精炼过程中大豆油及其脱臭馏出物中 生育酚的变化Changes of tocopherol in soybean oil and its deodorized distillate during refining process

Abstract

旨在为大豆油的精准适度加工以保留微量营养成分提供参考，对巴西和美国大豆原油、中和油、脱色油、脱臭油、脱臭馏出物的生育酚含量及其异构体占比进行了分析，探讨和研究生育酚在精炼各工段的变化及生育酚异构体的占比规律。结果表明：大豆油中生育酚在精炼各工段均有损失，脱臭工段损失最多,生育酚和α-、γ-、δ-生育酚异构体损失率分别为11.68%~19.37%、6.10%~1764%、11.56%~19.68%、17.29%~25.51%，在脱臭和整个精炼过程中3种生育酚异构体的损失率均表现为δ-生育酚>γ-生育酚>α-生育酚；与原油相比较，精炼后大豆油中α-、γ-生育酚占比分别增加了0.4~2.1百分点和0.1~1.2百分点，δ-生育酚占比减少了1.3~2.7百分点，说明大豆油中的δ-生育酚更容易被高温分解或挥发而被汽提蒸汽夹带进脱臭馏出物中；美国大豆原油酸值（KOH）在1.5 mg/g以下，其脱臭馏出物中生育酚含量在97 419~109 123 mg/kg，为原油的80~89倍，巴西大豆原油酸值（KOH）在1.5 ~3.3 mg/g，其脱臭馏出物中生育酚含量在34 678~83 803 mg/kg，为原油的59~84倍，美国和巴西的大豆油脱臭馏出物中α-、γ-、δ-生育酚占比分别为6.5%~9.3%、61.0%~62.4%、26.7%~31.4%和8.4%~9.9%，58.0~61.8%，28.0%~304%，与对应脱臭油相比较，美国和巴西的大豆油脱臭馏出物中α-、γ-生育酚占比分别减少了0.1~2.5百分点、4.5~6.7百分点和0.5~2.9百分点、2.9~69百分点，δ-生育酚占比分别增加了5.5~8.2百分点和5.6~7.8百分点，说明脱臭工段生育酚因挥发而被汽提蒸汽夹带的速率大小为δ-生育酚>α-生育酚>γ-生育酚。因此,应该优化脱臭工段的工艺条件，以最大程度避免生育酚的过度损失。Aiming to provide a reference for accurate and moderate processing of soybean oil to retain micronutrients, the content of tocopherol and its isomers proportion in crude oil, neutralized oil, decolorized oil, deodorized oil, and deodorized distillate processed with the soybean from Brazil and the United States was determined to study the changes rule of tocopherol in various refining stages and the proportion rule of tocopherols isomers. The results showed that tocopherol was lost in all refining stages, and the loss in deodorization stage was the largest with the loss rates of tocopherol and α-, γ-,δ- tocopherol were 11.68%-19.37%, 610%-1764%, 11.56%-19.68%, and 17.29%-2551%, respectively, and 3 isomers in deodorization stage and the whole refining both showed the following loss rates: δ- tocopherol>γ- tocopherol>α- tocopherol. Compared with crude oil, the proportion of α-,γ-tocopherol in refined soybean oil increased by 0.4-2.1 percentage points and 0.1-1.2 percentage points, respectively, and the proportion of δ-tocopherol decreased by 1.3-2.7 percentage points, indicating that δ- tocopherol was more easily decomposed or volatilized at high temperatures, and was carried into the deodorized distillate by the stripping steam. The acid value of US crude soybean oil was below 1.5 mgKOH/g, and the content of tocopherol in deodorized distillate was 97 419-109 123 mg/kg, which was 80-89 times that of crude oil. The acid value of Brazilian crude soybean oil was 1.5-3.3 mgKOH/g, and the content of tocopherol in deodorized distillate was 34 678-83 803 mg/kg, which was 59-84 times that of crude oil. The proportion of α-,γ-,δ- tocopherol in US and Brazilian deodorized distillate were 6.5%-9.3%,61.0%-62.4%,26.7%-31.4% and 84%-9.9%，58.0-61.8%，28.0%-30.4%, respectively. Compared with the corresponding deodorized oil, the proportion of α- tocopherol and γ-tocopherol decreased by 0.1-2.5 percentage points，4.5-6.7 percentage points and 05-2.9 percentage points，2.9-6.9 percentage points, respectively, and the proportion of δ- tocopherol increased by 5.5-8.2 percentage points and 5.6-78 percentage points,indicating that the rate of tocopherol trapped by stripping vapor was δ -tocopherol> α -tocopherol> γ -tocopherol. Therefore, the process conditions of the deodorization stage should be optimized to avoid excessive loss of tocopherol to the greatest extent possible.

Keywords

• 大豆油；脱臭馏出物；精炼过程；生育酚；生育酚异构体；损失率；占比
• soybean oil; deodorized distillate; refining process; tocopherol; tocopherol isomer; loss rate; proportion