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Current studies regarding the effect of different nitrogen sources on gut microbiota have thus far disregarded the ability of probiotics and coliforms to compete for protein. This study aimed to investigate the differences in the utilization of soybean protein (SPro) and its derived peptides (SPep) by the gut microbiota of Sprague Dawley (SD) rats. The SPro and SPep prepared in this study showed extensive SPro molecular weight distribution, while that of SPep was minimal, ranging between 150 and 1000 Da and primarily consisting of two to five amino acids. The cecum microflora composition of the rats was determined via 16S rDNA amplicon sequencing, showing that the SPro and SPep significantly increased the abundance and uniformity of the gut microbiota after 35 days of feeding. The Firmicutes/Bacteroidetes (F/B) ratios of the SPep, SPro, and casein groups were 2.49 ± 0.60, 2.98 ± 1.12, and 2.59 ± 0.74, respectively. Although the rats fed with SPro and SPep displayed similar gut microbiome structures, SPep significantly promoted Lactobacillus and Phascolarctobacterium growth. The results showed that SPep significantly increased the diversity of the gut microbiota and elevated the probiotic proportion. PRACTICAL APPLICATION: SPro and SPep are two nutritious and high-quality nitrogen sources. The results showed that SPro and SPep regulated the structure of gut microbiota in rats, and the effect of SPep was better. This study provides a theoretical basis for developing SPep functional foods able to regulate gut microbiota and maintain health.

Calcium is one of the most important mineral elements in the human body and is closely related to the maintenance of human health. To prevent calcium deficiency, various calcium supplements have been developed, but their application tends to be limited by low calcium content and highly irritating effects on the stomach, among other side effects. Recently, calcium–peptide chelates, which have excellent stability and are easily absorbed, have received attention as an alternative emerging calcium supplement. Calcium-binding peptides (CaBP) are usually obtained via the hydrolysis of animal or plant proteins, and calcium-binding capacity (CaBC) can be further improved through chromatographic purification techniques. In calcium ions, the phosphate group, carboxylic group and nitrogen atom in the peptide are the main binding sites, and the four modes of combination are the unidentate mode, bidentate mode, bridging mode and α mode. The stability and safety of calcium–peptide chelates are discussed in this paper, the intestinal absorption pathways of calcium elements and peptides are described, and the bioavailability of calcium–peptide chelates, both in vitro and in vivo, is also introduced. This review of the research status of calcium–peptide chelates aims to provide a reasonable theoretical basis for their application as calcium supplementation products.

Bifidobacterium is a common probiotic that plays a vital role in the intestinal tract. This study aimed to explore the different effects of soybean protein and soybean peptides on the growth and metabolism of Bifidobacterium animalis subsp. animalis JCM 1190. Soybean protein and soybean peptides were digested in vitro, after which different nitrogen source containing media were prepared and used for the monoculture of Bifidobacterium animalis subsp. animalis JCM 1190 and the co-culture of Bifidobacterium animalis subsp. animalis JCM 1190 and Escherichia coli JCM 1649. During the culture process, the viable cell number and lactic acid and acetic acid contents were measured, while non-targeted metabonomics was used to detect the differential metabolites and metabolic pathways. The results showed that soybean protein and soybean peptides promoted the growth and metabolism of Bifidobacterium animalis subsp. animalis JCM 1190, while digested soybean peptides had a better effect. Digested soybean peptides increased the viable cell number and lactic acid and acetic acid contents in the monoculture by regulating glycine, serine, and threonine metabolism, as well as pyruvate metabolism, the TCA cycle, glycolipid metabolism, and other metabolic pathways, balanced the ability of Bifidobacterium animalis subsp. animalis JCM 1190 and Escherichia coli JCM 1649 to utilize nitrogen sources during the early period and enhanced the competitiveness of Bifidobacterium animalis subsp. animalis JCM 1190 during the later period in co-culture.

Soybean peptides were reported to promote the growth and metabolism of Lacticaseibacillus rhamnosus (L. rhamnosus) Lra05. However, the relationship between L. rhamnosus Lra05 and the characteristics of soybean peptides is still unclear. Therefore, digested soybean peptides (dPEP) after 36 h utilization by L. rhamnosus Lra05 were identified and analyzed. We found that L. rhamnosus Lra05 tends to utilize hydrophobic peptides with three to five amino acids residues, and hydrophilic peptides with more than five residues. They also prefer peptides with proline at penultimate C-terminal position or arginine at ultimate C-terminal position. Moreover, fraction 1 (F1) and fraction 7 (F7) acquired from dPEP using RP-HPLC exhibited the strongest growth and metabolism promoting effects, and the utilized characteristics of F1 and F7 were similar with those of dPEP. These results explained why soybean peptides could promote L. rhamnosus to some extent and strengthen theoretical basis for the application of soybean peptides as potential prebiotics.

Soybean protein (Pro) and soybean oligopeptide (Pep) were subjected to simulated digestion in vitro to study the effect of Pep on the growth and metabolism of Lactobacillus acidophilus JCM 1132. First, the molecular weight distribution differences of samples before and after digestion were compared, and the samples were used to replace the nitrogen source components in the culture media. Then, the viable cell numbers, lactic acid and acetic acid content, differential metabolites, and metabolic pathways during the culturing process were measured. Results showed that the digested soybean oligopeptide (dPep) was less efficient than MRS medium in promoting the growth, but by increasing the content of the intermediates during the tricarboxylic acid (TCA) cycle, its metabolic capacity was significantly improved. Besides, due to the low molecular weight of dPep, it can be better transported and utilized. And dPep significantly strengthened the amino acid metabolism and weakened the glycerol phospholipid metabolism, so the ability of dPep in promoting the growth and metabolism of Lactobacillus acidophilus JCM 1132 is higher than the digested soybean protein (dPro).

Lactic acid bacteria are one of the most pivotal probiotics. Promoting their viability could be an effective method to modulate the balance of intestinal flora, thereby improving human health. The current solution is to take advantage of carbon-sourced prebiotics, while protein and peptides with potential prebiotic functions have not been investigated. Soy proteins and peptides have been proven to enhance the growth and metabolism of Lactobacillus. However, research on the relationship between strains of lactobacilli and the structure of soybean peptides is still limited. In the present study, soybean protein and peptides effectively increased the growth and organic acid secretion of Limosilactobacillus reuteri LR08. Additionally, soybean peptides and fructooligosaccharides showed synergistic effects in modulating Limosilactobacillus reuteri LR08. Fraction 1 acquired from soy peptides using RP-HPLC exhibited the most effectiveness and several novel peptides were identified. These results could theoretically and practically benefit soybean peptide application as a potential prebiotic.

The purpose of this study was to investigate whether soybean protein isolates (SPIs2 PEP: soybean peptides; dPEPs: digested soybean peptides; SPIs: soybean protein isolates; dSPIs: digested soybean protein isolates; MRS: Man Rogosa Sharpe broth; LN: MRS reduced nitrogen content by half; LN+PEP: LN supplemented with an equivalent nitrogen content from soybean peptides; LN+SPI: LN supplemented with an equivalent nitrogen content from soybean protein isolates; LN+dPEP: LN supplemented with an equivalent nitrogen content from digested soybean peptides; LN+dSPI: LN supplemented with an equivalent nitrogen content from digested soybean protein isolates.2) and soybean peptides (PEPs), as well as their hydrolysates after simulated gastrointestinal digestion (dSPIs and dPEPs), can promote the growth and short chain fatty acid (SCFA) production of Lactobacillus rhamnosus (L. rhamnosus) in vitro under mono-culture and co-culture with Escherichia coli (E. coli). We found that all the treatment groups could enhance the viable cell numbers, while the effects of PEP and dPEP occurred earlier than those of SPI and dSPI, and the production of SCFAs was improved mainly by the dPEP and dSPI groups in mono-culture. In the co-culture system, dPEP weakened the competitiveness of E. coli and improved the competitive capacity of L. rhamnosus, and the viable cell numbers of L. rhamnosus were higher than the numbers in the treated mono-culture after 8 h and 12h of cultivation.

Although traditional meat products are highly popular with consumers, the high levels of unsaturated fatty acids and cholesterol present significant health concerns. However, simply using plant oil rich in unsaturated fatty acids to replace animal fat in meat products causes a decline in product quality, such as lower levels of juiciness and hardness. Therefore, it is necessary to develop a fat substitute that can ensure the sensory quality of the product while reducing its fat content. Consequently, using emulsion gels to produce structured oils or introducing functional ingredients has attracted substantial attention for replacing the fat in meat products. This paper delineated emulsion gels into protein, polysaccharide, and protein–polysaccharide compound according to the matrix. The preparation methods and the application of the three emulsion gels as fat substitutes in meat products were reviewed. Since it displayed a unique separation structure, the double emulsion was highly suitable for encapsulating bioactive substances, such as functional oils, flavor components, and functional factors, while it also exhibited significant potential for developing low-fat or functional healthy meat products. This paper summarized the studies involving the utilization of double emulsion and gelled double emulsion as fat replacement agents to provide a theoretical basis for related research and new insight into the development of low-fat meat products.

The effect of an antioxidative peptide Met-Lys-Ala-Val-Cys-Phe-Ser-Leu (MKAVCFSL) on oxidative stress in Caco-2 cell lines was investigated. Caco-2 cells exposed to excess oxidative stress could be restored when pretreated with the peptide. Reactive oxygen species (ROS) and malondialdehyde (MDA) within the cells could be scavenged by MKAVCFSL. The peptide could also enhance the activity of glutathione peroxidase (GPx), glutathione reductase (GR), and superoxide dismutase (SOD), while catalase (CAT) activity did not show a significant difference between treatment and control samples. Meanwhile, it was observed that peptide treatment increased the concentration of glutathione (GSH). Yet the content of glutathione disulfide (GSSG) was hardly affected. The stability of MKAVCFSL was also assessed and an intact peptide was observed after simulated gastrointestinal digestion. Part of the peptide was hydrolyzed into fragments including MKA, FSL, AVCFSL, and MKAVCF. This study demonstrated that MKAVCFSL derived from bighead carp hydrolysates could ameliorate oxidative stress to protect the Caco-2 cells.

Probiotics are live microorganisms that provide health benefits to the host when consumed in adequate concentrations. The strains most frequently used as probiotics include Lactobacillus and Bifidobacteria. Probiotics have demonstrated significant potential as therapeutic options for various diseases. In addition to oligosaccharides, proteins, hydrolysates and peptides have also been shown function as prebiotics to promote the growth of probiotics. Therefore, this review provides a summary of the available information and current knowledge on the effects of various proteins on probiotics, focusing on how proteins influence probiotics, although uncertainties and disagreements about how the metabolism of proteins promotes probiotics still exist. Understanding the relationship between proteins and probiotics will allow appropriate prebiotic selection and the development of effective methods to promote the proliferation of probiotics.

Soybean protein and peptides have the potential to promote the growth of Lactobacillus, but the mechanisms involved are not well understood. The purpose of this study is to investigate differentially expressed genes (DEGs) of Limosilactobacillus reuteri (L. reuteri) LR08 responding to soybean protein and peptides using transcriptome. The results showed that both digested protein (dpro) and digested peptides (dpep) could enhance a purine biosynthesis pathway which could provide more nucleic acid and ATP for bacteria growth. Moreover, dpep could be used instead of dpro to promote the ABC transporters, especially the genes involved in the transportation of various amino acids. Interestingly, dpro and dpep played opposite roles in modulating DEGs from the acc and fab gene families which participate in fatty acid biosynthesis. These not only provide a new direction for developing nitrogen-sourced prebiotics in the food industry but could also help us to understand the fundamental mechanism of the effects of dpro and dpep on their growth and metabolisms and provides relevant evidence for further investigation.

Lacticaseibacillus rhamnosus (L. rhamnosus) is a probiotic strain that has exhibited probiotic properties in the prevention and treatment of intestinal flora imbalance. In order to investigate the morphological differences and molecular mechanisms underlying the effects of simulated gastrointestinal digested soybean protein isolate (dpro 2 ) and digested soybean peptide (dpep) treatment on L. rhamnosus, microscopic observation and iTRAQ-based proteomics and bioinformatics analysis were performed. 1462 proteins were identified, and differentially abundant proteins (DAPs) were screened accurately, including 66 DAPs in the dpep group compared with the Man Rogosa Sharpe broth (M) group and 66 DAPs in the dpep/dpro group. Bioinformatic analysis revealed that DAPs in dpep/M and dpep/dpro mainly differed in cellular carbohydrate and nitrogen compound catabolic processes and transport. Some of the DAPs overlapped in the three comparison groups might be pivotal proteins involved in growth and morphologic changes of the dpep and dpro treatments.