为了提高水酶法提取亚麻籽油的提油率,该文探究了亚麻籽表面黏质物的存在对水酶法提取亚麻籽油提油率的影响,并对热水浸提法脱除亚麻籽黏质物的工艺进行优化.结果表明,水酶法提取亚麻籽油的提油率随亚麻籽表面黏质物的减少而升高,未脱黏亚麻籽的提油率为69.20%±1.51%,渣相含油量为26.00%±1.24%.经100 ℃浸提脱黏后,黏质物的脱除率为94.69%±1.94%,此时亚麻籽的提油率可达84.26%±0.63%,渣相含油量降低至10.45%±0.89%.对热水浸提脱除黏质物的工艺(浸提温度、浸提时间、体系pH值、料水比以及浸提次数)进行了单因素优化,发现在浸提温度85 ℃、pH值3、料水比1:7 g/mL、浸提2次,每次浸提60 min的条件下,黏质物的脱除效果最好,脱除率为97.88%±0.69%,脱黏后亚麻籽的提油率可达84.47%±0.53%,亚麻籽油和蛋白质的损失率分别为0.70%±0.16%和10.78%±0.41%,且浸提脱黏过程对水酶法提取亚麻籽油的品质(酸值和过氧化值)无显著影响.此外,浸提脱黏过程还可有效去除亚麻籽中的抗营养因子生氰糖苷,使生氰糖苷的含量由浸提前的(242.6±0.8)mg/kg显著降低到浸提后的(7.1±0.6)mg/kg.该研究提供了一种简单高效的热水浸提脱黏工艺,显著提高了后续水酶法提取亚麻籽油的提油率,同时也有利于亚麻籽多糖的回收和亚麻籽粕的进一步利用,为亚麻籽资源的综合利用提供有益参考.%Flaxseed, which is also called linseed, is an kind of important oilseed in the world. The nutritional components of flaxseed are oil, protein, lignans, soluble fiber, minerals, and vitamin, and so onetc. It is known as the richest source of the n-3 fatty acid, alpha linolenic acid (n-3 fatty acid), which comprises approximately 55% of the total fatty acids, and this percentage is 5.5 times higher than that in the second next-highest sources. Flaxseed plays an important role in functional foods for its nutritional and pharmaceutical values. In recent years, aqueous enzymatic extraction, an emerging alternative to hexane-based oilseed extraction regarding product safety and simultaneous recovery of high quality protein products and high yield of vegetable oils has drawn increasing attentions over decades. However, due to the high water-holding capacities, stabilization and emulsification properties of flaxseed mucilage, extraction and separation of flaxseed oil from raw flaxseed by aqueous enzymatic method are proved to be inefficient and even prohibitive. In order to improve the yield of flaxseed oil extracted by aqueous enzymatic method, the effect of demucilage on the aqueous enzymatic extraction of flaxseed oil was investigated by comparing the yield of flaxseed oil before and after removal of flaxseed mucilage through hot water extraction. Results showed that the mucilage on the surface of flaxseed significantly impeded the separation of oil from aqueous enzymatic extraction system, thus resulting in a low extraction yield of flaxseed oil. More specifically, the oil yield of raw flaxseed was only 69.20%±1.51% and residual oil content in insoluble phase was 26.00%±1.24%, while after removal of 94.69%±1.94% mucilage by hot water extraction treatment at 100 ℃ (the removal rate of 94.69%±1.94%), the yield of flaxseed oil significantly increased to 84.26%±0.63% and residual oil content in insoluble phase decreased to 10.45%±0.89%. Mucilage removal conditions were optimized by single- factor experiments and the optimal conditions were obtained as follows:eExtraction temperature was 85 ℃, pH value was 3, flaxseed- to- water ratio was 1:7 g/mL, extraction time was 60 min and extraction was repeated twice. Under the optimum conditions, the mucilage removal efficiency was 97.88%±0.69%, the yield of the flaxseed oil reached to 84.47%±0.53%, and the loss ratios of flaxseed oil and protein were 0.70%±0.16% and 10.78%±0.41%, respectively. Acid value and peroxide value of the flaxseed oil before and after demucilage by hot water extraction treatment were determined and it was found that the demucilage process had no obvious influence on the quality of flaxseed oil extracted by aqueous enzymatic method. In addition, after the hot water extraction process, the content of cyanogenic glycosides in flaxseed was significantly decreased from 242.6±0.8 mg/kg to 7.1±0.6 mg/kg. The proposed flaxseed demucilage -method was simple and efficient, which not only significantly improved the yield of flaxseed oil with aqueous enzymatic method, but also laid a good foundation for preparation of flaxseed gum from the extract and further utilization of the flaxseed meal. Therefore, it presentsed a promising technology for the comprehensive utilization of flaxseed on industrial scale.
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