As an important functional protein resource in dairy products, milk protein has become a research hotspot due to its excellent nutritional value and multiple biological activities. Recent studies have made breakthrough progress in the preparation and functional analysis of milk protein-derived peptides. There are various bio-processing methods to precisely release bioactive peptides with specific functions from milk protein, such as directed enzymatic hydrolysis and controlled fermentation. These active components demonstrate significant health benefits in antioxidant defense, pathogen inhibition, immune homeostasis regulation, and blood pressure control. This paper systematically reviews the technologies for the preparation of milk protein-derived peptides, including enzymatic hydrolysis, microbial fermentation, chemical synthesis and computer simulation and prediction techniques, and conducts a comparative analysis the effectiveness and characteristics of these technologies. Furthermore, it elucidates the mechanisms by which milk protein-derived peptides exert their biological activities and their bioavailability, and evaluates their potential for application in functional foods and pharmaceutical formulations. By integrating existing research findings, this review provides a scientific basis for optimizing the production process of milk proteinderived peptides and expanding their application scenarios, thereby promoting their industrial development.

As the global population is aging, elderly individuals are increasingly facing significant health challenges, especially mental health issues such as emotional problems, sleep disturbance, and cognitive impairment. Probiotics, defined as live microorganisms that confer health benefits upon the host, have emerged as an effective means to improve the mental health of the elderly. Studies have shown that the gut microbiota regulates brain development and behavior in older adults through the gut-brain axis. This article focuses on summarizing the characteristics of the nervous system in the elderly and its connection to the gut microbiota, the characteristics of the gut microbiota in older individuals, and the mechanisms underlying the regulation of the nervous system in the elderly by the gut-brain axis. It also discusses recent advancements in understanding the role of probiotics in improving mental health conditions of the elderly, such as mild cognitive impairment, insomnia, depression, and Alzheimer’s disease, with the aim of providing a theoretical basis for the clinical application of probiotics and the management of mental health in older adults.