Effects of different drying technology on the quality of lotus-seed

Effects of different drying technology(sun drying, hot-air drying, vacuum drying, freezing drying, microwave drying and combined microwave and hot-air drying) on the shrinkage, rehydration ratio, resistant starch(RS) content, color and organization structure of lotus-seed were studied. The results show that lotus-seeds obtain less shrinkage, higher rehydration ratio, lower RS content, less distortion and better color by combined microwave and hot-air drying. Its color and organization structure is close to the fresh lotus-seed. The quality of lotus-seed by microwave drying is next to those by combined microwave and hot-air drying. Freezing drying makes lotus-seeds the lest shrinkage and the highest rehydration ratio, but higher RS content, worse color and obvious distortion and shrinkage. The quality of lotus-seeds by sun drying, hot-air drying and vacuum drying are inferior to the others. So combined microwave and hot-air drying is the optimal technology.