富硒酸奶发酵条件优化及贮藏期间理化性质研究

Optimization of fermentation conditions of selenium-enriched yogurt and its physicochemical properties during the storage

文章以复原乳为原料,利用富硒青春双歧杆菌和干酪乳杆菌发酵制备一种新型的富硒酸奶。在单因素试验基础上,利用中心组合试验优化得到富硒酸奶的最优发酵条件如下:奶粉添加量为12%,蔗糖添加量为5%,低聚异麦芽糖添加量为1%,亚硒酸钠添加量为61.8μg/kg,酪蛋白酸钠添加量为1.4%,接种量为4.5%,发酵温度为40℃,发酵时间为7h。该富硒酸奶呈乳白色,凝乳完全,无乳清析出,组织细腻均匀,奶香纯正,酸甜适中,其有机硒的质量比为29.2μg/kg。在25d(4℃)冷藏期间,pH值、乳酸菌数、蛋白质、脂肪和非脂乳固体质量分数呈不同程度下降趋势,但均符合国家标准的要求,有机硒的质量比相对稳定。

A novel selenium-enriched yogurt was prepared with reconstituted milk and by fermentation with strains of ＇selenium-enriched Bifidobacterium adolescentis and Lactobacillus casei. The following optimal conditions were explored by single-factor and CCD experimental design methods： the adding amount of milk powder was 12%, sucrose 5 %, isomaltose hypgather 1%, sodium caseinate 1.4%, so- dium selenite was 61.8 μg/kg, inoculation concentration was 4. 5 %, fermentation temperature was 40 ℃ and fermentation time was 7 h. The selenium-enriched yogurt was milk-white, curded complete- ly, without whey dissolved, well flavoured, and it tasted soft and pure with smooth organization. The content of organic selenium in the selenium-enriched yogurt was 29.2μg/kg. During the cold storage （4℃） in 25 days, the pH value, numbers of lactic acid bacteria, content of protein, fat and non-fat solids were tending to decline, but up to the requirements of state standard, and the organic selenium content was relatively stable.