Knowledge Management System Of Institute of process engineering,CAS
|关键词||微藻 油脂 食用 Epa 精炼|
近年来，使用微藻生产食用油脂进入了人们的视野。微藻油脂以甘油三酯为主，脂肪酸组成与植物油类似，有些还含有极具健康价值的多不饱和脂肪酸。本文考察了几种常见富油微藻生产食用油脂的潜力，并以微拟球藻藻粉为原料，建立了富含多不饱和脂肪酸的微藻油脂提取和精炼工艺。考察了小球藻、栅藻和微拟球藻油脂和藻渣应用于生产食用油的前景。使用适用于食用油生产的正己烷获得微藻油脂，小球藻和微拟球藻油脂收率均在50%左右，是栅藻的两倍，且小球藻藻油的中性脂含量最高；三种藻油脂的中性脂脂肪酸组成均以C16和18脂肪酸为主，微拟球藻中还含有具有保健功能的ARA和EPA；植醇是三种藻藻油中不皂化物的主要成分，小球藻藻油中含有有益于人体健康的麦角甾醇；微拟球藻藻油具有最高的抗氧化活性。三种藻渣都具有较高的蛋白质含量，微拟球藻藻渣蛋白最符合人类需要。综合来看，使用小球藻生产烹调食用油最为经济；而微拟球藻适合生产具有保健作用的功能性油脂，其藻渣也可生产为优质蛋白产品。以微拟球藻粉为原料，建立了藻油提取工艺。提取温度和时间的适当提高和延长有助于EPA的提取；针对藻油的一次提取，使用正己烷作为提取溶剂，选择1:20 (g/mL)的固液比，在60℃下提取8-10 h即可。相较使用新鲜溶剂，混合油提取时油脂得率下降幅度不大，且在本实验的最佳条件（提取温度为60℃，提取时间为10 h）下，使用混合油提取比使用新鲜溶剂提取的溶剂用量减少了47.3%。使用正己烷对藻渣进行二次提取4 h即可达平衡，油脂得率达到了23%左右。超声法促进油脂释放效果最好，油脂得率提高了43.0%。参考食用油质量标准和精炼步骤，确立了针对微藻毛油的精炼工艺。发现水化脱胶法藻油脱胶率略低于酸法和超滤法，但其最为简单，脱胶效果也可以接受。对于溶剂脱酸，随甲醇用量的加大，藻油脱酸率提高到约49.5%后不再明显变化，而油脂收率持续降低、EPA损失率不断升高；对于碱炼脱酸，随NaOH加入浓度的增大，可接近完全去除游离脂肪酸，且油脂回收率保持在93-94%左右；使用粉末活性炭达到95%以上的藻油脱色率时，油脂收率为77.5%，EPA的损失率为62.7%。所选择的精炼工艺为：针对含有4mg藻油/mL的混合油，加热到55℃，使用混合油体积10-20%的65℃水作用30 min脱胶；采用碱炼脱酸法，在55℃下，添加120%理论碱量的氢氧化钠溶液作用30 min脱酸；使用4 mg/mL混合油添加量的粉末活性炭在60℃下作用30 min可达95%以上的藻油脱色率。精炼后藻油中的EPA含量降为6.28%，但极性脂和游离脂肪酸含量大幅下降。
In recent years, microalgae have attracted much attention as a potential edible oil resource. Triacylglycerol is the predomnant lipid in microalgae with fatty acid compositions resembling vegetable oils. Some of the algal lipids contain valuable therapeutic polyunsaturated fatty acids (PUFA). In this work, lipids from several oleaginous algae were analyzed to evaluate their potential to produce edible oil. The extraction and purification process for edible oil production from a PUFA-rich algae were investigated.To assess the potential for edible oil production, the characterization of lipids from Chlorella vulgaris (C.vulgaris), Scenedesmus obliquus (S.obliquus) and Nannochloropsis oceanica (N.oceanica) was evaluated. C.vulgaris and N.oceanica had similarly much higher lipid contents than that of S.obliquus. The fatty acid compositions of neutral lipids from C.vulgaris and S.obliquus were mainly C16 and C18, resembling that of vegetable oils. ARA and EPA were the specific valuable fatty acids in total lipids from N.oceanica but the content of which were lower in its neutral lipids. Phytol was identified as the major unsaponifiable component in lipids of the three algaes. Based on the highest ratio of SFA/MUFA/PUFA, (n-6):(n-3), and the lowest content of free fatty acids, lipids obtained from C.vulgaris displayed the great potential for edible oil production. Lipids of N.oceanica showed the highest antioxidant activity, also, its residue contained the largest amounts of protein and the amino acid compositions best met the need of human beings.N.oceanica was used for investigation on oil extraction in this work. It was beneficial to increase the amount of EPA by increasing extraction time and temperature moderately. As for batch extraction, the lipid recovery reached the highest value in 8-12 h with hexane as extraction solvent at the solid-liquid ratio of 1:20 under the temperature of 60℃. Although the oil extraction using mixed algal oil could not compare to extraction using fresh solvent in lipid recovery, the dosage of the solvent decreased 47.3% under the same condition. As for the residue, 4 h was enough for re-extraction using hexane and the oil yield increased nearly 23%. Compared with other methods, ultrasonication released most lipids from the cells and the oil yield increased 43.0%.The refining process of crude algal oil was set up with reference to that of other edible oils. Compared with acid degumming and membrane degumming, hydrate degumming was easy and the efficiency was acceptable in spite of the slightly lower degumming rate. The highest FFA removal of solvent deacidification was 49.5%. However, the oil recovery decreased and the content of EPA decreased with the addition of methanol. As for alkali deacidification, the FFAs could be removed thoroughly with the oil recovery of 93%. When decolorization rate of the oil exceeded 95%, the oil recovery was 77.5% and the loss of EPA was 62.7% with the use of activated carbon. The refining process were studied for the mixed oil with 4 mg crude lipids in 1 mL algal miscella. In the degumming step, the mixed oil was heated to 55℃ and treated with water in the volume ratio of 10-20% at 65℃ for 30 min. The mixed oil was then deacidified for 30 min at 55℃ with sodium hydroxide solution with the dosage of 120% of the theoretical amount. At last, 4 mg of activated carbon was utilized to completely decolorize 1 mL mixed oil at 60℃ for 30 min. The content of EPA in the refined algal oil decreased to 6.28% after refining, but that of polar lipids and FFAs also declined significantly.
|黄燕飞. 微藻食用油脂的提取与净化[D]. 北京. 中国科学院研究生院,2016.|
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