Pigments and colour characteristics: Influence of drying methods on Nigerian pepper (Capsicum frutescence)

Abstract

Drying conditions such as temperature and duration leads to pepper modifications that can results into quality degradation. In this study matured red fresh Capsicum frutescens var. Baccatum (FB) and Capsicum frutescens var longum (FL) were dried using sun drying (SFB and SFL) and hot air cabinet drying (CFB and CFL) methods. Effects of drying was investigated on moisture content, water activity, carotenoid (capsorubin, violaxanthin, capsanthin, antheraxanthin and zeaxanthin) and colour characteristic (extractable, surface colour, non-enzymic browning index [NEBI]). Cabinet drying significantly (P < 0.05) reduced the moisture content and water activity to 7.7% and 0.41 in CFB and 7.5% and 0.42 in CFL compared to 8.5% and 0.45 in SFB and SFL by sun drying. Capsorubin was the most abundant carotenoid in both species (51 and 29%) and capsanthin (43 and 25%) in FB and FL. Extractable colour loss in FB was 31 and 26% due to sun and cabinet drying, while FL recorded 42 and 24%. The chromatic coordinates (a*, b × and L*) in the fresh C. frutescens var baccatum and C. frutescens var longum were significantly affected by the drying methods with values ranging from 23 to 28, 20–24 and 36–41 in the dried peppers. The highest NEBI values of 113 and 123 were recorded for the C. frutescens var baccatum while the lowest colour difference was recorded in C. frutescens var longum. Cabinet drying method provided higher NEBI with CFB having the highest values indicating that cabinet drying may be considered a better drying alternative for dehydration of red pepper due to better colour retention of the dried products.