搅拌型酸羊奶加工关键技术

搅拌型酸羊奶加工关键技术

中文

羊奶营养价值丰富，含有大量的蛋白质、脂肪、乳糖、矿物质及多种维生素，其酪蛋白与乳清蛋白比例接近人乳，有利于人体消化吸收。利用羊奶生产的酸奶具有组织状态光滑细腻、风味独特的特点，深受消费者欢迎。与牛奶相比，羊奶中酪蛋白含量较低，在制作酸奶时，易出现凝乳特性差，乳清易析出的缺陷，尤其是在生产搅拌型酸羊奶时，搅拌过程不可避免的要对凝乳产生机械作用，使酸奶出现乳清析出和分层现象。为了解决这一问题，在搅拌型酸奶生产中通常采用添加稳定剂的方法来解决，这在一定程度上影响了酸奶的风味和质量。因此，本研究从搅拌型酸羊奶的加工过程中的关键技术出发，对影响酸羊奶质量的乳酸菌的发酵特性、搅拌工艺、乳蛋白、乳固形物浓度及贮藏温度等多个因素进行优化，以期获得稳定性较好、质量较高的搅拌型酸羊奶，为开发优质的搅拌型酸羊奶提供理论依据。

本课题研究的主要内容分为四个部分。

第一部分主要研究乳酸菌对搅拌型酸羊奶质量的影响。对分离纯化的8株乳酸菌的发酵特性研究表明，4株嗜热链球菌中S.t-499菌株的产粘能力较强，4株保加利亚乳杆菌中L.b-300菌株的后发酵能力较弱，当嗜热链球菌S.t-499菌株与保加利亚乳杆菌L.b-300菌株按2：1比例混合制作发酵剂，发酵剂添加量为2%，发酵温度为39℃时搅拌型酸羊奶的粘度较高，稳定时间较长。

第二部分主要研究搅拌工艺对搅拌型酸羊奶质量的影响。通过对搅拌型酸羊奶搅拌过程中的搅拌速度、搅拌时间和搅拌温度的研究表明，搅拌型酸羊奶发酵结束后，迅速冷却至15℃，然后在搅拌速度为12r/min、搅拌时间为15min、搅拌温度为20℃时，酸羊奶的质量较好。

第三部分主要研究乳清蛋白和酪蛋白对搅拌型酸羊奶质量的影响。结果表明，在搅拌型酸羊奶中添加乳清蛋白和酪蛋白对其质量无明显影响。

第四部分主要研究乳固形物浓度和贮藏温度对搅拌型酸羊奶质量的影响。结果表明，乳固形物浓度在12%～14%时，搅拌型酸羊奶的质量较好，稳定性较高；贮藏温度较低时，搅拌型酸羊奶具有较高的质量和稳定性。

译文

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 www.txlwdxw.com 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.