Influence of Chemical Pretreatment on the Quality of Dried Whole Red Bell Pepper (Capsicum annuum var L)

Abstract

Chemical pretreatment of vegetables prior to drying is widely used to improve colour, texture and overall acceptability. Thus, this study investigated the effect of chemical pretreatment on some physico-chemical properties, colour and rehydration properties of dried red bell pepper. Fresh samples of whole red bell peppers were soaked for 10 min in (0.3% (w/w) Potassium metabisulphite, 1% (w/w) Ascorbic acid, 1% (w/w) Calcium chloride, 0.3% (w/w) Potassium metabisulphite combined with 1% (w/w) Citric acid and 0.3% (w/w) Potassium metabisulphite combined with 1% (w/w) Calcium chloride) prior to drying. The results showed significant (p < 0.05) differences in all the qualities investigated. The values of vitamin C content, TSS and pH of the samples ranged from 39.22 to 72.2 mg/100g, 7.28 to 9.50 %, and 4.22 to 4.68, respectively. In terms of colour parameters, L*, a* and b* values ranged from 24.49 to 26.00, 38.34 to 55.20 and 27.47 to 30.96, respectively. The rehydration ratio and coefficient of rehydration ranged from 4.24 to 5.53, and 0.39 to 0.49, respectively. Dried whole red bell pepper soaked in 0.3% potassium metabisulphite combined with 1% calcium chloride prior to drying gave the most desirable colour and rehydration properties while the highest value of vitamin C was obtained in whole red pepper samples soaked in 1% ascorbic acid.

Keywords: Pepper, pretreatment, physic-chemical, colour, rehydration properties