PREDICTION MODELS FOR COLOUR CHANGES IN ORANGE FLESHED SWEET POTATO (Ipomoea batatas L. Lam.) DURING HOT AIR DRYING
Abstract
The main objective of this study was to investigate the effect of different temperatures of hot air drying on the quality attributes of orange fleshed sweet potato including colour parameters and colour sensory quality. The drying experiments were carried out at five air temperature of 40, 50, 60, 70 and 80oC. The colour parameters, L (whiteness/darkness), a (redness/greenness) and b (yellowness/blueness) for colour change of the materials were quantified by the Hunter Lab system. These values were also used for calculation of total change (ΔE), hue angle, chroma and browning index. A consumer preference test was conducted with 80 consumers to assess the colour quality of five dried orange fleshed sweet potato samples. Relationship between colour sensory scores of consumer’s taste and quantification of three Hunter parameters using least square regression indicated that all colour values significantly affect colour quality ranking of dried orange fleshed sweet potato. The zero-order model appeared best suited to explain the colour change kinetics during hot drying orange fleshed sweet potato slices at 70oC.