Water temperature for hydrocooling field cucumbers in relation to chilling injury during storage

The objective of this study was to test the hypothesis that water temperatures less than the lowest recommended storage temperature (10 degrees C) for cucumbers could be used for hydrocooling without inducing chilling injury or negatively affecting storage life. Field cucumbers were hydrocooled with water at 1.5, 3.5, 6, 8 or 10.5 degrees C until the internal cucumber temperature reached 12 degrees C, or hydrocooled with water at 1.5 degrees C until the internal cucumber temperature reached 1.7, 8 or 12 degrees C. Cucumber temperature at harvest was approximate to 20 degrees C and the storage temperature was 12 degrees C. Little or no visual symptoms of chilling injury were observed after 10-12 days of storage. However, chlorophyll fluorescence measurements indicated some chilling stress at the membrane level in cucumbers hydrocooled with water at temperatures below 6 degrees C and in cucumbers hydrocooled with water at 1.5 degrees C until the internal product temperature was 1.7 degrees C, as indicated by lower F-v/F-m values. Approximately one third of the cucumbers from all hydrocooling treatments developed rot. There were no significant differences in % marketable cucumbers or in % mass loss after 10 or 12 days of storage. These results suggest that cucumbers could be hydrocooled using water at temperatures below the recommended storage temperature of 10 degrees C. However, it is not recommended to use water below 6 degrees C or to cool the cucumbers below this temperature, due to increased risk of chilling injury as indicated by the chlorophyll fluorescence measurements. (C) 2000 Elsevier Science B.V. All rights reserved.