Milk protein is an important source of dietary protein for humans. In the modern food industry, milk and milk protein have become essential components in various processed foods. Milk protein is one of the most common allergens, and the problem of food allergies caused by milk protein has become a topical issue in the field of food safety. With the development of the dairy industry, non-milk derived food ingredients have been introduced in various dairy products, which may interact with milk protein, altering the protein’s structure and affecting its antigenic epitopes and consequently its allergenicity. Herein, we discuss the effects of food components on milk protein allergenicity from macronutrients, micronutrients and functional activities contained in the food base, and other substances. We hope that this review can improve the scientific understanding of milk protein allergenicity in food components, guide food processing safety to reduce milk protein allergenicity, and provide a basis for food allergenicity risk assessment.

Renal health problems have become major public health issues but are easily overlooked. Existing studies demonstrate that probiotic regulation of the intestinal flora is a new intervention pathway to protect renal health. Nevertheless, little research attention has been paid to the role of probiotics in protecting kidney health. In this paper, we review the protective effects and action mechanisms of probiotics used in food on renal health problems such as chronic nephritis, hemodialysis, hyperuricemia, and hyperoxaluria. We hope that this review can provide theoretical support for the exploitation of new probiotics and the targeted development of probiotic products.

In order to evaluate the functional characteristics of Tibetan kefir, the conditions for the fermentation of skim milk with Tibetan kefir were preliminarily optimized by one-factor-at-a-time method based on titratable acidity and sensory evaluation, and the antioxidant capacity and cholesterol-lowering ability of the fermented milk were studied in vitro. It was found that the optimal fermentation conditions were as follows: inoculum size 6%, fermentation time 7.5 h, and temperature 37 ℃. The fermented milk produced under the optimized conditions had a medium acidity, delicate taste, uniform texture and unique flavor, and its lactic acid bacterial population was 1.48 × 108 CFU/mL. The hardness of the fermented milk was 178.43 g, higher than that of traditional fermented milk, the adhesion was -103.52 g·s and the non-fat solid content, protein content and titratable acidity all conformed to the national standard for fermented milk. The quality of the fermented milk was good overall. Compared with traditional fermented milk, its antioxidant activity was not particularly prominent, but the cholesterol-lowering ability was particularly considerable, with removal rate of as high as 37.98% (fermented skim milk) and 40.68% (fermented whole milk).

Yogurt fermented by probiotics represents an important application of probiotics in the food field. In this paper, the recent progress in the study of yogurt fermented by probiotics is summarized, with a focus on the studies on its functional activities and mechanisms of action in the past five years. A large number of studies have shown the functional activities of yogurt fermented by probiotics including maintaining gastrointestinal, oral, and skin health; improving metabolism abnormalities like hypertension, hyperlipidemia, hyperglycemia, obesity and osteoporosis; regulating immune function like improving food allergy, relieving respiratory allergy, and elevating antioxidant capacity; and regulating mental and emotional functions. It is expected that this review will provide theoretical support for the development and research of fermented products with probiotics.

While research on the functional effects of probiotics has been extended to include their roles in prevention and treatment of immune, metabolic and neuroemotional disorders, a systematic review of the numerous studies in this regard is still lacking in the literature. In this paper, we summarize recent animal and clinical studies on the two probiotics, Lactobacillus and Bifidobacterium and recent studies on their mechanism of action. A number of studies demonstrate that the application of probiotics as a functional food ingredient will help further improve people’s health and living standard. The mechanism of action of probiotics on human diseases and disorders especially the body’s responses to different probiotics, which allows the development of therapeutic strains for clinical applications, will represent an important direction of research in the future.

Nowadays, probiotics are a hot concern in the health market. In this paper, the functional activities of the two main probiotics, Lactobacillus and Bifidobacterium, in the prevention and treatment of skin, oral, respiratory, liver, gastrointestinal and female genital tract diseases are summarized including the activities in animal experiment and clinical trials and the related mechanisms. This review will provide important theoretical support for further scientific research and product development of probiotics.

Lactobacillus plantarum is a probiotic bacterium with various biological effects. Its ability to relieve muscle fatigue and injury has aroused market concerns, which is associated with glutamine synthetase (GS) activity. However, the literature currently lacks reports on the production of GS by fermentation with Lactobacillus plantarum. In this study, the GS activity of L. plantarum Lp-G18 was enhanced by adding L-glutamic acid to the medium and optimizing the carbon sources and metal ion concentrations. The optimized medium was composed of glucose 40 g/L (222 mmol/L), MgSO4·7H2O 4.92 g/L (20 mmol/L), MnSO4 0. 025 g/L (1.5 mmol/L), L-glutamic acid 8.82 g/L (60 mmol/L), peptone 10 g/L, beef extract powder 10 g/L, yeast extract powder 5 g/L, K2HPO4 2 g/L, NaAc 5 g/L, diammonium hydrogen citrate 2 g/L, and Tween-80 1 g/L. The GS activity obtained using the optimized medium was 2.4 times higher than that from basal MRS medium.

Lactobacilus acidophilus is a kind of probiotics with great commercial value. The high cell density fermentation of Lactobacilus acidophilus has important application value for its industrial production. In this paper, we review the nutritional requirements of Lactobacilus acidophilus, its strategies for adapting to a freezing environment and its high cell density fermentation, aiming to provide theoretical reference for the production of Lactobacilus acidophilus.

Pseudomonas is a genus of bacteria commonly found in contaminated raw milk. This bacterial genus can form a biofilm on equipment surfaces during the production of dairy products which causes equipment corrosion and is difficult to remove. The biofilm formed by Pseudomonas not only promotes the secretion of heat-resistant peptidases but also provides a substrate for the growth of pathogenic bacteria, posing a great risk to the safety of dairy products. This article outlines recent progress in understanding the mechanisms for the regulation of Pseudomonas biofilm formation and the environmental factors affecting Pseudomonas biofilm formation, which is helpful for the prevention and control of Pseudomonas bioflim.

Pseudomonas frequently occur in refrigerated raw milk as the predominant bacteria,which secret heat-resistant enzymes that can cause milk spoilage.A total of 102 strains of Pseudomonas isolated from raw milk were identified by rpoB gene sequencing at the species level,and azocasein was used to quantify the proteolytic activity and heat resistance of their extracellular peptidases under two sets of cultivation conditions (30 ℃ for 2 days or 6 ℃ for 8 days).Pseudomonas fluorescens was the most dominant Pseudomonas species in the samples,followed by Pseudomonasfragi and Pseudomonas sp1.A significant variation in the proteolytic activity of different Pseudomonas species was observed.Most isolates of Pseudomonasfluorescens (23/41) showed proteolytic activity after cultivation at two temperatures (30 or 6 ℃),while most isolates of Pseudomonas sp1 did not.In addition,all isolates of Pseudomonasfragi (13/13) showed proteolytic activity only after cultivation at 6 ℃.Temperature stability of their extracellular peptidases was determined.After cultivation at 6 ℃,P.fluorescens M02 had the highest peptidase activity (11.78 ΔA/(h·mL)).The peptidase showed maximum activity at pH 6.5 and 40 ℃.The addition of 103 CFU/mL P.fluorescens M02 resulted in destabilization of skim milk during 5 days of culture at 6 ℃.Monitoring the predominant psychrotrophic bacteria at species level will be useful in designing effective monitoring methods and tools to improve the quality and safety of raw milk or dairy products.

Psychrotrophic bacteria and their heat-resistant enzymes are common contaminants in raw milk,leading to dairy product spoilage.The biodiversity of psychrotrophic bacteria isolated from raw milk in Shanghai was investigated by 16S rRNA sequencing and the individual isolates were evaluated for protease and lipase activities by plate culture.All isolates were classified into 33 genera in 9 classes,with Pseudomonas (55％),Acinetobacter (10％) and Flavobacterium (5％) being predominant,and the remaining 30 genera accounting for 30％ of the total number of isolates.Most isolates had the ability to produce protease or lipase,and different genera had different enzymatic profiles.Pseudomonas and Flavobacterium exhibited considerable protease activity,whereas Klebsiella showed strong lipase activity.On the other hand,most Acinetobacter isolates could produced neither protease nor lipase.

Microwave is a technology that enables fast heating. In this review, the recent progress in the application of microwave in the dairy industry with respect to its effect on milk quality and its use in the detection of dairy products and the degradation of dairy wastes. It is showed that microwave has broad prospects for application in the dairy industry.

Pseudomonas is highlighted as predominant psychrotrophic spoilage bacteria in milk and dairy products. Its extracellular proteases are heat-resistant, and have residual activity even after ultra high temperature sterilization (UHT) treatment leading to short life of UHT milk. The current article summarizes recent studies on extracellular proteases of psychrotrophic Pseudomonas in milk, with special emphasis on their catalytic mechanisms as well as the application of protease genes including apr X to identify Pseudomonas. At last, the further research directions in this area are discussed.

In this study, corn germ meal was defatted by supercritical CO2 fluid extraction and applied for the production of a composite dairy beverage. The optimization of dairy beverage formulations for improved stability and sensory quality was carried out using combination of single factor and orthogonal array experiments. The results showed that the optimal formulation consisted of 3% of defatted corn germ, 0.2% of citric acid, 0.25% of compound stabilizer, 2.5% of milk powder, and 10% of soft white sugar. The obtained beverage was characterized by homogenous texture, unique flavor, soft and delicate taste, a good balance of sweet and sour, and good stability.

The psychrophilic bacteria present in raw milk can grow under cold storage conditions and secrete protease and lipase which degrade milk protein and fat, resulting in the deterioration of milk quality. The present article summarizes the major species of psychrophilic bacteria in raw milk, with an emphasis on the recent progress that has been made in understanding the hazards of psychrophilic Bacillus including their species, hazard characteristics, proteases and lipases. At last, the future research direction of psychrotrophilic Bacillus is discussed.

A composite beverage was developed from milk with the addition of rice bran protein. Its formulation was optimized by one-factor-at-a-time and orthogonal array design to obtain the best sensory quality and emulsion stability. Meanwhile the storage stability of the composite beverage was investigated. The optimal formulation was found to consist of 2% whole milk powder, 0.7% rice bran protein, 10% white sugar, 0.3% citric acid and 0.2% composite stabilizer. The resulting product had a delicate taste and high nutritive value, and its emulsion stability and protein content were 97.52% and 1.0%, respectively.