Effects of pretreatments involving ohmic heating and infrared radiation on the drying process of bananas using hot air

Abstract

AbstractNowadays, the hot air drying process is the most widely used method for producing dried food and agricultural products due to its suitable investment and low operational costs. However, one of the disadvantages of drying with hot air is the prolonged drying time, which sometimes leads to serious damage to the quality characteristics of the resulting products, especially at high temperatures. Therefore, there is a need to find the most suitable conditions for producing high‐quality dried products. To conduct this experiment, after determining the desired number of samples, infrared preheating and ohmic heating were performed sequentially. In the first stage of preheating, the samples were placed in the ohmic heating device, and in the second stage, they were exposed to infrared radiation. Then, the samples were transferred to a hot air dryer for complete drying. The results showed that the antioxidant content increased with the increase in the thickness of the banana slices. Moreover, an increase in the drying temperature and the number of infrared lamps led to a reduction in the antioxidant content. The slices with less thickness and higher drying temperatures had the minimum phenol content. The maximum and minimum measured values of the total phenol content were 34.51 and 37.32, respectively. The range of variation in the solid soluble content was between 11.708% and 19.5437% Brix. In addition, at the same temperature values, an increase in the thickness of the banana slices resulted in a decrease in the solid soluble content of the samples. Furthermore, with an increase in the temperature for slices of the same thickness, the solid soluble content of the samples increased.Practical applicationsThe purpose of this research is to evaluate the effect of the thickness factors of the sample pieces, the temperature of the hot air dryer along with ohmic heating pretreatments, and the infrared lamps in the hot air dryer on the quality indicators of banana.