Studies on Air-Dry Processing of Onions (Alium cepa)

摘要

The drying process of hot air oven drying was evaluated and compared with open sun and solar drying. Onion slices were dried using the open sun, solar dryer and hot air oven dryer. The results show that hot air oven drying of onions elicited higher mass and heat transfer coefficients than open sun and solar drying thereby resulting in a higher drying rate leading to a faster drying time. The effects of temperature and sample size on the dry rates and drying time of sliced onions were determined. Drying rate curves were characterised by a constant phase followed by a falling rate phase. Drying rate generally increased with increasing temperatures and decreasing sample sizes.