New Insight into the Effects of Endogenous Protein and Lipids on the Enzymatic Digestion of Starch in Sorghum Flour.

The effects of endogenous lipids and protein in sorghum flour on starch digestion were studied following the depletion of lipids and/or protein and after the reconstitution of separated fractions. The removal of protein or lipids moderately increases the digestibility of starch in raw (uncooked) sorghum flour to values close to those for purified starch. Rapid Visco Analyzer data (as a model for the cooking process) show that cooked sorghum flours with lipids have a lower starch digestibility than those without lipids after RVA processing, due to the formation of starch-lipid complexes as evidenced by their higher final viscosity and larger enthalpy changes. Additionally, the formation of a starch-lipid-protein ternary complex was identified in cooked sorghum flour, rather than in a reconstituted ternary mixture, according to the unique cooling stage viscosity peak and a greater enthalpy of lipid complexes. After heating, the sorghum flour showed a lower digestibility than the depleted flours and the reconstituted flours. The results indicate that the natural organization of components in sorghum flour is an important factor in facilitating the interactions between starch, lipids, and protein during RVA processing and, in turn, reducing the starch digestion.

Biomass attachment and microbiota shifts during porcine faecal in vitro fermentation of almond and macadamia nuts differing in particle sizes.

Nuts are highly nutritious and good sources of dietary fibre, when consumed as part of a healthy human diet. Upon consumption, nut particles of various sizes containing lipids entrapped by the plant cell walls enter the large intestine where they are fermented by the resident microbiota. This study investigated the microbial community shifts during in vitro fermentation of almond and macadamia substrates, of two particle sizes including fine particles (F = 250-500 µm) and cell clusters (CC = 710-1000 µm). The aim was to determine how particle size and biomass attachment altered the microbiota. Over the 48 h fermentation duration, short chain fatty acid concentrations increased due to particle size rather than nut type (almond or macadamia). However, nut type did change microbial population dynamics by stimulating specific genera. Tyzzerella, p253418B5 gut group, Lachnospiraceae UCG001, Geotrichum, Enterococcus, Amnipila and Acetitomaculum genera were unique for almonds. For macadamia, three unique genera including Prevotellaceae UCG004, Candidatus Methanomethylophilus and Alistipes were noted. Distinct shifts in the attached microbial biomass were noted due to nut particle size. Bacterial attachment to nut particles was visualised in situ during fermentation, revealing a decrease in lipids and an increase in attached bacteria over time. This interaction may be a pre-requisite for lipid breakdown during nut particle disappearance. Overall, this study provides insights into how nut fermentation alters the gut microbiota and the possible role that gut microbes have in lipid degradation.

Bringing back a forgotten legume-Sensory profiles of Australian native wattleseeds reveal potential for novel food applications.

Documented as one of the oldest living civilizations, there is now evidence that Indigenous communities in Australia followed a sustainable lifestyle with well-designed agricultural practices and adequate physical activity. Commonly known as wattleseeds in Australia, unique cultivars of Acacia have been consumed by Indigenous Australians for over 60,000 years. This research used descriptive sensory profiling to develop a lexicon for the aroma and flavor profiles of four wattleseed species before and after being subjected to different processing techniques. The processing methods selected were pressure cooking, dry roasting, wet roasting, and malting. The species included were Acacia kempeana, Acacia adsurgens, Acacia colei, and Acacia victoriae. Sensory differences were observed between the different cultivars as well as between the different food processing techniques. Results show that wattleseed species diversity is a key driver in determining the aroma profile, while taste profiles are modified by the type of processing method applied. PRACTICAL APPLICATION: This study provides foundational knowledge on these culturally significant seeds, supporting practical opportunities to diversify the uses of wattleseeds in food products.

Characterization of structure-function properties relevant to copper-activated pyrite depression by different starches.

Starches can adsorb on and depress copper-activated pyrite desirably during flotation, an important process in ore mineral extraction. In order to develop structure/function relationships, adsorption on and depression properties of copper-activated pyrite at pH 9 by normal wheat starch (NWS) and high-amylose wheat starch (HAW), dextrin, and a range of oxidized normal wheat starches (peroxide and hypochlorite treated) were investigated. Adsorption isotherms and bench flotation performance were compared with kinematic viscosity, molar mass distribution, surface coverage, and substituted functional groups assay. The differences in molar mass distribution and substituted functional groups among oxidized starches had little influence on the depression of copper-activated pyrite. However, the introduction of -C=O and -COOH substituents, combined with depolymerization, improved solubility and dispersibility, reduced aggregated structures, and strengthened surface binding of oxidized polymers, compared with NWS and HAW. At high concentrations, HAW, NWS, and dextrin were adsorbed onto the pyrite surface more than oxidized starches. However, at the low concentrations of depressant used in flotation, oxidized starches were more effective at selectively masking copper sites. This study suggests that a stable chelation between Cu(I) and starch ligands is necessary for depression of copper-activated pyrite at pH 9, which can be achieved with oxidized wheat starch.

Determination of glucosinolates and isothiocyanates in glucosinolate-rich vegetables and oilseeds using infrared spectroscopy: A systematic review.

Cruciferous vegetables and oilseeds are rich in glucosinolates that can transform into isothiocyanates upon enzymic hydrolysis during post-harvest handling, food preparation and/or digestion. Vegetables contain glucosinolates that have beneficial bioactivities, while glucosinolates in oilseeds might have anti-nutritional properties. It is therefore important to monitor and assess glucosinolates and isothiocyanates content through the food value chain as well as for optimized crop production. Vibrational spectroscopy methods, such as infrared (IR) spectroscopy, are used as a nondestructive, rapid and low-cost alternative to the current and common costly, destructive, and time-consuming techniques. This systematic review discusses and evaluates the recent literature available on the use of IR spectroscopy to determine glucosinolates and isothiocyanates in vegetables and oilseeds. NIR spectroscopy was used to predict glucosinolates in broccoli, kale, rocket, cabbage, Brussels sprouts, brown mustard, rapeseed, pennycress, and a combination of Brassicaceae family seeds. Only one study reported the use of NIR spectroscopy to predict broccoli isothiocyanates. The major limitations of these studies were the absence of the critical evaluation of errors associated with the reference method used to develop the calibration models and the lack of interpretation of loadings or regression coefficients used to predict glucosinolates.

Nutritional and techno-functional properties of Australian Acacia seed flour: Effects of roasting on chemical composition, physicochemical properties, and in vitro digestibility and intestinal iron absorption.

Acacia seed (AS) is rich in protein and iron but contains protease inhibitors that can reduce protein digestibility (PD). The seeds are generally roasted prior to consumption, although no information on the PD of roasted AS is available. This study investigated the effect of roasting time (5, 7 and 9 min at 180 °C) on the chemical composition, physicochemical properties, and in vitro PD and intestinal iron absorption of three wild harvested Australian AS species, Acacia victoriae, A. coriacea and A. cowleana. Roasting A. victoriae and A. coriacea seeds for 7 min significantly increased PD in the seeds by 36 and 61 %, respectively. A 9-min roasting time was required to achieve 75 % reduction in trypsin inhibitor activity in A. coriacea seed, while a shorter roasting time (RT) was sufficient to achieve similar reduction rates in the other two Acacia species. Among the functional properties, water and oil absorption capacities were significantly enhanced as RT increased. The starch granules in 7- and 9-min roasted A. victoriae seed flour detached from the protein matrix while random coil increased in 7-min roasted A. victoriae and 9-min roasted A. coriacea and A. cowleana, thus, contributing to enhanced PD. Although the SDS-PAGE in 7- and 9-min roasted A. cowleana samples showed reductions in the intensity of bands for high molecular weight proteins, PD was not affected by RT. However, intestinal iron absorption was not significantly affected by roasting as compared to raw digesta samples. Compared to commercial roasted Acacia seed, the considerably shorter RT used in this study improved PD in the AS flour with less adverse effects on techno-functional properties.

Effects of incorporating processed Acacia seed as an emulsifying agent on the quality attributes of beef sausage.

In this study, partial or full replacement of 6% soy protein isolate (SPI) with 2, 4 and 6% roasted Acacia seed flour (ASRo) and Acacia seed protein concentrates (ASPC) in emulsified beef sausage were investigated. Emulsion stability and cooking loss were lower in samples formulated with ASPC at all levels and control samples compared to ASRo formulated samples. ASRo generated softer and less chewy sausages than ASPC. Cooked 2% ASPC sausages had similar L* and a* values as the control but with lower colour difference (ΔE) values that were similar to cooked 6% SPI sausages' values. An organized protein network structure was observed in the sausages formulated with ASPC at all levels and in the control samples. Therefore, ASPC, particularly at 2 and 4% inclusion, can be used as a functional ingredient to prepare emulsified beef sausages with good quality attributes.

Holistic approach to effects of foods, human physiology, and psychology on food intake and appetite (satiation & satiety).

Appetite (satiation and satiety) is an essential element for the control of eating behavior, and as a consequence human nutrition, body weight, and chronic disease risk. A better understanding of appetite mechanisms is necessary to modulate eating behavior and food intake, and also provide a practical approach for weight management. Although many researchers have investigated the relationships between satiation/satiety and specific factors including human physiology, psychology, and food characteristics, limited information on the interactions between factors or comparisons between the relative importance of factors in contributing to satiation/satiety have been reported. This article reviews progress and gaps in understanding individual attributes contributing to perceived satiation/satiety, the advantages of considering multiple factors together in appetite experiments, as well as the applications of nondestructive sensing in evaluating human factors contributing to relative appetite perception. The approaches proposed position characterization of appetite (satiation and satiety) for personalized and precision nutrition in relation to human status and healthy diets. In particular, it is recommended that future studies of appetite perception recognize the inter-dependence of food type and intake, appetite (satiation and satiety), and individual status.

Amorphous packing of amylose and elongated branches linked to the enzymatic resistance of high-amylose wheat starch granules.

To elucidate starch structural features underlying resistant starch formation, wheat starch granules with three (A-, B- and C- type) crystalline polymorphisms and a range of amylose contents were digested in vitro. The changes in multi-level structure of digestion residues were compared. In the residues of A- and C-type starches, the molecular fine structure (distributions of chain length and whole molecular size), as analyzed by size exclusion chromatography (SEC), remained similar during digestion. In contrast, B-type high amylose wheat starch (HAWS) showed distinct changes in multi-level structures of digestion-resistant fractions: (1) the peak of longer amylopectin branches shifted to a lower degree of polymerization (40 DP); (2) production of α-limit dextrin (~2 nm hydrodynamic radius) in the residues; (3) a small increase of double helix content during digestion, in contrast to 6 % reduction for the A-type starch; (4) a decrease (6 °C lower) in the melting temperature of amylose-lipid complexes. The comparison suggests that elongated branches in B-type starch contribute to the formation of resistant fraction (including α-limit dextrin) against α-amylase. The amorphous packing of starch polymers with elongated branches together with the absence of surface pores and channels is proposed to be the basis for the enzymatic resistance of granular HAWS.

Integrating Effects of Human Physiology, Psychology, and Individual Variations on Satiety-An Exploratory Study.

Satiety can influence food intake, and as a consequence has the potential to affect weight and obesity. Human factors such as physiology and psychology are likely to be important in determining satiety. However, it is not well-understood how these factors (individual variations) alone or combined contribute to satiety feelings. In addition, there have been limited or no attempts to use a holistic approach to evaluate satiety. In this study, three plant-based foods were used as mid-morning snack for 52 participants to evaluate satiety response (during three consecutive days, one-day-one-food type). The foods were served ad libitum until participants felt comfortably full prior to satiety monitoring. The study explored diverse human factors (n = 30) that might contribute to satiety including those related to oral physiology, metabolic factors, body composition and psychology. It identified important variables for satiety as well as the interactions among them and the influences of age, gender, and low satiety phenotype (consistently lower reported fullness scores) on satiety. Overall, combinations of factors rather than individual ones contributed to self-reported satiety. Food factors (e.g., type, composition) had limited effects, but there were only three types used in the study. The combination of metabolic factors [respiratory quotient, age, and body energy usage type (e.g., carbohydrate or fat)], oral sensitivity & processing, personality traits (agreeableness, conscientiousness, and neuroticism), and eating behavior (e.g., emotional and external eating) were the most important for explaining individual satiety responses. Older participants had significantly higher reported satiety than younger participants, associated with significant differences in oral physiology, increased body fat, and mature psychological characters. Moreover, different satiety phenotypes had significant differences in relationships with body fat, oral physiology, personalities, food neophobia, and eating behaviors. The results of this study indicate that much greater insights into the factors determining satiety responses can be obtained by combining multiple food and human physiological and psychological characteristics. This study used more diverse measures of individual variation than previous studies of satiety and points the way toward a more holistic approach to understanding the (control of) perceptions of fullness at both individual and group levels.

In vitro fermentation profiles of undigested fractions from legume and nut particles are affected by particle cohesion and entrapped macronutrients.

Insoluble undigested food residues are the predominant dietary form of 'fibre' from food plants, with the potential for fermentation by microbial species resident within the large intestine. Here we present results on in vitro fermentation of undigested fractions of legumes (chickpea flour, lentil flour, mung bean flour), and nuts (peanut, almond, macadamia) using a pooled faecal inoculum from pigs fed a nut- and legume-free diet. All substrates were pre-digested in vitro. Nuts were also separated into two particle sizes (PS), cell cluster (CC = 710-1000 µm) and fine (F = 250-500 µm), to test the effect of PS. All substrates tested were fermented for 48 hours, and measured according to gas production, with lentil (within legume flours) being the highest gas producer, and peanut being the highest gas producer within nuts. Undigested fractions from Nuts_F had significantly higher gas production than those from Nuts_CC, consistent with differences in surface area between the two PS. Relative short chain fatty acid concentrations between samples as metabolite end-products were consistent with relative gas production. Analysis of unfermented residues after different fermentation times, showed that cellular integrity was a major factor controlling fermentation rates and that entrapped protein/starch (legumes) and lipid (nuts) all contributed to the fermentation outcomes.

Predicting Satiety from the Analysis of Human Saliva Using Mid-Infrared Spectroscopy Combined with Chemometrics.

The aim of this study was to evaluate the ability of mid-infrared (MIR) spectroscopy combined with chemometrics to analyze unstimulated saliva as a method to predict satiety in healthy participants. This study also evaluated features in saliva that were related to individual perceptions of human-food interactions. The coefficient of determination (R2) and standard error in cross validation (SECV) for the prediction of satiety in all saliva samples were 0.62 and 225.7 satiety area under the curve (AUC), respectively. A correlation between saliva and satiety was found, however, the quantitative prediction of satiety using unstimulated saliva was not robust. Differences in the MIR spectra of saliva between low and high satiety groups, were observed in the following frequency ratios: 1542/2060 cm-1 (total protein), 1637/3097 cm-1 (α-amino acids), and 1637/616 (chlorides) cm-1. In addition, good to excellent models were obtained for the prediction of satiety groups defined as low or high satiety participants (R2 0.92 and SECV 0.10), demonstrating that this method could be used to identify low or high satiety perception types and to select participants for appetite studies. Although quantitative PLS calibration models were not achieved, a qualitative model for the prediction of low and high satiety perception types was obtained using PLS-DA. Furthermore, this study showed that it might be possible to evaluate human/food interactions using MIR spectroscopy as a rapid and cost-effective tool.

Starch structure and exchangeable protons contribute to reduced aging of high-amylose wheat bread.

Breads were prepared from wild-type wheat flour (WTWF) and high-amylose wheat flour (HAWF) with amylose content (AM) 71% and 84%. Melting enthalpy of recrystallized amylopectin (ΔHAP) increased significantly on storage for wild-type (WT), slightly for 71% AM but not at all for bread with 84% AM. Firmness of bread was positively related to AM content and ΔHAP. Exchangeable proton populations and mobility in high-amylose wheat bread (HAWB) crumb were higher than WT bread measured by 1H T2 NMR, consistent with the higher water content needed to make doughs from HAWF leading to the crumb network being more plasticized and hindering crumb aging. Although starch recrystallization and bread firming increased, no increase in enzyme-resistant starch (RS) content was observed during bread aging, with RS content only dependent on AM content. Although HAWB has a harder crumb than wild-type, it has greater shelf-life stability and higher nutritional value.

Effect of processing on the solubility and molecular size of oat ß-glucan and consequences for starch digestibility of oat-fortified noodles.

White wheat salted noodles containing oats have a slower digestion rate those without oats, with potential health benefits. Oat ß-glucan may play an important role in this. Effects of sheeting and shearing during noodle-making and subsequent cooking on ß-glucan concentration, solubility, molecular size and starch digestibility were investigated. The levels of ß-glucan were reduced by 16% after cooking, due to the loss of ß-glucan into the cooking water. Both the noodle-making process and cooking increased the solubility of ß-glucan but did not change its average molecular size. Digestion profiles show that ß-glucan in wholemeal oat flour did not change starch digestion rates compared with isolated starch, but reduced the starch digestion rate of oat-fortified wheat noodles compared to the control (wheat noodles). Confocal laser scanning microscopy suggests that interaction between ß-glucan and protein contributes to the starch-protein matrix and changes noodle microstructure, and thus alters their digestibility.

A preliminary study on the utilisation of near infrared spectroscopy to predict age and in vivo human metabolism.

The objective of this study was to evaluate the ability of a portable near infrared (NIR) instrument to analyse different tissues in healthy individuals in vivo and relate the spectral data with age, resting metabolic rate (RMR), respiratory quotient (RQ), body fat (BF) and body mass index (BMI). A NIR (950-1600 nm) instrument was used to collect the spectra of different tissues and partial least squares (PLS) regression was used to relate the NIR with RMR, RQ, BF and BMI. Results shown that non-destructive techniques such as those based in vibrational spectroscopy have potential to be used as tools to better categorise and understand the complex inter-individual differences that determine interactions between physiology and nutrition.

Molecular-structure evolution during in vitro fermentation of granular high-amylose wheat starch is different to in vitro digestion.

This study investigates the evolution of the distributions of whole molecular size and of chain length of granular wheat starches (37 ~ 93% amylose content), subjected to in vitro fermentation with a porcine faecal inoculum or digestion with pancreatic enzymes. The results showed that the molecular structures of high-amylose starch (HAS) unfermented residues largely remained unchanged during the fermentation process, while wild-type starch (37% amylose content) showed a preferential degradation of the amylopectin fraction. In contrast, under simulated digestion conditions, the undigested residues of HAS showed structural changes, including a decrease in amylose content, a shift of amylose peak position towards lower degrees of polymerisation, and an enzyme-resistant fraction. These changes of starch structure are likely to be dependent on the different starch-degrading enzyme activities present in pancreatic vs. microbial systems. Molecular changes in response to fermentation metabolism revealed by size-exclusion chromatography can help understand the microbial utilization of resistant starch.

Interplay between grain digestion and fibre in relation to gastro-small-intestinal passage rate and feed intake in pigs.

PURPOSE: The combined effects of grain digestibility and dietary fibre on digesta passage rate and satiety in humans are poorly understood. Satiety can be increased through gastric distention, reduced gastric emptying rate and when partially digested nutrients reach the terminal ileum to stimulate peptide release through the ileal/colonic brakes to slow the rate of digesta passage. This study determined the effects of grain digestibility and insoluble fibre on mean retention time (MRT) of digesta from mouth-to-ileum, feed intake (FI), starch digestion to the terminal ileum and faecal short chain fatty acids (SCFA) in a pig model. METHOD: Twelve grain-based [milled sorghum (MS), steam-flaked-sorghum, milled wheat, and steam-flaked-wheat (SFW)] diets with different intrinsic rates of starch digestion, assessed by apparent amylase diffusion coefficient (ADC), and fibre from oat hulls (OH) at 0, 5 and 20% of the diet were fed to ileal-cannulated pigs. RESULT: MRT was affected by grain-type/processing (P < 0.05) and fibre amount (P < 0.05). An approximate tenfold increase in ADC showed a limited decline in MRT (P = 0.18). OH at 20% increased MRT (P < 0.05) and reduced FI (P < 0.05). Ileal digestibility of starch increased and faecal SCFA concentration decreased with ADC; values for MS being lower (P < 0.001) and higher (P < 0.05), respectively, than for SFW. CONCLUSIONS: Lower ileal digestibility of starch, higher faecal SCFA concentration and longer MRT of MS than SFW, suggest the ileal/colonic brakes may be operating. FI appeared to decrease with increasing MRT. MRT increased and intake decreased with grain-based foods/feeds that have low starch digestibility and substantial amounts of insoluble fibre.

Towards personalised saliva spectral fingerprints: Comparison of mid infrared spectra of dried and whole saliva samples.

The aims of this study were to compare two sample presentations (dry and whole) as well as the effects of both gender and age on the mid infrared (MIR) fingerprint spectra of human saliva. Unstimulated saliva was collected from 52 Female (31 subjects, aged 40.9 ± 14.6 year) and Male (21 subjects, aged 34 ± 11.8 year) participants, stored frozen, and subsequently thawed and analysed by MIR spectroscopy as whole and dried saliva, respectively. Data were analysed by means of principal components analysis (PCA) and partial least squares (PLS) to interpret and compare the effects of presentation (dry vs whole), age and gender on the MIR spectra of saliva. Interpretation of the MIR spectra of both whole and dried samples revealed specific characteristic and different spectral signals when gender and age were compared in the amide I and amide II of proteins (e.g. albumin) and DNA. While whole saliva analysis might be more convenient for rapid test, dried saliva spectra were more consistent across replicates, demonstrating greater ability to distinguish individual differences. The interpretation of the PCA and PLS loadings of both whole and dried saliva samples allowed identification of specific MIR regions associated with age and gender of participants between 1000 cm-1 and 1800 cm-1. In particular, the MIR regions associated with the absorption of polysaccharides, glycosylated proteins, and nucleic acid phosphate groups present in saliva were the most dominant. This paper demonstrates that MIR spectroscopy can be used to measure saliva samples and to interpret individual differences in participants due to age in either dry or whole samples. No clear trends were observed in the MIR spectra of the samples associated with gender when all samples were analysed together. However, PLS regression models were able to predict gender in a subset of samples having similar age. The approach described in this study shows promise for potentially using saliva as a tool in food studies (e.g. saliva interactions between food and consumers).

Interaction of cellulose and xyloglucan influences in vitro fermentation outcomes.

To investigate the effects of interactions between cellulose and xyloglucan (XG) on in vitro fermentation, a composite of bacterial cellulose (BC) incorporating XG during pellicle formation (BCXG), was fermented using a human faecal inoculum, and compared with BC, XG and a mixture (BC&XG) physically blended to have the same BC to XG ratio of BCXG. Compared to individual polysaccharides, the fermentation extent of BC and fermentation rate of XG were promoted in BC&XG. XG embedded in the BCXG composite was degraded less than in BC&XG, while more cellulose in BCXG was fermented than in BC&XG. This combination explains the similar amount of short chain fatty acid production noted throughout the fermentation process for BCXG and BC&XG. Microbial community dynamics for each substrate were consistent with the corresponding polysaccharide degradation. Thus, interactions between cellulose and XG are shown to influence their fermentability in multiple ways.

Wheat cell walls and constituent polysaccharides induce similar microbiota profiles upon in vitro fermentation despite different short chain fatty acid end-product levels.

Plant cell walls as well as their component polysaccharides in foods can be utilized to alter and maintain a beneficial human gut microbiota, but it is not known whether the architecture of the cell wall influences the gut microbiota population. In this study, wheat flour cell walls (WCW) were isolated and compared with their major constituents - arabinoxylan (AX), mixed linkage (1,3)(1,4)-ß-glucan (MLG) and cellulose - both separately and as a physical mixture of polysaccharides (Mix) equivalent in composition to WCW. These samples underwent in vitro fermentation with a faecal inoculum from pigs fed a diet free of cereals and soluble-fibre to avoid prior adaptation to substrates. During fermentation, samples were collected for DNA extraction and 16S rRNA gene amplicon sequencing. Bioinformatics analyses revealed that the microbial communities promoted during fermentation by AX, MLG, Mix and WCW were similar at the genus level, but differed from the microbiota observed for the cellulose substrate. Differences in proportions of propionate and butyrate end-products were associated with differences in the relative levels of genera. These findings show that, in this experiment, the microbes that flourished were able to utilize diverse WCW polysaccharides alone, in mixtures or in intact cell walls in a similar way, but that different fermentation end-products were associated with AX (propionate) or MLG (butyrate) polysaccharides.