A modified spectrophotometric method for the assay of carotene and vitamin A in butter

Abstract

The carotene, xanthophyll and vit. A values of 70 English butters, determined spectrophotometrically, show that on the av. the carotene-xanthophyll ratio is 14:1 by wt. The method previously developed for determining carotene and vit. A in butter may be shortened and improved for routine purposes by assuming that 94% of the light absorption of butter unsaponifiable matter in CHCl3, at 455-460 m[mu], is due to carotene. The results on individual samples are sufficiently close to those actually determined after removal of the xanthophyll, to justify the economy in time and material effected. Details of the modified method are given.