Bactericidal effects of various kinds of AWASEZU (processed
vinegar, 2.5% acidity) on food-borne pathogenic bacteria including Escherichia coli O157:H7 and other bacteria were examined. the order of bactericidal activities was NIHAIZU (3.5% NaCl was added) > SANBA-IZU (3.5% NaCl and 10%
sucrose were added) > plain
vinegar (spirit
vinegar) > AMAZU (10%
sucrose was added). This indicates that their activities were enhanced by the addition of
sodium chloride and suppressed by the addition of
sugar. On the other hand, when soy sauce was used instead of
sodium chloride, the order of bactericidal activities was plain
vinegar > AMAZU > NIHAIZU > SANBAIZU. This is mainly because their activities were suppressed by the increase in the pH value. The effect of
sodium chloride (0.01-15%) and temperature (10-50 degrees C) on bactericidal activities against E. coli O157:H7 in spirit
vinegar (0.5-2.5% acidity) was further examined. When
vinegar was used in combination with
sodium chloride, predominant synergism on the bactericidal activity was observed. Their activities were markedly enhanced by the addition of
sodium chloride in proportion to the concentration. In addition to this, at higher temperatures spirit
vinegar killed bacteria much more rapidly. It should be noted that the bactericidal activity of spirit
vinegar was extremely enhanced by the combined use of the addition of
sodium chloride and the rise of temperature. For example, in 2.5% acidity
vinegar, the time required for 3 log decrease in viable cell numbers at 20 degrees C was shortened to 1/140-fold by the addition of 5%
sodium chloride, shortened to 1/51-fold by the rise of the reaction temperature at 40 degrees C, and shortened to 1/830-fold; 0.89 minutes by both the addition of 5%
sodium chloride and the rise of temperature at 40 degrees C. In order to propose the methods to prevent
food poisoning by
bacterial infection, bactericidal activities of
vinegar solution containing
sodium chloride on cooking tools and raw vegetables were examined.
Vinegar solution (1-2% acidity, 3-7% NaCl) produced more than 3 log decrease in viable cell numbers of E. coli O157:H7 on the surface of cutting board, and cabbage and cucumber at 20-50 degrees C. These results suggested that the treatment with
vinegar solution containing
sodium chloride may be one of the useful methods to prevent
food poisoning.