Effect of recipe composition and storage conditions on Salmonella survival in sauces made from contaminated tahini...

Tahini paste, a low-moisture food, has been implicated in 20 salmonellosis outbreaks since 1995, with over 1,600 reported cases of illness. When used to prepare high-moisture foods (e.g., tahini sauce, hummus), contaminated tahini paste can pose an increased risk to consumers due to potential bacterial growth. This study examined three naturally contaminated tahini samples to assess microbial load and evaluated the impact of preparation and storage practices on Salmonella replication in tahini sauces made from tahini paste. Naturally contaminated tahini paste harbored low concentrations of Salmonella (~0.4 most probable number [MPN]/100 g), with no correlation to background microbiota. Tahini sauces made with artificially contaminated tahini paste and various diluents (water, oil, and lemon juice) with and without garlic powder showed variable Salmonella recovery at 22°C and 4°C. Salmonella levels in water-based sauces (a_w = 0.9969) increased by 6 logs over 24 h at 22°C. In contrast, levels in oil-based sauces were stable at 2 log CFU/g (a_w = 0.1918). Sauces prepared with lemon juice had reduced levels of Salmonella recovery, with fewer cells recovered at higher concentrations of lemon juice (<1 log CFU/g with 50% lemon juice [vol/vol], pH 3.6). At 4°C, Salmonella levels in both water- and oil-based sauces remained stable for two weeks at 2 log CFU/g, whereas no Salmonella were recovered from lemon juice-based sauce (50% vol/vol) by one week of storage. Garlic powder (0.7%, wt/vol) did not affect Salmonella recovery. These findings support the use of lemon juice and refrigeration by end-users as effective interventions to help mitigate Salmonella risk in tahini sauces.IMPORTANCETahini paste, a seed butter made from sesame seeds, has been implicated in numerous salmonellosis illnesses and product recalls. The use of contaminated tahini paste as an ingredient in ready-to-eat sauces and dips such as hummus poses a risk to human health. In order to understand these risks and to provide guidance to consumers, this study examined the influence of recipe ingredients and storage conditions on the growth of Salmonella in sauces prepared with contaminated tahini. Ingredient choice, particularly the incorporation of an acidulant such as lemon juice, had a strong negative impact on Salmonella replication, while refrigerated storage of prepared sauces further reduced bacterial recovery. These findings offer practical strategies for consumers and food service professionals to reduce Salmonella risk and enhance the food safety of products made with tahini paste.