Survival of Salmonella on basil plants and in pesto

Yesterday at the school tuck shop, we made 280 sushi rolls (I cooked the chicken but felt naked without my misplaced thermometer, Chapman is mailing me more) 70 sausage rolls and 10 orders of pesto pasta.

basil.salmonellaThe pesto is part of the garden-to-kitchen initiative. I have my food safety concerns about such things but am trying to not alienate all the parent volunteers at once.

They got messages about handwashing and rice storage this week.

And I was also in charge of prepping the pesto pasta, so I made sure it was heated.

But, as reported by Eckner et. al, leafy greens, including fresh herbs, have repeatedly been involved in outbreaks of foodborne disease. Although much effort has been put into studying leafy greens and products such as head lettuce and baby leaves, less is known about fresh leafy herbs, such as basil.

The goal of this study was to investigate the survival of Salmonella on basil plants and in pesto. A mix of three Salmonella strains (Reading, Newport, and Typhimurium) was inoculated onto basil leaves and pesto and survived during the experimental period.

Whereas the mix of Salmonella survived in pesto stored at 4°C for 4 days, Salmonella was recovered from inoculated leaves for up to 18 days at 20 to 22°C. Although the steady decline of Salmonella on leaves and in pesto suggests a lack of growth, it appears that pesto is a hostile environment for Salmonella because the rate of decline in pesto was faster (0.29 log CFU/g/day) than on leaves (0.11 log CFU/g/day).

pesto.basil.cyclosporaThese findings suggest that the dilution of contaminated ingredients and the bactericidal effect of the pesto environment helped to further reduce the level of enteric organisms during storage, which may have applications for food safety.

Survival of Salmonella on basil plants and in pesto


Journal of Food Protection®, Number 2, February 2015, pp. 240-476, pp. 402-406(5)

Eckner, Karl F.; Høgåsen, Helga R.; Begum, Mumtaz; økland, Marianne; Cudjoe, Kofitsyo S., Johannessen, Gro S.

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About Douglas Powell

A former professor of food safety and the publisher of, Powell is passionate about food, has five daughters, and is an OK goaltender in pickup hockey. Download Doug’s CV here. Dr. Douglas Powell editor, retired professor, food safety 3/289 Annerley Rd Annerley, Queensland 4103 61478222221 I am based in Brisbane, Australia, 15 hours ahead of Eastern Standard Time