Application of infrared radiation in the drying of food products

Drying is an important method to preserve food products. Although many traditional drying technologies (hot air, freeze, microwave drying) have been applied successfully to various food products, each drying technique has its own advantages and disadvantages. Novel drying methods such as infrared drying, have become very popular. This study gives an overview on the application of infrared radiation in the drying of food products in the last decade. The effects of main parameters (infrared power, intensity, distance, wavelength and drying temperature) and the introduction of infrared radiation on drying kinetics and food quality were discussed. Inconsistencies were pointed out and analyzed in detail. Key findings and conclusions: Drying kinetics was improved by introducing infrared radiation and increased with increasing infrared power, intensity, drying temperature and decreasing infrared distance. However, a very high infrared power, intensity, drying temperature and a very low infrared distance should be avoided as the food products will be overheated. The effects of infrared parameters on food quality were unpredictable. The energy consumption under infrared radiation was also variable. When the reduction of drying time was considerable, the energy consumption decreased. When the reduction was insufficient, the energy consumption increased. The application of infrared radiation will also affect the food quality. Generally, the infrared radiation can decrease the water activity, reduce the total color change and improve the nutrient retention.