Optimization of Production Process and Stability Analysis of Lonicera Caerulea Sugar-Free Yogurt by Response Surface Methodology
Lonicera caerulea sugar-free yogurt is made from raw cow milk and Lonicera caerulea powder,with erythritol and xylitol instead of white granulated sugar,and fermented by Lactobacillus bulgaricus and Streptococcus thermophilus.On the basis of single factor tests,response surface analysis was used to optimize the optimal Lonicera caerulea sugar-free yogurt production process:the content of Lonicera caerulea powder was 0.6%,the content of erythritol was 6.75%,and the content of xylitol was 2.25%.The sugar-free yogurt with good taste,good condition and good nutritional quality was obtained after fermentation at 42 ℃ for 4.5 h and then after ripening for 12 h.Moreover,the pH value,acidity,water retention capacity,viscosity,Lactobacillus number and microorganisms were measured and monitored.The yogurt prepared under this process condition can keep all the indexes qualified within 21 days.