Fermented Milk Beverage Dispensing And Effect Of Polymerized Whey Protein Concentrate On The Stability Of Fermented Milk Beverage

In this study, the fermented milk beverage was used as the research object, and response surface analysis method was used to optimize the mixing proportion of fermented beverage. The effect of the addition amount of whey protein concentrate, acidification process and fermentation method on the stability of fermented milk beverage was discussed. The effects of the concentration of whey protein concentrate instead of total protein ratio(0%, 10%, 20%, 30%, 40%) on the centrifugal sedimentation rate, absorption ratio, particle size, viscosity, endogenous tryptophan, surface hydrophobicity, and free thiol of fermented milk beverage were studied, The effects of p H(4.4, 4.2, 4.0, 3.6, 3.8) on the particle size, free thiol group and surface hydrophobicity of fermented milk beverage were also affected by acidification process before and after fermentation. The effect of heat polymerized whey protein on the microstructur e of fermented milk beverage was analyzed by means of transmission electron microscope(TEM). The results are showed as following:Research shows that three factors three levels using the response surface analysis method, based on the analysis of interaction between the factors and the significance to optimize the best mix proportion is: on the basis of the amount of adding stabilizer is 0.25%, sugar content of 6%, p H 4.2. After fermentation, the centrifugal sedimentation rate of fermented milk beverage was significantly lower than that of the fermented milk beverage(P<0.05) without the addition of polymerized whey protein concentrate by 85℃, 30 min heat polymerized whey protein concentrate; With the increase of the proportion of total protein, the absorption ratio of fermented milk beverage increased slightly and then decreased slightly; The viscosity of fermented milk beverage increased gradually, but the particle size of fermented milk beverage increased slightly, and the total protein replacement ratio was 30%; The hydrophobicity of fermented milk beverage and the free thiol group gradually increased, The free thiol group of fermented milk beverage with the proportion of the total protein in the whey protein concentrate instead of 10%-40% the total protein was significantly larger than that of the blank(P<0.05)., and the fluorescence intensity of the system increased gradually. After fermentation to add after 85 ℃, 30 min thermal polymerization the proportion of total protein in the whey protein concentrate was 30%, 40% of the fermented milk beverage centrifugal sedimentation rate was significantly lower than polymerization alternative to 0%,10%total protein whey protein concentrate(P < 0.05)of the fermented beverage;The absorption ratio of fermented milk beverage increased gradually with the increase of the proportion of the total protein of whey protein concentrate instead of the total protein; The viscosity of fermented milk beverage was increased gradually; But the fermented milk drink had no change after the particle size of the fermented milk beverage; The hydrophobicity, fluorescence intensity and free thiol group of fermented milk drink increased gradually.The study also found that the acidification process before fermentation to add polymeric whey protein concentrate(85℃, 30min), fermented milk drink with the size of p H(4.4, 4.2, 4.0, 3.8, 3.6) decreased after almost no change, almost no change in the free thiol, the surface hydrophobicity increased. After acidification added during the polymerization fermented whey protein concentrate(85 ℃, 30min), the particle diameter of fermented milk beverage after first p H(4.4,4.2,4.0,3.8,3.6) decreases and then increases, almost no change in free sulfhydryl gr oups, the surface increased hydrophobicity.Transmission electron microscopy showed that the proportion of pre fermented whey protein concentrate(85 ℃, 30min) instead of the total protein increased, the more whey protein aggregation in casein micelles, the formation of the network structure more closely.The above results showed that the appropriate addition of polymerized whey protein concentrate was beneficial to the stability of fermented milk beverage. The application of polymerized whey protein as a thickener in food processing is of great significance for the development of the comprehensive utilization of whey protein.