Manjula S, Subramanian R
Department of Food Engineering, Central Food Technological Research Institute, Mysore, India.
Crit Rev Food Sci Nutr. 2006;46(7):569-92. doi: 10.1080/10408390500357746.
A membrane process offers several advantages over the conventional method of oil refining. Conceptually, membranes could be used in almost all stages of processing. In the present review, various attempts made by the researchers towards degumming, dewaxing, deacidifying, and decolorizing edible oils using membrane technology with and without using solvents have been discussed. Attempts made with UF and nonporous membranes have demonstrated the ability of these membranes to separate phospholipids from undiluted and hexane-diluted oils and a high oil flux was obtained with UF membranes in hexane-diluted oils. MF membranes were very effective for dewaxing undiluted oils while UF membranes were effective in dewaxing hexane-diluted oils without a precooling step. Deacidification was successful only with either addition of an alkali followed by membrane filtration or by following an indirect route of selective solvent extraction of FFA followed by membrane separation. Consistent color reduction in terms of pigments (chlorophyll and xanthophylls) and other instrumental measurements (Lovibond and visible spectra) could be achieved only with nonporous membranes. Interestingly, these membranes did not have selectivity for alpha-and beta-carotenes. UF membranes are best suited for degumming and dewaxing applications, while nonporous membranes appear to be a better choice for achieving simultaneous degumming, dewaxing, and decolorization of oils. Hexane-dilution improved the oil flux of nonporous membranes by one order of magnitude, but further improvement is desirable for industrial adoption.
与传统的炼油方法相比，膜工艺具有几个优点。从概念上讲，膜几乎可用于加工的所有阶段。在本综述中，讨论了研究人员使用膜技术在有无溶剂的情况下对食用油进行脱胶、脱蜡、脱酸和脱色的各种尝试。使用超滤（UF）膜和无孔膜的尝试已证明这些膜能够从未稀释和己烷稀释的油中分离磷脂，并且在己烷稀释的油中使用超滤膜可获得高油通量。微滤（MF）膜对未稀释的油脱蜡非常有效，而超滤膜在无需预冷步骤的情况下对己烷稀释的油脱蜡有效。脱酸只有在添加碱后进行膜过滤或通过先选择性溶剂萃取游离脂肪酸（FFA）再进行膜分离的间接路线才能成功。只有使用无孔膜才能在色素（叶绿素和叶黄素）以及其他仪器测量（罗维朋比色法和可见光谱）方面持续降低色泽。有趣的是，这些膜对α-和β-胡萝卜素没有选择性。超滤膜最适合脱胶和脱蜡应用，而无孔膜似乎是实现油同时脱胶、脱蜡和脱色的更好选择。己烷稀释使无孔膜的油通量提高了一个数量级，但为了工业应用还需要进一步改进。
