牛乳中反式脂肪酸在不同热处理条件下的含量变化及热杀菌工艺评价
发布时间：2019-05-24 03:29
【摘要】：反式脂肪酸(Trans fatty acids，TFA)是不饱和脂肪酸的异构体，其结构中一般含有至少一个反式构型的双键。TFA过多摄入，可能对人体健康造成不良影响。主要表现：影响必需脂肪酸的消化吸收、导致心血管疾病发生、可能引起大脑功能衰退，影响婴幼儿的生长发育，也是老年痴呆症的主要诱因之一等。在国内外，关于TFA的相关研究已被学界高度重视，在餐饮业和食品加工方面已有大量研究报道。 反刍动物（如牛、羊）的乳、脂肪组织及其制品中一般含有少量天然TFA成分，，其中体脂中的TFA含量比较多，占到总脂肪酸含量的4%-11%；牛乳和羊乳中的TFA含量占到总脂肪酸的3%-5%，一般不会对人体造成危害。牛乳脂中的TFA通常是不饱和的单烯键结构，双键一般在Δ6与Δ16位置之间比较多，含量最多的单烯酸一般是C11T-C18T之间，以C16T和C18T为主。不恰当的热处理工艺可能造成牛乳中TFA含量的升高，甚至可能达到危害人体健康的程度。 目前，关于各类食品中TFA含量和组成的研究已经较多，但是乳品加工过程中TFA的相关研究鲜见报道，特别是牛、羊乳在不同热处理工艺加工后产品中TFA的含量变化是否对人体造成危害，未见相关研究报道。 本研究采用罗兹-哥特里法提取乳中脂肪，经三氟化硼-甲醇甲酯化反应后进行气相色谱分析，对牛乳中的TFA含量进行分析比较。旨在探讨牛乳中反式脂肪酸（TFA）在不同热处理条件下的变化规律，为牛乳加工热杀菌工艺参数确立提供参考依据。主要结论如下： 1.三种甲酯化方法检测乳脂中C16T含量的对比研究。结果表明：对于同一样品，采用氢氧化钾-甲醇常温甲酯化的方法效率最低，C16T含量为0.050±0.003mg/mL；加热回流方法检测出含量为0.052±0.002mg/mL，比常温法效率稍高；采用三氟化硼催化-甲醇加热回流的方法甲酯化效率最高，为0.060±0.001mg/mL，与氢氧化钾-甲醇常温甲酯化方法相比差异显著（P0.05），结论：样品甲酯化采用三氟化硼催化-甲醇加热回流的方法最优。 2.气相色谱检测条件的优化研究。对甲酯化的脂肪酸分别采用三种气相条件进行检测，最终检测条件优化为：色谱柱：Rtx-1701毛细管柱(30m×0.25mm×0.25μm)；载气：N2，柱流量0.8mL/min，恒流模式；进样口温度250℃；检测器温度280℃；升温程序：180℃保留5min，4℃/min升至200℃，再以1℃/min升至210℃，最后以20℃/min升至230℃。此条件能够全面表征牛乳中脂肪酸及反式脂肪酸组成与含量。 3.不同热杀菌处理条件下TFA的含量变化研究。结论：①巴氏杀菌（85℃）条件下，随着加热时间的延长，牛乳中C16T和C18T的含量均处于上升趋势（P0.05）。当加热时间延长到90s时，乳中C16T和C18T含量达到检测峰值，分别为0.15±0.01mg/mL和1.82±0.04mg/mL，比原奶中有显著升高(P0.05)；②超高温条件下（T133℃），热处理时间（4s）不变，随着加热温度的升高，C16T含量0.056±0.002mg/mL-0.066±0.005mg/mL间波动，无明显的变化差异；C18T含量在0.8±0.04mg/mL-0.95±0.08mg/mL间波动，无明显差异，但其含量均高于原料奶。即超高温处理对乳中TFA含量存在影响，但其作用效果不明显(P0.05)。③高温条件（130℃）保持不变，延长灭菌时间，乳中TFA含量显著上升。当加热至300s时乳中C18T含量已高达2.11±0.2mg/mL，接近对人体造成危害的限量。高温条件下时间对TFA含量的影响差异显著(P0.05)。因此，UHT灭菌工艺应严格控制灭菌时间。 4.不同生产季节对产品中TFA的影响。通过对不同月份的产品中TFA含量进行分析比较，结果表明：十月份乳中TFA含量最低，其中C16T含量为0.056±0.002mg/mL，C18T为0.82±0.04mg/mL；C16T含量在七月份达到最高，为0.068±0.002mg/mL，C18T含量在八月份最高，为0.95±0.03mg/mL。七、八月份与4月和10月间牛乳中TFA含量存在显著差异（P0.05）其它各月份间TFA含量的差异并不明显（P0.05），结论：季节对产品中TFA的含量也有一定影响，但不明显。
[Abstract]:Trans-fatty acids (TFA) are the isomers of unsaturated fatty acids, which generally contain at least one double bond in the trans configuration. Excessive TFA intake may have an adverse effect on human health. The main performance is that the absorption of essential fatty acid is affected, which leads to the occurrence of cardiovascular diseases, which can cause the function of the brain to decline, which can affect the growth and development of the infant, and is one of the main causes of the senile dementia. At home and abroad, the related research on TFA has been highly valued by the academic field, and a large number of research has been reported in the field of catering and food processing. The milk, adipose tissue and its products of ruminants (such as cattle and sheep) generally contain a small amount of the natural TFA component, in which the TFA content in the body fat is much higher, accounting for 4% to 11% of the total fatty acid content; the TFA content in the milk and the goat milk accounts for 3% to 5 of the total fatty acid %, in general, will not cause danger to the human body The TFA in the milk fat is usually an unsaturated monoethylenically unsaturated structure, and the double bond is generally more abundant between the position 6 and the position 16, and the most content of the monoenoic acid is typically between C11T-C18T, in the order of C16T and C18T. The improper heat treatment process may cause an increase in the content of TFA in the milk and may even reach a range of harm to the health of the human body Degree. At present, there are more studies on the content and composition of TFA in various foods, but the relevant research of TFA in dairy processing has been reported, especially whether the content of TFA in the products after the processing of different heat treatment processes has been made to the human body. As a hazard, no relevant research is found. In this study, the fat in milk was extracted by the Roz-Gothic method, and the content of TFA in the milk was determined by gas-phase analysis after the reaction of the boron trifluoride-methanol methyl ester. The purpose of this study was to study the change of trans-fatty acid (TFA) in milk in different heat treatment conditions, and to establish the parameters of heat sterilization process for milk processing. for reference. Main The conclusion is as follows:1. Three methyl esterification methods to detect C16T in milk fat The results showed that, for the same sample, the efficiency of using potassium hydroxide-methanol at normal temperature was the lowest, and the content of C16T was 0.050 to 0.003 mg/ mL, and the content was 0.052 to 0.002 mg/ mL, and the ratio was 0.052 to 0.002 mg/ mL. The efficiency of methyl esterification with boron trifluoride catalyst-methanol was the highest, which was 0.060 and 0.001 mg/ mL, and the difference was significant (P0.05). the best method of the reflux method.2. Gas chromatography The detection conditions were optimized. Three gas-phase conditions were used to detect the methyl ester, and the final detection conditions were as follows: column: Rtx-1701 capillary column (30 m, 0.25 mm, 0.25. mu.m); carrier gas: N2, column flow of 0.8 mL/ min, constant current mode; injection port temperature of 250 鈩
本文编号：2484516
[Abstract]:Trans-fatty acids (TFA) are the isomers of unsaturated fatty acids, which generally contain at least one double bond in the trans configuration. Excessive TFA intake may have an adverse effect on human health. The main performance is that the absorption of essential fatty acid is affected, which leads to the occurrence of cardiovascular diseases, which can cause the function of the brain to decline, which can affect the growth and development of the infant, and is one of the main causes of the senile dementia. At home and abroad, the related research on TFA has been highly valued by the academic field, and a large number of research has been reported in the field of catering and food processing. The milk, adipose tissue and its products of ruminants (such as cattle and sheep) generally contain a small amount of the natural TFA component, in which the TFA content in the body fat is much higher, accounting for 4% to 11% of the total fatty acid content; the TFA content in the milk and the goat milk accounts for 3% to 5 of the total fatty acid %, in general, will not cause danger to the human body The TFA in the milk fat is usually an unsaturated monoethylenically unsaturated structure, and the double bond is generally more abundant between the position 6 and the position 16, and the most content of the monoenoic acid is typically between C11T-C18T, in the order of C16T and C18T. The improper heat treatment process may cause an increase in the content of TFA in the milk and may even reach a range of harm to the health of the human body Degree. At present, there are more studies on the content and composition of TFA in various foods, but the relevant research of TFA in dairy processing has been reported, especially whether the content of TFA in the products after the processing of different heat treatment processes has been made to the human body. As a hazard, no relevant research is found. In this study, the fat in milk was extracted by the Roz-Gothic method, and the content of TFA in the milk was determined by gas-phase analysis after the reaction of the boron trifluoride-methanol methyl ester. The purpose of this study was to study the change of trans-fatty acid (TFA) in milk in different heat treatment conditions, and to establish the parameters of heat sterilization process for milk processing. for reference. Main The conclusion is as follows:1. Three methyl esterification methods to detect C16T in milk fat The results showed that, for the same sample, the efficiency of using potassium hydroxide-methanol at normal temperature was the lowest, and the content of C16T was 0.050 to 0.003 mg/ mL, and the content was 0.052 to 0.002 mg/ mL, and the ratio was 0.052 to 0.002 mg/ mL. The efficiency of methyl esterification with boron trifluoride catalyst-methanol was the highest, which was 0.060 and 0.001 mg/ mL, and the difference was significant (P0.05). the best method of the reflux method.2. Gas chromatography The detection conditions were optimized. Three gas-phase conditions were used to detect the methyl ester, and the final detection conditions were as follows: column: Rtx-1701 capillary column (30 m, 0.25 mm, 0.25. mu.m); carrier gas: N2, column flow of 0.8 mL/ min, constant current mode; injection port temperature of 250 鈩
本文编号：2484516
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