Adriana Lordi, Amalia Conte, Matteo Alessandro Del Nobile
The valorization of vegetable processing by-products is increasingly recognized as a key strategy for improving sustainability and supporting circular economy principles. This study evaluated the effects of freeze-thaw pretreatment and cold-press dewatering prior to dehydration on the energy demand of whole tomato by-product processing. Tomato by-products were divided into different batches and subjected to freezing and thawing and/or to cold-press dewatering before dehydration at 60 °C. Only the cold-pressed samples, with or without freeze-thaw pretreatment, were also evaluated at 50 and 70 °C. A mathematical model previously reported in the literature was applied to estimate water removal during dehydration and quantify the energy demand associated with cold-press extraction, drying, and milling operations, enabling comparison among the investigated processing strategies. The results showed that the inclusion of a cold-press dewatering step decreased the energy demand, as the energy required for dewatering was lower than that needed to evaporate the same amount of water during drying. Freeze-thaw pretreatment further reduced the amount of free water to be removed in the subsequent dehydration stage. Although drying temperature had a limited effect on total energy demand, a slight decrease was calculated when increasing the temperature from 50 to 70 °C. These findings demonstrate the potential of combining freeze-thaw and cold-press dewatering as pretreatments for reducing energy demand throughout tomato by-product processing.