An integrated look at the effect of structure on nutrient bioavailability in plant foods

Microbial tryptophan catabolism as an actionable target via diet-microbiome interactions

In recent years, the role of microbial tryptophan (Trp) catabolism in host-microbiota crosstalk has become a major area of scientific interest. Microbiota-derived Trp catabolites positively contribute to intestinal and systemic homeostasis by acting as ligands of aryl hydrocarbon receptor and pregnane X receptor, and as signaling molecules in microbial communities. Accumulating evidence suggests that microbial Trp catabolism could be therapeutic targets in treating human diseases. A number of bacteria and metabolic pathways have been identified to be responsible for the conversion of Trp in the intestine. Interestingly, many Trp-degrading bacteria can benefit from the supplementation of specific dietary fibers and polyphenols, which in turn increase the microbial production of beneficial Trp catabolites. Thus, this review aims to highlight the emerging role of diets and food components, i.e., food matrix, fiber, and polyphenol, in modulating the microbial catabolism of Trp and discuss the opportunities for potential therapeutic interventions via specifically designed diets targeting the Trp-microbiome axis.

Regulation of glycose and lipid metabolism and application based on the colloidal nutrition science properties of konjac glucomannan: A comprehensive review

The physicochemical properties of dietary fiber in the gastrointestinal tract, such as hydration properties, adsorption properties, rheological properties, have an important influence on the physiological process of host digestion and absorption, leading to the differences in satiety and glucose and lipid metabolisms. Based on the diversified physicochemical properties of konjac glucomannan (KGM), it is meaningful to review the relationship of structural characteristics, physicochemical properties and glycose and lipid metabolism. Firstly, this paper bypassed the category of intestinal microbes, and explained the potential of dietary fiber in regulating glucose and lipid metabolism during nutrient digestion and absorption from the perspective of colloidal nutrition. Secondly, the modification methods of KGM to regulate its physicochemical properties were discussed and the relationship between KGM's molecular structure types and glycose and lipid metabolism were summarized. Finally, based on the characteristics of KGM, the application of KGM in the main material and ingredients of fat reduction food was reviewed. We hope this work could provide theoretical basis for the study of dietary fiber colloid nutrition science.

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.

How germination time affects protein hydrolysis of lupins during gastroduodenal digestion and generation of resistant bioactive peptides

Germination time is a critical factor that influences the digestibility and bioactivity of proteins in pulses. The objective was to understand the effect of sprouting time on protein hydrolysis (PH) and the release of bioactive peptides during digestion of lupin (Lupinus angustifolius L.) to provide recommendations on the optimum germination time for maximum nutritional and health benefits. Protein hydrolysis was monitored during germination and digestion by gel electrophoresis, size exclusion chromatography, and the analysis of soluble protein (SP), peptides (PEP), free amino acids (FAA) and free amino groups. The anti-inflammatory activity of intestinal digests was investigated in cell culture assays. Peptidomic and in silico analyses of intestinal digesta were conducted to identify digestion-resistant bioactive fragments. Germination time increased SP, PEP, and FAA. During digestion, the PH and release of small peptides was higher in sprouted lupin than control flour. Intestinal digests from sprouted lupin flour for 7 days exhibited the highest anti-inflammatory activity. In this sample, 11 potential bioactive peptides were identified. These findings open the exploration of novel food formulations based on sprouted lupins with higher protein digestibility and health-promoting potential.

The therapeutic potential of dietary intervention: based on the mechanism of a tryptophan derivative-indole propionic acid on metabolic disorders

Tryptophan (TRP) contributes to individual immune homeostasis and good condition via three complex metabolism pathways (5-hydroxytryptamine (5-HT), kynurenine (KP), and gut microbiota pathway). Indole propionic acid (IPA), one of the TRP derivatives of the microbiota pathway, has raised more attention because of its impact on metabolic disorders. Here, we retrospect increasing evidence that TRP metabolites/IPA derived from its proteolysis impact host health and disease. IPA can activate the immune system through aryl hydrocarbon receptor (AHR) and/or Pregnane X receptor (PXR) as a vital mediator among diet-caused host and microbe cross-talk. Different levels of IPA in systemic circulation can predict the risk of NAFLD, T2DM, and CVD. IPA is suggested to alleviate cognitive impairment from oxidative damage, reduce gut inflammation, inhibit lipid accumulation and attenuate the symptoms of NAFLD, putatively enhance the intestinal epithelial barrier, and maintain intestinal homeostasis. Now, we provide a general description of the relationships between IPA and various physiological and pathological processes, which support an opportunity for diet intervention for metabolic diseases.

Variety-dependent accumulation of glucomannan in the starchy endosperm and aleurone cell walls of rice grains and its possible genetic basis

Plant cell wall plays important roles in the regulation of plant growth/development and affects the quality of plant-derived food and industrial materials. On the other hand, genetic variability of cell wall structure within a plant species has not been well understood. Here we show that the endosperm cell walls, including both starchy endosperm and aleurone layer, of rice grains with various genetic backgrounds are clearly classified into two groups depending on the presence/absence of β-1,4-linked glucomannan. All-or-none distribution of the glucomannan accumulation among rice varieties is very different from the varietal differences of arabinoxylan content in wheat and barley, which showed continuous distributions. Immunoelectron microscopic observation suggested that the glucomannan was synthesized in the early stage of endosperm development, but the synthesis was down-regulated during the secondary thickening process associated with the differentiation of aleurone layer. Significant amount of glucomannan in the cell walls of the glucomannan-positive varieties, i.e., 10% or more of the starchy endosperm cell walls, and its close association with the cellulose microfibril suggested possible effects on the physicochemical/biochemical properties of these cell walls. Comparative genomic analysis indicated the presence of striking differences between OsCslA12 genes of glucomannan-positive and negative rice varieties, Kitaake and Nipponbare, which seems to explain the all-or-none glucomannan cell wall trait in the rice varieties. Identification of the gene responsible for the glucomannan accumulation could lead the way to clarify the effect of the accumulation of glucomannan on the agronomic traits of rice by using genetic approaches.

Protein blends and extrusion processing to improve the nutritional quality of plant proteins

Plant proteins have low protein nutritional quality due to their unbalanced indispensable amino acid (IAA) profile and the presence of antinutritional factors (ANFs) that limit protein digestibility. The blending of pulses with cereals/pseudocereals can ensure a complete protein source of IAA. In addition, extrusion may be an effective way to reduce ANFs and improve protein digestibility. Thereby, we aimed to improve the protein nutritional quality of plant protein ingredients by blending different protein sources and applying extrusion processing. Protein blends were prepared with pea, faba bean, quinoa, hemp, and/or oat concentrates or flours, and extrudates were prepared either rich in pulses (texturized vegetable proteins, TVPs) or rich in cereals (referred to here as Snacks). After extrusion, all samples showed a reduction in trypsin inhibitor activity (TIA) greater than 71%. Extrusion caused an increase in the total in vitro protein digestibility (IVPD) of TVPs, whereas no significant effect was shown for the snacks. According to the molecular weight distribution, TVPs presented protein aggregation. The results suggest that the positive effect of decreased TIA on IVPD is partially counteracted by the formation of aggregates during extrusion which restricts enzyme accessibility. After extrusion, all snacks retained a balanced amino acid score whereas a small loss of methionine + cysteine was observed in the TVPs, resulting in a small reduction in IAA content. Thus, extrusion has the potential to improve the nutritional quality of TVPs by reducing TIA and increasing protein digestibility.

Effect of whole foods on the microbial production of tryptophan-derived aryl hydrocarbon receptor agonists in growing pigs

Effects of whole foods on the microbial production of tryptophan-derived aryl hydrocarbon receptor (AhR) ligands in the intestine were investigated in a pig model. Ileal digesta and faeces of pigs after feeding of eighteen different foods were analyzed. Indole, indole-3-propionic acid, indole-3-acetic acid, indole-3-lactic acid, kynurenine, tryptamine, and indole-3-aldehyde were identified in ileal digesta, which were also identified in faeces but at higher concentrations except indole-3-lactic acid, together with skatole, oxindole, serotonin, and indoleacrylic acid. The panel of tryptophan catabolites in ileal digesta and faeces varied across different foods. Eggs induced the highest overall concentration of catabolites in ileal digesta dominated by indole. Amaranth induced the highest overall concentration of catabolites in faeces dominated by skatole. Using a reporter cell line, we observed many faecal samples but not ileal samples retained AhR activity. Collectively, these findings contribute to food selection targeting AhR ligands production from dietary tryptophan in the intestine.

Enhanced secretion of satiety-promoting gut hormones in healthy humans after consumption of white bread enriched with cellular chickpea flour: A randomized crossover study

BACKGROUND

Dietary intake of pulses is associated with beneficial effects on body weight management and cardiometabolic health, but some of these effects are now known to depend on integrity of plant cells, which are usually disrupted by flour milling. Novel cellular flours preserve the intrinsic dietary fiber structure of whole pulses and provide a way to enrich preprocessed foods with encapsulated macronutrients.

OBJECTIVES

This study aimed to determine the effects of replacing wheat flour with cellular chickpea flour on postprandial gut hormones, glucose, insulin, and satiety responses to white bread.

METHODS

We conducted a double-blind randomized crossover study in which postprandial blood samples and scores were collected from healthy human participants (n = 20) after they consumed bread enriched with 0%, 30%, or 60% (wt/wt) cellular chickpea powder (CCP, 50 g total starch per serving).

RESULTS

Bread type significantly affected postprandial glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) responses (time × treatment, P = 0.001 for both). The 60% CCP breads elicited significantly elevated and sustained release of these anorexigenic hormones [between 0% and 60% CPP-GLP-1: mean difference incremental area under the curve (iAUC), 3101 pM/min; 95% CI: 1891, 4310; P-adjusted < 0.001; PYY: mean difference iAUC, 3576 pM/min; 95% CI: 1024, 6128; P-adjusted = 0.006] and tended to increase fullness (time × treatment, P = 0.053). Moreover, bread type significantly influenced glycemia and insulinemia (time × treatment, P < 0.001, P = 0.006, and P = 0.001 for glucose, insulin, and C-peptide, respectively), with 30% CCP breads eliciting a >40% lower glucose iAUC (P-adjusted < 0.001) than the 0% CCP bread. Our in vitro studies revealed slow digestion of intact chickpea cells and provide a mechanistic explanation for the physiologic effects.

CONCLUSIONS

The novel use of intact chickpea cells to replace refined flours in a white bread stimulates an anorexigenic gut hormone response and has potential to improve dietary strategies for prevention and treatment of cardiometabolic diseases. This study was registered at clinicaltrials.gov as NCT03994276.

The influence of different cooking treatments on vegetables' bolus properties

The influence of boiling, steaming, grilling and sous-vide treatments on bolus properties of vegetables was investigated. Cooking produced potato boluses with large particles or pasty boluses unsuitable for analysis. Celeriac preserved its brittleness and produced more small particles as mastication prolonged. Eggplant and zucchini were similar and both produced relatively large particles throughout the mastication. Saliva incorporation results showed an uncommon trend since boluses from the moment of swallowing did not have the highest moisture content. It was inferred that boiling had similar effects as steaming on one side, and grilling had similar effects as sous-vide on the other.

The Effect of Vibratory Grinding Time on Moisture Sorption, Particle Size Distribution, and Phenolic Bioaccessibility of Carob Powder

Carob pod powder, an excellent source of health-promoting substances, has found its use in a wide range of food products. Grinding conditions affect the physical and chemical properties of the powder, but their influence on the bioaccessibility of phenolic compounds in carob pod powder has not yet been determined. The carob pods were ground for 30-180 s in a vibratory grinder. The median values (D₅₀) of particle size decreased after 60 s of grinding (87.9 μm), then increased to 135.1 μm. Lightness showed a negative correlation with D₅₀ and a_w, while the values of redness and yellowness decreased with the reduction in particle size and water activity. The smaller the value of D₅₀, the higher the equilibrium moisture content of carob powder. Phenolic acids (vanillic, ferulic, cinnamic) and flavonoids (luteolin, naringenin, apigenin) were found in all samples of carob powder. The grinding time influenced their content in carob powder, with maximum values at 180 s. Similar observations were made when assessing antioxidant capacity. The in vitro digestion process only improved the bioaccessibility of catechin content in all samples. However, the bioaccessibility of the phenolic compounds and the total phenolic and flavonoid contents decreased with the increase in grinding time. Our findings revealed that the grinding of carob pods for 180 s improved the extractability of phenolics; however, their bioaccessibility was reduced. It is sufficient to ground the carob pod for 30 s, ensuring good availability of nutraceuticals and lower energy cost for grinding.

Legume Seed Protein Digestibility as Influenced by Traditional and Emerging Physical Processing Technologies

The increased consumption of legume seeds as a strategy for enhancing food security, reducing malnutrition, and improving health outcomes on a global scale remains an ongoing subject of profound research interest. Legume seed proteins are rich in their dietary protein contents. However, coexisting with these proteins in the seed matrix are other components that inhibit protein digestibility. Thus, improving access to legume proteins often depends on the neutralisation of these inhibitors, which are collectively described as antinutrients or antinutritional factors. The determination of protein quality, which typically involves evaluating protein digestibility and essential amino acid content, is assessed using various methods, such as in vitro simulated gastrointestinal digestibility, protein digestibility-corrected amino acid score (IV-PDCAAS), and digestible indispensable amino acid score (DIAAS). Since most edible legumes are mainly available in their processed forms, an interrogation of these processing methods, which could be traditional (e.g., cooking, milling, extrusion, germination, and fermentation) or based on emerging technologies (e.g., high-pressure processing (HPP), ultrasound, irradiation, pulsed electric field (PEF), and microwave), is not only critical but also necessary given the capacity of processing methods to influence protein digestibility. Therefore, this timely and important review discusses how each of these processing methods affects legume seed digestibility, examines the potential for improvements, highlights the challenges posed by antinutritional factors, and suggests areas of focus for future research.

Effect of processing and microstructural properties of chickpea-flours on in vitro digestion and appetite sensations

Nowadays, pulse flours are ingredients that are more and more used as substitutes in traditional staples (i.e., pasta, bread). In this study, cellular chickpea-flour was used as an ingredient to replace conventional raw-milled chickpea-flour in suspensions and semi-solid purees. The contribution of cellular integrity on in vitro macronutrient digestion and the subsequent effect on in vivo appetite sensations were investigated. Alternating the flour preparation sequence by interchanging hydrothermal treatment and mechanical disintegration (thermo-mechanical treatment) resulted in three chickpea-flours with distinct levels of cellular integrity, and thus nutrient accessibility. The study showed that cellular integrity in chickpea-flours was preserved upon secondary hydrothermal treatment and led to significant attenuation of in vitro macronutrient digestion as compared to conventional chickpea-flour. In a randomized crossover design, significant increase of mean in vivo subjective appetite sensations satiety and fullness along with decreases in hunger, desire to eat, and prospective food consumption were achieved when cellular integrity was kept without an effect on palatability and appearance of the purees (n = 22). In vitro digestion along with microstructural assessment confirmed the importance of cellular integrity for attenuating macronutrient digestion and thereby contributing to enhanced subjective satiety and fullness in pulses. Overall, this study highlights the promising potential of altarenating the flour preparation sequence resulting in macronutrient and energy-matched flours with different nutrient encapsulation which lead to different in vitro digestion kinetics and in vivo appetite sensations.

Evaluating the Nutritional Properties of Food: A Scoping Review

There are many methods or indicators used for evaluating the nutritional value of foods; however, it is difficult to accurately reflect the comprehensive nutritional value of a food with a single indicator, and a systematic evaluation system is lacking. In this article, we systematically summarize the common evaluation methods and indicators of the nutritional value of foods. The purpose of this review was to establish an evaluation procedure for nutritional properties of foodstuffs and to help scientists choose more direct and economical evaluation methods according to food types or relevant indicators. The procedure involves the selection of a three-level evaluation method that covers the whole spectrum of a food’s nutritional characteristics. It is applicable to scientific research in the fields of agricultural science, food science, nutrition, and so on.

Bioaccessibility of phenolics from carob (Ceratonia siliqua L.) pod powder prepared by cryogenic and vibratory grinding

Carob pod powder prepared by cryogenic (CG) and vibratory grinding for 4 min (VG-4) and 8 min (VG-8) was evaluated for its antioxidant properties, and phenolic content. The bioaccessibility of phenolics was determined after the oral, gastric, and intestinal digestion phases in vitro. CG carob powder had a higher total phenolic content (6.46 mg gallic acid/g) and antioxidant capacities in terms of DPPH (15.60 mg Trolox/g) and ABTS (28.58 mg Trolox/g) assays. Quercitrin (44.54-64.68 μg/g) and cinnamic acid (27.48-31.40 μg/g) were the most abundant phenolics in all carob powder samples determined by liquid chromatography. The bioaccessibility of only ferulic acid (108%) had increased after digestion of the CG carob powder. Vibratory grinding (VG-4 and VG-8) improved the bioaccessibility of cinnamic acid (86-87%), vanillic acid (87-95%), quercitrin (33-34%), and naringenin (19-22%). A better bioaccessibility of phenolic constituents was observed for vibratory ground carob powder.

Metabolomic analysis of the grain pearling fractions of six bread wheat varieties

Bread wheat is a staple food crop that is consumed worldwide. In this study, using widely targeted LC-MS/MS, we conducted a high-throughput metabolomic analysis and determined the contents and spatial distribution of metabolites in pearled fractions of the dried kernels of six representative bread wheat varieties cultivated in China. Our aim was to explore the cultivars and pearling fractions with a view toward developing functional food products. We accordingly identified notable differences in the nutrient and bioactive metabolomes, and established that the pearling fractions of each cultivar had distinct metabolic profiles. Flavonoids varied the most amongst the cultivars and were found in higher concentration in the outer layers of the grain, but only at low concentrations in the kernel. Data from this study add further evidence of benefits of whole grain wheat consumption but, specifically, medium-gluten and pigmented wheat offer other nutrient and bioactive benefits whole grain products.

Utilizing Hydrothermal Processing to Align Structure and In Vitro Digestion Kinetics between Three Different Pulse Types

Processing results in the transformation of pulses’ structural architecture. Consequently, digestion is anticipated to emerge from the combined effect of intrinsic (matrix-dependent) and extrinsic (processed-induced) factors. In this work, we aimed to investigate the interrelated effect of intrinsic and extrinsic factors on pulses’ structural architecture and resulting digestive consequences. Three commercially relevant pulses (chickpea, pea, black bean) were selected based on reported differences in macronutrient and cell wall composition. Starch and protein digestion kinetics of hydrothermally processed whole pulses were assessed along with microstructural and physicochemical characteristics and compared to the digestion behavior of individual cotyledon cells isolated thereof. Despite different rates of hardness decay upon hydrothermal processing, the pulses reached similar residual hardness values (40 N). Aligning the pulses at the level of this macrostructural property translated into similar microstructural characteristics after mechanical disintegration (isolated cotyledon cells) with comparable yields of cotyledon cells for all pulses (41–62%). We observed that processing to equivalent microstructural properties resulted in similar starch and protein digestion kinetics, regardless of the pulse type and (prolonged) processing times. This demonstrated the capacity of (residual) hardness as a food structuring parameter in pulses. Furthermore, we illustrated that the digestive behavior of isolated cotyledon cells was representative of the digestion behavior of corresponding whole pulses, opening up perspectives for the incorporation of complete hydrothermally processed pulses as food ingredients.

A Physiological-Based Model for Simulating the Bioavailability and Kinetics of Sulforaphane from Broccoli Products

There are no known physiological-based digestion models that depict glucoraphanin (GR) to sulforaphane (SR) conversion and subsequent absorption. The aim of this research was to make a physiological-based digestion model that includes SR formation, both by endogenous myrosinase and gut bacterial enzymes, and to simulate the SR bioavailability. An 18-compartment model (mouth, two stomach, seven small intestine, seven large intestine, and blood compartments) describing transit, reactions and absorption was made. The model, consisting of differential equations, was fit to data from a human intervention study using Mathwork’s Simulink and Matlab software. SR urine metabolite data from participants who consumed different broccoli products were used to estimate several model parameters and validate the model. The products had high, medium, low, and zero myrosinase content. The model’s predicted values fit the experimental values very well. Parity plots showed that the predicted values closely matched experimental values for the high (r² = 0.95), and low (r² = 0.93) products, but less so for the medium (r² = 0.85) and zero (r² = 0.78) myrosinase products. This is the first physiological-based model to depict the unique bioconversion processes of bioactive SR from broccoli. This model represents a preliminary step in creating a predictive model for the biological effect of SR, which can be used in the growing field of personalized nutrition.

Substrate-Driven Differences in Tryptophan Catabolism by Gut Microbiota and Aryl Hydrocarbon Receptor Activation

SCOPE

This study aims to investigate the effect of tryptophan sources on tryptophan catabolism by gut microbiota and the aryl hydrocarbon receptor (AhR) activation.

METHODS AND RESULTS

Four substrates (free tryptophan, soybean protein, single and clustered soybean cells) containing an equimolar amount of tryptophan, but with a different bioaccessibility are studied using in vitro batch fermentation. Tryptophan catabolites are identified by LC-MS/MS. AhR activity is measured by HepG2-Lucia AhR reporter cells. The total amount of tryptophan-derived catabolites increases with decreasing level of substrate complexity. Indole is the major catabolite produced from tryptophan and it is the most abundant in the free tryptophan fermentation. Indole-3-acetic acid and indole-3-aldehyde are abundantly generated in the soybean protein fermentation. The soybean cell fermentation produced high concentrations of tryptamine. Interestingly, large amounts of short-chain fatty acids (SCFAs) are also found in the soybean cell and protein fermentation. Both tryptophan-derived catabolites and SCFAs are able to increase AhR reporter activity over time in all four groups.

CONCLUSION

This study illustrates that bacterial catabolism of tryptophan and resulting AhR activation in the gut is modulated by the food matrix, suggesting a role for food design to improve gut health.

Structural breakdown of starch-based foods during gastric digestion and its link to glycemic response: In vivo and in vitro considerations

The digestion of starch-based foods in the small intestine as well as factors affecting their digestibility have been previously investigated and reviewed in detail. Starch digestibility has been studied both in vivo and in vitro, with increasing interest in the use of in vitro models. Although previous in vivo studies have indicated the effect of mastication and gastric digestion on the digestibility of solid starch-based foods, the physical breakdown of starch-based foods prior to small intestinal digestion is often less considered. Moreover, gastric digestion has received little attention in the attempt to understand the digestion of solid starch-based foods in the digestive tract. In this review, the physical breakdown of starch-based foods in the mouth and stomach, the quantification of these breakdown processes, and their links to physiological outcomes, such as gastric emptying and glycemic response, are discussed. In addition, the physical breakdown aspects related to gastric digestion that need to be considered when developing in vitro-in vivo correlation in starch digestion studies are discussed. The discussion demonstrates that physical breakdown prior to small intestinal digestion, especially during gastric digestion, should not be neglected in understanding the digestion of solid starch-based foods.

Big particles, best nutrition? Absorption and excretion of protein by Anastrepha obliqua larvae (Diptera: Tephritidae)

For purposes of mass-rearing fruit flies, nutrient intake through artificial diets is a challenge, artificial food content and processing should promote sufficient absorption and availability to ensure fly fitness. Bulking agents play an essential role in creating a quality diet, but its physical characteristics, such as particle size, may establish a better microenvironment for feeding and development. Currently, there is a lack of information about protein metabolism in mass-reared fruit flies. Therefore, we evaluated whether the particle size of the bulking agent affects the absorption and excretion of the proteins, as well as their effect on the life-history traits of Anastrepha obliqua. We determined the protein content of hemolymph and feces, as well as the presence of nitrogen end-products as indicators of their level of absorption in a diet elaborated with coarse and fine corn cob particles as a bulking agent. The bromatological composition showed that coarse particles increased the bioavailability and content of crude, digestible, and soluble protein for the diet and hemolymph protein of larvae alike. We found an inverse relationship between the protein content of the hemolymph and feces of the larvae. Ammonium was determined to be a product of the catabolism of proteins. Also, A. obliqua improved its development (yield and pupal weight) and fitness (adult emergence and flight ability) when larvae were reared on a coarse particle diet. In conclusion, a diet elaborated with a coarse bulking agent features increased protein bioavailability and nutritional quality, which, in turn, increases the life-history traits of A. obliqua.

Food Matrix and Macronutrient Digestion

Food digestion may be regarded as a physiological interface between food and health. During digestion, the food matrix is broken down and the component nutrients and bioactive compounds are absorbed through a synergy of mechanical, chemical, and biochemical processes. The food matrix modulates the extent and kinetics to which nutrients and bioactive compounds make themselves available for absorption, hence regulating their concentration profile in the blood and their utilization in peripheral tissues. In this review, we discuss the structural and compositional aspects of food that modulate macronutrient digestibility in each step of digestion. We also discuss in silico modeling approaches to describe the effect of the food matrix on macronutrient digestion. The detailed knowledge of how the food matrix is digested can provide a mechanistic basis to elucidate the complex effect of food on human health and design food with improved functionality.

Conducting research on diet-microbiome interactions: A review of current challenges, essential methodological principles, and recommendations for best practice in study design

Diet is one of the strongest modulators of the gut microbiome. However, the complexity of the interactions between diet and the microbial community emphasises the need for a robust study design and continued methodological development. This review aims to summarise considerations for conducting high-quality diet-microbiome research, outline key challenges unique to the field, and provide advice for addressing these in a practical manner useful to dietitians, microbiologists, gastroenterologists and other diet-microbiome researchers. Searches of databases and references from relevant articles were conducted using the primary search terms 'diet', 'diet intervention', 'dietary analysis', 'microbiome' and 'microbiota', alone or in combination. Publications were considered relevant if they addressed methods for diet and/or microbiome research, or were a human study relevant to diet-microbiome interactions. Best-practice design in diet-microbiome research requires appropriate consideration of the study population and careful choice of trial design and data collection methodology. Ongoing challenges include the collection of dietary data that accurately reflects intake at a timescale relevant to microbial community structure and metabolism, measurement of nutrients in foods pertinent to microbes, improving ability to measure and understand microbial metabolic and functional properties, adequately powering studies, and the considered analysis of multivariate compositional datasets. Collaboration across the disciplines of nutrition science and microbiology is crucial for high-quality diet-microbiome research. Improvements in our understanding of the interaction between nutrient intake and microbial metabolism, as well as continued methodological innovation, will facilitate development of effective evidence-based personalised dietary treatments.

Plant-based Milks: A Review of the Science Underpinning Their Design, Fabrication, and Performance

Many consumers are interested in decreasing their consumption of animal products, such as bovine milk, because of health, environmental, and ethical reasons. The food industry is therefore developing a range of plant-based milk alternatives. These milk substitutes should be affordable, convenient, desirable, nutritional, and sustainable. This article reviews our current understanding of the development of plant-based milks. Initially, an overview of the composition, structure, properties, and nutritional profile of conventional bovine milk is given, because the development of successful alternatives depends on understanding the characteristics of real milk. The two main production routes for fabricating plant-based milks are then highlighted: (i) disruption of plant materials (such as nuts, seeds, or legumes) to form aqueous suspensions of oil bodies; (ii) formation of oil-in-water emulsions by homogenization of oil, water, and emulsifiers. The roles of the different functional ingredients in plant-based milks are highlighted, including oils, emulsifiers, thickeners, antioxidants, minerals, and other additives. The physicochemical basis of the appearance, texture, and stability of plant-based milks is covered. The importance of the sensory attributes and gastrointestinal fate of bovine milk and plant-based alternatives is also highlighted. Finally, potential areas for future work are discussed.

Effect of process-induced common bean hardness on structural properties of in vivo generated boluses and consequences for in vitro starch digestion kinetics

In the present study, we evaluated the effect of process-induced common bean hardness on structural properties of in vivo generated boluses and the consequences for in vitro starch digestion. Initially, the impact of human mastication on the particle size distribution (PSD) of oral boluses from common beans with different process-induced hardness levels was investigated through a mastication study. Then the effect of structural properties of selected boluses on in vitro starch digestion kinetics was assessed. For a particular process-induced hardness level, oral boluses had similar PSD despite differences in masticatory parameters between participants of the mastication study. At different hardness levels, a clear effect of processing (P<0·0001) was observed. However, the effect of mastication behaviour (P=0·1141) was not significant. Two distinctive fractions were present in all boluses. The first one was a cotyledon-rich fraction consisting of majorly small particles (40-125 µm), which could be described as individual cells based on microscopic observations. This fraction increased with a decrease in process-induced hardness. The second fraction (>2000 µm) mostly contained seed coat material and did not change based on hardness levels. The in vitro starch digestion kinetics of common bean boluses was only affected by process-induced hardness. After kinetic modelling, significant differences were observed between the reaction rate constant of boluses generated from the hardest beans and those obtained from softer ones. Overall this work demonstrated that the in vitro nutritional functionality of common beans is affected to a greater extent by structural properties induced by processing than by mechanical degradation in the mouth.

Mycoprotein: The Future of Nutritious Nonmeat Protein, a Symposium Review

Mycoprotein is an alternative, nutritious protein source with a meat-like texture made from Fusarium venenatum, a naturally occurring fungus. Its unique method of production yields a significantly reduced carbon and water footprint relative to beef and chicken. Mycoprotein, sold as Quorn, is consumed in 17 countries, including the United States. In line with current dietary guidelines, mycoprotein is high in protein and fiber, and low in fat, cholesterol, sodium, and sugar. Mycoprotein may help maintain healthy blood cholesterol levels, promote muscle synthesis, control glucose and insulin levels, and increase satiety. It is possible that some susceptible consumers will become sensitized, and subsequently develop a specific allergy. However, a systematic evidence review indicates that incidence of allergic reactions remains exceptionally low. Mycoprotein's nutritional, health, and environmental benefits affirms its role in a healthful diet. Future research that focuses on the long-term clinical benefits of consuming a diet containing mycoprotein is warranted.