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ARS Home » Southeast Area » Raleigh, North Carolina » Food Science Research » Research » Publications at this Location » Publication #56597
Title: MICROBIOLOGICAL CONTROL OF CUCUMBER HYDROCOOLING WATER WITH CHLORINE DIOXIDE

Author
item REINA L R - NCSU
item FLEMING H P - 6645-10-00
item HUMPHRIES E G - NCSU

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/1994
Publication Date: N/A
Citation: N/A

Interpretive Summary: There is a trend toward consumer preference for less acidic, milder-flavored, pickled cucumbers. Some of these products receive no heat treatment and no acidification. Proper sanitation and refrigeration are essential to prevent growth by spoilage, and possibly pathogenic, microorganisms in such products. We have found that addition of 1.3 parts per million of chlorine dioxide to the water used to cool cucumbers prior to their packaging is sufficient to kill nearly all of the microorganisms in the water. The cooling water can safely be used for up to 1 day with little concern for buildup of spoilage or pathogenic microorganisms. Although chlorine can also be used for this purpose, much higher concentrations (e.g., 7-fold) are required. Chlorine forms harmful chemicals when they react with organic matter. Chlorine dioxide does not. Also, chlorine dioxide is less corrosive than chlorine and, thus, less destructive to equipment. Use of chlorine dioxide could benefit both the processor and consumer by helping to insure safer, nonacidified pickle products.

Technical Abstract: The time required to cool size 2B (3.43-3.75 cm diameter) pickling cucumbers by a commercial spray-type hydrocooler to less than 9 deg C was about 18 min at typical initial fruit temperatures of 25-29 deg C. During this period, the fruit was exposed to the recycled water, which reached relatively high populations of bacteria during a typical day's operation. These numbers exceeded those present on the unwashed fruit, depending upon the volume of fruit previously cooled. Residual chlorine dioxide at 1.3 ppm was found to optimally control (2-6 log cycles reduction) the numbers of bacteria. At 0.95 ppm chlorine dioxide, the numbers of bacteria in the water were relatively static, while at 2.8 and 5.1 ppm the odor of chlorine dioxide became excessive. The bacterial populations in/on the cucumbers were not greatly influenced by chlorine dioxide, even at 5.1 ppm. Apparently, microorganisms of the fruit were protected from the chlorine dioxide. Thus, the use of chlorine dioxide in hydrocooling water of cucumbers seems to be an effective means of controlling microbial buildup in the water, but has little effect upon microorganisms of the fruit.