ISO 660:2009规定了三种方法（两种滴定法和一种电位法），用于测定动植物脂肪和油中的酸度。酸度优选以酸值表示，或者作为常规计算的酸度表示。 ISO 660:2009适用于精制和粗制的植物油或动物油脂，肥皂脂肪酸或工业脂肪酸。这些方法不适用于蜡。 由于这些方法是完全非特异性的，它们不能用于区分无机酸，游离脂肪酸和其他有机酸。因此，酸值也包括可能存在的任何无机酸

ISO 660:2009 specifies three methods (two titrimetric and one potentiometric) for the determination of the acidity in animal and vegetable fats and oils. The acidity is expressed preferably as acid value, or alternatively as acidity calculated conventionally. ISO 660:2009 is applicable to refined and crude vegetable or animal fats and oils, soap stock fatty acids or technical fatty acids. The methods are not applicable to waxes. Since the methods are completely non-specific, they cannot be used to differentiate between mineral acids, free fatty acids, and other organic acids. The acid value, therefore, also includes any mineral acids that may be present.