Response surface modeling of the pomegranate arils (Shahsavar Yazdi cultivar) weight loss, vitamin C and color characteristics variation during the infrared drying process

Drying is one of the oldest methods of food preservation, which usually have adverse effect on the physicochemical properties and nutritional value of the final product too. Today, the demand for application of rapid drying methods such as using microwave and infrared beams has increased to prevent or reduce undesirable changes in foods. In this study, the effect of infrared drying process condition (drying temperature and time) on weight loss, vitamin C and color properties of Shahsavar Yazdi pomegranate arils were investigated and optimized by response surface method. The results showed that the amount of weight loss and L* value of pomegranate samples, increased with increasing drying time and temperature, while the amount of vitamin C decreased. Drying temperature had a greater effect on weight loss and vitamin C changes compared to drying time; however, variation of L* value under the influence of infrared drying time are more severe than the drying temperature. The amount of a* and b* value increased with increasing drying temperature while decreased with increasing infrared drying time. The best conditions for infrared drying of pomegranate arils are using drying temprature of 55 °C for 600 minutes and by applying the optimal conditions, the amount of weight loss, vitamin C and the total color difference (DE) of the produced pomegranate arils are equal to 69.5, 12.89 and 5.79 respectively. The results of the optimal conditions validation test showed that by applying the obtained conditions from the optimization process, the quality attributes of pomegranate such as weight loss, amount of vitamin C and the total color difference (DE) of the produced samples were 70, 12.45 and 7.75 respectively, which are very similar to the obtained results from the optimal conditions predicted by the response surface method.