The influence of blanching parameters (time and temperature), variety and yam thickness on cellular exchanges and on calcium, ascorbic acid and β-carotene contents during blanching and/or subsequent drying was investigated. Yam slices (2, 3 and 4 mm thickness) of the yellow and orange variety of D. schimperiana were blanched in hot water at 70 and 100°C for 0 to 60 sec in order to study the cellular exchange during blanching. Kinetic of calcium loss was determined during blanching at 100°C. Yams slices of the orange variety blanched at 100°C for one minute were dried at 50°C in a cross flow cabinet dryer. Losses in β-carotene and ascorbic acid were calculated after one minute of blanching at 100°C and along the drying process. The results show a strong intraspecific variability in cellular exchange during blanching. Blanching in hot water at 100°C result in a higher loss in calcium, β-carotene and ascorbic acid. These losses continue during subsequent drying. The moisture diffusivity during drying of blanched slices varied from 1.07x10-10 (4 mm) to 4.33x10-11 (2 mm). Twenty six to fifty percent of the β-carotene and more than 50% of ascorbic acid were loss during blanching depending upon slices thickness. Blanching is the limiting factor in β-carotene and ascorbic acid loss during blanching and subsequent air drying. Blanching parameters (temperature and time), slices thickness and variety influenced cellular exchanges and losses in calcium, β-carotene and ascorbic acid.
M.S. Leng, I. Gouado and R. Ndjouenkeu, 2011. Blanching and Drying Behavior of Dioscorea schimperiana and Impact on Cellular Exchanges and on Calcium, Ascorbic Acid and β-carotene Contents. American Journal of Food Technology, 6: 362-373.