热处理条件下米糠油中谷维素的损失规律研究Loss law of oryzanol in rice bran oil under heating treatment

旨在为米糠油的精准适度加工及其在食品工业中的应用提供科学指导，研究了常压和充氮加热（60~260 ℃）处理0~12 h条件下米糠油中谷维素及其4种主要组分〔环木菠萝烯醇阿魏酸酯（CAFA）、24-亚甲基环木菠萝烯醇阿魏酸酯（24-MCAFA）、菜油甾醇阿魏酸酯（CampFA）及 β-谷甾醇阿魏酸酯（SitoFA）〕的损失规律。结果表明：两种加热方式下谷维素及其4种主要组分的损失率随加热时间的延长均呈线性上升趋势（R2>0.90），损失速率随着加热温度升高而升高；在常压加热条件下，当温度达到220 ℃时谷维素开始快速损失，260 ℃下加热12 h时谷维素总量损失率最高（74.14%）；谷维素4种主要组分在两种热处理过程中热稳定性相似，即不高于140 ℃时各组分之间热稳定性总体无显著差异，不低于180 ℃时各组分热稳定性大小顺序为CampFA>CAFA>24-MCAFA>SitoFA；充氮加热下谷维素损失率变化趋势与常压加热下相似，但其损失率显著低于常压加热（除140 ℃和60 ℃），在220 ℃下加热12 h时两者相差最大（32.34百分点）。综上，米糠油应采用适度加工工艺及在食品工业应用中应合理控制加热条件以减少谷维素的损失，提高米糠油的营养品质。Aiming to provide scientific guidance for the precise and moderate processing of rice bran oil and its application in the food industry, the loss law of oryzanol and its four main components 〔cycloartenyl ferulate (CAFA),24-methylene cycloartenyl ferulate（24-MCAFA）,campesterol ferulate（CampFA）,β-sitosterol ferulate（SitoFA）〕 in rice bran oil heated by atmospheric pressure heating and nitrogen-filled heating respectively under the conditions of heating temperature 60-260 ℃ and heating time 0-12 h was studied. The results showed that the loss rate of oryzanol and its four main components showed a linear increasing trend with the extension of heating time (R2>0.90) under the two heating methods, and the loss rate was positively correlated with the heating temperature. Under the conditions of atmospheric pressure heating, oryzanol began to lose rapidly when the temperature reached 220 ℃, and the loss rate of oryzanol reached the highest (74.14%) when the temperature reached at 260 ℃ for 12 h. The thermal stability of the four main components of oryzanol was similar during the two heat treatment processes. There was overall no significant difference in the stability among the four components when the temperature was not higher than 140 ℃, whereas their stability was order as CampFA>CAFA>24-MCAFA>SitoFA when the temperature was not lower than 180 ℃. The variation trend of oryzanol loss rate under nitrogen-filled heating was similar to that under atmospheric pressure heating, whereas the loss rate under nitrogen-filled heating was significantly lower than that under atmospheric pressure heating(except for 140 ℃ and 60 ℃), and the difference was the highest (32.34 percentage) at 220 ℃ for 12 h. To sum up, rice bran oil should use moderate processing techniques and reasonable control heating conditions in food industry applications to reduce the loss of oryzanol, thereby enhancing the nutritional quality of rice bran oil.