Drying Kinetics, Physicochemical and Microbiological Properties of SolarTent and Open Sun-Dried Sweet Potato (<i>Ipomoea batatas</i>) Chips

Abstract

The drying characteristics, physiochemical and microbiological properties of sweet potato chips dried by sun and solartent drying  methods were determined. The potato slices of 2 mm thickness were dried for 40 and 52 hours, respectively in the solar tent, which was  constructed and open to sun drying methods. The drying kinetics, physicochemical and microbiological properties of the dried potato  chips were determined. A total drying time of 52 hours was required to reduce the moisture content from 69.56 to 0.94% wb for the open  sun-dried chips. However, a lesser time (40 hours) was required to reduce the moisture content of the solar tent-dried chips(70.29-0.58%  wb). The effective moisture diffusivity of the open sun and solar tent-dried samples were 1.0421×10^-7 and 2.1069×10^-7 m² /s, respectively. The results of the physicochemical properties of dried potato samples for the two drying methods were 0.45-0.57g/ cm³ , 0.53-0.63 g/cm³   , 35.44-37.09%, 79.09-92.46%, 53.54-57.31% and 18.40-18.99%, respectively for tapped density, loose bulk density, water absorption  capacity, oil absorption capacity, swelling index and water solubility index. The total viable counts of the dried chips ranged  from 3.53×10⁶ to 2.95×10⁷ cfu/while the total mould counts varied from 6.83×105 to 1.05×10⁶ cfu/cm³ . There was no coliform growth in  the dried chips for the two drying methods. It is concluded that solar-tent drying produced sweet potato chips of better quality than open  sun drying.