VALORIZATION OF PAPAYA SEEDS STABILIZATION BY PULSED ELECTRIC FIELD

Papaya (Carica papaya) fruit is widely cultivated in tropical regions, with Brazil being the second largest producer. The large amounts of coproducts from the fruit processing, mostly seeds, contain valuable compounds such as bioactive, lipids and proteins. Due to their high perishability, drying is crucial for preserving functional and nutritional components by reducing the water activity and delaying deterioration. Because drying is a time and energy-consuming step, pulsed electric field (PEF) emerges as a sustainable technology to improve mass transfer operations through electroporation. Thus, this study investigated the kinetics and mechanisms of drying and rehydration of fresh and frozen papaya seeds, with and without PEF application. Clean and sanitized samples were subjected to PEF (2 kV/cm, 50 pulses), and dried at 50 °C in a convective oven for 24 h. For rehydration, 10 g of seeds were immersed in water at 30 °C until they reached equilibrium moisture content, by weighing at predefined intervals.The Page model, used for drying kinetics, demonstrated excellent fit to the experimental data (R²adj > 0.991; RMSE < 0.0281). In fresh seeds, PEF increased the drying rate k (0.00083±0.0002 min⁻¹) compared to untreated seeds (0.00009±0.00002 min⁻¹). In frozen seeds, the rates were higher than for fresh ones, ranging from 0.00934±0.00148 min⁻¹ without and 0.01221±0.00285 min⁻¹ with PEF, with no significant difference. It occurred due to the matrix disintegration caused by freezing, disguising the electroporation effect. The parameter n>1 in fresh seeds suggested a superdiffusion process compared to subdiffusion in frozen seeds (n<1). When modeling the rehydration process using the Peleg model, PEF-treated fresh seeds absorbed water 110% faster initially (0.1871 g water·g dry matter⁻¹·min⁻¹) than those untreated (0.0888 g water·g dry matter⁻¹·min⁻¹). In frozen seeds, the increase in the water absorption rate was smaller (47%), even though the values were higher in magnitude compared to fresh samples (0.4615 g water·g dry matter⁻¹·min⁻¹ for untreated and 0.6830 g water·g dry matter⁻¹·min⁻¹ for PEF-treated samples). Therefore, the PEF application was effective for drying and rehydration, making the seed valorization more efficient.