Effects of Freeze–Thaw Pretreatment and Cold-Press Dewatering on the Downstream Energy Demand of Hot-Air Drying of Whole Tomato By-Product Powder Production

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.