Combination of Hot Water and Ethanol to Control Postharvest Decay of Peaches and Nectarines.

Spores of Monilinia fructicola or Rhizopus stolonifer were immersed in water or 10% ethanol (EtOH) for 1, 2, 4, or 8 min at temperatures of 46 or 50°C to determine exposure times that would produce 95% lethality (LT95). EtOH reduced the LT95 by about 90%. Peaches and nectarines infected with M. fructicola were immersed in hot water alone or with EtOH to control decay. EtOH significantly increased the control of brown rot compared to water alone. Immersion of fruit in water at 46 or 50°C for 2.5 min reduced the incidence of decayed fruit from 82.8% to 59.3 and 38.8%, respectively. Immersion of fruit in 10% ethanol at 46 or 50°C for 2.5 min further reduced decay to 33.8 and 24.5%, respectively. Decay after triforine (1,000 µg ml-1) treatment was 32.8%. Two treatments, 10% EtOH at 50°C for 2.5 min and 20% EtOH at 46°C for 1.25 min, were selected for extensive evaluation. The flesh of EtOH-treated fruit was significantly firmer, approximately 4.4 N force, than that of control fruit among seven of nine cultivars evaluated. No other factor evaluated was significantly influenced by heated EtOH treatments. The EtOH content of fruit treated with 10 or 20% EtOH was approximately 520 and 100 µg g-1 1 day and 14 days after treatment, respectively.

Reduction of Microbial Populations on Prunes by Vapor-Phase Hydrogen Peroxide †.

Vapor-phase hydrogen peroxide (VPHP) was used to disinfect prunes. Concentrated hydrogen peroxide solution (35%, wt/wt) was volatilized into a stream of dried air to approximately 3.1 mg/l (wt/vol) of hydrogen peroxide. Dried prunes obtained from commercial dehydrators were treated with VPHP and compared to untreated prunes. Microbial populations were determined for treatment comparisons. Untreated dried prune microbial populations were 155, 107, and 111 CFU/g of prunes on aerobic plate count agar, potato dextrose agar, and dichloran rose bengal agar, respectively. In contrast, VPHP-treated prune microbial populations were reduced to near zero on all media after 10 minutes of VPHP exposure. The color of prunes exposed for 20 min or longer, however, showed oxidation damage. No hydrogen peroxide residues were detected 90 days after treatment.