A pilot scale electrical infrared dry-peeling system for tomatoes: Design and performance evaluation

• Infrared heating was successfully demonstrated for tomato peeling in a pilot scale.
• Smaller tomatoes exhibited a higher percentage of fully peeled product.
• The highest peelability was 94% for medium size tomatoes after 120 s of IR heating.
• IR peeling had products with better firmness and integrity than steam peeling.
• Tomato skins from IR peeling were chemical free and good as value-added products.

A pilot scale infrared dry-peeling system for tomatoes was designed and constructed. The system consisted of three major sections including the IR heating, vacuum, and pinch roller sections. The peeling performance of the system was examined under different operational conditions using tomatoes with different cultivars and sizes. Three lines of tomatoes were heated and processed at the same time at a residence time of 125 s and achieved a percentage of fully peeled tomatoes of 85%, a peeling yield of 82%, and an average thickness of peeled tomato skin of 0.75 mm. When tomatoes were loaded as a single line, the required heating time was reduced to a range from 80 to 100 s, depending of tomato size, for achieving the same level of peeling percentage and yield. The presence of the vacuum section could achieve cracks in 100% of the tomatoes after IR heating. The peeled products from IR heating had high firmness and appealing surface integrity, which indicated desirable quality characteristics. Because the dry-peeling is a chemical- and water-free process, residuals of tomato skins after IR peeling could be easily utilised as value-added by-products.