The preparation and distribution of fresh-cut produce is a rapidly developing industry that provides the consumer with convenient and nutritious food. However, fresh-cut fruits and vegetables may represent an increased food safety concern because of the absence or damage of peel and rind, which normally help reduce colonization of uncut produce with pathogenic bacteria. In this study, we found that Salmonella Enteritidis populations can (i) survive on fresh-cut melons and apples stored at 5 degrees C, (ii) increase up to 2 log units on fresh-cut fruits stored at 10 degrees C, and (iii) increase up to 5 log units at 20 degrees C during a storage period of 168 h. In addition, we examined the effect of lytic, Salmonella-specific phages on reducing Salmonella numbers in experimentally contaminated fresh-cut melons and apples stored at various temperatures. We found that the phage mixture reduced Salmonella populations by approximately 3.5 logs on honeydew melon slices stored at 5 and 10 degrees C and by approximately 2.5 logs on slices stored at 20 degrees C, which is greater than the maximal amount achieved using chemical sanitizers. However, the phages did not significantly reduce Salmonella populations on the apple slices at any of the three temperatures. The titer of the phage preparation remained relatively stable on melon slices, whereas on apple slices the titer decreased to nondetectable levels in 48 h at all temperatures tested. Inactivation of phages, possibly by the acidic pH of apple slices (pH 4.2 versus pH 5.8 for melon slices), may have contributed to their inability to reduce Salmonella contamination in the apple slices. Higher phage concentrations and/or the use of low-pH-tolerant phage mutants may be required to increase the efficacy of the phage treatment in reducing Salmonella contamination of fresh-cut produce with a low pH.

A bstract. Kinetin in concentrations of 10-e to 10-4 M, stimuated ethylene production in 3 and 4-day old etiolated seedlings of Alaska pea (Pisucm sativum L. var. Ala-ka). Seedlings of other species responded similarly. The response to kinetin depended on the age of the seedlings.Kinetin alone did not influence ethylene production in 6-day old stem sections, but it greatly increased the enhancing effect of IAA.Gibberellic acid had no effect on ethylene production by pea seedlings during the first 6 days of growth. Ethylene and gibberellic acid are antagonistic in their effects on growth of the seedlings; ethylene interfered severely with the action of gibberellic acid but did not completely suppress it.The inhibitors cycloheximide, cupferron, and N-ethylmaleimid?, caused considerable inhibition of kinetin-induced ethylene production but were much less effective in the endogenous ethylene-forming system. Materials and MethodsPlant Materials. Alaska pea seeds (Pisunm sativum L. var. Alaska) were soaked in a beaker in the dark, in running tap water bubbled with air. The soaking was carried out for 48 hr at 250, a treatment which was found to produce uniform, disease-free seedlings. Thev were then planted on wet "Kimpack" (an absorbent of one-eighth inch thick packing paper) and grown at 25°and about 95 % relative humidity. The seedlings were grown in darkness up to 6 days with occazional dim "safe green" light. Seedlings were transferred to 50 ml flasks in the dark, at different ages, for the experiments. Age of seedlings was measured from the time the soaking started. In some experiments 2-cm apical sections were cut from 6-day old seedlings and used as experimental material. In experiments in which 1 day old seedlings were tested, the dry seeds were placed directly into 50 ml flasks, containing 2 ml of water or the test solution. Dwarf pea seeds (Pisumn sativuins L. var. Progress No. 9) were germinated in the same way.In other experiments seeds of radish (Raphantus sativus L. var. Early Scarlet Globe), bean (Phaseolius vulgaris L. var. Tendergreen Improved), cucumber (Citrumis sativus L. var. Boston Pickling), 2029www.plantphysiol.org on May 10, 2018 -Published by Downloaded from

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