Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2000
Publication Date: 8/1/2000
Citation: Breidt, F., Hayes, J.S., Fleming, H.P. 2000. Reduction of microflora of whole pickling cucumbers by blanching. J. Food Sci. 65:1354-1358.
Interpretive Summary: There is increasing interest in developing methods to control the presence of disease-causing microorganisms on fresh fruits and vegetables. Current methods to remove bacteria from fruits and vegetables, such as washing or sanitizing agents, are not very effective. This is partly because bacteria can be protected by the plant surface features, or they can reside within the healthy plant tissue. We found that a 15-sec blanching procedure for whole cucumbers was more effective in killing bacteria than washing or sanitizing agents typically used for this purpose. This procedure did not significantly affect sensory properties of the fresh cucumbers. We also developed new methods to determine how heat affects the different kinds of bacteria typically found on fruits and vegetables. Not all bacteria have the same sensitivity to heat, and some disease causing bacteria are more resistant to heat than other microorganisms. Understanding the effects of heat on mixed populations of bacteria may have broad scientific applications for the food industry. Use of this or similar blanching procedures may result in safer products and expanded markets for the U.S. produce industry.
Technical Abstract: There is increasing interest in developing methods to control the presence of pathogenic and spoilage microorganisms on fresh fruits and vegetables. Blanching whole pickling cucumbers for 15 sec at 80 deg C reduced microbial cell counts by 3 log cycles from an initial population of typically 106 CFU/g. Vegetative microorganisms survived this blanching process, presumably because they were located beneath the surface of the cucumber. The sensitivity to heat for selected populations was measured by determining D values for pooled microorganisms (termed Dp values) isolated from fresh cucumbers. The Enterobacteriaceae population and the total aerobic microflora had similar Dp values to each other and to a selected lactic acid bacterium.