Fay ML, Salazar JK, Zhang X, Zhou X, Stewart D. Long-Term Survival of Listeria monocytogenes in Nut, Seed, and Legume Butters.
J Food Prot 2023;
86:100094. [PMID:
37086973 DOI:
10.1016/j.jfp.2023.100094]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 04/12/2023] [Accepted: 04/17/2023] [Indexed: 04/24/2023]
Abstract
Nut, seed, and legume butters have become increasingly popular with consumers. Listeria monocytogenes contamination of a variety of butters has resulted in several recalls, although no known outbreaks have been identified. L. monocytogenes has been shown to survive on a variety of seeds for up to 6 months, legumes and nuts for over 12 months, and in peanut butter and peanut-chocolate spreads for 21 to 60 weeks depending on formulation; however, long-term survival in other butters has not yet been characterized. In this study, the survival of L. monocytogenes in various nut, seed, legume, and chocolate-containing butters (n=10) based on inoculation level, storage temperature, and the pH, aw, and nutrient contents of the butters, was examined. First, butters were inoculated with L. monocytogenes at 4 log CFU/g and stored at either 5 or 25°C with enumeration and/or enrichment at intervals over 12 months. L. monocytogenes survived in all butters examined with no significant change in population after storage at 5°C, whereas the population was reduced to <1.70 log CFU/g in as little as 3 months at 25°C; the only exception was for sunflower butter, where L. monocytogenes decreased approximately 1 log CFU/g. Subsequently, all butters were inoculated at 1 log CFU/g and stored at 25°C for 6 months with enrichment during storage. L. monocytogenes was detected in all butters, except pecan butter, after 6-month storage. Butters containing chocolate did not inhibit L. monocytogenes survival, regardless of the inoculation level. Results indicate there may be association between high fat and carbohydrate level and survivability of L. monocytogenes in various types of butters. This work highlights the need to mitigate the potential for cross-contamination of L. monocytogenes into nut, seed, and legume butters due to the potential for long-term survival. Running title: Listeria survival in butters.
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