title: Prevalence of Salmonella in Cashews, Hazelnuts, Macadamia Nuts, Pecans, Pine Nuts, and Walnuts in the United States.
abstract: Nuts have been identified as a vector for salmonellosis. The objective of this project was to estimate the prevalence and contamination level of Salmonella in raw tree nuts (cashews, pecans, hazelnuts, macadamia nuts, pine nuts, and walnuts) at retail markets in the United States. A total of 3,656 samples of six types of tree nuts were collected from different types of retail stores and markets nationwide between October 2014 and October 2015. These samples were analyzed using a modified version of the Salmonella culture method from the U.S. Food and Drug Administration's Bacteriological Analytical Manual. Of the 3,656 samples collected and tested, 32 were culturally confirmed as containing Salmonella. These isolates represented 25 serotypes. Salmonella was not detected in pecans and in-shell hazelnuts. Salmonella prevalence estimates (and 95% confidence intervals) in cashews, shelled hazelnuts, pine nuts, walnuts, and macadamia nuts were 0.55% [0.15, 1.40], 0.35% [0.04, 1.20], 0.48% [0.10, 1.40], 1.20% [0.53, 2.40], and 4.20% [2.40, 6.90], respectively. The rates of Salmonella isolation from major or big chain supermarkets, small chain supermarkets, discount, variety, or drug stores, and online were 0.64% [0.38, 1.00], 1.60% [0.80, 2.90], 0.00% [0.00, 2.40], and 13.64% [2.90, 35.00], respectively (Cochran-Mantel-Haenszel test: P = 0.02). The rates of Salmonella isolation for conventional and organic nuts were not significantly different. Of the samples containing Salmonella, 60.7% had levels less than 0.003 most probable number (MPN)/g. The highest contamination level observed was 0.092 MPN/g. The prevalence and levels of Salmonella in these tree nut samples were comparable to those previously reported for similar foods.
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Guodong
authors.initials: G
authors.lastname: Zhang
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Lijun
authors.initials: L
authors.lastname: Hu
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: David
authors.initials: D
authors.lastname: Melka
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Laasri
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Eric W
authors.initials: EW
authors.lastname: Brown
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Errol
authors.initials: E
authors.lastname: Strain
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Marc
authors.initials: M
authors.lastname: Allard
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Vincent K
authors.initials: VK
authors.lastname: Bunning
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Musser
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Rhoma
authors.initials: R
authors.lastname: Johnson
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Sofia
authors.initials: S
authors.lastname: Santillana Farakos
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Virginia N
authors.initials: VN
authors.lastname: Scott
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Régis
authors.initials: R
authors.lastname: Pouillot
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Jane M Van
authors.initials: JM
authors.lastname: Doren
authors.affiliation: U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, 5001 Campus Drive, College Park, Maryland 20740, USA.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Hammack
mesh_terms: D031021:Anacardium; D031325:Carya; D031211:Corylus; D005506:Food Contamination; D031324:Juglans; D039106:Macadamia; D009754:Nuts / Q000382:microbiology*; D015995:Prevalence; D012475:Salmonella / Q000302:isolation & purification*; D014481:United States
keywords: Low moisture; Low water activity; Nutmeat; Serotype; Tree nuts