Document Type : Original Article
Authors
1 Sokoine University of Agriculture (SUA), Morogoro, Tanzania
2 Dar es Salaam Institute of Technology (DIT), Mwanza campus, Tanzania
3 Tanzania Agricultural Research Institute (TARI), Kibaha, Pwani, Tanzania
Abstract
In Tanzania, tomatoes (Solanum lycopersicum) are widely cultivated and consumed, yet substantial postharvest losses occur due to their high perishability. Drying is a promising method to extend shelf life and add value to tomato products. This study evaluated the physicochemical, nutritional, microbiological, and sensory qualities of tomato soup powders produced using solar tunnel and electric dryers, stored in paper and plastic packaging at room temperature for five months. Two soup formulations were prepared using blends of dried tomato, garlic, onion, ginger, turmeric, cinnamon, monosodium glutamate, and cornstarch, differing in ingredient ratios. The pH, titratable acidity, total soluble solids, lycopene, β-carotene, vitamin C, and yeast and mold counts were measured to assess the effects of drying techniques, packaging materials, and storage duration. Results showed that drying method and packaging significantly influenced nutrient retention and microbial stability (p < 0.05). Soups dried with an electric dryer and packed in polyethylene retained higher nutrients, with lycopene decreasing from 17.35 to 13.12 mg/100 g, β-carotene from 5.20 to 3.85 mg/100 g, and vitamin C from 42.30 to 28.10 mg/100 g over five months. Microbial counts in polyethylene-packed samples remained below 10³ CFU/g after four months but exceeded limits in paper-packed samples. Sensory evaluation indicated both products were acceptable, with a slight preference for electric-dried soups. Overall, combining electric drying with polyethylene packaging effectively preserved the nutritional quality, microbial safety, and sensory acceptability of tomato soup powders for up to four months, offering a practical approach to reducing tomato postharvest losses.
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