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Cetaceans play a crucial role in marine ecosystems; however, research on their gastrointestinal microbiota remains limited due to sampling constraints. In this study, we collected hindgut samples from 12 stranded cetaceans and performed 16S rRNA gene amplicon sequencing to investigate microbial composition and functional potentials. Analysis of ZOTUs profiles revealed that the phyla Firmicutes, Proteobacteria, and Bacteroidetes dominated all hindgut samples. However, unique microbial profiles were observed among different cetacean species, with significant separation of gut microbiota communities according to biological evolutionary lineages. Different genera that contain pathogens were observed distinguishing delphinids from physeteroids/ziphiids. Delphinid samples exhibited higher abundances of Vibrio, Escherichia, and Paeniclostridium, whereas physeteroid and ziphiid samples showed higher abundances of Pseudomonas, Enterococcus, and Intestinimonas. Functional analysis indicated convergence in the gut microbiota among all cetaceans, with shared bacterial infection pathways across hindgut samples. In addition, a comparison of the gastrointestinal microbial composition between a stranded short-finned pilot whale (Globicephala macrorhynchus) and a stranded roughtoothed dolphin (Steno bredanensis) using 16S rRNA gene sequencing revealed distinct microbial community structures and functional capacities. To the best of our knowledge, this study represents the first report on the gastrointestinal microbiota of the pantropical spotted dolphin (Stenella attenuata), Blainville’s beaked whale (Mesoplodon densirostris), and rough-toothed dolphin, with various comparisons conducted among different cetacean species. Our findings enhance the understanding of microbial composition and diversity in cetacean gastrointestinal microbiota, providing new insights into co-evolution and complex interactions between cetacean microbes and hosts. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms involved in food breakdown in the human gastrointestinal (GI) tract is essential in food digestion research. Research to study food digestion in the human GI tract requires in vivo and in vitro approaches. In vivo methods involving human or animal subjects are often cost-prohibitive and raise ethical concerns. For these reasons, in vitro approaches are becoming more common. Several dynamic in vitro models that mimic one or more components of the GI tract have been developed at various research institutions and by commercial companies. While there is evidence of considerable novelty and innovation in the design of these models, there are many differences among them in how the mechanical breakdown of solid foods is accomplished. In some systems, modulating water pressure is used to achieve peristaltic contractions of the gastric antrum, whereas, in other models, the flexible walls of a gastric chamber are compressed by the movement of rollers or clamps outside the walls of the test chamber. Although much progress has been made in standardizing the biochemical environment appropriate to the food digestion process, there is a lack of standard protocols to measure mechanical forces that result in the breakdown of solid foods. Similarly, no standardized methods are available to evaluate the results obtained from in vitro trials for validation purposes. Due to the large variability in the design features of in vitro models used for food digestion studies, developing consensus-based standards for the mechanical aspects of food breakdown is needed.

This review highlights the involvement of mass transfer in animal food-digestion processes. There may be several mass-transfer steps during the dissolution of food components, starting from the food itself, moving into the digestive juices, then moving through the walls of the gastrointestinal tract. These steps create a sequence of film resistances to mass transfer, where one film resistance often limits the overall mass-transfer process. Mass-transfer rates, mass-transfer coefficients, and the time scales and time constants for different parts of the food-digestion process are all interlinked, and the connections have been explained. In some parts of the food-digestion process, the time constants for the mass-transfer process are similar to the residence times for food digestion, emphasising the importance of mass transfer in these parts of food digestion, such as the duodenum. The mass-transfer and transport behaviour for in vivo human digestive systems and in vitro guts-on-a-chip may be very similar, suggesting that cells on the intestine walls, whether in vitro (guts-on-a-chip) or in vivo, may see similar transport behaviour for both nutrients towards the cells, and waste products away from them. [ABSTRACT FROM AUTHOR]

Cetaceans play a crucial role in marine ecosystems; however, research on their gastrointestinal microbiota remains limited due to sampling constraints. In this study, we collected hindgut samples from 12 stranded cetaceans and performed 16S rRNA gene amplicon sequencing to investigate microbial composition and functional potentials. Analysis of ZOTUs profiles revealed that the phyla Firmicutes, Proteobacteria, and Bacteroidetes dominated all hindgut samples. However, unique microbial profiles were observed among different cetacean species, with significant separation of gut microbiota communities according to biological evolutionary lineages. Different genera that contain pathogens were observed distinguishing delphinids from physeteroids/ziphiids. Delphinid samples exhibited higher abundances of Vibrio , Escherichia , and Paeniclostridium , whereas physeteroid and ziphiid samples showed higher abundances of Pseudomonas , Enterococcus , and Intestinimonas . Functional analysis indicated convergence in the gut microbiota among all cetaceans, with shared bacterial infection pathways across hindgut samples. In addition, a comparison of the gastrointestinal microbial composition between a stranded short-finned pilot whale ( Globicephala macrorhynchus ) and a stranded rough-toothed dolphin ( Steno bredanensis ) using 16S rRNA gene sequencing revealed distinct microbial community structures and functional capacities. To the best of our knowledge, this study represents the first report on the gastrointestinal microbiota of the pantropical spotted dolphin ( Stenella attenuata ), Blainville's beaked whale ( Mesoplodon densirostris ), and rough-toothed dolphin, with various comparisons conducted among different cetacean species. Our findings enhance the understanding of microbial composition and diversity in cetacean gastrointestinal microbiota, providing new insights into co-evolution and complex interactions between cetacean microbes and hosts., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Fan, Kang, Lv, Zhai, Jia, Yang, Shi, Zhou, Diao, Li, Jin, Liu, Kristiansen, Zhang, Chen and Li.)

A low-glycaemic diet is crucial for those with diabetes and cardiovascular diseases. Information on the glycaemic index (GI) of different ingredients can help in designing novel food products for such target groups. This is because of the intricate dependency of material source, composition, food structure and processing conditions, among other factors, on the glycaemic responses. Different approaches have been used to predict the GI of foods, and certain discrepancies exist because of factors such as inter-individual variation among human subjects. Besides other aspects, it is important to understand the mechanism of food digestion because an approach to predict GI must essentially mimic the complex processes in the human gastrointestinal tract. The focus of this work is to review the advances in various approaches for predicting the glycaemic responses to foods. This has been carried out by detailing conventional approaches, their merits and limitations, and the need to focus on emerging approaches. Given that no single approach can be generalised to all applications, the review emphasises the scope of deriving insights for improvements in methodologies. Reviewing the conventional and emerging approaches for the determination of GI in foods, this detailed work is intended to serve as a state-of-the-art resource for nutritionists who work on developing low-GI foods. [ABSTRACT FROM AUTHOR]

Food digestion is a complex, multiscale process that has recently become of interest to the food industry due to the developing links between food and health or disease. Food digestion can be studied by using either in vitro or in vivo models, each having certain advantages or disadvantages. The recent interest in food digestion has resulted in a large number of studies in this area, yet few have provided an in-depth, quantitative description of digestion processes. To provide a framework to develop these quantitative comparisons, a summary is given here between digestion processes and parallel unit operations in the food and chemical industry. Characterization parameters and phenomena are suggested for each step of digestion. In addition to the quantitative characterization of digestion processes, the multiscale aspect of digestion must also be considered. In both food systems and the gastrointestinal tract, multiple length scales are involved in food breakdown, mixing, absorption. These different length scales influence digestion processes independently as well as through interrelated mechanisms. To facilitate optimized development of functional food products, a multiscale, engineering approach may be taken to describe food digestion processes. A framework for this approach is described in this review, as well as examples that demonstrate the importance of process characterization as well as the multiple, interrelated length scales in the digestion process.

Understanding the mechanisms involved in food breakdown in the human gastrointestinal (GI) tract is essential in food digestion research. Research to study food digestion in the human GI tract requires in vivo and in vitro approaches. In vivo methods involving human or animal subjects are often cost-prohibitive and raise ethical concerns. For these reasons, in vitro approaches are becoming more common. Several dynamic in vitro models that mimic one or more components of the GI tract have been developed at various research institutions and by commercial companies. While there is evidence of considerable novelty and innovation in the design of these models, there are many differences among them in how the mechanical breakdown of solid foods is accomplished. In some systems, modulating water pressure is used to achieve peristaltic contractions of the gastric antrum, whereas, in other models, the flexible walls of a gastric chamber are compressed by the movement of rollers or clamps outside the walls of the test chamber. Although much progress has been made in standardizing the biochemical environment appropriate to the food digestion process, there is a lack of standard protocols to measure mechanical forces that result in the breakdown of solid foods. Similarly, no standardized methods are available to evaluate the results obtained from in vitro trials for validation purposes. Due to the large variability in the design features of in vitro models used for food digestion studies, developing consensus-based standards for the mechanical aspects of food breakdown is needed., Competing Interests: The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Singh.)

Encapsulation technologies have achieved encouraging results improving the stability, bioaccessibility and absorption of bioactive compounds post-consumption. There is a bulk of published research on the gastrointestinal behavior of encapsulated bioactive food materials alone using in vitro and in vivo digestion models, but an aspect often overlooked is the impact of the food structure, which is much more complex to unravel and still not well understood. This review focuses on discussing the recent findings in the application of encapsulated bioactive components in fabricated food matrices. Studies have suggested that the integration of encapsulated bioactive compounds has been proven to have an impact on the physicochemical characteristics of the finished product in addition to the protective effect of encapsulation on the fortified bioactive compound. These products containing bioactive compounds undergo further structural reorganization during digestion, impacting the release and emptying rates of fortified bioactive compounds. Thus, by manipulation of various food structures and matrices, the release and delivery of these bioactive compounds can be altered. This knowledge provides new opportunities for designing specialized foods for specific populations.

Story of Pavlov’s studies on food digestion including his Nobel Prize in 1904 are presented. Some new ideas and concepts are also viewed based on 3th International Conference on Food Digestion held in Wageningen (the Netherlands) in 2014.

Background; The structure of many plant- and fungal-based foods is determined by cell walls which are the primary source of dietary fiber. Several studies have shown that consumption of cell wall fibers from plants and fungi can modulate digestion leading to health-promoting effects such as increasing satiety and reducing the risk of cardiovascular diseases and type-2 diabetes. Scope and Approach; We focus on the impact of the food structure determined by plant and fungal cell walls on digestion and subsequent physiological responses. The underlying mechanisms promoting health effects may differ between plant and fungal cell walls, considering their different structural and biochemical organizations. Fungal cell walls have been vastly understudied compared to plant cell walls in this regard. Therefore, we highlight differences and similarities of plant- and fungal-based foods that may underlie the observed health benefits. Key Findings and Conclusions; The ability of the plant cell walls in our diet to influence digestion and improve human health has been intensely investigated over many years. The health outcomes observed following plants and fungi consumption appear similar, despite fundamental differences between the two kingdoms of life. The possible mechanisms underlying the health effects are the control of nutrient bioaccessibility, binding and sequestration of digestive components, increasing viscosity, and colonic fermentation. Mechanisms by which cell walls influence bioaccessibility of nutrients from fungal and plant cell walls are discussed. Moreover, consistent evidence for the fungal counterpart is still lacking, and further studies focusing on the whole structure of fungi are required. • Cell walls are the main source of dietary fiber and linked to disease prevention. • Cell walls from fungi and plants have different composition and structure. • Similar health outcomes are linked with both plant and fungal fiber consumption. • The release of digested nutrients may vary between plant and fungal cell walls. • Research on fungal cell walls and health is lacking compared to those of plants. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the peptidome of a red tide forming species Noctiluca scintillans based on mass-spectrometry (MS) analysis. N. scintillans cells were collected at the initiation and peak phases of its bloom. Peptides were extracted by ultrafiltration with cutoff of 10 and 3 kDa in acidic condition. Optimal mass spectra were generated after purification with C18 column. MS analysis and peptide identification was undertaken by Linear Trap Quadropole (LTQ) Velos MS/MS instrument. Using this method, 239 and 332 peptide sequences from the samples collected at the initiation and peak phases of N. scintillans bloom were identified, respectively. These sequences were classified and they were affiliated to 68 and 93 groups of precursor proteins, respectively, at the initiation and peak phases, with a compositional dissimilarity of 49.5%. Meanwhile, majority of the peptides were conjectured to come from contents digested by N. scintillans. Thirty-three groups of precursor proteins were detected at both phases. These peptides involved in various intracellular physiological activities, most of them responsible for functions of digestion activities such as oxidoreductase activity, catalytic activity, hydrolase activity and cofactor/ion binding. The compositions of precursor proteins, molecular weights, functions and cell compartments of the obtained peptides were quite different between two bloom stages. This is the first attempt to study peptidomics of N. scintillans, which provide important information on the functional studies of peptidomics in N. scintillans, especially food digestion and dietary protein utilization, as well as their relationship with bloom development.

Personalisation of foods opens for improving individuals' quality of life. In the personalised food approach, the focus of research is food, its components and the possibilities of different processes throughout the food value chain to impact on individuals and their needs. In this paper, we will provide an overview of how research from a personalised food perspective can benefit consumers that require special food offerings. The paper is structured along the food chain addressing the following topics: i) Food raw material and components, ii) Food processing and culinary aspects, iii) Food digestion and microbiota, iv) Food perception. The paper highlights how food and its composition influence personal requirements, and how processing of the foods can contribute to optimised products for consumer groups. Furthermore, much attention has been accorded how digestion and microbiota are sensitive to food consumed and how this vary with consumer group. Finally, consumers' perceptions and preferences play an important part in how foods are presented and chosen. More research is needed to utilise the possibilities of personalising foods to improve life for consumers with different needs. • Personalisation of food can be addressed throughout the value chain of food. • Food raw material can be selected, modified and treated for personalisation. • Food processing techniques can improve nutrient availability of personalised food. • Food digestion and gut microbiota influence personalisation of food. • Sensory attributes are important for personalisation of food. [ABSTRACT FROM AUTHOR]

Previous research suggests that students use metaphors when asked to explain digestive processes and nutritional uptake. In this paper, we describe the results of a study designed to gain a deeper understanding of how metaphors and anthropomorphisms are used by students when describing such processes. We applied analyses based on the systemic-functional grammar framework to 123 student responses to a question about nutrition on a Swedish national test in biology in order to identify, describe and analyse how students use metaphors and to understand the linguistic structure of those metaphors. We also considered how the metaphors are linked to metaphor systems and anthropomorphisms, thereby gaining a deeper understanding of the role of metaphors in this area. The results of our analyses provide important insights into how students understand digestion and nutrition and could provide the basis for improved teaching materials and methods for these important topics. [ABSTRACT FROM AUTHOR]

A model stomach system was used to investigate disintegration of various foods in simulated gastric environment. Food disintegration modes and typical disintegration profiles are summarized in this paper. Mechanisms contributing to the disintegration kinetics of different foods were investigated as related to acidity, temperature, and enzymatic effect on the texture and changes in microstructure. Food disintegration was dominated by either fragmentation or erosion, depending on the physical forces acting on food and the cohesive force within the food matrix. The internal cohesive forces changed during digestion as a result of water penetration and acidic and enzymatic hydrolysis. When erosion was dominant, the disintegration data (weight retention vs. disintegration time) may be expressed with exponential, sigmoidal, and delayed-sigmoidal profiles. The different profiles are the result of competition among the rates of water absorption, texture softening, and erosion. A linear-exponential equation was used to describe the different disintegration curves with good fit. Acidity and temperature of gastric juice showed a synergistic effect on carrot softening, while pepsin was the key factor in disintegrating high-protein foods. A study of the change of carrot microstructure during digestion indicated that degradation of the pectin and cell wall was responsible for texture softening that contributed to the sigmoidal profile of carrot disintegration.

Solutions of okra gum and mucin were studied during pH cycling (7–3–7), as to model the interactions between these components in the oral-gastrointestinal tract. Okra gum aggregates with mucin at pH close to 3, while they redissolve back at pH 7 due to electrostatic interactions. Fluorimetry shows that complexes form at low pH, and break-up upon return to pH 7. At pH 3 both static and transient complexes are detected. Shear viscosities reduce upon pH lowering from 7 to 3 pH 3 and then are partially restored back at pH 7, suggesting a hysteresis in the macromolecular rearrangement after pH cycling. Hysteresis is more pronounced in the extensional rheology, leading to Trouton ratios with a strong dependence on the pH. Thus flow can be regulated in different ways in compartments with different pH (mouth, stomach, intestine). Image 1 • Okra gum and mucin in solution form pH-dependent complexes. • Okra gum–mucin interactions are generally pH-reversible at the molecular level. • Shear viscosity is reversible upon pH cycling. • Extensional rheology shows hysteresis during pH cycling due to surface phenomena. • The relative importance of shear vs. extensional rheology changes during pH cycling. [ABSTRACT FROM AUTHOR]

The current allergenicity assessment of novel proteins is based on the EFSA GMO guidance. Recently, EFSA launched a new guidance document on allergenicity assessment of GM plants (2017). This document describes, amongst other topics, the new scientific and regulatory developments on in vitro protein digestibility tests. The EFSA GMO Panel stated that for in vitro protein digestibility tests, additional investigations are needed before any additional recommendation in the form of guidance can be provided. To this end, an interim phase is considered necessary to evaluate the revisions to the in vitro gastrointestinal digestion test, proposed by EFSA. This prompted the establishment of a joint workshop through two COST Action networks: COST Action ImpARAS and COST Acton INFOGEST. In 2017, a workshop was organised to discuss the relevance of digestion in allergenicity risk assessment and how to potentially improve the current methods and readouts. The outcome of the workshop is that there is no rationale for a clear readout that is predictive for allergenicity and we suggest to omit the digestion test from the allergenicity assessment strategy for now, and put an effort into filling the knowledge gaps as summarized in this paper first. • Protein digestion is relevant for allergenicity of some proteins, but not for all. • It is not clear yet how different factors exactly influence digestion and how these factors can be included. • Including all factors will complicate the elaboration of a simple and predictive digestion assay. • There is no rationale for a clear readout that is predictive for allergenicity. • We suggest to omit the digestion test from the allergenicity assessment for now and put effort into filling the knowledge gaps. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ enzyme treatments can be exploited to generate low-sugar functional foods. • Fructo-oligosaccharides (FOS) were enzymatically synthesized at 60 ℃ and pH 5.0. • A strawberry preparation with 50 % (w/w) FOS and less 80 % sucrose was obtained. • The caloric value of the prebiotic-treated preparations was lowered in 26–31 %. • More than 90 % of the FOS resisted to the in vitro digestion. Food industry has been pressed to develop products with reduced sugar and low caloric value, while maintaining unchanged their rheological and physicochemical properties. The development of a strawberry preparation for the dairy industry, with prebiotic functionality, was herein investigated by in situ conversion of its intrinsic sucrose content into prebiotic fructo-oligosaccharides (FOS). Two commercial enzymatic complexes, Viscozyme® L and Pectinex® Ultra SP-L, were evaluated for the synthesis of FOS. Operational parameters such as temperature, pH, and enzyme:substrate ratio (E:S) were optimized to maximize FOS yield. The rheological and physicochemical properties of the obtained strawberry preparation were evaluated. For functional analysis, the resistance of FOS to the harsh conditions of the gastro-intestinal digestion was evaluated by applying the standardized INFOGEST static protocol. At optimal conditions (60 ℃, pH 5.0), Pectinex® produced 265 ± 3 g·L−1 FOS, yielding 0.57 ± 0.01 g FOS ·g initial sucrose −1 after 7 h reaction (E:S: 1:40); and Viscozyme® produced 295 ± 1 g·L−1 FOS, yielding 0.66 ± 0.00 g FOS ·g initial sucrose −1 after 5 h (E:S: 1:30). The obtained strawberry preparations contained more than 50 % (w/w) prebiotic FOS incorporated (DP 3–5), with 80 % reduction of its sucrose content. The caloric value was therefore reduced by 26–31 %. FOS showed resistance to gastrointestinal digestion being only slightly hydrolysed (<10 %). 1F-Fructofuranosylnystose was not digested at any phase of the digestion. Although the physicochemical properties of the prebiotic preparations were different from the original one, parameters such as the lower °Brix , water activity, consistency and viscosity, and its different color, may be easily adjusted. Results indicate that in situ synthesis strategies are efficient alternatives in the manufacture of reduced sugar and low-caloric food products with prebiotic potential. [ABSTRACT FROM AUTHOR]

The fish intestinal microbiota is affected by dietary shifts or diet-related seasonal fluctuations making it highly variable and dynamic. It assists with the digestion and absorption of food that is a common, yet dynamic process. However, fundamental dynamics of microbial ecology associated with food digestion in intestine and stomach are poorly understood in fish. We selected the southern catfish, Silurus meridionalis, as the targeted species, owing to its foraging behavior with a large meal that can assure clear periodic rhythms in food digestion, to study spatial variations of the microbial community along the gastrointestinal (GI) tract. We further evaluated temporal microbial dynamics by collecting GI tract samples at time intervals 03, 12, and 24h after feeding. High-throughput sequencing results showed higher microbial diversity in the stomach than in the intestine and distinguishable community structures between stomach and intestine. Firmicutes were dominated by both Clostridium and unclassified Clostridiaceae, which was the most abundant taxon in the stomach, whereas Fusobacteria were dominated by Cetobacterium, which prevailed in the intestine. Firmicutes was significantly increased and Fusobacteria was decreased after feeding. Furthermore, inter-stomach microbial variability was greater than inter-intestine microbial variability. These results demonstrate that GI microbial assemblies are specific per anatomical site and are highly dynamic during food digestion, indicating that digestive status and/or sampling time are factors potentially influencing the microbial compositions. Furthermore, the finding of high spatial and temporal variations of the microbial community along the GI tract suggests limitations of single sampling regime to study food-derived microbial ecology.

Background In vitro digestion models show great promise in facilitating the rationale design of foods. This paper provides a look into the current state of the art and outlines possible future paths for developments of digestion models recreating the diverse physiological conditions of specific groups of the human population. Scope and approach Based on a collective effort of experts, this paper outlines considerations and parameters needed for development of new in vitro digestion models, e.g. gastric pH, enzymatic activities, gastric emptying rate and more. These and other parameters are detrimental to the adequate development of in vitro models that enable deeper insight into matters of food luminal breakdown as well as nutrient and nutraceutical bioaccessibility. Subsequently, we present an overview of some new and emerging in vitro digestion models mirroring the gastro-intestinal conditions of infants, the elderly and patients of cystic fibrosis or gastric bypass surgery. Key findings and conclusions This paper calls for synchronization, harmonization and validation of potential developments in in vitro digestion models that would greatly facilitate manufacturing of foods tailored or even personalized, to a certain extent, to various strata of the human population. [ABSTRACT FROM AUTHOR]

[Display omitted] • DTB and BF were conjugated to beads for ratiometric imaging. • The probe was favorable for monitoring dextranase activity in the agarose gel. • A linear relationship of I green / I red was obtained against C / C 0. • I green / I red increased more rapidly with a greater diffusion coefficient of dextranase. Molecular bioimaging of enzyme activity is rapidly emerging as a powerful strategy for accurate disease diagnostics. This work aims to prove that bioimaging of enzyme activity in food digestion with a fluorescent probe is feasible. In this study, a dual-labeled fluorescent probe with dextran-tetramethylrhodamine (TMR)-biotin conjugate (DTB) as the enzyme-cleavable unit, and biotin-(5-fluorescein) conjugate (FB) as the reference unit, was developed. It was immobilized in the agarose gel (the model food matrix) for the fluorescence quantification of dextranase activity. The probe manifested significantly ratiometric fluorescent signals (I green / I red) in response to the enzyme-active reaction. Linear relationships of I green / I red were obtained against the dextranase concentration ratio (C / C 0). I green / I red increased more rapidly with a greater dextranase diffusion rate, also supported by the more significant diffusion coefficient of fluorescently labeled dextranase in 0.5 wt% agarose gel (1.87 × 10-6 cm2 s−1). Our work provides more mechanistic evidence for enzyme activity imaging in food digestion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quantitative analysis of peptide release kinetics during chymotrypsin hydrolysis. • Broad specificity with preference towards F, Y, W and to a lower extent M, L. • Hydrolysis rates of individual cleavage sites (selectivity) differed a lot. • Hindrance by proline when occupying positions P 3, P 1′ or P 2′ but not in P 2 and P 3′. • Other neighbouring amino acids had no major effects on selectivity. Chymotrypsin is one of the major proteases in intestinal protein digestion. Observations about the type of bonds that are hydrolysed (specificity and preference) were in the past derived from the peptide composition after digestion or hydrolysis rates of synthetic peptides. In this study, the path of hydrolysis by bovine chymotrypsin, i.e formation and degradation of peptides, were described for α-lactalbumin, β-lactoglobulin and β-casein. The peptide compositions, determined with UPLC-PDA-MS at different time points were used to determine the digestion kinetics for individual cleavage sites. It was evaluated how statements on (secondary) specificity from literature were reflected in the release kinetics of peptides. β-Lactoglobulin reached the highest degree of hydrolysis (10.9 ± 0.1 %) and was hydrolysed fastest (28 ± 1 mM peptide bonds /s/mM enzyme), regardless of its globular (tertiary) structure. Chymotrypsin showed a preference towards aromatic amino acids, methionine and leucine, but was also tolerant to other amino acids. For the cleavage sites within this preference, ̴73% of the cleavage sites were hydrolysed with high or intermediate selectivity. For the missed cleavages within the preference, 45 % was explained by hindrance of proline, which affected hydrolysis only when in positions P 3, P 1′ or P 2′. No clear indication (based on primary structure) was found to explain the other missed cleavages. A few cleavage sites were hydrolysed extremely efficient in α-lactalbumin (F9, F31, W104) and β-casein (W143, L163, F190). This study gave unique and quantitative insight in peptide formation and degradation by chymotrypsin in the digestion of proteins. The approach used showed potential to explore the path of hydrolysis for other proteases with less defined specificity. [ABSTRACT FROM AUTHOR]

High blood glucose and insulin concentrations, even if within the normal range, are associated with an increased risk to develop type 2 diabetes and cardiovascular diseases. Dietary carbohydrates are the main determinants of blood glucose levels in the postprandial period; therefore, the effects of dietary carbohydrates on human health are strongly related to their rate of digestion in the small intestine. This has raised much interest on food properties able to retard carbohydrate digestion and absorption. This review is focused to examine food properties which influence carbohydrate digestion in order to predict their potential influence on health markers. Among them, it is worth to underline the role of viscosity, the physical form of the food, cooking methods and processing, the type of starch (amylose or amylopectin), the presence of anti-nutrients and the amount of fiber, fat, and proteins. In this respect particularly relevant is the type of starch present in the food, since amylose is slowly digested by intestinal α-amylases while the digestion of amylopectin is faster. However, the food component that has the strongest impact on digestion and absorption of dietary carbohydrates is dietary fiber that modulates the postprandial glucose rise by multiple mechanisms. In fact, dietary fibers may increase ingesta viscosity, thus delaying the gastric emptying time and slowing both carbohydrate digestion and the rate of glucose transport to enterocytes. In addition, they can influence the composition of the gut microbiota and induce the production of short-chain fatty acids that beneficially affect glucose and lipid metabolism. In short, the knowledge of food characteristics able to retard carbohydrate digestion and absorption in the intestine can help modify food properties with the aim of improving their functionality. [ABSTRACT FROM AUTHOR]

Two whey protein emulsion gels containing 10 mM NaCl (soft gel) or 200 mM NaCl (hard gel) were formed and subjected to sequential digestion, including an in vitro gastric step followed by an in vitro intestinal step. The breakdown of gel particles, stability of oil droplets, microstructure and free fatty acid release during digestion were examined. The results showed that after 60 and 240 min gastric digestion the digesta of both gels had different physicochemical forms. The 60 min gastric digesta of both gels was mainly composed of gel particles ranging from ∼1 to ∼1000 μm. The 240 min gastric digesta of the soft gel mainly consisted of individual oil droplets and small gel particles (∼10 μm) while that of the hard gel mainly consisted of small gel particles (∼10 μm). During intestinal digestion, the breakup and coalescence of oil droplets occurred simultaneously for all gastric digesta. The remaining network structure of gel particles hindered their breakdown especially in the hard gel during intestinal digestion, which delayed lipid digestion significantly. Lipolytic products appeared to accumulate around oil droplet surfaces. Needle-shaped crystals that may be composed of free fatty acids were also found during intestinal digestion. [ABSTRACT FROM AUTHOR]

The gastrointestinal tract facilitates food digestion, with the gut microbiota playing pivotal roles in nutrient breakdown and absorption. However, the microbial molecules and downstream signaling pathways that activate food digestion remain unexplored. Here, by establishing a food digestion system in C. elegans , we discover that food breakdown is regulated by the interaction between bacterial outer membrane proteins (OMPs) and a neural-immune pathway. E. coli OmpF/A activate digestion by increasing the neuropeptide NLP-12 that acts on the receptor CCKR. NLP-12 is homologous to mammalian cholecystokinin, known to stimulate dopamine, and we found that loss of dopamine receptors or addition of a dopamine antagonist inhibited OMP-mediated digestion. Dopamine and NLP-12-CKR-1 converge to inhibit PMK-1/p38 innate immune signaling. Moreover, directly inhibiting PMK-1/p38 boosts food digestion. This study uncovers a role of bacterial OMPs in regulating animal nutrient uptake and supports a key role for innate immunity in digestion. [Display omitted] • C. elegans food digestion model reveals roles for E. coli OMPs in regulating digestion • Activation of digestion by E. coli OMPs is conserved • OMPs act via dopamine and NLP-12-CKR-1 to inhibit p38 innate immunity for digestion • Innate immunity acts as a "switch" for food digestion system The gut microbiota plays roles in food breakdown, but the specific pathways are undefined. Geng et al. establish a food digestion system in C. elegans and find that bacterial outer membrane proteins activate animal food digestion by inhibiting PMK-1/p38 innate immune signaling through neuronal dopamine and neuropeptide signaling. [ABSTRACT FROM AUTHOR]

Cockroaches have long been recognized as a major source of allergens in the human environment. As some allergens produced by cockroaches are accumulated within their tiny faeces and may persist unseen in the environment, development of a reliable method for monitoring cockroach faeces distribution and abundance is crucial. Our aim was to explore the rate of consumption of fluorescent bait and defecation of UV-light-detectable fluorescent faeces from Blattella germanica (L.) ( Blattodea: Ectobiidae) as a prerequisite for the establishment of faeces monitoring in the field. Laboratory experiments revealed that (1) the fluorescent bait was accepted by cockroaches as a food source and faeces produced after its consumption were fluorescent as well; (2) there was a positive relationship between the fluorescent bait consumed and production of fluorescent faeces; (3) single and brief consumption of fluorescent bait led to continuous fluorescent faeces production, giving cockroaches enough time (ca. 27 h) to deposit fluorescent faeces in an entire area of cockroach activity as well as in shelters. The amount of fluorescent bait consumed and the amount of fluorescent faeces produced was nevertheless different among males, non-gravid females, and gravid females. We subsequently validated the new fluorescent faeces-based monitoring technique in a semi-field experiment with human observers, which revealed that fluorescent faeces were reliably identified and distinguished from environmental dirt when illuminated with a UV flashlight. We further discuss the biological perspectives of our findings and recommendations for practical use. [ABSTRACT FROM AUTHOR]

The increasing world population, impact of food production on climate change, and ongoing issues with diet-related diseases (e.g., malnutrition and obesity) are global major challenges. Recent advances in how food structure impacts the extent and kinetics of uptake of nutrients and its consequent effects on the physiological outcomes are beginning to shift our understanding of nutrition. This understanding is important to designing future foods that provide optimum nutrient bioavailability and deliver healthy outcomes. We discuss perspectives and scientific challenges in understanding the complex relationship between food structure/matrix modification during the digestion process and the absorption of nutrients as well as designing food structures with more sustainable materials.

We have cloned the cDNA and genomic DNA of an active intronless cathepsin L from Metapenaeus ensis. The encoded enzyme has the shortest prosequence among cathepsin L subgroup. It was predominantly expressed in hepatopancreas with an expression level of at least 10 times higher than in any other tissues. It also has expression in stomach, intestine, eye, testis, ovary and muscle. Western blots visualized the mature enzyme in hepatopancreas and a procathepsin L in ovary, intestine and stomach. Metapenaeus cathepsin L (MeCatL) is localized in the large digestive vacuole of the digestive B cell of hepatopancreas. MeCatL has a role in food digestion. An interesting finding is that it exists in the nucleus of oocyte. MeCatL might have a specified physiological role in the nucleus of oocyte. MeCatL might also have a house-keeping function as is suggested for mammalian cathepsin L. [Copyright &y& Elsevier]