EFFECT OF SLICE THICKNESS AND PRETREATMENT ON THE DRYING KINETICS AND SOME QUALITY PARAMETERS OF TOMATO (Lycopersicon esculentum)

Tomato (Lycopersicon esculentum) is considered as one of the most important vegetables and considered as one of the important sources of vitamin C and carotenoids. However, it is highly perishable which results in bulky post-harvest losses. This study investigated the drying kinetics of tomato and studied the effect of slice thickness (4, 6 and 8 mm) and pretreatment (using sodium metabisulphite, potassium metabisulphite and citric acid) of some quality parameters of tomato using hot-air drying method at 60°C. Drying time for samples treated with sodium metabisulphite, potassium metabisulphite, citric acid and control samples was 300, 360, 300, and 360 min, for 4 mm slices; 360, 400, 360 slice and 420 min for 6 mm; and 420, 480, 420 and 540 min for 8 mm, respectively. Lycopene content ranged from 0.126 – 0.137, β-carotene values ranged from 0.951 – 1.59 mg/100 g, ascorbic acid value ranged from 5.295 – 7.979 mg/100 g and total soluble solid values range from 1.200 – 2.1% for all the pretreatment used. There was a significant difference between all the pretreated and the control samples. It was observed that tomato slices treated with sodium metabisulphite and citric acid had high rate of moisture removal. It was also observed that sample treated with potassium metabisulphite had better retention of lycopene, β-carotene and vitamin C.