With the increasing per capita demand for animal protein, there is a growing interest in the abundant abalone protein resources. Abalone proteins are known for their nutritional and functional properties that contribute to flavor and texture. We systematically constructed the relationship between abalone protein, processing, and proteomics. This paper reviews the nutritional properties of abalone proteins and evaluates the effects of different thermal processing techniques, non-thermal processing, and freezing on abalone proteins. In addition, we synthesize published abalone proteomics studies and the use of proteomics technology to better elucidate the quality changes of abalone and its products, and as a technical basis for the study of blue food marker proteins. It is important direction to clearly explain the protein composition and meat quality mechanism of abalone in the processing and storage by proteomic. During various types of thermal processing, non-thermal processing, and freezing of abalone, the various chemical forces between protein molecules are disrupted, which in turn leads to different degrees of denaturation, aggregation, and gelation, which may have an impact on the organoleptic properties, bioavailability, and digestibility of abalone muscle. Proteomics is used in abalone biology studies to understand developmental biology, physiology, disease, stress, and species identification and can also be a powerful tool to characterize processing methods on abalone quality properties.

In order to study the synergistic effects of lotus seed resistant starch (LRS) as a prebiotic and sodium lactate (SL) as a postbiotic on the intestinal flora and metabolic profile of rats, 24 male SD rats were randomly divided into normal control (NC), LRS, SL, and LRS + SL groups. After four weeks of oral administration, the diversity of intestinal flora and differential metabolites were analyzed by high-throughput gene sequencing and non-targeted metabolomics, respectively. The results showed that LRS, SL and their combination could increase the richness of intestinal flora. Compared with the NC group, the relative abundance of Lachnospiraceae_NK4A136_group was increased, while the relative abundance of Coriobacteriaeae_UCG-002 and Enterrhabdus in the small intestine of rats was decreased in the LRS group; in the SL group, the relative abundance of Lactococcus and unclassified_f__Micrococcaceae was decreased increased, respectively; in the LRS + SL group, the relative abundance of unclassified_f__Ruminococcaceae and Lachnospiraceae_NK4A136 was increased, whereas the relative abundance of Vagococcus and Allobaculum was decreased. Compared with the LRS and SL groups, the relative abundance of Allobaculum was decreased, while the relative abundance of unclassified_f__Ruminocaceae was increased. The non-targeted metabolomic analysis showed that the levels of (R)-lipoic acid, α-curcumin, ginkgolide A, cervonoyl ethanolamide and steroid hormones in the small intestine of rats in the LRS group were upregulated, while the levels of LysoPC(17:0) and L-serine were down-regulated compared with the NC group, and there were significant differences in steroid hormone metabolic pathways between the two groups. In the SL group, cervonoyl ethanolamide was up-regulated, and the metabolic pathways of steroid hormones and bile acids changed significantly. In the LRS + SL group, pantothenic acid was up-regulated, whereas LysoPC(17:0) was down-regulated, and amino acid metabolic pathways changed significantly. There were significant differences in metabolic pathways of lipid, bioactive substances and vitamin between the LRS + SL group and the LRS and SL groups. Intervention with LRS and SL could optimize the structure of intestinal flora and inhibit the reproduction of potentially harmful bacteria, thereby promoting the increase of potentially beneficial metabolites. The combination of LRS and SL was more effective in increasing the diversity of intestinal flora, regulating vitamin metabolism, amino acid metabolism and lipid metabolism, and enhancing the defense system in the body. These results will provide a theoretical basis for studies on the synergistic effects of prebiotics and postbiotics.

In order to study the hypolipidemic effect of different types of ginger resistant starch on experimentally induced hyperlipidemia in rats, physiological and biochemical indicators of hyperlipidemic rats were measured, and histopathological characteristics of blood vessel, colon and liver tissues were examined. By measuring the contents of primary and secondary bile acids in serum, a serum metabolic profile of bile acids was constructed. The results showed that compared to the hyperlipidemic model (HM) group, the body mass and liver index of rats in the positive control (PC, simvastatin), ginger resistant starch type 2 (GRS2), ginger resistant starch type 3 (GRS3), ginger resistant starch type 4 (GRS4) and high amylose maize starch (HMS) groups were significantly reduced, PC and GRS4 being the most effective in this regard. Simvastatin, ginger resistant starch and HMS significantly reduced the contents of total triglyeride (TG), total cholesterol (TCHO), low density lipoprotein cholesterol (LDL-C), and the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) (P < 0.05), and increased the level of high density lipoprotein cholesterol (HDL-C) in the rat serum (P < 0.05), and the best effect was found with GRS3 and GRS4. According to histopathological observation, ginger resistant starch could improve the vascular layer, intimal structure and outer wall structure of hyperlipidemia rats, increase the thickness of the colonic muscularis, the thickness of the mucous membrane and the length of villi, make the structure of colonic crypts and goblet cells clearer, and reduce the number and size of fat vacuoles in the liver cytoplasm. In this regard, GRS3 and GRS4 were more effective than HMS. In addition, GRS3 and GRS4 improved lipid metabolism in hyperlipidemic rats mainly by reducing the contents of free primary bile acids (cholic acid, chenodeoxycholic acid, β-murocholic acid and α-murocholic acid) and deoxygenated secondary bile acids (hyodeoxycholic acid, ursodeoxycholic acid, deoxycholic acid, taurohyodeoxycholic acid and glycoursodeoxycholic acid) in the serum.

Resistant starch is not easily digested and absorbed in the small intestine, but it can be utilized by the large intestinal microflora to produce metabolites such as short-chain fatty acids, which in turn can regulate the intestinal microfloral balance and bile acid metabolism. Therefore, this article puts forward the “resistant starch-intestinal flora-metabolite” nutrition axis to systematically summarize the mechanism of action by which RS mediates the production of metabolites by regulating the intestinal microflora. It compares the effects of intestinal microbial fermentation on the apparent, crystal and molecular structure of RS, describes the relationship of the structural characteristics of RS with the intestinal community structure, the production of short-chain fatty acids and the excretion of bile acids, and summarizes the mechanism of RS for improving metabolic diseases by regulating the intestinal microflora and intestinal metabolites. Besides, an outlook is given on future studies on the pathways of the interaction among resistant starch, the intestinal microflora and bile acid, and on the mechanism of RS interaction with bile acids and short-chain fatty acids in metabolic diseases.

This study was to investigate the structure and rat fecal microbial fermentation properties of a polysaccharide fraction (PHP2) isolated from the red marine alga Porphyra haitanensis. PHP2 was characterized as a sulfated glucogalactan, with a hypothetical backbone structure of →4)Gα(1→6)G4Sβ(1→4)Glc(1→ and a side chain of Man(1→6)Glc. PHP2 had an irregular spherical chain conformation. The 16S rRNA sequence analysis revealed that PHP2 modulated the rat fecal micro-flora composition, with a similar effect to inulin, changing the dominant genus (Lactobacillus and Escherichia-Shigella) and promoting the growth of organisms that degrade sulfur-containing polysaccharides, such as Desulfovibrio, Ruminococcaceae_UCG-005, and Ruminococcus_2. PHP2 can promote production of acetic, propionic and butyric acid by rat fecal micro-flora. Prediction of metabolic function suggested that PHP2 could modulate cholesterol metabolism. The sulfated glucogalactan fermentation behavior may be associated with its monosaccharide composition, chain branching and chain conformation. PHP2 appeared to have considerable potential as functional food, and was associated with sulfur-containing polysaccharides in general.

Fortunella margarita polysaccharides (FMPS) are composed of 4 polysaccharide fragments, namely mannogalactoglucan, galactoglucan, glucan and arabinoglucan. This study investigated the in vitro fermentation of FMPS fractions and their effect on the fecal microbiota of mice and short chain fatty acids (SCFAs) production. The results showed that the structure of the fecal microbiota was changed after FMPS fermentation. At the phylum level, the polysaccharide fractions reduced the relative abundance of Bacteroidetes compared with the inulin group. At the genus level, the polysaccharide fractions increased the abundance of Lactobacillus, and decreased the abundance of Granulicatella, Proteus and Rummeliibacillus. Polysaccharide fractions could promote the proliferation of beneficial bacteria (Lactobacillus), and decreased harmful bacteria (Granulicatella, Proteus, Rummeliibacillus and Serratia). Furthermore, there was a significant distinction in the genus level flora processed by different polysaccharide fractions, especially mannogalactoglucan. Polysaccharide fractions showed potential prebiotic effects, with mannogalactoglucan, in particular, promoting proliferation of SCFA-producing bacteria. SCFAs were regulated by monosaccharide composition, molecular weight of the FMPS fractions, and the composition of the fecal bacteria. Polysaccharide fractions could modulate metabolic function of the fecal microbiota, altering the levels of SCFAs. These results suggested that FMPS are important functional components in gut health, especially mannogalactoglucan.