ABSTRACT
Infrared (IR) radiation has been used in food processing applications for its unique high heating efficiency. There is a great need to address the radiation absorption and heating effect during the application of IR in the processing of foods. The radiation wavelength determines the nature of the processing, and it is mainly affected by the type of emitter, operating temperature, and the power supplied. The penetration depth of the IR on food material plays a critical role in the heating level along with the optical characteristics of the IR and food product. The IR radiations cause a significant change in the food components like starch, protein, fats and enzymes. The facility to generate wavelength-specific radiation output can hold the potential of momentously increasing the efficiency of IR heating operations. IR heating is gaining importance in 3D and 4D printing systems, and the application of artificial intelligence in IR processing is being explored. This state-of-art review gives a detailed view of the different emitters of IR and mainly emphasizes the behavior and changes of major food components during IR treatment. The penetration depth of IR, optical characteristics and selective spectral heating based on the target product are discussed.
ABSTRACT
Different wavelength emitting infrared (IR) lamps (transparent quartz tungsten (TQT), ruby-coated quartz tungsten (RCQT), and ceramic) were used for dry peeling and evaluating the spectral characteristics of emitted radiations. The maximum temperatures for ceramic, RCQT, and TQT were 560, 662, and 861°C, respectively. The peak wavelength determined by Wien's law was between 3.37 and 21.47 µm. Comparatively, longer wavelength was emitted by ceramic lamp. The spectral emissive power determined by Stefan Boltzmann's law was 1.14-37.49 kW m-2 using the IR emitters at different power levels. The radiant efficiency was higher for the ceramic lamp. The peak wavelength and emissive power had a major influence on the peeling performance and quality during IR peeling. The optimized parameters for IR dry peeling of shallots are 60 mm distance between lamp and product, 59.74% IR power level, 15 min of heating time using the ceramic (peak wavelength 8.16 µm) lamp. Practical Application: Infrared dry peeling of shallots is a sustainable alternative to traditional peeling methods that leaves adverse environmental footprints. Spectral characteristics of the infrared lamp can be used to determine the suitable emitter for the dry-peeling operation. It is necessary to check the wavelength emitted by the source for designing the IR system based on the food product and application. This study will be helpful in food processing industries to use an effective infrared lamp that can efficiently peel the agricultural product and sustainably maintain quality.
