The impact of adding polysaccharides extracted from liquid-cultured mycelia of Inonotus obliquus into yak yogurt on its sensory evaluation score and titratable acidity was investigated to determine the optimal addition amount of the polysaccharides. The process parameters for producing yak yogurt with added Inonotus obliquus polysaccharides were optimized, and the quality of the yogurt prepared under optimized conditions was evaluated and compared with that of yogurt without added Inonotus obliquus polysaccharides as a control. The results showed that addition of 0.4% Inonotus obliquus polysaccharides to yak yogurt led to the highest sensory score together with a moderate acidity. Using orthogonal array design, the optimal process conditions were determined as follows: ratio of Streptococcus thermophilus G2 to Lactobacillus paracasei L9, 1:1; fermentation time, 14 h; temperature, 38 ℃; and sucrose concentration, 8 g/100 mL. Compared with the control, the as-prepared yogurt increased the number of viable lactic acid bacteria, titratable acidity and water-holding capacity by 34.1%, 11.0% and 16.8% respectively, and the pH value decreased accordingly. Addition of Inonotus obliquus polysaccharides into yak yogurt improved its firmness and viscosity as well as flavor.

Molecular biology studies have confirmed that bioactive polysaccharides are naturally occurring polymers that have a variety of physiological and biochemical functions. The water-complexing ability, high viscosity, antioxidant and anti-aging properties of bioactive polysaccharides lay the foundation for their application in the fields of food, and the use of bioactive polysaccharides as a bioactive ingredient in functional foods has become a current research focus. Fermented milk has good flavor and probiotic properties, but it also has the disadvantages of short shelf life, poor curd quality, and general probiotic performance. How to improve the quality of fermented milk is a current major challenge. This article focuses on recent progress in the application of different types of bioactive polysaccharides in fermented milk, and reviews the effects and mechanisms of action of bioactive polysaccharides on the physicochemical, gel and probiotic properties of fermented milk. Furthermore, it discusses future prospects for the application of bioactive polysaccharides in fermented milk. This review is expected to provide a reference for exploring the functions of bioactive polysaccharides and improving the quality of fermented milk.

Brown yogurt is a new type of yogurt with a burned flavor formed by the nonenzymatic Maillard reaction and silky smooth mouthfeel that contains high-quality nutrients and has become a new hotspot in the yogurt market. As Gansu province is one of the major livestock production areas and dairy processing bases in China, this region is bound to development the brown yogurt industry and seize market share. This article reviews the current status of the development of Gansu’s brown yogurt industry and existing problems. This review covers a summary of the history of the development of this industry and the problems encountered during the development process, the barriers to and driving forces for the research and development of brown yoghurt, the current status and challenges of brown yogurt processing, and the current trends and future prospects of brown yogurt.

Tea polyphenols, secondary metabolites found in green tea, are widely used in the food and medicinal industries because of their antioxidant and anti-cancer activity and preventive effect against cardiovascular diseases. The interaction of tea polyphenols with milk proteins can alter the structure of milk proteins and further affect the functional properties and bioavailability of dairy products. There have been widespread concerns about the binding of phenolic compounds to milk proteins due to the special structures of milk proteins. This review describes the mechanism of polyphenol-milk protein interaction, the factors influencing this interaction, the characteristics of reaction products, the methods used to analyze the mechanism, and the effects of this interaction on the functional properties and bioavailability of dairy products. Through this review, we aim to lay a theoretical basis for the development of new products based on the combination of tea polyphenols and milk proteins.