FLAVOUR REVERSION IN HYDROGENATED LINSEED OIL: II. EFFECT OF VARIATIONS IN PROCESSING PROCEDURES

Abstract

Shortenings prepared from various linseed oils by different methods were stored at 43.3 °C. (110° F.) and sampled at eight-week intervals for 56 weeks. Storage life in terms of flavour reversion was not highly correlated with mean peroxide value or unsaturation. All shortenings were resistant to normal oxidation, but unstable to reversion unless hydrogenated to a very low iodine number. Hot and cold pressed oils yielded products equally susceptible to flavour reversion. Changes in stability attributable to variations in methods of alkali refining, bleaching, and hydrogenation were only minor. High alkali concentrations (30° to 40° Bé.) were beneficial, while hydrogenation at 190 °C. (374° F.) was preferable to hardening at lower temperatures (140 °C. (284° F.) and 115 °C. (239° F.)). Blending with other vegetable oils, or the use of hydroquinone or a wheat-germ oil preparation as antioxidants, slightly retarded the onset of reversion. None of the laboratory or commercially prepared samples examined was considered to be a satisfactorily stable product.