Kinetics of Colour Change on Mango Slices Using Different Drying Methods

Abstract

Colour is a key quality attribute that influence consumer preference and also serves as an indicator of nutrient degradation in fruits and vegetables. Colour information helps in selecting drying methods that minimize nutrient loss during food processing. Thus, this study investigated kinetics of colour change on mango slices using different drying methods. Freshly harvested Julie variety mango fruits (Magifera indica) usually known as Ogbomoso mango were sorted, washed, peeled and cut into slice thicknesses of 3, 6 and 9 mm. The slices were dried using three drying methods: oven (40, 45 and 50 °C), solar and sun drying. Colour value (CIE L*, a*, and b*) was used to determine the colour change of the samples. The values l* (lightness), a* (redness-greenness), b* (yellowness-blueness), were determine while total colour change (ΔE), Chromaticity difference (ΔC), Hue angle, and Browning index (BI) were calculated from the L*, a*, and b* value. The values of l* at 40, 45, 50 ºC, solar and sun ranges from 29.77- 67.99, 25.66 – 69.07 27.09 -73.15, 44.54 – 71.51 and 35.28 -68.51, respectively. The value of a* ranged from 8.71 -70.71, 5.77 - 40.67, 7.85 – 45.92, 9.45 – 32.68 and 6.07 – 24.57 for 40, 45, 50 ºC, solar and sun, respectively. The b* value for 40, 45, 50 ºC, solar and sun were 53.99 – 95.42, 29.26 – 92.21, 21.98 98.64, 35.96 – 78.64 and31.95 – 75.64, respectively. The value for ΔE were 48.08 – 132.37, 52.27 – 127.70, 31.25 – 128.85, 27.11 – 107.02 and 43.28 – 102.71 for 40, 45, 50 ºC, solar and sun, respectively. This study has shown that mango sample of slice thickness of 3 mm dried at 40 ºC and 3mm solar dried sample had better colour retention. Thus, the findings could be used in effective processing of mango slices.