[Bactericidal effect of hydrated lime in aqueous solution]

Area of Science:

• Environmental Microbiology
• Food Safety
• Disinfection Science

Background:

• Bacterial contamination of produce poses a significant public health risk.
• Effective disinfection methods are crucial for ensuring food safety.
• Calcium hydroxide (Ca(OH)2) is a widely available and cost-effective compound.

Purpose of the Study:

• To evaluate the bactericidal efficacy of common lime and micronized calcium hydroxide (Ca(OH)2) solutions.
• To compare the effectiveness of Ca(OH)2 with other disinfectants against various foodborne pathogens.
• To assess the in situ efficacy of lime solution in reducing bacterial load on produce.

Main Methods:

• In vitro testing of bactericidal substances against multiple bacterial strains, including Vibrio cholerae 01, V. parahaemolyticus, Escherichia coli, Salmonella typhimurium, Shigella flexneri, Sh. sonnei, and Sa. enterititidis.
• Quantification of surviving bacteria using colony-forming units (CFU) after varying incubation times.
• In situ evaluation of lime solution's effectiveness on V. cholerae contamination on strawberries and radishes.

Main Results:

• Calcium hydroxide (Ca(OH)2) demonstrated the most potent bactericidal effect against Vibrio cholerae 01, achieving significant reduction within 3 minutes.
• Other tested enterobacteria exhibited resistance to Ca(OH)2 for up to 30 minutes.
• In situ tests indicated a reduction in V. cholerae on produce treated with lime solution.

Conclusions:

• Saturated solutions of common lime and calcium hydroxide (Ca(OH)2) exhibit significant bactericidal properties, especially against Vibrio cholerae 01.
• Ca(OH)2 offers a promising disinfection agent for food safety applications, though efficacy against other enterobacteria requires further investigation.
• Lime solutions show potential for reducing bacterial contamination on fresh produce.