oleïne

Oleïne, also written olein, is the liquid fraction of fats and oils obtained by fractional separation. It consists mainly of triglycerides that remain liquid at room temperature and is contrasted with the solid fraction, known as stearin.

In fat processing, fats can be fractionated by cooling (winterization) or by distillation after partial saponification. The liquid portion, oleïne, is enriched in unsaturated fatty acids and yields a lower-melting component, while the solid stearin is richer in saturated fatty acids such as palmitic and stearic.

Oleïne is predominantly triglycerides of oleic acid and other unsaturated fatty acids, with composition varying by source, such as palm olein, olive oil olein, or soybean olein.

In modern industry, oleïne fractions are used as cooking oils and as components of margarines. In palm oil fractionation, the liquid fraction is referred to as palm olein and the solid fraction as palm stearin.

Historically, oleïne was a central term in fat chemistry, though contemporary terminology tends to name the fraction after its source and its intended use, reflecting a shift toward more specific classification of fat fractions.