Phenolic compounds in frozen avocados

Abstract

Abstract The ethyl acetate‐soluble phenolic compounds present in frozen ripe Fuerte avocados were extracted with methanol and ethyl acetate. The compounds were separated by two‐dimensional paper chromatography with n ‐butanol‐acetic acid‐water (4:1:5, v/v) and 2% acetic acid solvents. Fifteen spots were found when the chromogenic reagent was FeCl 3 ‐K 3 Fe(CN) 6 . The individual compounds were identified by their R f values, colour reactions, fluorescent behaviour and absorption spectra. Chlorogenic and p ‐coumarylquinic acid isomers, catechins, leucoanthocyanidins, isoflavone and caffeic and p ‐coumaric acids were present in the extracts of frozen avocados. Ascorbic acid‐treated frozen avocado chunks did not darken when kept under vacuum at —26°C, but turned dark if left exposed to air. Darkening of frozen chunks was associated with disappearance of most phenolic substances, except the simple cinnamic acid derivatives. Formation of new phenolic substances, especially leucoanthocyanidins and catechins, was observed during storage of the frozen chunks under vacuum.