Effect of Pretreatments on the Characteristics of Dried Grey Oyster Mushroom (Pleurotus sajor - caju)

Abstract

Sodium hypochlorite, sodium metabisulphite and glycerol were effective in reducing the browning of dried mushrooms. Addition of glycerol also improved the texture of rehydrated dried mushrooms while CaCl2 and alum produced a firm textured product, calcium being more effective than alum. Pretreatment with 0.3% cysteine-HCl helped preserve 82% of the ascorbic acid content in dried mushrooms compared to fresh mushrooms. The best drying temperature for colour and texture was 40'C; 60'C was best for ascorbic acid retention. Glycerol reduced shrinkage during drying and improved the ability of the dried mushrooms to rehydrate almost to an extent characteristic offresh mushrooms. Sensory evaluation showed that dried grey oyster mushrooms were well accepted; pretreatments caused a significant improvement in texture and colour (P < 0.05). The panellists gave insignificantly different scores for flavour and overall acceptability for all the rehydrated dried mushrooms even when compared to the fresh mushrooms.