Studies in the stability of vitamins A and D. I

Abstract

A conc. containing 50% of vit. A absorbed 6% of its wt. of O when heated in O for 5i hrs. at 100[degree]C. The I value, acetyl value, E 1% 1cm328m[mu] and biological activity were decreased by the treatment. A 2d concen-tiate containing 70% of vit. A was heated in air at 100[degree]C for 3, 9, 24, and 48 hrs. The I value, acetyl value, E 1% 1cm 328m[mu], Carr-Price value and biological activity decreased in amts. corresponding to the time of heating, the saponification value, mol. wt., O content and aldehyde and ketone content similarly increased. The hydroxyl group of vit. A was probably oxidised to aldehyde and the unsaturated linkages to peroxides. The peroxides either reacted with unsaturated linkages to give polymers or disrupted to give aldehydes or ketones. The decrease in biological activity was more rapid than the decrease in E 1% 1cm 328m[mu] and Carr-Price value, hence the ratio Biological activity/E1% 1cm328m[mu] was less the more highly oxidised the material. The hypothesis was advanced that the factor for converting E 1% 1cm328m[mu]. into I.U. was lower for commercial concentrates of vit. A and for stale fish-liver oils than for freshly prepared fish-liver oils, because the former contained large amts. of oxidised vit. A.