Butter and Other Milk Fat Products | Properties and Analysis

Butter is a high-energy concentrated natural dairy product consisting mainly of milk fat (≥80%), water (≤16%) and nonfat solids (proteins 0.6–0.7%, lactose 0.7–0.8%, minerals ≈0.2%, plus traces of vitamins, particularly A and D). It has a unique delicate flavor, which in combination with its characteristic and pleasant mouthfeel is an unparalleled selling point. However, its poor spreadability at refrigeration temperature and high level of saturated fatty acids makes butter less attractive to consumers. Butter is mainly a water-in-oil emulsion and its properties are dominated by those of the continuous liquid fat phase derived from the breakdown of the milk fat globules during buttermaking. Within this liquid fat are dispersed the crystalline fat (quantity depending on temperature and the diet of the cow), undamaged and damaged fat globules plus milk serum and any added water. Approximately 98% of the lipid material in butter is triacylglycerols, with 0.3% each of diacylglycerols, monoacylglycerols, phospholipids and sterols (principally cholesterol). Free fatty acids (FAs) account for ≈0.1% of lipid and there are traces of waxes, squalenes and carotenoids. There is a very wide range (>400) of FAs, though only 15 are present at >1%. Bovine milk fat is characterized by a relatively high level of short-chain FAs (C4–C10), especially butyric acid. The unsaturated FAs make up about one-third of the total, with one minor component, trans-11-C18:1, providing a precursor for conjugated linoleic acid, which is highly bioactive.