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The objective of this study was to investigate the effect of starch debranching followed by differential ethanol precipitation on the formation and in vitro fermentation of starch-lipid complexes. Three groups of linear glucan chains, with a degree of polymerization (DP) of 383∼2950, 37∼75, and 3∼8, were obtained after debranched maize starch (DMS) was fractionated by differential ethanol precipitation. The glucan fraction with DP 383∼2950 formed only type II

The effect of extracts from four types of tea made from Camelia sinensis (green, white, black, and oolong) on in vitro amylolysis of gelatinized starch and the underlying mechanisms were studied. Of the four extracts, black tea extract (BTE) gave the strongest inhibition of starch digestion and on α-amylase activity. Fluorescence quenching and surface plasmon resonance (SPR) showed compounds in BTE bound to α-amylase more strongly than those in the green, white, and oolong tea extracts. Individual testing of five phenolic compounds abundant in tea extracts showed that theaflavins had a greater inhibitory effect than catechins on α-amylase. SPR showed that theaflavins had much lower equilibrium dissociation constants and therefore bound more tightly to α-amylase than catechins. We conclude that BTE had a stronger inhibitory effect on in vitro enzymatic starch digestion than the other tea extracts, mainly due to the higher content of theaflavins causing stronger inhibition of α-amylase.

The aim of the present study was to reveal the mechanisms underlying the formation of ternary complexes with a model system of amylose (AM), lauric acid (LA), and β-lactoglobulin (βLG) using experimental studies and molecular dynamics (MD) simulations. Experimental analyses showed that hydrophobic interactions and hydrogen bonds contributed more than electrostatic forces to the formation of the AM-LA-βLG complex. MD simulations indicated that interactions between AM and βLG through electrostatic forces and hydrogen bonds, and to a less extent van der Waals forces, and interactions between AM and LA through van der Waals forces, were mostly responsible for complex formation. The combination of experimental results and MD simulations has provided new mechanistic insights and led us to conclude that hydrophobic interactions, van der Waals forces between AM and LA, and van der Waals forces and hydrogen bonds between AM and βLG were the main driving forces for the formation of the AM-LA-βLG complex.

Granular starch octenyl succinic anhydride (OSA) esters have most often been prepared in aqueous media, resulting in low reaction efficiencies and degree of substitution. In this study, granular ma...

Structure-function relationships of starch isolated from eight cultivars of foxtail millets grown in China were investigated. The starch granules were polygonal with diameters between 5 μm and 10 μm. The amylose content ranged from 16.8% to 26.8%, and the relative crystallinity and the full width at half maximum (FWHM) of the Raman band at 480 cm−1 varying between 33.2% and 36.4% and 15.72 to 15.91, respectively. There were only small differences in amylopectin chain length distribution of the eight foxtail millet starches. Significant differences were noted in swelling power, gelatinization, pasting, gel textural properties of starches, but not in vitro enzymic digestibility. Correlation analysis results showed that amylose content and chain length distribution of amylopectin were more important determinants of functional properties of starch than the structural order of the starch granules.

Physical interactions often occur between major food components during food processing. These interactions may involve starch, lipids, and proteins forming V-type starch-lipid complexes or ternary starch-lipid-protein complexes of larger molecular size and greater structural order. Complexes between starch and lipids have been the subject of intensive research for over half a century, whereas the study of starch-lipid-protein complexes is a relatively new field with only a limited amount of knowledge being gained so far. The formation of these complexes can significantly affect the functional and nutritional properties of finished food products in terms of flavor, texture, shelf life, and digestibility. This article provides a comprehensive review of starch-lipid and starch-lipid-protein complexes, including their classification, factors affecting their formation and structure, and preparative and analytical methods. The review also considers how complexes affect the physicochemical and functional properties of starch, including digestibility, and potential applications in the food industry.

Starch is a major part of the human diet and an important material for industrial utilization. The structure of starch granules is the subject of intensive research because it determines functionality, and hence suitability for specific applications. Starch granules are made up of a hierarchy of complex structural elements, from lamellae and amorphous regions to blocklets, growth rings and granules, which increase in scale from nanometers to microns. The complexity of these native structures changes with the processing of starch-rich ingredients into foods and other products. This review aims to provide a comprehensive review of analytical methods developed to characterize structure of starch granules, and their applications in analyzing the changes in starch structure as a result of processing, with particular consideration of the poorly understood short-range ordered structures in amorphous regions of granules.

The present study investigated the effect of octenyl succinic anhydride (OSA) modification of starch on the formation of starch-lipid complexes. The complexing index (CI) showed that native maize starch (NMS) formed more complexes with monopalmityl glycerol (MPG) than with palmitic acid (PA), whereas dipalmityl glycerol (DPG) was not effective in forming complexes with NMS. After OSA modification, the complexation between OSA-starch and lipids was greatly enhanced, especially for PA and DPG, and the CI values increased from 79.6 to 93.3% for OSA-starch-PA and from 80.3 to 93.2% for OSA-starch-DPG complexes with increasing DS of OSA-starch. Structural analyses showed that OSA-starch-lipid complexes had higher degrees of long- and short-range molecular orders than the corresponding NMS-lipid complexes. This study showed for the first time that DPG can form complexes with OSA-starch, which was attributed to the increased dispersion of DPG in water by the emulsifying ability of OSA-starch. The finding is of great significance for a better understanding of the formation of starch-lipid complexes.

The effect of the anionic structure of ionic liquids (ILs) and water/IL ratio on the dissolution behavior of maize starch at room temperature (22-23 °C) was investigated. The ILs used were 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), 1-ethyl-3-methylimidazolium formate ([C2mim][HCOO]), and 1-ethyl-3-methylimidazolium acetate ([C2mim][CH3COO]). The structural analysis indicated that the long- and short-range molecular order in the starch after treatment with water/[C2mim][Cl] and water/[C2mim][HCOO] mixtures decreased with the decreasing water/IL ratio from 10:1 to 2:1 and was completely disrupted at the 2:1 ratio. However, the ordered structure of starch was disrupted completely in the water/[C2mim][CH3COO] ratio of 5:1. The disruption extent of starch structures followed the order: [C2mim][CH3COO] > [C2mim][HCOO] > [C2mim][Cl] at water/IL ratios of 10:1 and 5:1, but the opposite was observed at lower water/IL ratio (2:1). Our results clearly showed that both the nature of the anion and water/IL ratio affected the dissolution behavior of maize starch. The hydrogen bonding capacity of IL anions and viscosity of water/IL mixtures were proposed to play the key roles in the structural disruption of starch. These findings would be of great importance for rationally designing "green and sustainable" processes for the utilization of promising natural biopolymers.

Potato starch was pre-treated with CaCl2 solutions prior to modification with octenyl succinic anhydride (OSA). Starch pre-treated with 1.0 M CaCl2 showed higher degree of substitution (DS) and reaction efficiency (RE) on OSA modification, whereas pre-treatment with CaCl2 solutions at 0.05 M, 0.1 M and 0.5 M had no effect on DS and RE. CaCl2 pre-treatment decreased the swelling power, paste clarity, peak viscosity (PV), breakdown (BD) and some textural parameters of potato starch, with the effects being greater at higher concentrations of CaCl2. Pre-treatment with 1.0 M CaCl2 caused a small disruption to starch crystallinity and granule morphology. OSA modification significantly decreased the textural parameters, PV, BD, relative crystallinity, swelling power, gelatinization temperatures and enthalpy of potato starch, but it increased the paste clarity and emulsifying activity. OSA-1.0 M-starch showed improved functional properties over OSA-starch, indicating that CaCl2 pre-treatment provides advantages for improving the functional characters of succinylated starch.

The purpose of this study was to understand the dissolution behavior of maize and potato starches in 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]):water mixtures at room temperature. With an increasing ratio of ionic liquid (IL):water, the long- and short-range ordered structures and granule morphology of both starches were disrupted progressively. The multiscale structure of maize starch was disrupted completely after treatment with the [Emim][OAc]:water mixture of 6:4, indicating good dissolution performance of this mixture for maize starch. This mixture seemed to provide a balance between the viscosity of the solvent and availability of ions to disrupt starch H-bonds. The different dissolution behaviors of maize and potato starches in [Emim][OAc]:water mixtures were attributed to structural differences of the granule surfaces. Our results showed that the dissolution behavior of starches was affected by both starch sources and properties of [Emim][OAc]:water mixtures, which may provide guidance for the development of green technology for processing of biopolymers with low energy consumption.

The dissolution behavior of maize starch in water:ionic liquid (IL) mixtures at ambient temperature (22–23 °C) was studied. The ionic liquids used were 1-butyl-3-methylimidazolium chloride ([C4 mim][Cl]), 1-propyl-3-methylimidazolium chloride ([C3 mim][Cl]), and 1-ethyl-3-methylimidazolium chloride ([C2 mim][Cl]). Structural analyses indicated that long- and short-range molecular order in the starch decreased with decreasing water:IL ratio. At water:IL ratios of 10:1 and 5:1, the extent of disruption of starch structure followed the order [C4 mim][Cl] > [C3 mim][Cl] > [C2 mim][Cl]. At lower water:IL ratio (2:1), the complete disruption of starch granule morphology and ordered structures in water:[C3 mim][Cl] and water:[C2 mim][Cl] mixtures indicated these mixtures were more effective in dissolving starch than water:[C4 mim]Cl mixture. Results from rheological, FTIR, and 1H NMR analyses of water:IL mixtures showed that as water:IL ratio decreased, the viscosity of solutions increased, the interaction betwe...

The effect of extracts from four types of tea made from

Evidence for plants rarely survives on Paleolithic sites, while animal bones and biomolecular analyses suggest animal produce was important to hominin populations, leading to the perspective that Neanderthals had a very-high-protein diet. But although individual and short-term survival is possible on a relatively low-carbohydrate diet, populations are unlikely to have thrived and reproduced without plants and the carbohydrates they provide. Today, nutritional guidelines recommend that around half the diet should be carbohydrate, while low intake is considered to compromise physical performance and successful reproduction. This is likely to have been the same for Paleolithic populations, highlighting an anomaly in that the basic physiological recommendations do not match the extensive archaeological evidence. Neanderthals had large, energy-expensive brains and led physically active lifestyles, suggesting that for optimal health they would have required high amounts of carbohydrates. To address this anomaly, we begin by outlining the essential role of carbohydrates in the human reproduction cycle and the brain and the effects on physical performance. We then evaluate the evidence for resource availability and the archaeological evidence for Neanderthal diet and investigate three ways that the anomaly between the archaeological evidence and the hypothetical dietary requirements might be explained. First, Neanderthals may have had an as yet unidentified genetic adaptation to an alternative physiological method to spare blood glucose and glycogen reserves for essential purposes. Second, they may have existed on a less-than-optimum diet and survived rather than thrived. Third, the methods used in dietary reconstruction could mask a complex combination of dietary plant and animal proportions. We end by proposing that analyses of Paleolithic diet and subsistence strategies need to be grounded in the minimum recommendations throughout the life course and that this provides a context for interpretation of the archaeological evidence from the behavioral and environmental perspectives.

The objective of this research was to compare the in vitro fermentability of three resistant starches (RS2, RS3, and RS5). Structural analyses showed that there were small changes in the long- and short-range ordered structure of three RSs after fermentation by human gut microbiota. The fermentation of RSs by gut microbiota produced large amounts of short-chain fatty acids, with RS5 producing more butyric acid and RS3 producing more lactic acid. RS3 and RS5 decreased the pH of the fermentation culture to a greater extent compared with RS2. Moreover, RS5 increased significantly the relative abundance of Bifidobacterium, Dialister, Collinsella, Romboutsia, and Megamonas. The results suggested that the form of RS was the main factor affecting the physiological function of RS and that RS5, as a recently recognized form of resistant starch, could be a better functional ingredient to improve health compared with RS2 and RS3.

In this study, the effects of debranching on the structure and properties of the starch-lauric acid (LA)-β-lactoglobulin (βLG) complex were studied. Gel permeation chromatography and high-performance anion-exchange chromatography showed that debranching of amylopectin generated short linear chains, which increased in proportions with debranching time. Analyses from differential scanning calorimetry, laser confocal micro-Raman spectroscopy, and X-ray diffraction showed that debranching promoted the formation of starch-LA and starch-LA-βLG complexes, as characterized by the increased enthalpy changes and crystallinity and decreased full width at half maximum of the band at 480 cm-1. Debranching treatment for 6 and 18 h promoted complexation between starch and LA, while extensive debranching was unfavorable for the formation of starch-LA complexes. Similar results were also observed for the starch-LA-βLG complexes. Starch-LA-βLG complexes had more type II and less type I crystallites than starch-LA complexes. From this study, we conclude that debranching of starch favors the formation of starch-LA and starch-LA-βLG complexes, with more type II crystallites formed in starch-LA-βLG complexes.

The impact of the COVID-19 pandemic on the food system has exposed the vulnerabilities of the supply chain, although the extent of disruption varies widely, globally and in Asia. However, food systems in Asia have been proven relatively resilient when compared with other regions. This paper considers the immediate effects of the COVID-19 pandemic on the food system, particularly in Asia, and initial responses of governments and global agencies to manage the crisis. A major focus of the paper is on the outlook for food system resilience in a post-COVID-19 environment and likely long-term effects of the pandemic. There is always a possibility of such shock events occurring in the future, hence it seems prudent to look at lessons that may be learned from the responses to the current pandemic.

The effect of interactions between beta-lactoglobulin (βLG) and lauric acid (LA) on the formation of ternary maize starch-LA-protein complexes was investigated. Analysis of the secondary structure of βLG by FTIR and changes in fluorescence λmax and intensity indicated that βLG and LA interacted during heating and cooling in a Rapid Visco Analyser (RVA). Results from RVA, DSC and Raman spectroscopy analyses showed that increasing the concentration of βLG from 25 to 200 mg increased the amount of ternary starch-LA-βLG complexes formed. There was little difference in the amounts of the ternary complexes formed when the amount of βLG was 25–150 mg, but a greater amount of starch-LA-βLG complexes was formed when 200 mg of βLG was pre-mixed with LA. From this study, we concluded that prior interaction between βLG and LA had no significant effect on the formation of ternary starch-LA-βLG complexes.

The effects of cooking and storage on the structure and in vitro enzymatic digestibility of complexes formed between fatty acids and debranched high-amylose starch (DHA7-FA) were investigated for the first time. Cooking greatly decreased the crystallinities of DHA7-lauric acid (LA) and DHA7-myristic acid (MA) complexes but had little effect on the crystallinities of DHA7-palmitic acid (PA) and DHA7-stearic acid (SA) complexes. Cooking increased the enthalpy-change (Δ H) values and short-range molecular orders of DHA7-FA complexes. Cooking decreased the in vitro enzymatic digestibility of DHA7-FA complexes, with the extent of the effect decreasing with increasing fatty acid chain length. Holding the samples at 4 °C for 24 h after cooking did not greatly affect the long- and short-range molecular orders nor the in vitro enzymatic digestibility of DHA7-FA complexes. From this study, we conclude that cooking disrupted the long-range crystalline structures of DHA7-LA and DHA7-MA complexes but enhanced the short-range molecular orders of all of the DHA7-FA complexes. The latter effect accounted mainly for the reduced in vitro enzymatic digestibility of DHA7-FA complexes.

This study aimed to understand mechanisms of starch gelatinization during heating of wheat (Triticum aestivum L.) flour, and its effects on in vitro starch amylolysis of cooked wheat flour. At water content of 20%, cooking did not disrupt greatly the crystalline structures of starch in wheat flour. Considerable disruption of ordered structures of starch occurred with cooking at a water content of 30%, and starch was fully gelatinized at a water content of 40%. The transition of the X-ray diffraction pattern from A to V types with increasing water content suggested the formation of starch-lipid complexes during cooking of flour. Typical starch pasting profiles of cooked wheat flour were observed at water contents of 40 and 50%, whereas longer cooking time decreased the pasting viscosities of the flour. Cooking the flour for only 5 min with 20% water greatly increased the rate and extent of in vitro enzymatic digestion of starch, which were not increased further by longer cooking or higher water content. From this study, we conclude that the progression of starch gelatinization during cooking was not greatly affected by non-starch components in wheat flour, and that some structural order in amorphous regions of starch contributed to the development of pasting viscosities.

Dental calculus is now widely used to recover information on items ingested in the past. It is particularly valuable in the earlier Paleolithic, where recovered data may represent the only evidence for plant use. Several recovery methods are used and each one produces different results. Biomolecular markers and genetic material recovered from dental calculus is providing new data on identifiable dietary and medicinal items and human microbial communities. The recovery of microfossils, in particular, starch granules, has triggered a new awareness of the role of plants in the diet throughout the Paleolithic. However, the minute amount of material recovered has little relationship with food eaten during a person's life, while salivary amylase breaks down cooked starch. Therefore, broader dietary interpretations and detection of cooked food are problematic. The study of ancient dental calculus holds great potential to recover information about past lives, within realistic parameters.

The nature of phase transitions of waxy maize starch heated in mixtures of water and ionic liquid (IL) was elucidated using a variety of analytical methods. The transition from a single endotherm to an exotherm followed by an endotherm, and then to a single exotherm was observed with the increasing concentration of IL. The results showed that at To of DSC phase transition no structural disruption had occurred. Except for the water/IL ratios of 1.5:1 and 1:1, there was considerable structural disruption of starch samples that were preheated to Tp or Tp2 of gelatinization transition. No residual structural order was observed at Tc of the gelatinization transition. An exothermic transition at water:IL ratios of 3:1 and 2:1 was attributed to the interaction of ionic liquid and amorphous regions in starch. The molecular disassembly of starch granules during gelatinization in different water:IL mixtures proceeded to completion at different rates.

The effect of water content and particle size on physicochemical properties and in vitro starch digestibility of three milled wheat fractions was investigated. The crystallinity of three milled fractions of particle sizes

Wild rice species represent valuable germplasm for breeding of elite genotypes with enhanced resistance to biotic and abiotic stresses. However, differences in endosperm morphology between wild and cultivated rice, and how these are affected by enhanced levels of atmospheric CO2 (eCO2) predicted for later this century, are largely unknown. Accessions of native rice species from northern Australia, Oryza australiensis and O. meridionalis, and a local cultivar, O. sativa cv. Doongara, were grown to maturity in glasshouses at ambient (aCO2, 400 ppm) and eCO2 (700 ppm). Endosperm morphology was studied from transverse sections of mature grains using scanning electron microscopy. Aleurone cell length and width were higher in eCO2 than in aCO2 in the O. meridionalis accession Howard Springs, but lower in Doongara. The average starch granule size in Doongara was greater than in the wild genotypes in both CO2 treatments. The area and length of the starch granule images were larger in eCO2 than in aCO2 in the O. meridionalis accession Cape York but smaller in Doongara. Responses of rice endosperm morphology to eCO2 were dependent on genotype. We conclude that endosperm morphology responds differentially to eCO2, both between and within rice species. Contrasts in these responses can be exploited by breeders.

The effects of chain length and degree of unsaturation of fatty acids (FAs) on structure and in vitro digestibility of starch-protein-FA complexes were investigated in model systems. Studies with the rapid visco analyzer (RVA) showed that the formation of ternary complex resulted in higher viscosities than those of binary complex during the cooling and holding stages. The results of differential scanning calorimetry (DSC), Raman, and X-ray diffraction (XRD) showed that the structural differences for ternary complexes were much less than those for binary complexes. Starch-protein-FA complexes presented lower in vitro enzymatic digestibility compared with starch-FAs complexes. We conclude that shorter chain and lower unsaturation FAs favor the formation of ternary complexes but decrease the thermal stability of these complexes. FAs had a smaller effect on the ordered structures of ternary complexes than on those of binary complexes and little effect on enzymatic digestibility of both binary and ternary complexes.

There is evidence that moderate coffee consumption is beneficial in the prevention of type 2 diabetes, however, the underlying mechanism is not understood. In this study, the effects of an extract of ground coffee on the in vitro enzymatic digestion of starch were investigated. The coffee extract decreased the rate and extent of starch digestion, with kinetic analysis showing that the extract reduced the binding affinity of the enzymes for the substrate and their catalytic turnover. Fluorescence quenching indicated that the coffee extract formed complexes with the digestive enzymes through a static quenching mechanism. Ultraviolet absorption and circular dichroism spectra of the digestive enzymes confirmed that the coffee extract decreased the proportion of β-sheet structures in the enzymes. Therefore, we conclude that compounds in the soluble coffee extract can interact with porcine pancreatic amylase and amyloglucosidase causing inhibition of the enzymes and decreasing in vitro starch digestion.

This study aimed to reveal the mechanism of formation of complexes between native maize starch (NMS) and different types of lipids, namely palmitic acid (PA), monopalmitate glycerol (MPG), dipalmitate glycerol (DPG), and tripalmitate glycerol (TPG). The complexing index followed the order of MPG (96.3%) > PA (41.8%) > TPG (8.3%) > DPG (1.1%), indicating that MPG formed more complexes with NMS than PA, and that few complexes were formed between NMS and DPG and TPG. The NMS-PA complex presented higher thermal transition temperatures and lower enthalpy change than the NMS-MPG complex, indicating that although MPG formed more starch complexes, they had less stable crystalline structures than the complex between NMS and PA. X-ray diffraction (XRD) and Raman spectroscopy showed that both MPG and PA formed V-type crystalline structures with NMS, and confirmed that no complexes were formed between NMS and DPG and TPG. We conclude that the monoglyceride formed more starch-lipid complex with maize starch than PA, but that the monoglyceride complex had a less stable structure than that formed with PA. The di- and triglycerides did not form complexes with maize starch.

This study evaluated the effects of different cooking methods on in vitro starch digestibility of three rice varieties. Results from differential scanning calorimetry and X-ray diffraction of cooked rice flours showed that rice starch was completely gelatinized after cooking. The overall paste viscosities of cooked indica hybrid flour (IHF) and japonica flour (JF) were lower than those of their corresponding raw flours. However, cooked waxy flour (WF) showed much higher paste viscosities than raw flours, especially the viscosity at the start of RVA testing. Cooking increased greatly the rate and extent of starch digestion of IHF and JF, but had a small effect on WF. There were small differences in rate and extent of starch digestion of rice after cooking under various conditions. Cooking methods were found to have little effect on in vitro starch digestibility of rice. Viscosity of the gelatinized waxy starch matrix affected in vitro starch digestibility. This study enables us to gain a better understanding of cooking effects on in vitro digestibility of starch in rice flour.

The effects of starch damage and yeast fermentation on the formation of acrylamide in wheat bread were studied. Four wheat cultivars were milled separately by three laboratory mills to obtain wheat flours with damaged starch content ranging from 1.7 to 6.6%. Reducing sugar contents increased with increasing damaged starch content in flour. Yeast fermentation decreased greatly the content of asparagine by 40–60% in the dough, but increased substantially the content of reducing sugar. Compared with the unleavened bread, dough fermentation significantly decreased the content of acrylamide in leavened bread. The content of acrylamide in bread increased with increasing damaged starch content in wheat flours from the same cultivar. This study clearly showed that damaged starch content in wheat flour and dough fermentation are two major determinants of the formation of acrylamide in bread. The mitigation of acrylamide formation in bread can be achieved by reducing damaged starch in flour and by fermentation of the dough.

This chapter considers the digestibility of starch in relation to its nutritional qualities and influences on human health. Rapidly digested starch (RDS) is associated with poor postprandial glycaemic and insulinemic control. Excessive dietary exposure over the long term increases the risks for obesity and diet-related illnesses. Slowly digested starch (SDS) moderates these postprandial responses and has a key role in producing satiety and limiting food intake. Starch that is not digested in the upper human gut is a good source of fermentable food for the gut microbiota, which are now recognised as having an essential role in the health of the host.

This chapter presents a brief overview of key discoveries that led to our current knowledge of starch. Due to the variability of natural starch, and the significance of this biopolymer to humans in foods and industrial applications, much attention has been given to gaining an understanding of its structure and functional properties. Early uses for starch are considered, as are developments in the growth of the starch industries, and how the molecular structure of starch was revealed.

The interaction of polyphenolic catechins from Camellia sinensis tea with α-amylase, and the effects of the interactions on the kinetics of starch amylolysis, were investigated. Binding studies using surface plasmon resonance (SPR) and enzyme kinetic analysis indicated that the in vitro digestibility of gelatinized wheat starch was decreased by the addition of catechins present in tea. Tea catechins decreased enzyme activity by reducing the maximum velocity (Vmax) of the α-amylase, but had little effect on the Michaelis-Menten constant (Km). Binding studies by SPR showed that the structure of the catechins influenced their affinity for α-amylase. Pearson correlation analysis showed that the decreased digestibility of starch in the presence of catechins was due to their binding of α-amylase interaction inhibiting the catalytic effectiveness of the enzyme. From this study, we concluded that the faster and stronger the binding of catechins and α-amylase, the greater reduction of starch digestion is.

Interspecific germplasm from wild species of Oryza will be increasingly applied to breeding programs over the coming decades. However, the concurrent impact of rising atmospheric CO2 concentrations (atm-CO2) on grain properties is unknown. Wild accessions of Australian native rice species (Oryza australiensis and O. meridionalis) and the local cultivar (O. sativa cv. Doongara) were grown to maturity in glasshouses at ambient (400 ppm; aCO2) and elevated (700 ppm; eCO2) atm-CO2 and physicochemical properties of the grains were compared. Seed length (Sl), seed width (Sw) and 1000-seed weight (TSW) were higher at eCO2 than aCO2, while nitrogen content (N) and apparent amylose content (AC) were not significantly changed, irrespective of genotype. Rapid viscosity analyser (RVA) profiles revealed increased peak viscosity (PV) for rice under eCO2, indicating differences in starch gelatinization. However, final viscosity (FV) increased in the wild rices in eCO2, whereas it decreased in Doongara. Increases in PV were accompanied by lower estimates of protein contents (PC) at eCO2 in all species. When AgNO3 was excluded from the RVA, it became apparent that its presence had enhanced the effects of eCO2 on flour pasting properties through inhibition of α-amylase activity of the flour. Our results suggest that grain morphology and pasting properties are differently affected by eCO2 in the wild rices compared with cultivated rice. These data will inform the breeding criteria for rice grain properties and inform the introgression of wild germplasm.

In this study, potato, lotus seed and wheat starch samples with different degree of gelatinization (DG) were prepared and their in vitro digestibility at low α-amylase activity evaluated by measuring the release of reducing sugar. The hydrolysis rate (k) and the final equilibrium concentration (C∞) of the three starches increased with increasing DG. Kinetic analyses showed that the Michaelis-Menten constant (Km) and the catalytic efficiency (kcat/Km) increased with increasing DG, indicative of the increasing affinity and catalytic efficiency of α-amylase with all three starch samples. Of the three starches, lotus seed starch showed a much greater increase in k and kcat/Km than potato and wheat starches as the DG of starch increased. From this study, we concluded that at low activity of α-amylase, DG is a major determinant for the binding affinity and catalytic efficiency of α-amylase to starch and in turn the digestion rate of starch.

The interactions of four starches-waxy maize starch (WMS), non-waxy maize starch (MS), potato starch (PS), wheat starch (WS)-with lauric acid (LA) and β-lactoglobulin (βLG) were investigated. Analysis of mixtures in the Rapid Visco Analyser (RVA) showed that the MS-LA and WS-LA systems presented a viscosity peak during the cooling and holding stages of the profile, PS-LA system showed only an increase in the final viscosity, whereas WMS-LA system displayed no obvious changes during the RVA cooling and holding stages. Structural analyses showed that wheat and maize starches formed more crystalline complexes with LA than potato starch, whereas no complexes were formed between WMS and LA. The addition of βLG increased the final viscosity of all starch-LA systems, with the most obvious increase observed for PS-LA systems. Structural analyses showed that the addition of βLG promoted the formation of starch-LA complexes, even for the WMS-LA system. From this study, it can be concluded that the nature of the starch affects the formation of starch-lipid complexes, and that these effects can be modified by βLG, which promotes the formation of starch-lipid complexes.

In this study, we elucidated the underlying mechanisms that are responsible for the rate-limiting step for wheat starch digestion. Wheat starch samples with a degree of gelatinization (DG) ranging from 0 to 100% were prepared. As DG increased, the ordered structures of the starch were disrupted increasingly. In contrast, almost all of the increase in the rate and extent of in vitro enzymatic digestion coincided with a DG of only 6% and a minor loss of structural order. As DG increased beyond 6%, digestibility of the starch increased only slightly. We propose that the access and binding of enzymes to starch is greatly increased with only a small DG, which is followed by the simultaneous hydrolysis of crystalline and amorphous areas in gelatinized starch. In vitro enzymatic digestibility of starch was determined predominantly by enzyme binding to starch rather than the ordered structures of starch.

Dental calculus (mineralized dental plaque) was first recognised as a potentially useful archaeological deposit in the 1970s, though interest in human dental calculus as a resource material has increased sharply in the past few years. The majority of recent research has focused on the retrieval of plant microfossils embedded in its matrix and interpretation of these finds as largely the result of deliberate consumption of plant-derived food. However, while most of the material described in published works does represent food, dental calculus is in fact a "depositional environment" as material can enter the mouth from a range of sources. In this respect, it therefore represents an archaeological deposit that can also contain extensive non-dietary debris. This can comprise a wide variety of cultural and environmental material which reaches the mouth and can become embedded in dental calculus through alternative pathways. Here, we explore the human behaviors and activities besides eating that can generate a flux of particles into the human mouth, the broad range of additional cultural and environmental information that can be obtained through the analysis and contextualisation of this material, and the implications of the additional pathways by which material can become embedded in dental calculus.