ISO 8156 | IDF 129:2005规定了一种测定不溶性指数的方法，作为评估全脂奶粉、部分脱脂奶粉和脱脂奶粉（非速溶或速溶）溶解度的方法。 该方法还适用于乳清粉、乳酪粉和基于乳粉的婴儿食品，以及所列乳脂已被另一种脂肪取代或已被滚筒干燥而非喷雾干燥的任何干燥产品。

ISO 8156|IDF 129:2005 specifies a method of determining the insolubility index, as a means of assessing the solubility, of dried whole milk, dried partly skimmed milk and dried skimmed milk, whether non-instant or instant. The method is also applicable to dried whey, dried buttermilk and dried milk-based baby food, as well as to any of the dried products listed in which milk fat has been replaced by another fat, or which has been roller-dried instead of spray-dried.