发酵羊乳脂肪酸组成的动态变化分析及生物除膻技术研究

发布时间：2018-03-04 17:25

  本文选题：发酵羊乳　切入点：脂肪酸组成　出处：《西北农林科技大学》2012年硕士论文　论文类型：学位论文

【摘要】：羊乳营养丰富，风味独特，蛋白、脂肪组分特性均异于牛乳。大量研究已初步证明，羊乳中高含量的短链脂肪酸及部分支链短链脂肪酸是羊乳特殊风味产生的根源；生物发酵能使羊乳中乳糖、蛋白质和脂肪各组分按不同途径代谢，尤其是乳脂的降解在提高羊乳营养价值的基础上，极大程度地改变了羊乳风味。为探讨生物发酵对羊乳特殊风味的改善机理以及对除膻技术参数的确定，本论文以陕西萨能奶山羊羊乳为原料，气相色谱法测定的脂肪酸百分含量为指标，首先将羊乳与牛乳制品脂肪酸对比分析结果结合感官评定确定了引起羊乳膻味的脂肪酸种类，之后研究了不同乳酸菌发酵对羊乳脂肪酸的影响差异，，以及菌种配比、接种量、发酵温度、发酵时间、加糖量和后熟时间等发酵条件对脂肪酸组成的影响规律，来筛选羊乳风味改良菌种确定较佳发酵条件，并对发酵除膻机理加以分析。本论文得出了以下主要结论。 （1）酮香型发酵除膻机理：丁二酮乳酸乳球菌能协同嗜热链球菌和保加利亚乳杆菌降解羊乳脂肪酸，在发酵乳后熟期间，膻味物质——短链脂肪酸降解转化为醛酮类香味物质，在降解膻味物质的基础上增加了香味物质。 （2）酮香型发酵乳的较佳工艺：菌种配比1:1:0.5、接种量3%，发酵温度36℃，发酵时间3h，加糖量6%，后熟时间18h为发酵羊乳的较佳工艺条件，此条件下发酵的羊乳短链脂肪酸、中链脂肪酸和长链脂肪酸含量分别为10.05%、15.93%和72.95%，丁二酮含量为2.44mg/L，乙醛含量为11.8mg/L。此时，发酵羊乳膻味小，发酵香味醇厚，低糖，保健功能高，符合现代人的“低能量、低脂肪、高蛋白”的膳食观，并具有很高的经济效益，为羊乳制品的推广提供了新的参考。
[Abstract]:Sheep milk is rich in nutrition, unique flavor, protein and fat components are different from milk. A large number of studies have preliminarily proved that the high content of short chain fatty acids and some branched short chain fatty acids in sheep milk is the origin of the special flavor of sheep milk. Biological fermentation can metabolize lactose, protein and fat components in goat milk in different ways, especially the degradation of milk fat on the basis of improving the nutritional value of goat milk. In order to study the mechanism of improving the special flavor of goat milk by biological fermentation and to determine the technical parameters of removing mutton, the goat milk of Shannen dairy goat was used as raw material in this paper. The fatty acid content determined by gas chromatography was used as the index. Firstly, the fatty acids that caused the flavor of goat milk were determined by comparing the results of fatty acids between sheep milk and cow dairy products combined with sensory evaluation. The effects of different fermentation conditions of lactic acid bacteria on fatty acid composition of sheep milk were studied, and the effects of fermentation conditions such as the proportion of bacteria, inoculation amount, fermentation temperature, fermentation time, sugar addition and post-ripening time on fatty acid composition were studied. In order to select the better fermentation conditions and analyze the mechanism of fermenting, the main conclusions of this paper are as follows. The mechanism of ketone flavor type fermentation is that Lactococcus lactis can degrade amniotic milk fatty acids in combination with Streptococcus thermophilus and Lactobacillus bulgaricus. During the ripening period of fermented milk, the fatty acid of the mutton taste substance, short chain fatty acid, is degraded into aldehydes and ketones. The aroma substance was added on the basis of the degradation of the smell substance. 2) the optimum technology of keto-flavored fermented milk was as follows: ratio of strain 1: 1: 0.5, inoculation amount 3, fermentation temperature 36 鈩

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