通过测定酸奶冷藏条件下pH值、酸度、酸乳的游离氨基氮质量浓度以及乳酸菌活菌数,以研究酸奶在货架期期间的质量变化。结果表明:酸乳货架期间,pH值降低,酸度上升,乳酸菌活菌数呈下降趋势,游离氨基氮质量浓度在冷藏初期有较小幅度的上升,随冷藏时间延长而缓慢降低,酸奶的感官评价都有所下降,但各项指标仍然符合国家标准的规定。

pH,acidity,mass concentration of free amino nitrogen and viable count of lactic acid bacteria of yogurt were tested under refrigerated conditions. The changes during the shelf life were compared. The results showed that during the yogurt shelf life,pH decreased,acidity increased,viable count of lactic acid bacteria was declined,nitrogen concentration of free amino acid increased a little in the beginning of refrigerated storage and then decreased with the frozen time. Sensory evaluation of decreased,but all indicators met national standards.