Comparative Study of Degradation Kinetics of Ascorbic Acid (Vitamin C) in Tray Drying, Solar Drying and open Sun Drying of Pineapple Slices

Abstract

A comparison of degradation kinetics of ascorbic acid was done on tray, solar and open sun drying of pineapples. Thin slices of 10mm±3 thickness were equally weighed and divided into three samples of 300g each. One 300g sample was placed in a tray dryer and dried at a temperature of 60oC, the next 300g sample was placed in the solar dryer and another 300g sample was placed on a tile for open sun drying and dried under fluctuating temperatures. Samples were taken at half hour intervals and analysed for vitamin C content over the drying period using the 2,6 dinitrophenolindophenol dye titration method. The residual vitamin C content in tray drying was least at 11.25 mg/100g of sample. This was followed by sun drying with a residual vitamin C content of 19.5mg/100g of sample. Solar dried sample showed the highest vitamin C retention with 29.25mg/100g of sample weight. The degradation kinetics were analysed using the first order fractional Model and the Weibull Model. The correlation coefficient (R2) was calculated for goodness of fit. The Weibull model had the best fit. However deviation from first order degradation kinetics of vitamin C was noted.