Effect of Blanching on Enzyme Activity and Colour Stability of Dried Okra in Benue State

Okra (Abelmoschus esculentus) is a nutritionally important vegetable widely cultivated and consumed in Benue State, North Central Nigeria. Inadequate pre-treatment before drying contributes to quality loss through enzymatic browning and chlorophyll degradation. This study investigates the effect of blanching treatments on peroxidase and polyphenol oxidase activity, colour parameters, and overall quality of dried okra slices. Fresh okra pods obtained from Makurdi markets were subjected to hot water blanching at 80 and 95 degrees Celsius for 1, 2, and 3 minutes, followed by hot-air drying at 65 degrees Celsius. Enzyme activity was measured spectrophotometrically, and colour was evaluated using a Hunter Lab colorimeter for L, a, and b values. Moisture content, texture, and overall acceptability were also assessed. Blanching at 95 degrees Celsius for 2 minutes produced the greatest inactivation of both peroxidase and polyphenol oxidase, with enzyme activity reduced to below 5 percent of the unblanched control. This treatment also yielded the best colour retention as measured by the highest L-value and lowest browning index. Sensory evaluation by a panel of 20 trained assessors indicated that blanched and dried samples were significantly more acceptable than unblanched controls. The findings contribute to the growing body of literature on pre-treatment optimisation for dried vegetables in tropical regions. Results have direct practical implications for okra processors and vegetable export stakeholders in Benue State. Keywords: okra, blanching, enzyme inactivation, drying, colour stability