Drying of cherry tomato by a combination of different dehydration techniques. Comparison of kinetics and other related properties

Dehydration of tomatoes is a process commonly used to preserve the product and extend shelf-life. However, the quality of the dehydrated product is often poor. Collapse of the structure, discoloration and a tough texture are frequent quality problems. No less important, although not visually apparent, is the lack of flavour and nutritional value. The combination of osmotic dehydration and microwave drying is a potential new process that could improve the quality of dried tomatoes. In the present work, various osmotic solutions formulated with salt, sugar and calcium lactate were used in an osmotic treatment prior to microwave assisted air drying. The influence of microwave energy on the kinetics was analyzed and correlated with the dielectric properties of the samples. The results showed that osmotic dehydration with ternary solutions (27.5% sucrose, 10% salt and water (w/w)) with the addition of 2% of calcium lactate combined with microwave assisted air drying makes it possible to obtain dried and intermediate moisture tomato products that are shelf stable and have better quality than the traditional product.