Performance of two terms exponential model on the drying kinetics of solar dried tomatoes (Lycopersicum esculentum L.) treated with and without chemical preservative

Open sun drying of horticultural produce results in contamination due to microbial and fungal attacks and could also be damaged by insects, pests, and rodents. Solar drying through solar collectors is, therefore, an important technique used for the preservation of foods and to extend the shelf life of produce, thereby reducing microbial attack and contamination. Therefore, an experiment was carried out to study the response of the drying kinetics of solar-dried tomatoes to the thin layer of preservatives on the drying and quality attributes. The tomato fruits were treated with natural preservatives (honey and aloe vera) and chemical preservatives (citric acid, sodium benzoate, and potassium meta-bisulfate). The tomato fruits were then kept at three (40, 45, and 50 degrees C) different temperatures using a parabolic trough solar air heater for drying purposes. Both the drying temperature and preservative levels significantly (P< 0.001) affected the drying and quality traits of tomato slices. At a temperature of 50 degrees C and with citric acid as a preservative, the tomato attained the best average results for moisture lost hr-1, drying time, drying rate, total soluble solids (TSS) degrees Brix, fruit juice pH, titratable acidity (%) and vitamin C. Based on the average maximum results, 50 degrees C temperature and citric acid as a coating material could be considered for attaining better quality attributes of dried tomatoes. A two-term exponential model on the moisture ratio of tomatoes was found to fit for correlation and regression.