Energy efficiency of different technologies incorporating solar thermal energy for pasteurizing a viscous vegetable homogenate

• Integration of solar thermal energy in dielectric heating has not been studied. • Integration of solar thermal energy brought energy savings during pasteurization. • Warming-up of the buffer tank represents a considerable share of the energy demand. • Radiofrequency pasteurization did not suppose higher electric energy consumption. • Radiofrequency has the potential to reduce the heat demand from the buffer tank. Thermal processing of foods can greatly benefit from using solar thermal energy technology, due to the relatively low temperatures required. Additionally, radiofrequency heating for pasteurization can enhance both energy and thermal efficiency, as it can be powered by renewable electricity. This study analyzes the use of solar thermal energy in combination with conventional and radiofrequency technologies for the pasteurization of a viscous vegetable homogenate ( salmorejo ). Throughout 2022, productions of salmorejo were carried out in a pilot-scale processing plant located in Monells (Spain), and seasonal differences in energy consumption and solar fraction were analyzed. Results were compared to the performance of the same system running on steam provided by an electric steam boiler. Results show that the integration of solar thermal energy brought about important reductions in electric energy consumption. In summer, solar fractions around 90 % were obtained for both technologies. This represents a great opportunity for energy savings in seasonal products like salmorejo, which peaks in summer. When compared to conventional pasteurization, radiofrequency pasteurization showed potential to maintain high solar fractions even during periods of low irradiance, which could greatly reduce the carbon footprint of the whole process specially if the radiofrequency unit is powered by renewable electricity.