Geometrical isomerization of polyunsaturated fatty acids in physically refined rapeseed oil during plant-scale deodorization
Geometrical isomerization of polyunsaturated fatty acids in physically refined rapeseed oil during plant-scale deodorization
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工厂规模脱臭过程中物理精炼菜籽油中多不饱和脂肪酸的几何异构化
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发表时间：
2007
期刊：
影响因子：
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通讯作者：
Z. Svoboda
中科院分区：
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作者：
J. Čmolík;J. Pokorný;M. Doležal;Z. Svoboda
在装置规模为10t/h的半连续盘式脱臭器中，考察了操作温度(220~270℃)对物理精炼菜籽油中亚油酸和亚麻酸反式异构体形成的影响。物理精炼的工业程序包括两步漂白和脱臭过程。在220~270℃温度范围内，亚油酸的异构化程度为0.33~4.77%，亚麻酸的异构化程度为4.43~45.22%。对于亚油酸和亚麻酸，异构化程度的对数与脱臭温度之间的关系可以用统计上极显著的线性函数来近似。油酸对热致几何异构化反应具有较强的耐受性。在230℃和240℃时，亚麻酸和亚油酸的异构化程度之比分别为13.6和12.9，且随温度升高略有下降。在脱臭菜籽油中检测到2个亚油酸的反式异构体和4个亚麻酸的反式异构体，其中仅1个双键异构体为反式构型，亚麻酸的4个反式异构体大多为1个双键异构体。亚麻酸被观察到是物理精炼菜籽油中几乎所有反式脂肪酸形成的主要来源。当脱臭温度为235℃时，植物规模物理精炼菜籽油中反式脂肪酸的含量低于总脂肪酸的1%，具有较好的应用前景。
The effect of the operating temperature (between 220 and 270 °C) on the formation of trans isomers of linoleic and linolenic acids in physically refined rapeseed oil during deodorization in a plant-scale semicontinuous tray-type deodorizer (capacity 10 t/h) was investigated. The industrial procedures of physical refining consisted of a two-step bleaching and deodorization process. The degree of isomerization of linoleic acid ranged from 0.33 to 4.77% and that of linolenic acid from 4.43 to 45.22% between 220 and 270 °C, respectively. A relation between the logarithm of the degree of isomerization and the deodorization temperature can be approximated by statistically highly significant linear functions for both linoleic and linolenic acids. Oleic acid was resistant to the heat-induced geometrical isomerization. The values found for the ratio between the degrees of isomerization of linolenic and linoleic acids, slightly decreasing with increasing temperature, were equal to 13.6 and 12.9 at 230 and 240 °C, respectively. Two trans isomers of linoleic acid, exclusively with one double bond isomerized into trans configuration, and four trans isomers of linolenic acid, mostly with one double bond isomerized into trans configuration, were determined in deodorized rapeseed oils. Linolenic acid was observed to be the main source responsible for the formation of nearly all trans fatty acids in physically refined rapeseed oil. At 235 °C, a deodorization temperature considered as a reasonable technological compromise, the content of trans fatty acids in plant-scale physically refined rapeseed oil was less than 1 % of total fatty acids, which would be acceptable for further application.