Study On The Key Processing Technology Of Goat Stirred Yoghurt

The Goat milk is rich in nutrient, which contains large amounts of protein, fat, lactose, minerals and vitamins. And its casein and whey protein ratio is closer to human milk, which is helpful for human body in digestion and absorption. The organization of yogurt produced by goat milk has smooth and delicate unique flavor characteristics, which is welcome by consumer. Goat milk contains lower casein than cow milk. So it appears a poor curd characteristic, easy to separate whey during producing yogurt, especially in producting stirred yoghurt. Stabilizer is often used to solve this problem in stirred yoghurt production, which, to a certain extent influence the flavor and quality of yogurt. Therefore, the stirred yoghurt processing technology of goat milk was study using goat milk powder as raw material. First, select lactobacillus strains with higher producing viscosity ability and better stability to the problem of soft curd. Second, study on the stirred process by changing the stirred speed, time and temperature to minimize the damage to yogurt from stirred. Third, optimize the processing technology through milk protein, dry matter content and storage temperature to develop the quality of the stirred goat yogurt, and provides the basis.This main content in this paper is divided into four parts. The influences of lactic acid bacteria to the quality on the stirred yogurt were studied. Lactic acid bacteria strains with higher producing viscosity ability and better stability were selected to produce stirred goat yogurt. And the factors of lactic acid bacteria ratio, addition of starter culture, fermentation temperature were optimized to obtain the optimal process. The results showed S.t-499 strain has higher producing viscosity ability and L.b-300 strain has weaker postacidification. The stirred goat yogurt has better quality while the ratio of fine strains St-499 and L.b-300 is 2:1, starter culture is 2%, fermentation temperature is 39℃.The stirred condition of stirred goat yogurt was studied in the second part, through optimizing the stirring speed, time and temperature to enhance the stability of goat yogurt and solve the problem of whey separation, and improve quality. The results showed the optimal stirring conditions were:stirring speed of 12r/min, stirring time of 15min, stirring temperature of 23℃.Influence of protein to the quality of goat yogurt was studied in the third part. The results showed that quality of goat yogurt was affected by adding whey protein or casin to goat milk.Influence of milk solid concentration and storage temperature to stirred goat yogurt stability was studied in the forth part. The result showed that when milk solid concentration was 12%～14%, storage temperature was lower, the yogurt quality was quite good.