米糠油加工过程中组成及品质变化的研究Composition and quality change of rice bran oil during processing

旨在为米糠油适度加工提供数据支撑，对来自国内3个工厂的不同加工阶段米糠油的理化指标、组成、色泽和微量成分进行了测定。结果表明：A、B、C 3个工厂的米糠油在精炼后酸值（KOH）分别由24.22、18.95、17.21 mg/g降至0.15 mg/g以下，脂肪酸脱除率高达99%以上，过氧化值分别降至0.99、1.54、0.71 mmol/kg，精炼后米糠油酸值、过氧化值均达到GB/T 19112—2003中一级油标准；3个工厂的米糠油在加工过程中其游离脂肪酸含量变化趋势与酸值的变化趋势一致；精炼后米糠油甘一酯含量降低了58.9%~84.9%，主要在物理脱酸和脱臭时脱除，甘二酯含量变化不大，甘三酯含量增加了12.8%~23.9%；3个工厂米糠油脂肪酸组成在加工过程中没有明显变化；精炼后米糠油中叶绿素被有效脱除，色泽均达到国标一级油标准；米糠油的微量成分在加工过程中变化极大，其中谷维素出现明显的损失，损失率高达80.8%~94.1%，主要在化学脱酸时损失，甾醇损失率为21.2%~42.6%，主要在化学脱酸时损失，维生素E含量变化趋势存在差异，A工厂维生素E含量增加30.2%，B、C工厂维生素E损失率分别为31.7%、55.6%；角鲨烯损失率为659%~963%，主要发生在脱臭工序。综上，企业应根据自己的定位，合理调整精炼工序，优化精炼工艺参数，生产出符合企业追求的米糠油产品。Aiming to provide data support for the moderate processing of rice bran oil, the physicochemical indexes, composition, colour and trace components of rice bran oil at different processing stages from three different plants in China were determined. The results showed that the acid value of rice bran oil from three plants A, B and C after refining reduced from 24.22, 18.95 mgKOH/g and 17.21 mgKOH/g to less than 0.15 mgKOH/g respectively, and the fatty acid removal rate is more than 99%. The peroxide value was reduced to 0.99, 1.54 mmol/kg and 0.71 mmol/kg respectively. The acid value and the peroxide value of the refined rice bran oil reached the standard of first-grade oil in the GB/T 19112-2003. The change trend of free fatty acid content in rice bran oil in three plants was consistent with that of acid value. The monoglyceride content in rice bran oil decreased by 58.9%-84.9%, mainly removed in the physical deacidification and deodorization, the diglyceride content did not change much, and the triglyceride content increased by 128%-239%. The fatty acid composition of rice bran oil in the three plants did not change significantly during processing. After refining, chlorophyll in rice bran oil was effectively removed, and the colour reached the national standard of first-grade oil. The trace componens of rice bran oil changed greatly during processing, among which oryzanol appeared obvious loss, with the loss rate 80.8%-94.1%, mainly loss in chemical deacidification; sterol loss rate was 21.2%-42.6%, mainly loss in chemical deacidification; vitamin E changed differently, vitamin E content increased by 30.2% in plant A, but reduced by 31.7% and 55.6% in plant B and plant C respectivevly. The loss rate of squalene was 659%-96.3%, mainly occurred in the deodorization. To sum up, the enterprise should adjust the refining process reasonably according to its own position, optimize the refining parameters, and produce the rice bran oil products in line with the enterprise′s pursuit.