Lactase was analyzed among several fruit including peach,plum,black plum,apple and apricot by Ultraviolet spectrophotometry.Optimal sterilizing method for fruit particles (1 cm3) was investigated.Results showed that black plum and apricot had higher lactase at the concentration of 0.034 U/mL and 0.018 U/mL,respectively.The GOS-contained bioactive fruit yogurt was prepared under the following conditions:fruit was cut into 1 cm3 of particles and sterilized at 65 ℃ for 30 min using water bath.The fruit was mixed with 12％ (w/v) sterilized reconstituted skim milk solution at the amount of 8％ (w/w).Lactobacillus delbrueckii subsp.bulgaricus LB340 and Bifidobacterium bifidum BB03 at the ratio of 1∶1 (w:w) were incubated into the mixture at the amount of 3％ and fermented at 42 ℃ for 10 h.Finally,1.10～1.40％ GOS was produced in the yogurt.During two weeks' storage at 4 ℃,viscosity of yogurt was maintained at (0.74±0.25)Pa·s,while acidity and pH was at (181.7±12.1)°T and 4.15±0.06,respectively.Viable Lactobacillus delbrueckii subsp.bulgaricus LB340 and Bifidobacterium bifidum BB03 was at the range of 1.50×1011 to 2.00×1015 mL-1.Physics and chemistry parameters of the GOS-rich yogurt in two weeks' storage at 4 ℃ were in accordance with China rational standards of Yogurt.%通过紫外分光光度法对5种水果包括桃、青李子、黑布林、苹果和杏进行乳糖酶的检测筛选和果粒巴氏消毒条件研究.结果表明:黑布林和杏富含乳糖酶,含量分别是0.034 U/mL和0.018 U/mL.确定了富含GOS的果粒发酵乳的最佳制备条件为:将黑布林和杏切成1 cm3大小的果粒,65℃水浴30 min巴氏消毒,按质量分数为8％添加到灭菌的复原脱脂乳中,Lactobacillus delbrueckii subsp.bulgaricus LB340和Bifidobacterium bifidum BB03质量比为1∶1,总接种量3‰(质量分数),在42℃,常规发酵10 h,产物中GOS质量分数达1.10％～1.40％.该酸乳在4℃保藏14d,产品黏度为(0.74±0.25)Pa·s,酸度为(181.7±12.1)°T,pH值为4.15±0.06,Lactobacillus delbrueckii subsp.bulgaricusLB340和Bifidobacterium bifidum BB03活菌数为1.50×1011～2.00×1015mL-1.因此在2周的储藏期内,酸奶的各项理化指标均符合发酵乳的国家标准.
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