The effects of various treatments were evaluated for extending shelf-life of fresh-sliced pears. Sliced Anjou pears had browning-free color for 30 d by dipping with 1.0% ascorbic acid and 1.0% calcium lactate, but texture was soft with juice leakage. The combination treatment of 0.01% 4-hexylresorcinol (4-HR), 0.5% ascorbic acid and 1.0% calcium lactate can provide 15 to 30 d shelf-life for Anjou, Bartlett, and Bosc pears when the pears are sliced at an average ripeness of 43, 49, and 38 Newton respectively, with 2 min dipping, partial vacuum packaging, and 2 to 5 °C storage. 4-HR residual content ranged from 1 to 7 ppm after 14 d storage. Panelists could detect a flavor difference between 0.01% 4-HR treated pears and controls.Key Words: fresh-sliced pears, extending shelf-life, 4-HR residue, sensory propertiesshelf-life of fresh-cut pears with retention of visually appealing color and acceptable texture. Results & Discussion Effect of calcium lactate on color and textureCalcium has been reported to maintain the cell wall structure in fruits by interacting with pectic acid in the cell wall to form calcium pectate which firms molecular bonding between constituents of cell wall (Fennema 1985). Thus, fruits treated with calcium are generally firmer than controls (Poovaiah 1986). Ponting and others (1972) evaluated both calcium lactate and calcium chloride as firming agents for canned apples and noted that calcium lactate gave a somewhat better flavor than calcium chloride. Calcium lactate as a firming agent helped Bosc pear slices maintain firmness, with increasing benefit from increased concentration (Fig. 1). Bosc pear slices treated with 1.0% calcium lactate had a significantly firmer texture than the control. However, no significant firming effect was obtained for Bartlett slices with calcium dipping treatments (data not shown). Visual observations revealed that the surfaces of both Bartlett and Bosc pear slices dipped with 1.0% calcium lactate were smooth, while treatments not containing calcium lactate had varying degrees of stickiness and mushiness on the surfaces.With respect to color, calcium lactate did not inhibit browning. Color values of CIE L* (lightness) and hue angle (color itself) for calcium lactate-treated Bosc pear slices decreased similarly for all treatments, indicating that no significant browning inhibition occurred for all calcium lactate concentrations tested. Results were similar for calcium lactate treated Bartlett pear slices (data not shown). These findings are in an agreement with those of Ponting and others (1972) who reported that calcium treatment alone resulted in poor color on apple slices. Gorny and others (1998) reported that 1.0% calcium chloride with 2.0% ascorbic acid applied as a dip for 1 min was effective in reducing pear slice surface browning. Ponting et al. (1972) also found that the combination of treatments with 1.0% ascorbic acid and 0.1% calcium chloride effectively inhibited browning in apple slices. The combination of 1.0% ascorbic acid with 1.0% calcium lactate ...

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The biological control agents Pseudomonas fluorescens A506 and Pantoea vagans C9-1 were evaluated individually and in combination for the suppression of fire blight of pear or apple in 10 field trials inoculated with the pathogen Erwinia amylovora. The formulation of pathogen inoculum applied to blossoms influenced establishment of the pathogen and the efficacy of biological control. Pantoea vagans C9-1 suppressed fire blight in all five trials in which the pathogen was applied as lyophilized cells but in none of the trials in which the pathogen was applied as freshly harvested cells. In contrast, Pseudomonas fluorescens A506 reduced disease significantly in only one trial. A mixture of the two strains also suppressed fire blight, but the magnitude of disease suppression over all field trials (averaging 32%) was less than that attained by C9-1 alone (42%). The two biological control agents did not antagonize one another on blossom surfaces, and application of the mixture of A506 and C9-1 to blossoms resulted in a greater proportion of flowers having detectable populations of at least one bacterial antagonist than the application of individual strains. Therefore, the mixture of A506 and C9-1 provided less disease control than expected based upon the epiphytic population sizes of the antagonists on blossom surfaces. We speculate that the biocontrol mixture was less effective than anticipated due to incompatibility between the mechanisms by which A506 and C9-1 suppress disease.