基于微波预处理油菜籽的压榨油和浸出油理化品质比较

微波预处理油菜籽可显著提高压榨出油率,但压榨后的饼粕中仍残留油脂,可采用浸出法提取饼中残油。为比较压榨油和浸出油的主要理化品质,在2450MHz、800W的微波条件下,分别对油菜籽预处理0～7min,冷却至室温后压榨制油,继而对饼粕中残油用正己烷萃取。结果表明,微波处理时间、压榨和浸出的制油方式对菜籽油酸价、过氧化值、p-茴香胺值、水分含量均有显著影响（P〈0.05）。压榨油和浸出油的酸价、p-茴香胺值随微波时间的延长而增加,过氧化值呈先增加后减少的趋势,浸出油酸价、过氧化值和p-茴香胺值高于压榨油。压榨油水分含量随微波时间的延长而增加,而浸出油的则减少,压榨油水分含量高于浸出油。压榨油和浸出油的色泽（罗维朋比色）随微波时间的延长逐渐变深,浸出油色泽更深;加热试验（至280℃）中压榨油无析出物,而浸出油产生絮状析出物。由此可见基于微波预处理油菜籽的压榨油仅需水洗、过滤或离心分离即可满足国家标准,浸出油则需要进行脱胶、脱酸、脱色等精炼处理。

Physicochemical quality of pressed oil and solvent- extracted oil from rapeseed pretreated by microwave

Microwave pretreatment increases the oil extraction yield from rapeseed,but still some oils remained in the press- cake. To compare the physicochemical quality of press oil and the solvent- extracted oil from press- cake,rapeseeds with moisture of 12% were treated with microwaves under 800W for 1 to 7 min at frequency of 2 450MHz,and pressed oil from cold seeds,as well as extracted from the press- cake by ultrasonic assisted n-hexane solvents. Results indicated that microwave time and oil extraction method（ by press and by solvent） had significant effects on acid values（ AVs）,peroxide values（ POVs）,p- anisidine values（ p- AnVs）,and moisture contents of the two oils（ P 0. 05）. The AVs and p- AnVs of two oils increased with increasing microwave time,and the POVs increased initialy and then decreased depending on the time of microwave radiation. The AVs, POVs,and p- AnVs of pressed oils were higher than those of solvent- extracted. The moisture contents of oils extracted by press were higher,and would increase with the increasing microwave time,while the extracted oil decreased. The Lovibond color of extracted oil was darker,and the longer the pretreat time,the deeper color of both oils. No precipitates were found in pressed oils after heating（ at 280℃） test,while a lot of precipitates were produced in the extracts. In conclusion,pressed oil pretreated by microwaves only needed to be purified by washing, filtering or centrifuging before consumption,while the solvent- extracted oil must be refined by degumming,deacidification and bleaching.