EVALUATION OF POTATO SLICES DRYING USING SOLAR DRYER

Abstract

The objective of the present study was to investigate the drying characteristic curves and the drying duration when drying potato slices using natural convection solar dryer. For that sake an experimental setup was developed. Measurements of total solar radiation on the plane of the collector, ambient air temperature, drying air temperature and moisture loss in weight were collected. A group of experiments were conducted using potato slices with thickness of 1 mm to study the effect of pretreatments on drying characteristics. The maximum temperature attained in the drying chamber is 52 oc at 13:00 and 14:00 pm and the maximum temperature attained in the collector is 75oc at 14:00 pm while the corresponding values of solar radiation and ambient temperature were 876.5 W/m2and 38oc, respectively. The final moisture contents were 7.15 and 4.48 db in B(blanch + calcium chloride) and C (blanch + citric acid) treatments, while in A (blanch), D (blanch + potassium meta sulphate) and E (blanch + acitric acid) were 14.20, 22.35 and 13.73 db. Consequently, citric acid solution and calcium chloride solution were more effective solutions in potato slices drying. The slices treated with citric acid (C), potassium meta sulphite (D) and acetic acid (E) provided better color for drying compared with the slices that treated with blanch only (A) and with calcium chloride (B) under which the colors were brown. The effective moisture diffusivities of pretreated with treatments (A, B, C, D and E) were (1.35×10-11, 1.39×10-11, 1.45×10-11 , 1.23×10-11and 1.40×10-11m2/s), respectively. Based on these results, pretreated samples with citric acid solution (C) had the highest effective moisture diffusivity compared with other samples.