The effects of varied food acid ratios and egg components on Salmonella Typhimurium culturability from raw egg-based sauces

Abstract

Raw egg-based sauces, such as mayonnaise and aioli, are frequently identified as sources of Salmonella during outbreaks of human cases of foodborne gastrointestinal disease. In this study, we surveyed aioli and mayonnaise recipes from different popular food websites to identify potential risk factors that may lead to the survival of Salmonella Typhimurium. In laboratory experiments, different ratios of food acids were used to determine if lemon juice, vinegar, or a combination of both restricted Salmonella Typhimurium culturability. We found that as long as the pH was below 4.2, bacterial culturability was limited. The use of whole egg alone or in combination with egg yolk was also investigated. Sauce preparations containing whole egg exhibited higher pH and supported Salmonella Typhimurium culturability longer than those containing yolk only. Ten restaurant prepared sauces were also obtained to further characterize the effect of preparation variability. Sauce preparations with a pH ≤ 3.8 did not support bacterial culturability after 4 h incubation at any temperature. The higher the pH the longer Salmonella Typhimurium remained culturable. Based on this study, it is recommended that raw egg-based foods are acidified, then stored at room temperature for at least 4 h prior to consumption.