Synergistic Effects of Freeze–Thaw and Osmoconvective Treatments on the Physicochemical Quality, Bioaccessibility, and Consumer Acceptability of Dehydrated Spondias tuberosa Arr. Câm. (Umbu) Slices

This study evaluated the combined effects of freeze–thaw and osmotic dehydration (OD) pretreatments on the physicochemical, functional, and sensory qualities of umbu slices. Fresh and thawed umbu slices (thawed at 26 ± 3 °C for approximately 1 h after being frozen for at least 8 days) were submitted to OD or directly processed. All slices were then dehydrated by convective drying. Treatments varied by drying temperature (50 and 60 °C) and sucrose concentration (40, 50, and 60 °Brix), resulting in sixteen conditions, including four without OD. Freeze–thaw pretreatment significantly enhanced sucrose uptake (24.11–49.89%) during OD, affecting the slices’ physicochemical and functional attributes. It also improved appearance, color, and texture, leading to a higher sensory acceptance. Among OD treatments, experiment 2 (non-pre-frozen, 50 °Brix at 50 °C) exhibited the highest total phenolics (71.95 mg/100 g) and lowest phenolic losses during in vitro digestion. Experiment 1 showed the highest flavonoids (3.94 mg/100 g), anthocyanins (0.62 mg/100 g), and chlorophylls (0.78 mg/100 g). Phenolic bioaccessibility ranged from 10.88% (experiment 14) to 52,90% (experiment 16). Experiment 13 (pre-frozen, 40 °Brix at 60 °C) had the highest antioxidant activity among freeze–thawed samples and was notable for its greater perceived sweetness. Therefore, frozen storage combined with osmoconvective dehydration is a promising strategy for conserving and adding value to umbu fruit.