低温长时间发酵酸乳加工关键技术及品质研究

选用乳酸链球菌和保加利亚乳杆菌制作低温长时间发酵酸乳,利用DPS软件设计正交实验优化酸乳生产工艺,并对发酵结束和经4℃、后熟24h后以及4℃、冷藏3d后酸乳的酸度、pH值、纯蛋白、游离氨基酸、脂肪、双乙酰、乙醛、乳酸菌活菌数量等质量指标和风味成分进行分析检测。结果表明,最佳工艺为乳酸链球菌和保加利亚乳杆菌二4∶1,接种量3%,添加蔗糖8%,34℃培养10h左右。低温长时间发酵酸乳的酸度为69·35°T,乙醛含量为14·46mg/kg,双乙酰含量为4·72mg/kg,乳酸菌活菌数为7·15×109cfu/mL。经感官评定,酸乳的凝乳组织状态均匀细腻,香气浓郁纯正,酸甜适口,品质优良。

Study on Processing Technology and Quality of Low-temperature Long-term Fermented Yogurt

The Streptococcus lactis (Sl) and Lactobacillus bulgaricus (Lb) were mixed as starter to produce low-temperature and long-term fermented yogurt. DPS design method was used to analyze processing technology of low-temperature and long-term fermented yogurt. Sensory score,pH value,acidity,plate counts of lactobacillus,pure protein,free amino acid,fat,acetaldehyde,and diacetyl contents of the yogurt were measured for both the process of fermentation,for 24h at 4℃ and for 3 days at 4℃. The results indicated that the optimal culture parameters of low-temperature and long-term fermented yogurt were: Sl∶Lb=4∶1, inoculums 3% by volume, sucrose 8%, and incubated at 34℃ for 10 hours. The sensory evaluation results showed that low-temperature long-term fermented yogurt had good coagulation and smooth texture with desirable flavor. The physical-chemical analysis showed that acidity of the yogurt was 69.35°T,acetaldehyde was 14.46 mg/kg,diacetyl was 4.72 mg/kg. The plate count of lactobacillus could reach 7.15×10~9 cfu/mL.