This study was conducted to reveal the effect of milk-clotting enzyme (MCE) produced by Bacillus licheniformis on the texture of Cheddar cheese during ripening. Cheddar cheese and Cheddar cheese analogue were prepared with the MCE and designated as CDF and CD3, respectively, and commercial chymosin was used as a control (CCF).The changes in the texture, rheology and microstructure of cheese during ripening were analyzed. The results were as follows: The hardness of the three cheeses increased with maturation time, while the elasticity and chewiness presented a downward trend. The hardness, springiness and chewiness of CDF were the lowest. The scanning electron microscope (SEM) results showed that the compactness of the protein structure decreased with increasing maturity, and the structure of CDF was looser than that of CCF. The rheological results showed that the storage modulus and loss modulus decreased with increasing ripening time up to six months and increasing sweep temperature. The tan δ value decreased during the ripening process, indicating that the fluidity of cheese decreased with increasing ripening time. The fluidity and fusibility of CDF were better than those of the other groups. The above results indicated that the mechanical properties of cheese made with Bacillus licheniformis MCE were better than those made with commercial rennet, while the latter had harder texture and denser protein network structure.

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.

Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains were isolated from commercial yogurts using selective media, and physiological and biochemical tests, sugar fermentation experiments and 16S rDNA homology analysis were used to identify the isolated strains. Genotyping of the strains was performed by pulsed field gel electrophoresis (PFGE). It was found that both Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus were detected in all yogurt samples. Streptococcus thermophilus had the same genotyping only in two yogurts, while other Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus strains were different in different yoghurts. The results showed that PFGE was an effective method for genotyping of different strains of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus.

This study used a quadratic rotation-orthogonal composite experimental design with four independent variables at five levels each to establish optimal process conditions for industrial production of Mozzarella cheese. The process conditions investigated in this study included fermentation time, clotting time, whey pH and the amount of added NaCl. A regression model to optimize these process conditions was proposed and validated for its statistical significance. The optimal process conditions that provided the maximum yield of Mozzarella cheese (24.78%) were determined as follows: fermentation time 27.5 min, clotting time 37.5 min, whey pH 6.3, and addition of 2.07% NaCl. The resulting cheese had a nice flavor, a close, smooth and flexible texture and a homogeneous color and its fiber-drawing capacity, meltability and foaming properties were good. All these parameters were comparable to those of laboratory-made cheese and met the quality requirements for use in pizza. The optimized process parameters are suitable for large-batch production of Mozzarella cheese in industrial practice.

This study investigated the effect of addition of protein isolates from three different plants (pea, mung and soybean) on cheese properties to find the most suitable plant protein for application in cheese. Milk coagulation properties (coagulation time, curd strength and whey OD value) and textural properties (elasticity, cohesiveness and chewiness) were comparatively tested on the three cheese samples. Moreover, sensory evaluation was carried out fuzzy judgment as well. Results showed that pea protein isolate provided better quality of cheese than the other two protein isolates.