The field of the Chemistry of Starch is so wide and the complexities involved are so great that any attempt to solve the problems of the constitution of starch cannot be spread over the whole front, but must necessarily be confined to a few chosen points of attack. The following introduction, therefore, is not presented as a complete survey of literature of the subject but merely as a resumé of those parts bearing immediately on the topics studies, with special reference to the work of Dr. J. K. Rutherford, inasmuch as the present thesis is a continuation and amplification of her work.

Master of Science / Department of Grain Science and Industry / Yong Cheng Shi / Octenyl succinic anhydride (OSA) modified starch is widely used in emulsion and encapsulation applications. The functionality of OS starch depends on its molecular structure. A systematic study was performed to investigate the reaction of OSA with granular waxy maize (WM) starch, microporous WM starch and soluble maltodextrin. OS starches were prepared in an aqueous slurry system, and the degree of substitution (DS) of OS starches was determined by titration and [superscript]1H-NMR spectroscopy. For both 3% and 50% OSA treatment, OS maltodextrin had higher DS and reaction efficiency (RE) than OSA modified WM starch and microporous WM starch. The maximum DS of OSA modified granular WM starch was 0.14 and the highest DS of OS maltodextrin was 0.27. For the 3% OSA treatment, the RE for WM starch and maltodextrin was ~ 80% and ~100%, respectively. The structure of OSA modified WM starch and the locations of OS groups on anhydroglucose units (AGUs) were studied by [superscript]1H-NMR and [superscript]13C-NMR. As increasing OS substitution, [superscript]13C - signal at C-1 shifted to upper field. In addition, the [superscript]13C - signal at C-6 shifted to downfield when DS reached 0.073. The results suggested that OS groups were predominantly substituted at the O-2 position and started being substituted at O-6 position when DS was 0.073. FT-IR microspectroscopy was used to detect the heterogeneity OS starch products. Native WM starch, OSA modified WM starches (DS=0.019 and 0.073) and a starch blend with native starch to OSA modified WM starch (DS=0.073) ratio of 7:3 were examined. More than one hundred starch granules of each sample were analyzed one by one by FT-IR microspectroscopy. For the OS starch (DS=0.019), 7% starch granules showed carbonyl absorption. For the OS starch (DS=0.073), 99% starch granules showed carbonyl absorption but the intensity varied, indicating that OSA reacted with most starch granules when DS was 0.073. However, the OS contents of individual granules varied. For the starch blend, only 30% starch granules had carbonyl absorption. FT-IR microspectroscopy is a useful tool to detect heterogeneity of OS starch blends containing native starch.

Grain quality in chickpea (<i>Cicer arietinum</i> L.) is a major factor affecting its consumption for human nutrition and health benefits. Some of the major factors affecting chickpea grain quality are: seed weight, size, colour, protein, starch and amylose concentration, and amylopectin structure. The objectives of this study were to: 1) determine variation, repeatability and genotype by environment interaction on thousand seed weight, starch, amylose and protein concentration of chickpea cultivars adapted to western Canada; 2) assess variations in global chickpea germplasm for thousand seed weight, seed size, protein, starch and amylose concentrations; and 3) characterize the desi and kabuli type chickpea for starch concentration, composition, and amylopectin structure to study their effect on starch enzymatic hydrolysis. Limited variation was observed in seed composition of chickpea cultivars adapted to the western Canadian prairies. Significant genotype by environment interaction occurred for starch, amylose, and protein (except for kabuli) concentrations, seed yield and thousand seed weight indicating that testing over a wide range of environments is needed to identify genotypes for grain quality improvement. Repeatability of starch, amylose, and protein concentrations was low and inconsistent across chickpea market classes. Broad sense heritability was higher than repeatability across all traits for all market classes implying that repeatability estimates do not set upper limits to heritability if significant genotype by environment interaction is present. The negative relationship between seed constituents and yield indicates that selection for chickpea cultivars with desired seed composition may require compromise with yield and indirect selection. All the mini core accessions that had above average seed diameter score in both desi and kabuli also had above average score for thousand seed weight. Selecting mini core with promising intrinsic and extrinsic quality characteristics may reduce yield. Slowly digestible starch was negatively correlated with hydrolysis index in both pure starch and meal starch of desi and kabuli. Amylose had a strong relationship with resistant starch but not with rate of starch hydrolysis. Genotypes with a significantly higher rate of starch hydrolysis had significantly lower 60-80 µm starch granule size volume. Amylopectin B2 chains were related to slowly digestible starch of meal (except kabuli) and extracted starch. Resistant starch positively correlated with B1 fraction of amylopectin chain length in both desi and kabuli meal starch. Our results suggest that there is no major difference between starch composition in the two chickpea market classes, although only three genotypes of each class were tested. The meal components affect the starch hydrolytic properties and the effect is genotype specific. The results also show that amylopectin structure influences starch hydrolytic properties. These observations emphasize that complete characterization of seed components is needed to obtain meaningful results regarding the desired nutritional and health benefits attributed to any grain.

Grain quality in chickpea (<i>Cicer arietinum</i> L.) is a major factor affecting its consumption for human nutrition and health benefits. Some of the major factors affecting chickpea grain quality are: seed weight, size, colour, protein, starch and amylose concentration, and amylopectin structure. The objectives of this study were to: 1) determine variation, repeatability and genotype by environment interaction on thousand seed weight, starch, amylose and protein concentration of chickpea cultivars adapted to western Canada; 2) assess variations in global chickpea germplasm for thousand seed weight, seed size, protein, starch and amylose concentrations; and 3) characterize the desi and kabuli type chickpea for starch concentration, composition, and amylopectin structure to study their effect on starch enzymatic hydrolysis. Limited variation was observed in seed composition of chickpea cultivars adapted to the western Canadian prairies. Significant genotype by environment interaction occurred for starch, amylose, and protein (except for kabuli) concentrations, seed yield and thousand seed weight indicating that testing over a wide range of environments is needed to identify genotypes for grain quality improvement. Repeatability of starch, amylose, and protein concentrations was low and inconsistent across chickpea market classes. Broad sense heritability was higher than repeatability across all traits for all market classes implying that repeatability estimates do not set upper limits to heritability if significant genotype by environment interaction is present. The negative relationship between seed constituents and yield indicates that selection for chickpea cultivars with desired seed composition may require compromise with yield and indirect selection. All the mini core accessions that had above average seed diameter score in both desi and kabuli also had above average score for thousand seed weight. Selecting mini core with promising intrinsic and extrinsic quality characteristics may reduce yield. Slowly digestible starch was negatively correlated with hydrolysis index in both pure starch and meal starch of desi and kabuli. Amylose had a strong relationship with resistant starch but not with rate of starch hydrolysis. Genotypes with a significantly higher rate of starch hydrolysis had significantly lower 60-80 µm starch granule size volume. Amylopectin B2 chains were related to slowly digestible starch of meal (except kabuli) and extracted starch. Resistant starch positively correlated with B1 fraction of amylopectin chain length in both desi and kabuli meal starch. Our results suggest that there is no major difference between starch composition in the two chickpea market classes, although only three genotypes of each class were tested. The meal components affect the starch hydrolytic properties and the effect is genotype specific. The results also show that amylopectin structure influences starch hydrolytic properties. These observations emphasize that complete characterization of seed components is needed to obtain meaningful results regarding the desired nutritional and health benefits attributed to any grain.

Starch is an attractive raw material for biodegradable plastic applications due to its low cost, its availability in large quantities and its excellent thermal process-ability using conventional plastic processing equipments. Despite its attractive potential as a biopolymer material, the use of starch in biodegradable plastic applications is yet limited by its structural and functional properties, which are dictated by its genetic make up. This dissertation involves in-depth characterisations of a range of biotechnologically derived novel starches from different cereal sources to elucidate the relationship between starch structure and functionality. The importance of understanding starch structure-functionality relationship to further the development of starch biodegradable plastics are discussed to identify the research questions, which underlie the motivation of this dissertation and to contextualize the objectives of this dissertation. Diversities in starch macromolecular properties namely the amylose content and amylopectin chain length distribution are evident in these novel starches. The variation in amylopectin structure in these novel starches is explicable by considering the particular inhibition of starch biosynthesis gene expression in the generation of these starch mutants. Amylose content and amylopectin chain length distribution are two separate structural parameters in starch, which influence the granular and functional properties of starch. An improved method to analyse the 13C solid state NMR spectra for native starches was developed in this dissertation and provides the first elucidation on the occurrence of V-type polymorph, which is significant in high amylose starches. An increase in starch amylose content (or decrease in amylopectin content) leads to a decrease in the double helix content and crystallinity. A transition in the double helical packing arrangement of amylopectin side chains from A-type to B-type polymorph is noted for high amylose starches. This can be attributed to the changes in their amylopectin chain length distribution, which leads to the tendency of the glucan chains to form the B-type polymorph during crystallisation from thermodynamic considerations. The application of MTDSC provides the first elucidation on the step transition or heat capacity change, which is noted to occur within the gelatinisation endotherm for all starches. The use of Rheoscope, which allows for simultaneous monitoring of the changes in starch granular and rheological properties during gelatinisation, reveals that the manifested changes in viscosity can be attributed to the increase in the granules size as a result of swelling, the change in granules properties from rigid to more deformable granules due to water penetration and the increase in the viscosity of the continuous phase due to leaching of amylose. The variation in starch gelatinisation thermal properties namely the onset temperature, enthalpy and heat capacity change can be attributed to the variation in amylopectin chain length distribution, amylose content and the amount of starch structural order. A reduction in swelling power with increasing amylose content is consistently noted for all starch types. The variation in starch rheological responses during gelatinisation can be mainly attributed to the swelling ability of starch granules and their granule size distribution (to a lesser extent). Further MTDSC investigations on starch gelatinisation in the presence of water and glycerol with different concentrations indicate that plasticisation of starch granules prior to gelatinisation does not occur. The observed mid-temperature of the step transition (heat capacity change) is more likely due to a change in state of the starch macromolecules from being highly restrained within the granular packing to entangled macromolecules (as the order to disorder transition occurs) rather than due to glass transition. The addition of glycerol promotes starch gelatinisation in a similar way as the addition of water, which suggests that the same structural changes occur during gelatinisation regardless of the solvents used. In summary, the following starch structure-functionality relationships are deduced. The variation in starch macromolecular properties can be attributed to their corresponding mutation of starch biosynthetic genes expression. The variation in starch amylose content affects the extent of structural order inside the granules while the double helix packing arrangement is influenced by the amylopectin chain length distribution. Starch gelatinisation thermal properties are mainly influenced by the amylopectin chain length distribution while the swelling power and rheological properties are mainly affected by the amylose content.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Fish use carbohydrates less efficiently than proteins for energy production. Even so, the use of such source in the diet may reduce the catabolism of proteins and lipids for energy purposes. The objective of this study was to evaluate growth, metabolism and digestibility of nutrients with different proportions of amylose:amylopectin and thermal processing of starch in the diet of jundiá (Rhamdia quelen). Two completely randomized experiments were conducted, where jundiás were reared in water re-use system consisting of 12 units of 280L and 6 conical units of 200L (digestibility). In the first experiment three diets were tested for 60 days varying in proportions of amylose:amylopectin: P26:74 = 26% amylose and 74% amylopectin, P16:84 = 16% amylase and 84% amylopectin and P0:100 = 0% amylose and 100% amylopectin. The variation of amylose content of the diets did not affect growth, yield, body composition of fish or starch digestibility. For the biochemical variables, less quantity of amylose (P0:100) provided greater mobilization of triglycerides, decrease in the deposition of liver glycogen and increase in metabolism of amino acids and lactate in muscle, indicating gluconeogenesis. The glycemic response of fish was stable (linear, r2 = 0.67) with more amylose (P26:74). Starch with more amylopectin presented quadractly effect P16:84 (r2 = 0.76) and P0:100 (r2 = 0.93). In the second experiment, in a 2X2 factorial arrangement, diets were evaluated with two proportions of amylose:amylopectin and two physic starch forms, raw and gelatinization starch. The fish (14.3±0.6 g) were fed twice a day (4% body weight/day). The proportion of amylose:amylopectin did not affect the growth of jundiá, however, the gelatinization of the starch decreased growth, a higher hepatosomatic and lipid index in body composition of fish. The digestibility of the dry matter and starch was higher with starch gelatinized in the diet. Greater amount of amylopectin and the effect of gelatinization increased serum triglyceride levels. In liver tissues, higher levels of amylose and the process of gelatinization caused greater deposition of glycogen and amino acids. In conclusion, the proportion of amylose:amylopectin is not i change the digestibility of starch and the growth of jundiá, but the increase in amylose provided lower lipid mobilization and stable glycemic levels. The gelatinization of the starch decreased growth and increased the starch digestibility and deposition of body lipids. / Os peixes utilizam carboidratos menos eficientemente do que proteínas para produção de energia. Mesmo assim, a utilização dessa fonte na alimentação pode reduzir o catabolismo de proteínas e lipídeos para fins energéticos. O objetivo do trabalho foi avaliar o crescimento, metabolismo e digestibilidade dos nutrientes com diferentes proporções de amilose:amilopectina e o processamento térmico do amido na dieta de jundiás (Rhamdia quelen). Para isso foram conduzidos dois experimentos delineados inteiramente ao acaso, onde jundiás foram criados em sistema com recirculação de água constituído de doze tanques de 280L e seis tanques de formato cônico de 200L (digestibilidade). No primeiro experimento foram testadas por 60 dias três dietas variando nas proporções de amilose:amilopectina: P26:74=com 26% de amilose e 74% de amilopectina, P16:84=com 16% de amilose e 84% de amilopectina e P0:100=com 0% de amilose e 100% de amilopectina. A variação do teor de amilose das dietas não afetou o crescimento, rendimentos e composição corporais dos peixes, bem como a digestibilidade do amido. Para as variáveis bioquímicas, menor quantidade de amilose (P0:100) proporcionou maior mobilização de triglicerídeos séricos, diminuição na deposição de glicogênio hepático e aumento no metabolismo de aminoácidos e lactato no músculo, indicando gliconeogênese. A resposta glicêmica dos peixes foi estável (linear, r2=0,67) com mais amilose (P26:74). Amido com mais amilopectina apresentou efeito quadrático P16:84 (r2=0,76) e no P0:100 (r2=0,93). No segundo experimento, em arranjo fatorial 2X2, foram avaliadas dietas com duas proporções de amilose:amilopectina e duas formas físicas do amido, cru e gelatinizado Os jundiás (14,3±0,6g) foram alimentados duas vezes por dia (4% peso vivo/dia). A proporção de amilose:amilopectina não afetou o crescimento dos jundiás, já a gelatinização do amido causou diminuição no crescimento, maior índice hepatossomático e de lipídeos na composição corporal dos peixes. A digestibilidade da matéria seca e do amido foi maior com amido gelatinizado na ração. Maior quantidade de amilopectina e o efeito da gelatinização do amido aumentaram os triglicerídeos séricos. No tecido hepático, maiores níveis de amilose e o processo de gelatinização do amido causaram maior deposição de glicogênio e aminoácidos. Como conclusão, a proporção de amilose:amilopectina não causa alterações na digestibilidade do amido e no crescimento do jundiá, mas o aumento da amilose proporciona menor mobilização lipídica e glicemia estável. A gelatinização do amido diminuiu o crescimento, aumentou a digestibilidade do amido e causou maior deposição de lipídeos corporais.

Rice starch contains two types of glucose polymers, mainly linear amylose and hyper-branched amylopectin. Waxy rice has been characterised by the lack of amylose, the proportion of which being one of the most important parameters measured for rice quality. Germplasm collection work conducted in the Lao People’s Democratic Republic has previously demonstrated the diversity of this type of rice in terms of quality. The definition of a waxy rice variety is dependent on the meaning of amylose. The conventional method for determining amylose content has shown that waxy rice could have up to 5% amylose. However, including a 0% amylose standard in the standard curve causes the amylose content of these varieties to become 0-2%. In this work, the absence of amylose in waxy rice has been determined through three different approaches. Granule-bound starch synthase I (GBSS1), the enzyme which synthesises amylose, was not detected in waxy rice. Long linear chains associated with amylose were also not detected by size exclusion chromatography (SEC). The absence of these long chains affected functional properties of waxy rice, as indicated by the differences in viscosity curves between waxy and non-waxy rice. Moreover, these waxy varieties themselves exhibit differences in their viscosity curves, another indication of the diversity in coking properties in these varieties. A new approach, the ‘lnP(N) technique’, in analysing chain length distributions was applied to varieties with known mutations in two of the enzymes involved in the synthesis of amylopectin, and in determining gelatinisation temperature. It was determined that the presence of a novel feature, an interruption to linearity at DP 18-24, of the lnP(N) plot was found in rice samples with mutations in the alk gene, which codes for starch synthase (SS) IIa, and in samples with inactive branching enzyme (BE) IIb. Single nucleotide polymorphisms (SNPs) in the gene coding for SSIIa have been associated with lowered gelatinisation temperature. On the other hand, non-functionality of BEIIb changes the amylopectin structure such that gelatinisation temperature is increased. The novel feature of the lnP(N) plot is found when either or both SSIIa and BEIIb are non-functional. Waxy rice starch has hot-water-soluble (HWS) and insoluble (HWI) components. It has been confirmed that the soluble polysaccharides are structurally different from phytoglycogen, and are similar to amylopectin. Structural differences between the two fractions, which can account for their differences in solubility, were determined. At the level of the chain length distribution, the HWI fraction contained long chains not found in the HWS fraction. Considerable amounts of sucrose and glucose were found in the HWS fraction. At another level of structure, the degree of branching of the HWS components was higher than in the HWI fraction. On the other hand, the whole molecules of the HWS fraction were smaller than those of the HWI fraction. These structural differences between the two fractions potentially affected their physical behaviour, particularly solubility. The amount of leached material appears to be a property of the method, as varying cooking conditions changed the amount of HWS components. This amount reaches equilibrium at certain conditions, indicating the limited amount of the HWS material. On the other hand, the HWI component contains molecules that are insoluble in water, rather than molecules that solubilise slowly. Given the stability of the HWS fraction in solution, the ratio of the HWS fraction to the HWI fraction could potentially be used in measuring quality if the amount of the HWS fraction is variety-specific. However, the quantity of the HWS fraction appears to be a feature of the starch, rather than of the variety. Nevertheless, the fact that the soluble fraction is structurally and thermodynamically different from the insoluble fraction could presumably be grounds to classify the soluble component as a group of molecules distinct from amylopectin.

L'effet des traitements hydrothermiques et l’effet des arômes sur la structure de l'amidon et de ses propriétés physiques ont été étudiés. L’amidon de blé natif a été traité à 2 hydratations différentes (rapports eau-amidon: 50/50 et 80/20 g/g) et à 2 températures (65 et 85 °C) en présence d’ arômes (hexanoate d'éthyle et de 2-hexanone). Les échantillons fraîchement préparés ont été soumis à l’analyse calorimétrique (AED) et au dosage d’ arôme. Aucun complexe d'inclusion entre amidon et arôme n’a pu être détecté par AED cependant le résultat de l'analyse aromatique a prouvé qu'il y avait des interactions arôme-amidon. Les deux composés d’arôme (hexanoate d'éthyle et 2-hexanone) ont interagi avec l'amidon à des teneurs comparables. Les pertes d’arômes ont été trouvées les plus élevées dans les échantillons traités aux plus hautes hydratation et température . La perte d’arôme était principalement liée à l’évaporation lors des traitements hydrothermiques. Après les traitements hydrothermiques, les échantillons ont été lyophilisés ont montré une stabilité d’arôme à la lyophilisation. Les échantillons lyophilisés ont été soumis à diverses études: DSC (Tg), RVA, la taille des granules, XRD, WAXS, SAXS étude et de stockage. Les traitements hydrothermiques ont conduit à des échantillons avec des propriétés différentes. A haute hydratation, la température influence la taille des granules et des propriétés rhéologiques à la cuisson (pasting). Les échantillons chauffés à 65 °C présentaient des tailles de granules significativement plus importantes, une viscosité maximale (en RVA) inférieure à celles des échantillons chauffés à 85 °C mais de significative différence en % de cristallinité. A faible hydratation, la température de chauffage n’avait pas d’influencer significative sur la taille des granules, mais un effet significatif sur les propriétés rhéologiques à la cuisson, le degré de cristallinité et le profil SAXS. Les échantillons chauffés à 65°C avaient une viscosité maximale supérieure , un degré de cristallinité plus élevé et des pics SAXS plus importants qu’après un chauffage à 85 °C. La teneur résiduelle en arôme n'a eu aucune influence significative sur la structure, mais semble affecter les propriétés rhéologiques à la cuisson. En ce qui concerne l'étude à la conservations, les échantillons ont été stockés à 58 et 75% d'humidité relative et étudiés par analyse SPME, par extraction d’arôme et par AED pour un suivide relaxation d’enthalpie après de 2, 4 et 14 semaines de stockage. Les échantillons avaient une plus grande libération de l'arôme à 75% HR et l’hexanoate d’éthyle montré une plus grande libération de 2-hexanone. Les échantillons ont montré une augmentation de relaxation d'enthalpie de lors d'un stockage. / The effect of hydrothermal treatments and flavours addition on starch structure and its physical properties were studied. Native wheat starch was treated at 2 different hydrations (water-starch ratios: 50/50 and 80/20 g w/w) and temperatures (65 and 85 °C) in the presence of flavours (ethyl hexanoate and 2-hexanone). The freshly prepared samples were subjected to DSC and flavour analysis. Flavour inclusion complex could not be detected by DSC, however the result of flavour analysis proved that there were flavours interactions with starch. Both ethyl hexanoate and 2-hexanone interacted with starch at similar rates. The highest flavour loss was found in the samples at high hydration and heated at 85 °C. The loss of flavour was mainly due to vaporisation during hydrothermal treatments. After hydrothermal treatments, the samples subjected to freeze-drying and they showed flavour stability upon freeze-drying. The freeze-dried samples were subjected to various studies: DSC (Tg), RVA, granule size, XRD, WAXS, SAXS and storage study. The hydrothermal treatments resulted in samples with different properties. At high hydration, temperature influenced granule size and pasting properties. The samples heated at 65 °C had significantly greater granule diameter, lower peak viscosity than samples heated at 85 °C and no significantly difference in % crystallinity. At low hydration, heating temperature had no significantly influence on granule diameter but significantly affected pasting properties, % crystallinity and SAXS profile. The samples heated at 65 °C had a greater peak viscosity, % crystallinity and greater peak on SAXS than after a treatment at 85 °C. The residual flavour contenthad no significant influence on structure but affected pasting properties. Regarding storage study, the samples were stored at 58 and 75 % RH and withdrawn for SPME, flavour residual extraction and DSC (enthalpy of relaxation) at 2, 4 and 14 weeks of storage. The samples had greater flavour release at 75% RH and ethyl hexanoate showed greater release than 2-hexanone. The samples showed increasing of enthalpy relaxation upon storage.