动植物油脂. 过氧化值的测定. 碘量(可视)终点测定

[中文适用范围]： 本文件规定了采用目视终点检测的碘量法测定动植物油脂过氧化值的方法。 过氧化值是作为过氧化物、特别是氢过氧化物化学结合到油或脂肪上的氧的量的量度。 该方法适用于每公斤活性氧过氧化值在 0 毫克当量至 30 毫克当量（毫克当量）的所有动植物油脂、脂肪酸及其混合物。 它还适用于不同含水量的人造黄油和脂肪酱。 该方法不适用于乳脂，也不适用于卵磷脂。 值得注意的是，过氧化值是一个动态参数，其值取决于样品的历史。 此外，过氧化值的测定是一个高度经验性的过程，获得的值取决于样品质量。 需要强调的是，由于规定的样品质量，获得的过氧化物值可能略低于用较低样品质量获得的过氧化值。 奶和奶制品（或来自奶和奶制品的脂肪）不包括在本文件的范围内。 注 1：注 2 中规定了碘量法测定乳脂过氧化值的首选方法。 ISO 27107 中给出了电位滴定法测定过氧化值的方法。 [外文原描述]： ISO 3960:2017 specifies a method for the iodometric determination of the peroxide value of animal and vegetable fats and oils with a visual endpoint detection. The peroxide value is a measure of the amount of oxygen chemically bound to an oil or fat as peroxides, particularly hydroperoxides. The method is applicable to all animal and vegetable fats and oils, fatty acids and their mixtures with peroxide values from 0 meq to 30 meq (milliequivalents) of active oxygen per kilogram. It is also applicable to margarines and fat spreads with varying water content. The method is not suitable for milk fats and is not applicable to lecithins. It is to be noted that the peroxide value is a dynamic parameter, whose value is dependent upon the history of the sample. Furthermore, the determination of the peroxide value is a highly empirical procedure and the value obtained depends on the sample mass. It is stressed that, due to the prescribed sample mass, the peroxide values obtained can be slightly lower than those obtained with a lower sample mass. Milk and milk products (or fat coming from milk and milk products) are excluded from the scope of this document. NOTE 1 A preferred method for the iodometric determination of the peroxide value for milk fats is specified in ISO 3976. NOTE 2 A method for the potentiometric determination of the peroxide value is given in ISO 27107.