RESEARCH PROGRESS ON BLEACHING TECHNOLOGY OF VEGETABLE OILS

Vegetable oils are the most widely used edible oils.But the pigments in the oils will not only make the color of oils darker to affect their appearance,but also cause some harm to the quality of refined oils and reduce the storage stability of the oils.Bleaching is one of the main procedures in the refining process of vegetable oils,which is also one of the important procedures to ensure the quality of vegetable oils.Currently,adsorption decolorization is the most commonly used bleaching method in the oil processing enterprises.The present study was to overview of the three main sources of pigment in vegetable oils and the effects of pigments on the safety and oxidative stability of oils were also summarized.By combining the production practice,the process and mechanism of adsorption decolorization of vegetable oils under two different temperatures were discussed,respectively.The factors affecting the decolorization effect of vegetable oils were expounded,such as the types of adsorbents including some new adsorption material,adsorbent dosage,oil type and oil quality,bleaching time and bleaching temperature.The research progress and mechanism of some new bleaching technologies,such as membrane decolorization,ultrasonic assisted decolorization,light energy decoloration,chemical decolorization and enzymatic decolorization,were summarized.And some of the refining operations which have assist effect on the decolorization were explained.Meanwhile,the assessing methods of the bleaching effect of vegetable oils with different colors were described.Finally,the current situation of decolorization technology and equipments in the bleaching industry and the problems that need to be solved in oil bleaching were considered and forecasted.