From Waste to Value: Producing a Non-Astringent Persimmon Paste from Discarded ‘Rojo Brillante’ Fruit

‘Rojo Brillante’ persimmon has positioned Spain as the second largest producer worldwide. Its rapid expansion has increased seasonal overproduction and postharvest losses, particularly of astringent fruit unsuitable for fresh markets; however, the high soluble tannin content of this cultivar limits processing opportunities. In this study, a persimmon paste was developed from astringent discarded fruit. The combined effects of thermal treatment (70 and 100 °C) and sugar concentration (30 and 50%, w/w) on soluble tannin content and physicochemical properties were evaluated, together with their evolution during refrigerated storage. A ranking test was conducted to assess the astringency and other sensory attributes among formulations. Processed pastes contained a maximum of 1.01 mg GAE/g, compared with 7.3 mg GAE/g in fresh fruit, showing a decrease in the values measured by the Folin–Ciocalteu assay during processing. Importantly, these values did not increase significantly during refrigerated storage. Formulations with 50% sugar exhibited the lowest soluble tannin contents, with no significant differences attributable to thermal treatment. In contrast, samples with 30% sugar developed firmer gel structures, showing higher mechanical resistance. Pastes processed at 100 °C presented improved color stability during storage, likely associated with inactivation of enzymatic browning. Positive purchase intention was 70%, while the 100 °C/50% formulation was the most frequently selected for purchase (60%). These findings demonstrate the potential of persimmon paste as a sustainable valorization pathway for astringent ‘Rojo Brillante’ discarded fruit.