Effects of High-pressure Treatment on Mume Fruit (Prunus mume)

Physical and physiological changes in mume (Prunus mume Sieb. et Zucc.) subjected to a 10-minute hydrostatic high-pressure treatment at 5, 10, 50, 100, 150, and 200 MPa were investigated. Mume fruit exhibited substantial injury at pressures >5 MPa. All treatments induced color changes, which became more apparent at pressures >100 MPa. Fruit subjected to pressures ≥100 MPa deteriorated and were rendered commercially unacceptable. After transfer to atmospheric pressure all treated fruit exhibited lower CO2 evolution rates compared with control fruit. Only fruit subjected to 5 MPa exhibited an increase (27%) in titratable acidity. Ethylene production rate in mume fruit was very high, but consistently and dramatically decreased after treatment, regardless of the pressure applied. The decline in ethylene production was associated with a decrease in ACC oxidase activity. Chemical names used: 1-aminocyclopropane-1-carboxylic acid (ACC).