Investigation of effective parameters on quality Black Currant raisin

Achieving optimum drying conditions can affect the processing time and improvement of raisin quality. Temperature, air velocity and pretreatment are important factors in grape drying process and its quality. In this research, effect of the following conditions on quality of Black currant raisin was studied: air temperature at four levels of 50, 60, 70, and 80 ºC, air velocity at three levels of 1, 2 and 3 m/s, and four pretreatments including hot water, %5 potassium carbonate, %0.4 olive oil, %0.5 sodium hydroxide (caustic soda) and control without any pretreatment. The results showed that some factors such as air temperature, air velocity and pretreatment have qualitatively significant effects on browning index, rehydration ratio, and shrinkage. Similarly temperature and pretreatment factors have a significant effect on acidity. Raisins dried at 70ºC and pretreated in hot water, %5 potassium carbonate, %0.4 olive oil and %0.5 sodium hydroxide have better quality.