Postbiotics are a new means of intervention in the intestinal ecosystem that has emerged in recent years. Postbiotics refer to soluble factors (products or metabolic by-products) secreted by living bacteria or released after bacterial lysis, namely small molecules that regulate the health of the host, such as enzymes, peptides, teichoic acid, peptides derived from peptidoglycan, polysaccharides, cell surface proteins, and organic acids. Although the International Symposium of the International Scientific Association for Probiotics and Prebiotics has not yet published a consensus on postbiotics, this concept closely related to probiotics still attracts people’s attention. This paper briefly clarifies the classification and preparation methods of postbiotics, and discusses the advantages and potential application of postbiotics as functional ingredients in dairy products.

Protein is an important nutrient for human health, and milk protein is considered an important source of natural bioactive peptides. Milk-derived bioactive peptides, mainly derived from casein and whey proteins by enzymatic hydrolysis or microbial fermentation, contribute to the development of human nervous, gastrointestinal, cardiovascular and immune systems and play a vital role in preventing cancer, osteoporosis, high blood pressure and other health problems. In this paper, the application of milk-derived bioactive peptides in nutraceuticals and functional foods has received more and more attention. This article summarizes the production technologies and biological activities of milk-derived bioactive peptides, and provides an outlook on the future production and application of milk-derived bioactive peptides.

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder that causes abdominal pain, diarrhea and constipation, reducing the quality of life in patients. Probiotics have been shown to regulate the intestinal flora balance, enhance intestinal barrier function and modulate the immune response, thereby providing new approaches to treat IBS. This article aims to review the literature concerning the treatment of IBS with probiotics with respect to the subtypes of IBS, changes in the intestinal flora of IBS patients, the therapeutical effect of probiotics on IBS and the underlying mechanism for the purpose of providing useful information for applying probiotics to treat IBS and broadening their scope of application.

Caseins were separated from the fresh milk of grazing yak cows in Tianzhu county, Gansu province by microfiltration to investigate changes in their heat stability, hydrophobicity, particle sizes and molecular weights after different pH treatments (pH 6.4, 6.6, 6.8 and 7.0) and heat treatments (80, 100, 120 and 140 ℃). The results showed that functional properties of yak milk caseins at pH 6.8 revealed the most significant deterioration after each heat treatment. At a temperature far below the denaturing temperature the caseins exhibited good retention of functional properties. Both acid and heat treatments caused molecular polarization of the caseins, destroyed the hydrophobic force, which contributes to maintaining the spatial structure of the protein molecules, and accordingly induced their dissociation or aggregation, causing changes in their molecular structure and in turn affecting their functional properties.