Evaluation of selected electric infrared emitters for tomato peeling

Abstract

The performance of selected electric infrared (IR) emitters with different emissive powers was investigated examining tomato heating rate, peeling performance and final product quality. Four types of electric emitters, including ceramic full trough element (CFTE), pillared quartz element (PQE), quartz tungsten medium (QTM), and quartz halogen medium (QHM), were selected based on their ability to produce high emissive power with appropriate range of wavelengths. The electric emitters were tested to heat the tomato cultivar Hz 6410 for peeling, using a prototype IR heating system under similar conditions. The electric emitters attained high surface temperatures (602–825 °C) and emissive powers (27–37 kW m−2). High emissive powers of these electric emitters increased the heating rate of tomato, resulting in a high peeling performance and product quality in significant short times (≤25 s). Among all the studied emitters, PQE with the highest surface temperature (825 °C) and emissive power (37 kW m−2) took 10 s to heat the tomatoes to the degree that they had excellent peeling easiness while meeting the USDA peelability standard. However, tomatoes experienced undesirable skin burns when the heating time was too long at high emissive powers. The study provided valuable information about the suitability of different electric emitter with the IR wavelength spectrum (2.6–3.3 μm) for tomato peeling application.