Study of vacuum frying process of tomato slices and determination of optimal conditions

Tomatoes are widely produced and consumed worldwide due to their high nutritional value as well as unique sensory properties. The high perishability and low shelf life of tomatoes necessitate the use of modern processing methods. In this research, the possibility of using vacuum frying technology in the processing of tomato slices, the effect of process variables (processing time, oil temperature and pressure inside the chamber) on some quality characteristics of the final product (moisture and fat content, Shrinkage, ascorbic acid, color and texture brittleness) as well as determining the optimal processing conditions in a vacuum lab-scale frying system with precise control of process conditions were investigated. Initially, by performing pre-tests, the range of variables of the study included frying temperature, pressure inside the chamber and process time was determined. The results of study showed that the process temperature has significant effects on the moisture content, shrinkage, fat content, ascorbic acid content and texture brittleness, so that with increasing temperature, the content Moisture and ascorbic acid content decrease and shrinkage, fat content and tissue brittleness increase. Processing time showed significant effects on the moisture content, shrinkage, fat content and texture brittleness, so that with increasing process time, the moisture content decreased and shrinkage, the fat content and texture brittleness, increased. Pressure of the study area had significant effects only on shrinkage and total color change characteristics. Increasing the pressure inside the chamber led to a reduction in shrinkage and an increase in total color changes. Optimum vacuum frying conditions of tomato slices were a temperature of 135°C, time of 21.92 minutes and pressure of 260 mbar, under these conditions were the moisture content, shrinkage, fat content, amount of ascorbic acid, total color changes and the breaking force were 45.93%, 70.54%, 34.64%, 2.92 mg/100 mL, 64.86 and 2.58N, respectively.