"Nuts! How a foodborne outbreak serendipitously shaped a career," Linda J. Harris, Ph.D. CFS, professor of cooperative extension, UC Davis.

In 2001, an outbreak of salmonellosis (Salmonella Enteritidis Phage Type (PT) 30) in Canada and the U.S. was linked, for the first time, to consumption of raw California almonds. The traceback investigation identified the outbreak strain in the almonds at retail and all along the supply chain back to the orchard. Subsequent studies attempted to uncover potential routes of contamination of Salmonella during production, harvest and postharvest handling, and an explanation for long-term environmental persistence. At the same time, laboratory studies focused on methods to inoculate and recover microorganisms from almonds, survival of pathogens on almonds during storage, and evaluation of the thermal resistance of candidate surrogates when compared with Salmonella, Escherichia coli, and Listeria monocytogenes. These data, along with information on the prevalence and levels of Salmonella in almonds, enabled the development of quantitative microbial risk assessments, the establishment of appropriate target reductions for lethality process controls, and validation of several key commercial practices such as blanching and oil roasting. More recent studies have explored the risks associated with soaking almonds and a range of plant-based dairy analogs made from them. The presentation will cover the journey of over 20 years of research surrounding a single crop and pathogen pair that spans from orchards and production agriculture practices to final preparation and consumption.