Effects of Some Drying Methods on the Quality of Dried Nigerian Onion Varieties
O. O. Oniya *
Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria.
A.B. Fashina
Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria.
A.O. Adeiza
Nigerian Stored Products Research Institute, Km 3 Asa Dam Road, Ilorin, Kwara State, Nigeria.
O. Ogunkunle
University of Johannesburg, South Africa.
*Author to whom correspondence should be addressed.
Abstract
This research aimed to study the effects of some drying methods on the qualities of dried Nigerian onion varieties. Sliced onion samples of 1.5kg from each variety were dried in the three dryers at varying pre-determined temperatures of 50, 60, and 70oC. At 50, 60, and 70oC, the electrically powered dryer dried red onion for 13.55, 12.10, and 10.30 h, dried white onion for 14.10, 12.25, and 10.55 h, and dried cream onion for 14.10, 13.15, and 11.35 h. The kerosene-powered dryer at 50, 60, and 70oC dried red onion for 14.45, 13.22, and 11.55 h, dried white onion for 14.50, 13.15, and 11.15 h, and dried cream onion for 14.25, 13.05, and 12.20 h. The solar dryer at 57oC dried red onion for 72.45, dried white onion for 72.20 h, and dried cream onion for 72.50 h. Therefore, using kerosene, solar, and electrically powered dryers significantly affects onion quality (constituents and flavor). However, the electrically powered dryer could attain the required temperature quickly and further maintained the temperature, which proved to be the best method for drying the onions at 70oC.
Keywords: Drying, temperature, onion, quality, varieties