Evaluation of NSPRI Parabolic Shaped Solar Dryer (PSSD) for Drying of Tomatoes Under Semi-arid Climate Zone

Abstract

This study evaluated the performance of a Parabolic Shaped Solar Dryer (PSSD) developed at Nigerian Stored Products Research Institute Kano (NSPRI) and compared it with an Open Sun Drying (OSD) - Ambient. The evaluation was carried out using Tomatoes (Eka). After sorting and washing the fresh tomatoes were sliced into 15 mm thickness and then spread on trays in PSSD and OSD. A thermo-hygrometer was used to record daily temperature and relative humidity. The dried Tomatoes' average drying temperature and relative humidity were 68.2 ^oC and 50.5% for PSSD, 47.5 ^oC, and 66.6% for OSD. The average drying rate was 31.6 kg/day for PSSD and 19.7 kg/day for OSD. The result showed that PSSD recorded the highest temperature variation and drying for drying of Tomatoes when compared to OSD. Initial moisture of 89.12% was reduced to a final moisture content of 14.5% for PSSD and 17.8% for OSD after six days of drying. Physiochemical and functional properties of the dehydrated tomato were also carried out. The bacteria count was lower in PSSD (5.8 x 103 Cfu/ml) compared to OSD (7.6 x 10³ Cfu/ml). However, no fungal growth was observed in OSD where 4.1 x 10³ Cfu/ml was recorded in PSSD.