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Item Insights into wheat grain microstructure and composition for the development of novel flour with slow digestion properties and enhanced functional characteristics : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand(Massey University, 2025) AbhilashaWheat has been consumed as whole grains, broken grains, flattened format, and puffed format other than the flour format, which has a wide application in different types of food preparations. Wheat flour possesses a unique ability to form a cohesive dough that has viscoelastic properties. A range of products with wheat as their major ingredient are high glycaemic index (GI) foods as wheat flour contains highly digestible starch. However, the consumption of high GI foods is associated with chronic diseases such as diabetes, coronary heart disease, and obesity due to a rapid increase in blood glucose levels and secretion of insulin. The major objective of the research studies of this thesis included creating slowly digestible flour with improved functionality using slowly digested starch sources and non-starch components. Modifying wheat grain through different processing techniques alters the microstructure, and therefore, starch digestibility is impacted. Microstructure modification through various processing techniques, which can control the access of digestive enzymes to starch, could help develop products with controlled starch digestibility. To advance the understanding of the impact of wheat grain microstructure on starch hydrolysis, Chapter 3 explored a study on whole wheat grain in different commercially available forms (kibbled, cut grains, and flour) to understand the influence of microstructural changes on in vitro starch digestibility. The process of size reduction from raw intact grains to kibbled grains and flour caused an increase in overall starch hydrolysis (%) during simulated digestion in the order of flour>kibbled>cut>intact whole wheat grains. Cooking of these formats further increased their starch hydrolysis. However, both cooked cut and intact grains were low glycaemic with the expected glycaemic indices (eGI) of values of 54.08±0.03 and 41.98±0.04, respectively, revealing the role of intact microstructure in starch hydrolysis of wheat grains. Based on the role of intact microstructure, Chapter 4 investigated the possibility of reducing the starch hydrolysis in wheat grain formats (whole, flakes, and flour) by hydrothermal treatment and low-temperature storage of whole wheat grains. The extent of starch hydrolysis after oral-gastro-small intestinal digestion in vitro was significantly lower (p<0.05) in intact grains, flakes, and flours from the cold-stored grains than their non-cold-stored counterparts. In this study, scanning electron micrographs, pasting properties, water retention capacities, and relative crystallinity of the resulting flours revealed an enhanced degree of gelatinisation with the treatment temperature; however, cold-storage of treated grains resulted in a change in these properties due to the retrogradation of the starch. This study indicates that hydrothermal pre-treatment of grains followed by low-temperature storage for prolonged periods might help to reduce the starch digestibility of wheat grains and their resulting products and could be an effective strategy in developing reduced glycaemic impact grain products. However, in our preliminary trials, the flours from hydrothermally treated and low-temperature stored grains resulted in doughs of inferior viscoelastic properties. Furthermore, intending to create slowly digestible flour, Chapter 5 employed two approaches to modify a resistant starch: one involving soluble extracts from wheat flour and vital gluten (water solubles, salt-assisted water-solubles, and acid-solubles) and the other utilising hydrocolloids (guar gum, xanthan gum, locust bean gum, and carboxymethyl cellulose). Modifications from both approaches resulted in modified starch morphology with the formation of starch clusters mimicking the wheat flour. Moreover, the modification with hydrocolloids resulted in an improved pasting profile. Furthermore, in vitro digestion studies revealed that the starch hydrolysis rate was decreased for most of the cooked modified starches with wheat solubles and a slower starch hydrolysis profile until 60 min of simulated small intestinal digestion for most of the hydrocolloids used, carboxymethyl cellulose being the least effective in slowing the starch hydrolysis rate. Additionally, Chapter 6 evaluates the functionality and starch digestibility of a wheat flour system (dough and flatbread-chapatti) by utilising the modified starches created in Chapter 5 as low glycaemic ingredients. The interaction of the modified starches with vital gluten and wheat flour components resulted in improved viscosity of the functional flour. The microstructure of the functional flour dough indicated that the modified starches with wheat solubles (soluble extracts from wheat flour and vital gluten) and hydrocolloids improved the starch-protein matrix and gluten network. Furthermore, the in vitro digestion study revealed the overall starch hydrolysis of chapattis from all the functional flour formulations was significantly lower than the wheat flour chapatti. In conclusion, structural modifications of wheat grain could help reduce the overall starch hydrolysis of wheat grain products. Moreover, the wheat grain components have the potential to modify resistant starch sources to improve their functionality while retaining their slow digestion property. Also, utilising hydrocolloids to modify resistant starch sources could be an effective strategy to enhance the functionality of resistant starches in wheat-based systems. Modified resistant starches created using wheat solubles (soluble extracts from wheat flour and vital gluten) and hydrocolloids have potential applications with slow digestibility and improved functionality in wheat-based products.Item Value added wheat through applied genomic prediction : a genomic approach for breeding low gluten epitope wheat : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Breeding and Genetics at Massey University, Palmerston North, New Zealand. EMBARGOED until 24 July 2026.(Massey University, 2023) Macalister, JamieGluten epitopes are known to trigger coeliac disease (CD) in affected consumers and are believed to be linked to some cases of gluten intolerance. Research suggests that if consumers were exposed to wheat with reduced concentrations of gluten epitopes, the incidence of CD and gluten intolerance may be reduced. Methods have recently been developed allowing researchers to measure gluten epitope concentrations in wheat. This offers wheat breeders the potential to select towards varieties with lower epitope concentrations than existing cultivars. However, the methods for measuring epitope concentrations remain costly and time consuming. Therefore, it is proposed that a genomic based approach for breeding low epitope wheat lines is a more practical method than traditional phenotype-based selections. The genetic factors associated with epitope concentrations remain poorly understood. In this thesis, heritability estimates of between 0.37-0.93 are reported for concentrations of 6 distinct gluten epitopes. The associations between epitope concentrations and baking quality are also assessed and are shown to range from being near zero for some epitopes to strong positive correlations between other epitopes and particular baking quality characteristics. A Genome Wide Association Study and a model for genomic prediction are employed to determine the genetic factors associated with epitope concentrations. In these analyses, 3 significant genomic windows are identified as being associated with concentrations of 3 particular epitopes. Empirical prediction accuracies of between 0.16-0.53 are observed for predictions of epitope concentrations in a breeding population. Additionally, accuracies of between 0.37-0.67 are achieved by adjusting the population structure to represent the ideal circumstances that breeders would aim to achieve in their training and target populations. These results demonstrate that genomic selection (GS) will be an effective method for breeding low gluten epitope wheat. The outcome of this thesis will allow implementation of GS in the New Zealand Institute for Plant & Food Research wheat breeding program where epitope concentrations will be established as a new breeding target. This is expected to lead to the release of niche, low epitope cultivars with a value-add component that benefits growers, industry and consumers.Item Breakdown of rice and wheat-based foods during gastric digestion and its implications on glycemic response : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand(Massey University, 2022) Nadia, JoannaThe composition and structure of starch-based foods determine their breakdown behavior in the digestive tract and consequently their glycemic response. The glycemic response of starch-based foods is known to be influenced by their gastric emptying rate. However, the role of gastric digestion in regulating this process has not been well-understood, especially on how food breakdown behavior in the stomach may be related to the glycemic response. In this project, the link between food structure, food breakdown during gastric digestion, gastric emptying, and glycemic response was investigated in vivo using a growing pig model. Durum wheat- and white rice-based foods of varying physical structures (semolina porridge, rice- and wheat couscous, rice grain, rice noodle and wheat noodle/pasta) were studied. It was found that the foods with smaller-sized particles (semolina porridge and couscous products) had faster gastric breakdown rate and gastric emptying rate, resulting in higher glycemic impact (maximum change from the baseline and the overall impact) compared to the foods with larger-sized particles (rice grain and noodle products). The faster gastric breakdown rate of the smaller-sized foods was related to their acidification rate in the stomach, which caused their dilution or dissolution by gastric secretions. For larger-sized foods, their gastric breakdown rate and gastric acidification rate were slower, which extended their contact time with salivary amylase in the proximal stomach. To elucidate further the role of the proximal and distal phases of gastric digestion in solid food breakdown, a static in vitro digestion was conducted with the same food products. In the smaller-sized foods, both the proximal and distal phases led to their dissolution. Meanwhile, for the larger-sized foods, the extended contact time with α-amylase in the proximal phase contributed to the leaching of starch particles from the food, which was important to aid their breakdown during gastric digestion. The distal phase contributed to the softening of the larger-sized foods, but its softening effect was limited. The knowledge on the contributions of the phases of gastric digestion and the identified link between food structure, gastric digestion, and glycemic response in this thesis may be useful for structuring starch-based foods with controlled glycemic properties.Item Studies on lignification in wheat (Triticum aestivum var. Thatcher) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Botany at Massey University(Massey University, 1975) Le Gal, Patricia MargaretPART I Transections of the stem of Triticum were examined after staining with dyes specific for functional groups within the lignin polymer. Anatomical observations suggest that the basis for the rapid increase in the lignin content of this plant 35 to 40 days after germination, is the differentiation of subepidermal sclerenchyma fibres in the stem at this time. The lignin formed in the fibre walls appears to have a higher methoxyl content than the lignin of the xylem vessels. A comparison of the development of lignification with stem elongation and flowering was made and the interrelationship of these processes discussed. PART II The role of p-hydroxyphenyllactic acid in lignification in wheat was investigated. ¹⁴C-labelled tyrosine, p-hydroxyphenyllactic acid (HPLA), and ³H-labelled HPLA were administered separately to the cut ends of shoots of Triticum and the incorporation of label into ethanol-soluble and ethanol-insoluble ferulic (and in some cases only, p-hydroxycinnamic) acid was measured. On the basis of the pattern of incorporation of label from the ¹⁴C-tyrosine, experiments were carried out to determine the route by which HPLA is converted to lignin precursors. A failure to detect label from ³H-HPLA in the cinnamic acids suggests that HPLA is not dehydrated directly to p-hydroxycinnamic acid and is not of regulatory significance in lignification in either 10 or 40 day-old wheat plants. PART III Information from several levels of organization within the plant is drawn together and discussed. Suggestions for further work investigating the controlling factors in lignification are included.Item Seed quality and storage performance of wheat (Triticum aestivum.) and Soybean (Glycine max (L) Merrill) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agriculture Science in Plant Science (Seed Technology) at Massey University, Palmerston North, New Zealand(Massey University, 1996) Singkanipa, VarenyaFive seedlots of wheat (Triticum spp.)cvs. Norseman. Otane, Karamu and two unknown cultivars. and four seedlots of soybean (Glycine max (L) Merrill)cv. Davis, two seedlots of cv. CH187 and one unknown cultivar were assessed for prestorage quality by using different laboratory methods ie purity, thousand seed weight, seed moisture content, germination, accelerated ageing, conductivity and seed health. The results of this study showed quality differences between seedlots of both wheat and soybean. Using seed germination and vigour data, three lots of wheat with high quality, two seedlots of soybean with high quality and one seedlot with low quality were chosen and adjusted to two different seed moisture contents (10% and 14% in wheat .and 8% and 12% in soybean). Seed samples of both species were stored in open storage (muslin bags) or sealed storage (aluminium foil packets) at 20°c 75%RH or 30°c 50% RH for 8 months. All wheat seedlots and two soybean seedlots were also stored under open storage at 30°c 95%RH. Seed quality was assessed at intervals of 1,2,4, 6 and 8 months. The seed moisture content of both species in open storagechanged to reach equilibrium moisture content (EMC) with the prevailing relative humidity. At 30°c 95%RH moisture content of wheat and soybean seeds increased up to 18.5-20.5% and 22-23%. respectively while at the same temperature but lower RH (50%), SMC fell to 8.2-8.5% and 5.2-5.5%, respectively. Both low and high initial SMC of seed stored at 20°c 75%RH either increased or decreased to reach an EMC of 12.8-13.6% for wheat and 9.8-10.1% for soybean. Under sealed storage at different storage temperatures and relative humidities SMC did not change from initial levels. At 20°c 75%SMC the type of storage container had no significant effect on germination percentage or conductivity in wheat and soybean after 8 months. At 30°c, however, the germination percentage of wheat and soybean with high initial SMC in sealed storage and in open storage high RH declined more rapidly during storage than the other treatments. Germination percentage correlated reasonably well with conductivity, with conductivity readings increasing as vigour decreased. At 30°c 95% both open and sealed storage at high initial SMC resulted in seed showing a conductivity value increase with longer storage time, indicating seedlot deterioration. All field fungi were eliminated from seed open stored at 30°c 95% but storage fungi developed rapidly in all seedlots after two months. The main genus involved was Aspergillus spp. but Penicillium spp. were also found at low levels in soybean. However, under 30°c 50%RH and 20°c 75%RH storage conduction field ftingi levels in wheat and soybean were reduced during storage and seed was either disinfected or remained infected at only low levels after 8 months storage. The main field fungus present in wheat was Fusarium spp.. In soybean both Fusarium spp. and Alternaria spp. survived well along with low levels of Colletotrichum spp.. The implications of pre-storage seed quality, seed moisture levels and storage environment and their effects on seed deterioration rate and extent are discussed. The role of field and storage fungi in affecting loss of seed viability in storage and the possibility of exploiting the storage environment to obtain pathogen free seed for planting is also considered.Item A study of the aggregate supply function of New Zealand wheat : thesis presented in part fulfilment of the requirements for the degree of Master of Agricultural Science and Honours in the University of New Zealand(Massey University, 1955) Candler, WilfredThe acreage of wheat in New Zealand fluctuates quite markedly from year to year. The acreage grown depends upon economic conditions at the time of planting and certain technical factors. In this thesis an attempt has been made to identify the specific influence of certain of these economic and technical variables. Reducing the discussion to its simplest terms, the aim of this thesis has been to answer such questions as: "What is the effect on wheat acreage of 1d rise in the price of wheat?" or "If the fat lamb schedule next year is 1/3d per lb. , what will the effect on wheat acreage be?" or "Given such and such conditions, what is the best estimate of the acreage which will be sown in wheat?" and 'What conditions are necessary in order that New Zealand should produce 100,000/200,000/300,ooo acres of wheat?" Answers to these questions are useful on two counts. Passively, administrators will wish to forecast domestic production when making arrangements to import wheat; and acreage has a big influence on production. Actively, administrators, or the Government, may wish to influence production and answers to the above questions will tell them the conditions under which this may be done. [From Introduction]Item Root growth and crop yield of two varieties of wheat grown under differing irrigation regimes : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science at Massey University(Massey University, 1974) Piggot, Graeme JamesRoot growth and crop yield of Gamenya, a standard height variety, and Karamu, a semi-dwarf, spring wheat were compared under 3 irrigation regimes: daily watering; infrequent (fortnightly) watering; and sub-irrigation, where water was introduced into the soil profile at 40cm, the plots being protected from rainfall. Root growth and development were similar between varieties apart from an indication that the Karamu root system was more extensive at depth. The three irrigation treatments grew distinctly different root systems which was probably due partly to soil compaction differences between the treatments rather than the spatial distribution of the soil water supply. Karamu outyielded Gamenya because of a higher grain weight per ear due to higher floret viability and greater grain weight. Yield differences between irrigation treatments, where the infrequently irrigated treatment was superior, was due to ear population differences related to the differing root systems. With daily irrigation Gamenya used more water, due possibly to the lower leaf water potentials developed in the crop. An inverted water potential difference between the ear and the flag leaf was observed during the middle of the day.Item Genotypic variation of dormancy in wheat (Triticum aestivum L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science, Department of Plant Science, Massey University, Palmerston North, New Zealand(Massey University, 1996) Zvomuya, NormanEmbryo dormancy and α - amylase dormancy are desirable in wheat to minimise pre-harvest sprouting damage. The current work focuses on the embryo and graincoat colour. A loose association between grain redness and dormancy in wheat is common knowledge. But the causal relationships between colour and dormancy are not clear and need to account for dormancy variability in the gene - pool. The study's working hypothesis was that colour formation triggers hypo - oxia synthesis of ABA (vs. gibberellins) which triggers dormancy if the timing with embryo development is optimal. Development profiles for eight attributes (including dormancy) of grain were investigated from five white and five red wheat cultivars representing a wide genetic base. Tagged ears were sampled from pollination to harvest ripeness (days after pollination to 12.5% moisture). All the white - grained cultivars did not have dormancy at harvest ripeness, and there was considerable variation of dormancy levels in the red - grained cultivars. The total-grain abscisic acid was not associated with redness nor dormancy, and no evidence of ABA sensitivity could be found in cv. Brevor. The failure to detect the putative dormancy of cvs. Brevor and Kenya 321 was probably due to fine detail employed in the present work, but may also have been due to the single ripening environment used. Base α amylase and flavanol levels did not contribute to the variation in embryo dormancy. Gibberellic acid insensitivity in the Rht/Gai genotypes was not expressed in terms of embryo dormancy. Examination of the profiles suggested that redness was necessary to permit dormancy, but that dormancy timing was independent of colour. This led to varying levels of dormancy at harvest ripeness. No association with ABA was evident, nor with colour precursor. However timing and duration of polymerisation (flavanol) development (hypo-oxia) did show a weak association with dormancy delay and level. The new hypothesis suggests that colour formation hypo-oxia permits dormancy, but that its timing is flexible with respect to harvest ripeness. Broader genetic control (other than the Redness gene) is indicated. Heritability estimates indicated that timings, rather than levels, are more useful selection criteria. This included embryo dormancy attributes, colour, and harvest ripeness. For plant breeders it suggested that grain sampled at harvest ripeness could be selected for dormancy as measured in this study.Item Effects of genotype and environment on the sprouting propensity and other grain characters of wheat (Triticum aestivum L.): a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Plant Science at Massey University(Massey University, 1977) Cross, Richard J.Sprouting damage nay occur when wet weather initiates germination processes in unharvested grain, with subsequent deterioration in breadmaking quality. It is a potential hazard to wheat growing regions throughout the world, e.g. Europe (Olered, 1967; Belderok, 1968), Australia (Moss, et al., 1972) and New Zealand (Sanders, 1974; McEwan, 1976a). Seed dormancy is usually accepted as being related in some way to resistance to sprouting damage (e.g. Belderok, 1968a); that is, dormancy may be associated with lack of catabolic processes in the endosperm (Ching, 1972; Leshem, 1973; Villiers, 1972). Several enzymes initiated during the germination process are involved in the degradation of the starch and protein of the endosperm. These enzymes include alpha-amylase, which break the branch chain amylopectin starch molecules to dextrins and amylases, and beta-amylase which degrade these smaller compounds to low molecular weight dextrins and maltose (Kent-Jones and Amos, 1967; Pyler, 1969). Beta-amylase is present in the sound grain but its activity is restricted, as there are relatively few exo-groups at which this enzyme is capable of hydrolysing (Kent-Jones and Amos, 1967; Pyler, 1969). Alpha-amylase appears a major factor in starch dextrinisation, and levels of this enzyme relate to the degree of sprout damage (Johansson, 1976; Olered, 1967; Moss et al., 1972). Other enzymes may also be involved in early germination, such as proteolytic enzymes (Gordon, 1975; Kruger, 1976). In sprout damaged wheat, the increased level of starch dextrinisation results in an inferior loaf (Olered, 1967; Pyler, 1967; Moss et al., 1972). The loaf is reduced in volume, has a grey and sticky crumb, and a dark crust colour (Olered, 1967; Kent-Jones and Amos, 1968; Pyler, 1969; McDermott, 1971). Sprout damaged grain may also have a lighter bushel or test weight (Ghaderi and Everson, 1971; Fouler and de la Roche, 1975), and lowered milling yield (Belderok, 1968; McEwan, 1959). [From Introduction]Item Dormancy in wheat grain (Triticum aestivum L.) : studies on grain-coat pigment formation and abscisic acid content during the development of wheat grain of six genotypes : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Botany at Massey University(Massey University, 1978) Verry, Isabelle MarjorieDormancy in wheat grain has been associated with red pigmentation of the grain-coats. The development from anthesis to harvest-ripeness of two-white-grained and four red-grained genotypes of varying dormancy was investigated. Grain growth was measured as changes in fresh weight and dry matter. Dehydration to harvest-ripeness (17.5% moisture) was calculated. The developmental rates of grain of the six genotypes were similar. Dormancy-breaking germination tests showed that embryo maturity was attainted at similar stages of development of four genotypes. It appeared to be somewhat delayed in two red-grained genotypes, which also had the lowest germination rates in standard germination tests. Dormancy was estimated as the percentage of grains with mature embryos, which did not germinate in the standard germination tests. Grain of all the genotypes had a period of dormancy during development. However, in white-grained genotypes it had disappeared before harvest-ripeness was attained and it lasted only a little longer in one of the red-grained genotypes. In the other three red-grained genotypes, dormancy was prolonged for at least several weeks beyond harvest-ripeness. The concentrations of flavonoid precursors were similar in grains of all six genotypes throughout their development. Assays of crude extracts of a group of enzymes (phenolases) involved in pigment synthesis did not reveal peaks of activity associated with the appearance of mature grain-coat colour. Successive extractions of the grains showed that the pigment was probably a large flavonoid polymer. The amounts of endogenous abscisic acid in developing grains was analysed by high pressure liquid chromatography. Significant quantities of the 2-trans isomer, as well as of the common 2-cis isomer (abscisic acid) were found. The amounts did not appear to be related to either dormancy or to maturation and dehydration of the grain, as had been suggested. The mechanisns prolonging dormancy beyond harvest-ripeness in wheat grain were discussed with reference to pigmentation. It was considered that dormancy of the red-grained wheats was probably due to impermeability of the grain-coat to oxygen, possibly resulting from molecular properties of the pigment. These properties were the ability to absorb oxygen, which might prevent it reaching the embryo, and the ability to complex with the large proteins of the immature testa, which might prevent their degradation during grain development. During imbibition the complexed proteins might swell to create a physical barrier to oxygen permeation.
