Tea plants have a long cultivation history in the world, but there are few studies on polysaccharides from fresh tea leaves. In this study, tea polysaccharides (TPSs) were isolated from fresh tea leaves. Then, we investigated the characteristics of TPSs during in vitro simulated digestion and fermentation; moreover, the effects of TPSs on gut microbiota were explored. The results revealed that saliva did not significantly affect TPSs\' molecular weight, monosaccharide composition, and reducing sugar content, indicating that TPSs cannot be digested in the oral cavity. However, TPSs were partially decomposed in the gastrointestinal tract after gastric and intestinal digestion, resulting in the release of a small amount of free glucose monosaccharides. Our in vitro fermentation experiments demonstrated that TPSs are degraded by gut microbiota, leading to short-chain fatty acid (SCFA) production and pH reduction. Moreover, TPSs increased the abundance of Bacteroides, Lactobacillus, and Bifidobacterium but reduced that of Escherichia, Shigella, and Enterococcus, demonstrating that TPSs can regulate the gut microbiome. In conclusion, TPSs are partially decomposed by gut microbiota, resulting in the production of SCFAs and the regulation of gut microbiota composition and function. Therefore, TPSs may be used to develop a prebiotic supplement to regulate the gut microbiome and improve host health.

Bioactive peptides (BAPs) represent a unique class of peptides known for their extensive physiological functions and their role in enhancing human health. In recent decades, owing to their notable biological attributes such as antioxidant, antihypertensive, antidiabetic, and anti-inflammatory activities, BAPs have received considerable attention. Simulated gastrointestinal digestion (SGD) is a technique designed to mimic physiological conditions by adjusting factors such as digestive enzymes and their concentrations, pH levels, digestion duration, and salt content. Initially established for analyzing the gastrointestinal processing of foods or their constituents, SGD has recently become a preferred method for generating BAPs. The BAPs produced via SGD often exhibit superior biological activity and stability compared with those of BAPs prepared via other methods. This review offers a comprehensive examination of the recent advancements in BAP production from foods via SGD, addressing the challenges of the method and outlining prospective directions for further investigation.

Listeria monocytogenes exhibits varying levels of pathogenicity when entering the host through contaminated food. However, little is known regarding the stress response and environmental tolerance mechanism of different virulence strains to host gastrointestinal (GI) stimuli. This study analyzed the differences in the survival and genes of stress responses among two strains of L. monocytogenes 10403S (serotype 1/2a, highly virulent strain) and M7 (serotype 4a, low-virulence strain) during simulated gastrointestinal digestion. The results indicated that L. monocytogenes 10403S showed greater acid and bile salt tolerance than L. monocytogenes M7, with higher survival rates and less cell deformation and cell membrane permeability during the in vitro digestion. KEGG analysis of the transcriptomes indicated that L. monocytogenes 10403S displayed significant activity in amino acid metabolism, such as glutamate and arginine, associated with acid tolerance. Additionally, L. monocytogenes 10403S demonstrated a higher efficacy in promoting activities that preserve bacterial cell membrane integrity and facilitate flagellar protein synthesis. These findings will contribute valuable practical insights into the tolerance distinctions among different virulence strains of L. monocytogenes in the GI environment.

Iron chelating peptides have been widely utilized as iron supplements due to their excellent absorption capacity, However, the high cost and cumbersome manufacturing process of these peptides significantly limit their industrial application. In this study, fermentation was used for the first time to prepare iron chelating peptides. Bacillus altitudinis 3*1-3 was selected as the most suitable strain from 50 strains. The hydrolysates of fermented scallop skirts showed excellent iron-chelating capacity (9.39 mg/g). Aspartic acid, glutamic acid, and histidine are crucial for the binding of peptides to ferrous ions. The heptapeptide (FEDPEFE) forms six binding bonds with ferrous irons. Compared with ferrous sulfate, peptide-ferrous chelate showed more stability in salt solution and simulated gastrointestinal juice (p < 0.05). Furthermore, the fermentation method could save >50% of the cost compared with the enzymatic method. The results can provide a theoretical basis for the preparation of ferrous-chelated peptides using the fermentation method.

Herba Epimedii, known for its rich array of bioactive ingredients and widespread use in ethnopharmacological practices, still lacks a comprehensive understanding of its gastrointestinal biotransformation. In this study, we qualitatively explored the dynamic changes in Epimedium sagittatum components during in vitro simulated digestions, with a quantitative focus on its five major flavonoids. Notably, significant metabolism of E. sagittatum constituents occurred in the simulated small intestinal fluid and colonic fermentation stages, yielding various low molecular weight metabolites. Flavonoids like kaempferol glycosides were fully metabolized in the simulated intestinal fluid, while hyperoside digestion occurred during simulated colon digestion. Colonic fermentation led to the production of two known bioactive isoflavones, genistein, and daidzein. The content and bioaccessibility of the five major epimedium flavonoids-icariin, epimedin A, epimedin B, epimedin C, and baohuoside I-significantly increased after intestinal digestion. During colon fermentation, these components gradually decreased but remained incompletely metabolized after 72 h. Faecal samples after E. sagittatum fermentation exhibited shift towards dominance by Lactobacillus (Firmicutes), Bifidobacterium (Actinobacteria), Streptococcus (Firmicutes), and Dialister (Firmicutes). These findings enhance our comprehension of diverse stages of Herba Epimedii constituents in the gut, suggesting that the primary constituents become bioaccessible in the colon, where new bioactive compounds may emerge.

Previously, we found that whey proteins form biomolecular coronas around titanium dioxide (TiO2) nanoparticles. Here, the gastrointestinal fate of whey protein-coated TiO2 nanoparticles and their interactions with gut microbiota were investigated. The antioxidant activity of protein-coated nanoparticles was enhanced after simulated digestion. The structure of the whey proteins was changed after they adsorbed to the surfaces of the TiO2 nanoparticles, which reduced their hydrolysis under simulated gastrointestinal conditions. The presence of protein coronas also regulated the impact of the TiO2 nanoparticles on colonic fermentation, including promoting the production of short-chain fatty acids. Bare TiO2 nanoparticles significantly increased the proportion of harmful bacteria and decreased the proportion of beneficial bacteria, but the presence of protein coronas alleviated this effect. In particular, the proportion of beneficial bacteria, such as Bacteroides and Bifidobacterium, was enhanced for the coated nanoparticles. Our results suggest that the formation of a whey protein corona around TiO2 nanoparticles may have beneficial effects on their behavior within the colon. This study provides valuable new insights into the potential impact of protein coronas on the gastrointestinal fate of inorganic nanoparticles.

The potential application of succinylated chickpea protein (SCP) as a wall material for spray-dried microencapsulated probiotics was investigated. The results showed that succinylation increased the surface charge of chickpea proteins (CP) and reduced the particle size of the proteins. Meanwhile, succinylated modification decreased the solubility of protein under acidic conditions and increased the solubility in alkaline conditions. The effects of spray drying and in vitro gastrointestinal digestion on probiotics were investigated by microencapsulating chickpea protein with different degrees of N-succinylation. The results showed that all microcapsules had similar morphology, particle size and low water content. The microcapsules prepared by succinylated chickpea protein showed better stability and viability during spray drying and gastrointestinal digestion. The protective effect of probiotics was better as the degree of N-succinylation increased. In particular, the SCP-3-P sample (10 % succinic anhydride modified CP and maltodextrin) lost only 0.29 Log CFU/g throughout gastrointestinal digestion. The superior protective effect provided by succinylated CP in simulated gastric fluid (SGF) was mainly attributed to the reaction of succinic anhydride with protein to cause protein aggregation under gastric acidic conditions, reducing the infiltration of gastric acid and pepsin and maintaining the structural integrity of the microcapsules. Therefore, these findings provide a new strategy for probiotic intestinal delivery and application of chickpea protein.

Food-derived oligopeptides (FOPs) exhibit various bioactivities. However, little was known about their sequence changes in the gastrointestinal tract and the effect of changes on bioactivities. FOPs\' sequence features, changes and effects on bioactivities have been summarised. The sequence length of FOPs decreases with increased exposure of hydrophobic and basic amino acids at the terminal during simulated gastrointestinal digestion. A decrease in bioactivities after simulated intestinal absorption has correlated with a decrease of Leu, Ile, Arg, Tyr, Gln and Pro. The sequence of FOPs that pass readily through the intestinal epithelium corresponds to transport modes, and FOPs whose sequences remain unchanged after transport are the most bioactive. These include mainly dipeptides to tetrapeptides, consisting of numerous hydrophobic and basic amino acids, found mostly at the end of the peptide chain, especially at the C-terminal. This review aims to provide a foundation for applications of FOPs in nutritional supplements and functional foods.

This study develops hemp seed globulin (GLB)-alginate (ALG) nanoparticles (GANPs) for Cannabisin A (CA) stabilization under environmental stress and during pepsin digestion. The optimal GLB: ALG mass ratio of 1: 1.5 was determined for GANPs formation at pH 3.5, resulting in a high yield of 95.13 ± 0.91 %, a ζ-potential of -35.73 ± 1.04 mV, a hydrodynamic diameter of 470.67 ± 11.36 nm, and a PDI of 0.298 ± 0.016. GANPs were employed to encapsulate CA, achieving a high loading capacity of 13.48 ± 0.04 μg mg-1. FTIR analysis demonstrated that the formation of CA-GLB-ALG nanoparticles (CGANPs) involves electrostatic interactions, hydrogen bonding, and hydrophobic interactions. XRD and DSC analyses revealed that CA is amorphous within the CGANPs. CGANPs demonstrated remarkable dispersion stability as well as resistance to high ionic strength and high-temperature treatments, indicating their potential as efficient hydrophobic drug-delivery vehicles. When compared to free CA, CA coated within CGANPs displayed greater DPPH/ABTS scavenging activity. Furthermore, the ALG-shelled nanoparticles protected GLB from pepsin digestion and slowed the release of CA throughout the release process, extending their stay on the intestinal wall mucosa. These findings imply that CGANPs is an ideal delivery vehicle for CA as they may expand the application of CA in food items.

To explore the effect of different microbial strains on blueberry pomace with solid-state fermentation (SSF), three fungi strains and three lactic acid bacteria (LAB) strains were utilized to investigate with respect to polyphenol profiles, antioxidant capacities, and bioaccessibility. Different strains exhibited different capacities for metabolizing polyphenolic compounds in blueberry pomace. The contents of 10 phenolic acids and 6 flavonoids (except (+)-catechin) were increased in blueberry pomace fermented by Lactobacillus acidophilus (LA). A similar tendency was observed in blueberry pomace fermented by Aspergillus niger (AN) and Lactobacillus plantarum (LP), where the concentration of 8 phenolic acids and 5 flavonoids was enhanced, with the following exceptions: (+)-catechin, ferulic acid, vanillic acid, and quercitrin. Chlorogenic acid and quercetin were the maximum phenolic acids and flavonoids in blueberry pomace with SSF, upgraded at 22.96 and 20.16%, respectively. Contrary to the growth of phenolic acids and flavonoid compounds, all individual anthocyanins showed a decreased trend. Only in the blueberry pomace fermented by AN, all anthocyanidins exhibit a rising trend. After SSF, 2,2\'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2,2-diphenylpicrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) radical scavenging abilities were increased by up to 33.56, 59.89, and 87.82%, respectively. Moreover, the simulated gastrointestinal digestion system revealed that SSF improved the bioaccessibility of polyphenolic compounds. Compared with other strains, LA, LP, and AN showed better excellent capacities for metabolizing polyphenolic compounds, which led to a greater increase in antioxidant activity and bioaccessibility in fermented blueberry pomace.