發(fā)布時(shí)間：2018-03-04 17:25

  本文選題：發(fā)酵羊乳　切入點(diǎn)：脂肪酸組成　出處：《西北農(nóng)林科技大學(xué)》2012年碩士論文　論文類型：學(xué)位論文

【摘要】：羊乳營養(yǎng)豐富，風(fēng)味獨(dú)特，蛋白、脂肪組分特性均異于牛乳。大量研究已初步證明，羊乳中高含量的短鏈脂肪酸及部分支鏈短鏈脂肪酸是羊乳特殊風(fēng)味產(chǎn)生的根源；生物發(fā)酵能使羊乳中乳糖、蛋白質(zhì)和脂肪各組分按不同途徑代謝，尤其是乳脂的降解在提高羊乳營養(yǎng)價(jià)值的基礎(chǔ)上，極大程度地改變了羊乳風(fēng)味。為探討生物發(fā)酵對(duì)羊乳特殊風(fēng)味的改善機(jī)理以及對(duì)除膻技術(shù)參數(shù)的確定，本論文以陜西薩能奶山羊羊乳為原料，氣相色譜法測定的脂肪酸百分含量為指標(biāo)，首先將羊乳與牛乳制品脂肪酸對(duì)比分析結(jié)果結(jié)合感官評(píng)定確定了引起羊乳膻味的脂肪酸種類，之后研究了不同乳酸菌發(fā)酵對(duì)羊乳脂肪酸的影響差異，，以及菌種配比、接種量、發(fā)酵溫度、發(fā)酵時(shí)間、加糖量和后熟時(shí)間等發(fā)酵條件對(duì)脂肪酸組成的影響規(guī)律，來篩選羊乳風(fēng)味改良菌種確定較佳發(fā)酵條件，并對(duì)發(fā)酵除膻機(jī)理加以分析。本論文得出了以下主要結(jié)論。 （1）酮香型發(fā)酵除膻機(jī)理：丁二酮乳酸乳球菌能協(xié)同嗜熱鏈球菌和保加利亞乳桿菌降解羊乳脂肪酸，在發(fā)酵乳后熟期間，膻味物質(zhì)——短鏈脂肪酸降解轉(zhuǎn)化為醛酮類香味物質(zhì)，在降解膻味物質(zhì)的基礎(chǔ)上增加了香味物質(zhì)。 （2）酮香型發(fā)酵乳的較佳工藝：菌種配比1:1:0.5、接種量3%，發(fā)酵溫度36℃，發(fā)酵時(shí)間3h，加糖量6%，后熟時(shí)間18h為發(fā)酵羊乳的較佳工藝條件，此條件下發(fā)酵的羊乳短鏈脂肪酸、中鏈脂肪酸和長鏈脂肪酸含量分別為10.05%、15.93%和72.95%，丁二酮含量為2.44mg/L，乙醛含量為11.8mg/L。此時(shí)，發(fā)酵羊乳膻味小，發(fā)酵香味醇厚，低糖，保健功能高，符合現(xiàn)代人的“低能量、低脂肪、高蛋白”的膳食觀，并具有很高的經(jīng)濟(jì)效益，為羊乳制品的推廣提供了新的參考。
[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

本文編號(hào)：1566607