ASTRINGENCY REMOVAL OF 'ROJO BRILLANTE' PERSIMMON BY COMBINING CO2 AND ETHANOL APPLICATION

Abstract

‘Rojo Brillante’ belongs to the group of persimmon cultivars which are astringent at harvest. Therefore, fruit are routinely subjected to postharvest deastringency treatment based on fruit exposure to high concentration of CO2. The temperature of the process and the maturity stage of the fruit are key factors for the effectiveness of deastringency treatment. In the Mediterranean area, the application treatment of 95-100% CO2 for 24 h at 20°C has been established as the optimal conditions to ensure astringency removal of ‘Rojo Brillante’ persimmon throughout the season. However, this treatment is usually applied at room temperature in industrial scale which at the end of the season is as low as 12°C. It has been reported that the deastringency treatment at low temperature may be incomplete when it is applied to fruit at an advanced maturity stage. The aim of this work was to evaluate the effectiveness of an alternative deastringency treatment combining high-CO2 concentrations and ethanol application to persimmon fruit at an advanced maturity stage. Fruit were subjected to the standard treatment (98% CO2) and to the alternative treatment (98% CO2 + 0.5% ethanol) at two different temperatures (20 and 12°C) and three durations: 12, 18 or 24 h. Soluble tannin content, ethanol and acetaldehyde concentration and sensory evaluations were determined at harvest, immediately after treatments (d0) and after 1 (d1) and 2 (d2) days. Our results showed that the CO2-ethanol treatment for 24 h was the only treatment that allowed total astringency removal at 12°C. When treatments were performed at 20°C, the CO2-ethanol treatment enhanced the deastringency process leading to a faster astringency removal when compared with the application of high-CO2 only.