Studies on Solar Cabinet Drying of Green Peas (Pisum sativum)

Response surface methodology was used to optimize the pretreatment prior to solar cabinet drying (SCD) of green peas. Thirteen experiments were conducted using a central composite design (CCD) with two variables at two levels each, viz. blanching time (1-5min) and potassium metabisulphite (KMS) concentration (0.2-0.5%). Solar cabinet drying of pretreated green peas was carried out up to 6% (d.b) moisture content. During drying the air temperature, relative humidity, and air velocity in the dryer were in the range 40-60 degrees C, 40-50%, and 0.9-1m/s, respectively. After drying, color (a value) and hardness (g) of the dehydrated green peas were measured and taken as responses. During optimization, the best process conditions were found with 4.24-min blanching time and 0.49% KMS concentration resulting into -7.86 color (a value) and 548g hardness. Green peas were dried in solar cabinet dryer using the pretreatment at optimum conditions and some selected quality parameters like color (a value), hardness, rehydration ratio, shrinkage, overall acceptability, and drying time were used to compare the solar cabinet drying method with other drying techniques like freeze (FD), fluidized bed (FBD), and open sun drying (OSD). Drying kinetics and moisture diffusivity were determined and compared.