Bio-Engineering Studies for Tomato Pomace Powder Production as a Nutritional Valuable Material

Abstract

Processing tomatoes into industrial products leave behind large amounts of by-products. These by-products of tomato processing are attractive sources of high nutritional valuable components. Accordingly, the current research work aims to produce tomato pomace powder as a nutritional valuable material. Tomatoes were juiced, and the remaining pomace were further dried by various drying methods i.e., mechanical dryer at different air temperatures and velocities (60, 80 and 100 °C at 1, 1.5 and 2 m/s), oven drying (60, 80 and 100 °C) and microwave drying at different powers (200, 400, 600 and 800 W). The obtained results showed that the moisture content of the by-product decreases with growing temperature, velocity and microwave power. Dried tomato pomace samples were evaluated for quality attributes, viz. microbial activity, color, and chemical compounds (moisture content, dry matter, Ash, carbohydrate, protein, fat and total carotenoids). Drying process caused a considerable decrement in total microbial counts of tomato pomace samples (the best value was 1.9×103 cfu.ml-1) at mechanical dryer (100 °C and 2 m/s). In conclusion, using the mechanical drying method at 100 °C achieved the best results of minimum value of microbial load, minimum change in color parameters and higher total carotenoids for dried samples although the drying time is greater than the microwave method. Hence, these drying methods were applied to optimize the drying conditions in order to valorization by-products of tomatoes. Therefore, the authors recommended using a large scale of mechanical dryer for tomato pomace drying at the optimum operational condition mentioned above.