Analysis On The Key Technology And Production Process Of Yogurt

Yogurt is produced by bacterial fermentation of high quality fresh milk, with a certain amount of lactobacillus. Yogurt has good taste and high nutritive value, which is conductive to intestinal health and the absorption of trace elements, and is popular with consumers. At present, yogurt makers are developing fast domestically. However, the severe challenges from food safety and quality have been pushing yogurt makers to continuously improve production process and quality control. To enhance the yogurt quality and optimize the production process, the aim of the thesis was to study the key production process technology, including the fermentation culture addition, the stabilizer addition, the fermentation temperature and the fermentation time. The study utilized the mixture of Streptococcus thermophilus and Lactobacillus bulgaricus with a portion of 1 to 1 as fermentation culture, and gelatine as stabilizer to perform three-factor three-level orthogonal experiment with different additive proportion of the fermentation culture and the stabilizers, and different fermentation temperature. The experiment researched the correlation of the additive proportion fermentation culture and the stabilizer, and the fermentation temperature to affect the acidity, pH, and viscosity of yogurt through measuring the acidity, pH and viscosity of yogurt. The experimental results showed that:(1) The fermentation culture additive proportion, the fermentation temperature and the fermentation time played a critical role in influencing the yogurt's acidity. Meanwhile, although the stabilizer has little influence to yogurt's acidity, it affected the viscosity a lot.(2) According to the testing results of viscosity from the three-factor three-level orthogonal experiment, the priority among the three factors to the acidity of yogurt was as below: the fermentation temperature > the fermentation culture additive proportion > the stabilizer additive proportion. In addition, the priority among the three factors to the viscosity of yogurt was as below: the stabilizer additive proportion > the fermentation culture proportion > the fermentation temperature.(3) Based on the data analysis on above experiments, the best process parameters for yogurt production was with the fermentation culture additive proportion of 3%, and the stabilizer additive proportion of 3% at the fermentation temperature of 35? for eight hours.