Kinetic Modelling of Vitamin C Degradation in Leafy Vegetables during Blanching

Three different commonly used leafy vegetables in Nigeria ( moringa oleifera , hibiscus esculentus and hibiscus sabdarifa ) were analysed for their ascorbic acid (Vitamin C) contents. The vegetables were blanched in a steam blancher for 1- 6 minutes to analyse the effect of blanching time on their vitamin C content. Hibiscus esculentus had the lowest ascorbic acid content while hibiscus sabdarifa had the highest of Vitamin C concentration before blanching. After blanching for 6 minutes, hibiscus esculentus , Moringa oleifera and Hibiscus esculantus lost 69.7%, 64.2% and 54.2% of their initial Vitamin C contents respectively. Integral fitting of the experimental data shows that the kinetic degradation of ascorbic acid in all three vegetables follows first order reaction mechanism. The kinetic model parameters were determined using the integral method of data analysis for each vegetable. The pattern of ascorbic acid degradation in all the three vegetables was similar despite their different initial contents.