Pretreatments, Dehydration Methods and Packaging Materials: Effects on the Nutritional Quality of Tomato Powder

Abstract

Pretreatments and drying are commonly used before drying tomatoes to inactivate enzymes, improve the drying process, and improve the quality of dried tomato powders. In this review, the effects of different pretreatments (osmotic solutions), dehydration methods and packaging materials on quality attributes of tomato powder were summarized. They include pretreatments and osmotic agent solution (potassium metabisulphite, calcium chloride, sodium metabisulphite, ascorbic acid, citric acid, sodium chloride and sodium benzoate), thermal blanching (steam blanching and hot water) and non-thermal processes like freezing, sulfuring, etc. and drying methods (oven, sun and indirect solar dryer).Tomato powders have been dried in order to preserve, store, and transport them. Drying implies not only physical changes, which the consumer can easily detect through visual inspection, but also chemical modifications. These are responsible for alterations in color, flavor and nutritional value, which compromise the overall quality of the final tomato powder. Maximum lycopene and vitamins A and C content were found in freeze dried and direct sun dried than samples dried using other methods in low drying temperature, freeze driers showed in keeping the nutritional quality of tomato powder with combination of different pretreatments. Different pretreatments including osmotic agent solutions have their own merits and demerits on the final tomato powder. To overcome nutritional quality drawbacks, non-thermal pretreatment categories may be a better alternative to thermal blanching, and more fundamental research is required for better design and scale up.