Osman F, Zaher F A, EL-Nockrashy A S
Nahrung. 1976;20(5):475-82. doi: 10.1002/food.19760200503.
Colour fixed pigments can be detected in refined and bleached oils rather than in crude oils, since in the latter their absorption is masked up by the gossypol pigments. Isohexane is the most desirable hexane isomer. Though it produces darker crude oils, yet refinability and bleachability increases as the percentage of isohexane in normal hexan increases. It has also the advantage of extracting oils with lowest refining loss and with the highest gossypol content. Recovery of gossypol, which is alkali refinable, with the oil results in a superior quality of meal. Benzene, on the other hand, is the least desirable constituent in commercial hexane. Its presence with n-hexane results in darker coloured crude, refined and bleached oil colours, indicating the selectivity of benzene to colour fixed pigments. Highest refining loss were found in oils extracted with benzene or benzene-hexane solvent mixtures. Cyclohexane presence with n-hexane (35% to 60%) and methycyclopentane (6.0% to 12.0%) do not increase the degree of extraction of colour fixed pigments, however increase the refining loss of the extracted oils.
在精炼和漂白油中可以检测到色素固定的色素，而在原油中则检测不到，因为在原油中，它们的吸收被棉酚色素掩盖了。异己烷是最理想的己烷异构体。虽然它会使原油颜色变深，但随着正己烷中异己烷百分比的增加，可精炼性和可漂白性会提高。它还具有以最低的精炼损失和最高的棉酚含量提取油的优点。可碱精炼的棉酚与油一起回收，可得到质量更好的粕。另一方面，苯是商业己烷中最不理想的成分。它与正己烷共存会导致原油、精炼油和漂白油颜色变深，这表明苯对色素固定色素具有选择性。在用苯或苯 - 己烷溶剂混合物提取的油中发现了最高的精炼损失。环己烷与正己烷（35%至60%）和甲基环戊烷（6.0%至12.0%）共存不会增加色素固定色素的提取程度，但会增加提取油的精炼损失。
