shown to have an additional effect on the swelling and pasting properties of the starches. On the molecular level, increased amylose content was correlated with increased repeat spacing of the lamellae present in the semicrystalline growth rings. In agreement with current understanding of starch synthesis, amylose was shown to accumulate in both crystalline and amorphous parts of the lamella. Using waxy starch as a distinctive comparison with the other samples confirmed general trend of increasing amylose content being linked with the accumulation of defects within crystalline lamellae. Amylose content was shown to directly influence the architecture of semicrystalline lamellae, whereas thermodynamic and functional properties were proposed to be brought about by the interplay of amylose content and amylopectin architecture. Subjecting starch granules with varying amylose content to pancreatic α-amylase showed differences in their digestion patterns. Pancreatic α-amylase preferentially attacked amorphous regions of waxy starch granules, whereas these regions for initial preferential hydrolysis gradually diminished with increasing amylose content. Observed variations in the extent of enzymic digestion were concluded to be primarily determined by the level of swelling of amorphous growth rings, which can also explain observed morphologies of partly digested granules with varying amylose content. It was confirmed that access to the granular components is not a function of the extent of crystallinity but rather the spatial positioning of the crystalline regions within the granule. Digestion kinetics is governed by factors intrinsic to starch granules, whereas influence of enzyme type was shown to be critical in determining the absolute rate of hydrolysis. Wheat starches with increased amylose content offer the potential to be used as slow digestible starch, mostly in their granular form or when complexed with lipids. Differences among varieties largely diminished when starches were gelatinized or allowed to retrograde demonstrating the importance of granular structure on starch hydrolysis. Wheat varieties used in this study displayed widely differing pasting properties in a Rapid Visco Analyser (RVA) and textural characteristics of the respective retrograded starch gels. Varietal differences in starch chemical composition among wheat varieties were shown to have significant effect on the extent of the response of starch viscoelastic characteristics to the addition of monopalmitin. Amylose content was positively correlated with the increase in final viscosity, which was attributed to the presence of more amylose in non-aggregated state contributing to higher apparent viscosity of the starch paste. Comparison of stored gels obtained from amylose-rich starches with gel prepared from waxy wheat varieties confirmed the critical role of amylose on the formation of starch network and thus providing the strength of the gel. Lack of correlation between textural properties of stored gels with amylose content or rheological characteristics measured by the RVA indicated that subtle differences in starch structure may have far-reaching consequences in relation to the strength of the gels, although these differences may have only limited effect on pasting properties in the RVA Viscoelastic properties of starch paste prepared from commercial wheat starch were significantly altered depending on the chain length and saturation of the fatty acid of the monoglyceride added during repeated heating and cooling in the Rapid Visco Analyser. Varying effects of different monoglycerides on the paste viscosity were attributed to different complexation abilities of these lipids with starch. It was proposed that stability and structure of the starch-lipid complexes formed affect the viscosity trace of the paste subjected to multiple heating and cooling. Our study indicated that differing monoglycerides in combination with the number of heat-cool cycles can be used to induce form I or form II starch-lipid complexes and thus manipulate paste rheology, gel structure and resistant starch content.

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47

Messerli, Gaëlle Liliane Yolande. „Starch degradation in Arabidopsis thaliana leaves /“. Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17034.

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Ha, Seung-kyu. „Starch incorporated polymerization of thermoplastic polyurethan“. [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965659852.

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49

Demessie, Berhanu. „Ultrafiltration of Partially Degraded Starch Solution“. Doctoral thesis, Norwegian University of Science and Technology, Faculty of Natural Sciences and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-30.

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Desizing wastewater is largely responsible for the chemical oxygen demand (COD) load in the textile industry wastewater. A larger portion of COD comes from degraded starch in desizing wastewater. Removing the starch from the wastewater by an ultrafiltration process may reduce the environmental problem caused by the textile factory. If the treatment is made in such a way that all starch components are removed from the wastewater, the treated water can be reused by the factory. If the starch in the concentrate is stable, it can also be reused as a sizing agent. This will give the factory an economic advantage.

In this thesis we have studied the fouling mechanisms involved in the ultrafiltration of solution with partially degraded starch in order to find the treatibility of such solutions. The work has mainly been directed to uncover how the different fouling mechanisms depend on the operating parameters, and to find the performance of selected membranes. In addition, different models were evaluated for their validity in predicting the performance of the membranes and the data was fitted to the model that give the best prediction and are physically more meaningful. In addition, the starch solution was concentrated, and the flux, concentration, retention and rejection profiles as a function of concentrating time were investigated.

For the study, we used a partially degraded starch solution as a model solution. The solution was prepared in the laboratory by enzymatic degradation of potato starch to different levels. In order to evaluate the reproducibility of the degraded starch, three replicates were prepared. The reproducibility was determined by comparing the molar mass distribution from HPLSEC analysis and the concentration of reducing sugar from a DNS test for the replicates. The analyses show very good reproducibility. Three starch model solutions with three different degradation levels were chosen for our ultrafiltration experiments to investigate the effect of average molar mass of the starch.

For the ultrafiltration of the solution ES625 (from PCI) and MPT-U20 (from KOCH) membranes were used. Both membranes were used in the investigation of the contribution of different fouling mechanisms to the flux decline during ultrafiltration of the solution. In the evaluation of the performance of ultrafiltration of the starch solution, however, only the ES625 membrane was used. According to the manufacturers, both membranes have nearly equal pure water flux and MWCO. But in our test, we observed a higher and different pure water flux for each type of membrane. The ES625 had a lower flux (higher retention) than the MPTU20 membrane.

In the ultrafiltration of partially degraded starch solution the permeate flux declines very fast and, for a low feed concentration, it reaches a steady state in a very short time. The steady state time was observed to increase with concentration, molar mass and transmembrane pressure drop, and to decrease with cross flow velocity. All the three fouling mechanisms (concentration polarization, adsorption and deposition) were responsible for the flux decline. The major observed contributors are, however, adsorption and deposition. Adsorption is largely responsible at low-pressure operation while the deposition fouling effect is dominant at higher pressures, near or beyond the limiting flux.

For the ES625 membrane, the contribution of adsorptive fouling increases with concentration and decreases with molar mass of the starch, temperature and pH at a given transmembrane pressure and cross flow velocity. The effect of the operating parameters on the depositional fouling is in line with literature. It increases with pressure, concentration, molar mass and temperature, and decreases with cross flow velocity. Its dependence on pressure can be expressed by a power function with exponent larger than 1.0. This seems to due to an increase in thickness and compaction of the starch gel/deposit at the membrane surface as the transmembrane pressure drop is increased. The contribution of the concentration polarization is also dependent on concentration, cross flow velocity and pressure. Its relative contribution increases with concentration while it decreases with an increase in cross flow velocity. In the turbulent flow regime the relation between the resistance contributed by concentration polarization increases almost linearly with transmembrane pressure drop. In the laminar flow regime, however, the relative contribution of the resistance due to concentration polarization increases for the lower range of pressure and decreases for the higher range of pressure. Its relative contribution also increases with temperature and decreases with increasing molar mass. But the overall fouling resistance in the ultrafiltration of the starch solution increases with feed concentration, molar mass of the starch and transmembrane pressure drop and decreases with cross flow velocity and temperature.

The trend of the flux loss due to all fouling mechanisms for MPT-U20 membrane is similar to ES625 membrane except for adsorption and concentration polarization with changes in concentration and molar mass. The difference could be a result of the difference in morphological properties between the two membranes and the experimental procedures used in determining flux data that used for calculating the contributions. From the pure water flux and the retention data, the ES625 membrane seemed to have a smaller pore size than the MPT-U20 membrane.

Among the ultrafiltration models, the resistances-in-series model was chosen for its provision to include all the fouling mechanisms into the model. When our permeate flux data was fitted to the model, it gives a good fit. However, the model fails to give realistic estimates of the contribution of the individual fouling mechanisms. In order to improve this problem, the model was modified by introducing osmotic pressure across the membrane in such a way that the effect of concentration polarization is accounted for. This modified model is more physically meaningful and gives a realistic estimate of the contribution the reversible and irreversible fraction of the overall resistance.

In concentrating mode operation, the permeate was continuously withdrawn and hence, the concentration of starch in the feed tank was increased. At an early stage of ultrafiltration, the permeate flux appeared to increase slightly, which seems, a result a shear thinning of the starch solution when the solution was pumped through the system. For the rest of the operation, the flux was decreasing, the retention was increasing and the rejection of the membrane was shifted to a lower molar mass as the solution in the feed tank got more concentrated as expected. The shift of rejection to the lower molar mass region is due to the fouling layer that reduces the accessibility of the pores of the membrane.

Generally, the flux we obtained in ultrafiltration of a partially degraded starch solution with the ES625 tubular membrane is equal or better than the reported values from an existing ultrafiltration plant that has been used in the textile industry to recover a synthetic sizing agent (PVA) from the desizing wastewater. The retention is, however, rather low. Two or more stages of treatment are needed to get all starch components removed from the wastewater and make the treated water reusable (recycled).

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Glavas, Lidija. „Starch and Protein based Wood Adhesives“. Thesis, KTH, Skolan för kemivetenskap (CHE), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-31486.

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Different native starches, modified starches and plant proteins were evaluated as wood adhesives. They were combined with different synthetic polymers in order to achieve improved adhesive properties. The study was divided into two parts: development of starch based adhesive formulations and evaluation of an existing protein based adhesive. Eight different starches and two different plant proteins were used in the first part. Starch 1 and starch 2 as well as protein 1 and protein 2 were some of the used materials. These materials were dispersed in synthetic polymers such as poly (vinyl acetate) (PVAc), styrene-butadiene rubber (SBR), poly (vinyl alcohol) (PVA), poly (acrylic acid) (PAA) and poly (ethylene-co-vinyl acetate) (EVA). Five different cross-linking agents were also tested. In the second part of the study, protein 2 was used as a renewable material. It was dispersed in dispersing media 2 and filler 1 was used. In an effort to increase the amount of renewable material in the adhesive composition, six different renewable fillers were examined. Lower pressing temperatures as well as lower amounts of cross-linking agent 1 were evaluated in order to observe their influence on the adhesive properties of the protein based adhesive. All formulations were characterized by measurement of viscosity, solid content and pH. The adhesive properties of some of the formulations in both parts of the study were characterized according to SS-EN 204:2001 and EN 14257 (WATT 91). The best results, of the starch based formulations, were obtained when starch 1 and protein 2 were dispersed in dispersing media 2 or dispersing media 7. These formulations in combination with cross-linking agents were classified as D2 and passed the criteria for heat resistance (WATT 91). However, the results were comparable with the reference sample. It was possible to replace filler 1, totally or partly, in the protein based adhesive with renewable fillers. Protein based adhesive formulations with filler 2 and filler 4, amongst others, showed improvement of the adhesive properties. These formulations passed D3 and D4 – wet criteria and almost passed D4 – boiling criteria. The amount of renewable material in the protein based adhesive was increased from ~32 % to ~56 % in the formulations that obtained the best adhesive properties. The amount of non-petrochemical material was ~67 % in all new formulations as well as in the reference sample. By decreasing the pressing temperature from 110 °C to 90 °C or by decreasing the amount of cross-linking agent 1 from 15 % to 5 %, a protein based system that passes D3 criteria can be obtained.

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