Fermented milks were prepared using raw milk with different fat contents, and their flavor was evaluated. The pH trend during fermentation indicated that the change in milk fat content had no effect on the acid production of lactic acid bacteria. Rheological and texture measurements showed that with the increase in milk fat content, the elastic modulus and the viscous modulus decreased, hardness and cohesiveness did not obviously change, but gumminess significantly increased (P < 0.05). By gas chromatography-mass spectrometry (GC-MS), a total of 34 flavor substances were detected from 5 groups of fermented milk samples, including 7 hydrophilic ones and 27 lipophilic ones. Change in milk fat content greatly affected the content of flavor substanc es. Principal component analysis and correlation analysis showed that change in milk fat content caused significant differences in flavor between fermented milk samples, and the trend of flavor contents was related to their hydrophobicity. With the increase in milk fat content, the content of milk fat degradation products such as 2-nonanone and hexanal but not γ-butyrolactone increased first and then decreased. Among other substances, the content of hydrophilic flavor compounds increased first and then decreased, and the content of lipophilic compounds decreased continuously.

The purpose of this investigation was to study the influence of adjuvant starter cultures on the quality of fermented milk. Seven strains of common lactic acid bacteria, including Lactococcus lactis subsp. cremoris (Lcr), Lactococcus lactis subsp. lactis (Ll), Lactobacillus casei (Lca), Lactobacillus fermentum (Lf), Lactobacillus rhamnosus (Lr), and two Lactobacillus plantarum strains (Lp1 and Lp2), were used separately as adjuvants to a commercial starter culture for fermented milk. The results showed that addition of adjuvant starter cultures could shorten the fermentation time and affect the pH value of fermented milk during storage. Moreover, Lcr and Ll could cause significant changes in the oxidationreduction potential during fermentation. Rheological measurements indicated that these strains could increase the viscosity, and reduce the elasticity and fluidity of fermented milk. The texture analysis showed that all the strains could increase the water-holding capacity, and Lr, Lf and Lp1 could enhance the cohesiveness and adhesiveness of fermented milk. Gas chromatography-mass spectrometry (GC-MS) analysis and principal component analysis showed that Lr, Lp1, Lp2 had little effect on the flavor of fermented milk, while Lca could promote the formation of heptanol, benzaldehyde and 2-tridecanone, and Lf, Ll and Lcr could increase the content of flavor substances such as short-chain and medium-chain fatty acids in fermented milk.

Driven by the development of modern statistics, physiology and human bionics, sensory evaluation of dairy products nowadays has been increasingly mature and considered highly significant. This article reviews the definition and procedure for sensory evaluation of dairy products as well as the application of sensory evaluation for dairy products. Moreover, further prospects are discussed. The aim of this review is to provide a theoretical basis for sensory evaluation of dairy products.

Because of its gelling, thickening and stabilizing properties, marine polysaccharide can be used as stabilizer for stirred yogurt. In this study, the effects of carrageenan, sodium alginate, instant and ordinary agar on properties of stirred yoghurt were studied. The indexes observed were viscosity, acidity, fermentation state and flavor. In comparison, instant agar could improve the viscosity of yogurt, increase shear resistance, improve mouthfeel and enhance flavor, and decrease whey syneresis. The product with instant agar demonstrated smooth mouthfeel, a suitable viscosity, and extended shelf life. The stirred yogurt had the best taste when instant agar was added at 0.15%.

In order to obtain quality preference of caramel flavour, fruity, fermentation flavor, sweetness, acidity, astriction, combination weighting approach was employed by fuzzy mathematics comprehensive sensory evaluation expermienting 5 popular sterilization lactic acid fungus drink in market. Fuzzy relation curve was obtained finnally. Results showed that the overall sensory quality of 5 sterilization lactic acid fungus drink order was sample 5 > sample 2 > sample 4 = sample 1 > sample 3, which was slightly different from the results of simple ranking method: sample 2 > sample 4 = sample 1 > sample 5 > sample 3. The experiment results indicated that the fuzzy mathematics comprehensive sensory evaluation method was more scientific, reasonable and objective than simple ranking method.

Only by human clinical trials can the human health effect of probiotics be assessed. However, a very limited amount of useful data can be obtained from human clinical trials due to various restricting factors, so they are very valuable. In this article we present a review of the role of probiotics in improving intestinal health and regulating immunity as assessed by human clinical trials.