CAJ | 학술논문

水相法同时提取花生油脂和蛋白质工艺中往往形成可观的乳状液，经蛋白酶破乳可回收相当量的油脂，但得到的顽固乳状液十分稳定，需进一步研究其特性方可加以利用。该文对该顽固乳状液中可能起主要稳定作用的界面蛋白的电泳性质、疏水性质、乳化活性及乳化稳定性进行了研究，并通过激光共聚焦显微镜对顽固乳状液的微观结构进行了观察。结果表明，水相取油工艺碱提过程中，温度和pH值的协同作用，使含疏水性碱性亚基较多的蛋白质的构象发生变化，疏水基团暴露，表面吸附能力增强，促使乳状液稳定性提高。经酶解离心后，顽固乳状液中的油滴数量和油滴粒径大小明显降低，降解后形成的小分子亚基依赖二硫键的作用形成肽段聚集并紧紧吸附在油滴表面，形成黏弹性的膜，使得顽固乳状液稳定存在。应用超声辅助、冷冻解冻、热、极端pH值、乙醇辅助等方法处理顽固乳状液。结果显示，冷冻解冻和乙醇辅助处理可有效地使顽固乳状液中的油滴聚集。在乙醇体积分数为50%的条件下，乙醇辅助处理可使顽固乳状液的破除率达90%以上，从而使全工艺流程总游离油提取率从原来的88%提高到93%，极大地推进了水相法提取花生油脂工艺的产业化发展。
수상법동시제취화생유지화단백질공예중왕왕형성가관적유상액，경단백매파유가회수상당량적유지，단득도적완고유상액십분은정，수진일보연구기특성방가가이이용。해문대해완고유상액중가능기주요은정작용적계면단백적전영성질、소수성질、유화활성급유화은정성진행료연구，병통과격광공취초현미경대완고유상액적미관결구진행료관찰。결과표명，수상취유공예감제과정중，온도화pH치적협동작용，사함소수성감성아기교다적단백질적구상발생변화，소수기단폭로，표면흡부능력증강，촉사유상액은정성제고。경매해리심후，완고유상액중적유적수량화유적립경대소명현강저，강해후형성적소분자아기의뢰이류건적작용형성태단취집병긴긴흡부재유적표면，형성점탄성적막，사득완고유상액은정존재。응용초성보조、냉동해동、열、겁단pH치、을순보조등방법처리완고유상액。결과현시，냉동해동화을순보조처리가유효지사완고유상액중적유적취집。재을순체적분수위50%적조건하，을순보조처리가사완고유상액적파제솔체90%이상，종이사전공예류정총유리유제취솔종원래적88%제고도93%，겁대지추진료수상법제취화생유지공예적산업화발전。
During aqueous processing of peanuts for simultaneous oil extraction and protein recovery, large amounts of emulsion could be formed and after enzymatic demulsification, substantial amounts of oil would be recovered while stubborn emulsions still remain. The destabilization of the stubborn emulsion is the key to improve the total free oil yield. Before its utilization and further destabilization, studying the characterization of the stubborn emulsion, especially its surface protein, which may play an essential role in emulsion stabilization, was necessary. The surface protein was extracted and its electrophoresis property, hydrophobicity, emulsifying activity, as well as emulsifying stability were studied. Confocal laser scanning microscopy (CLSM) was used to investigate its microstructure. It was found that, though the protein from the emulsion surface had similar subunits (60, 41, 38.5, 37.5, and 18 kDa) with that from aqueous phase, its hydrophobicity and emulsion activity was significantly higher. This could be attributed to the synergistic effect of temperature and pH during the alkaline extraction, which led to the unfolding of some large peanut protein molecules containing hydrophobic basic arachins. This, consequently, caused the exposure of more hydrophobic groups and enhanced the hydrophobic and emulsifying properties of the protein. Thus emulsion formation was promoted. After enzymatic treatment, the protein in the emulsion was hydrolyzed into short peptides and no subunits with molecular weight higher than 20 kDa had been detected in Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). However, in non-reducing PAGE, except for the conarachin band of 60 kDa, protein from the stubborn emulsion surface showed similar bands with that from the emulsion surface and aqueous phase. This indicated that the hydrolyzed protein could still gather on the stubborn emulsion surface and contributed to its stability. Due to the hydrolysis of protein molecules, the hydrophobic property and emulsifying activity of protein from stubborn emulsion was lower than that from an untreated emulsion surface. CLSM observation showed that stubborn emulsion had less oil droplets and that their size was lower, while the surface protein concentration (Γ) was higher, as compared with untreated emulsion. This explained the high stability of stubborn emulsion, though its surface protein has lower surface activity. To demulsify the stubborn emulsion, various treatments, including ultrasound, freeze-thaw, heating, extreme pH value, phase inversion, or ethanol addition were attempted. Free oil was obtained after centrifugation and total free oil yield was calculated thereafter. The microstructure of the stubborn emulsion after different treatments was also observed with CLSM. Results show that freeze-thaw and ethanol addition could remarkably aggregate the oil droplets in stubborn emulsion, especially after 50% ethanol addition, most oil droplets were combined and 90%of the oil in stubborn emulsion could be recovered. Under this condition, the total free oil yield could be increased to 93%from 88%in the overall process.