Hot Water Treatment of Postharvest Mei Fruit to Delay Ripening

Abstract

Mei (Prunus mume `Daqinghe') fruit were immersed in 20 °C (control), 47 °C (HWT47), 50 °C (HWT50), or 53°C (HWT53) water for 3 min after harvest, then stored at 20 °C. Firmness, peel color, chlorophyll, chlorophyllase activity, soluble solids content (SSC), titratable acidity (TA), respiration, ethylene production, and pectinmethylesterase (PME) and polygalacturonase (PG) activity were monitored to determine the effects of hot water treatment in delaying fruit ripening. Control fruit displayed a typical climacteric pattern of respiration and ethylene production. Peak CO2 production and ethylene production were observed 6 days after harvest. Fruit softening was accompanied by decreases in hue angle, chlorophyll content, SSC, and TA and increases in chlorophyllase and PME and PG activity. Hot water treatment delayed the onset of the climacteric peaks of CO2 and ethylene production. The delays were associated with delays in fruit softening, consistent with lags in the rise of PME and PG activity; delays in yellowing and chlorophyll breakdown, consistent with lags in the rise of chlorophyllase activity; and delays in loss of SSC and TA. The shelf life of fruit increased by 6 days, or 60%, with HWT47, and by 8 days, or 80%, with HWT50 or HWT53.