Peeled tomatoes with infrared and ultrasound: saving energy and water

The aim is to reduce consumption in the tomato industry through the use of new technologies that are more efficient and able to cut the cost of thermal energy. This is the aim of the project developed by ENEA and the University of Salerno to optimise and make the industrial peeling of tomatoes more efficient.

The research (the results were published in the scientific journal Sustainabily) was carried out at a company in the province of Salerno that processes around 60,000 tonnes of tomatoes per year, and concerns a comparative assessment of the energy, economic and environmental impacts between traditional peeling methods and three innovative technologies using infrared, ultrasound and ohmic heating (the thermal process in which heat is generated inside the food through the passage of an electric current).

In the tomato processing industry, the most common peeling techniques are still steam and lye peeling. Although steam peeling is considered the more environmentally friendly alternative to chemical peeling, as pointed out by ENEA, 'it can produce softer fruit, with less consistency and greater product loss (15% vs. 13.6%). Moreover, both methods involve high energy and water consumption and generate large volumes of wastewater which, in the case of chemical peeling, is also polluted'.

"In order to respond to these critical issues, research is turning towards innovative and sustainable peeling techniques capable of improving efficiency, yield and product quality and minimising waste and environmental impact,' stresses Giovanni Landi, researcher at ENEA's Integrated Solutions Laboratory for Energy Efficiency and co-author of the study together with his colleague Miriam Benedetti and Gianpiero Pataro and Elham Eslami of the Department of Industrial Engineering at the University of Salerno. The solutions we propose in this study represent valid alternatives or complements to traditional techniques, paving the way for a more efficient and sustainable transformation of the agrifood industry.

The study shows that the new methods improve the degree of "peelability" of tomatoes with an increase in production capacity (2.6-9.2%) and a reduction in waste (16%-52%) compared to traditional techniques. On the environmental front, peeling with infrared technology (also called "dry peeling"), "is the most environmentally friendly method because it reduces the use of electrical and thermal energy, thanks to the infrared radiation that rapidly heats the surface of the product, favouring the peel removal without the use of water or chemicals". This treatment avoids the production of waste water and is faster, less expensive and with a reduced waste of tomatoes (9.8%).