Dried and Tested: Inoculation Method Impacts Low-Moisture Food Persistent Bacterial Populations

Pathogen contamination and harborage in low-moisture food (LMF) processing environments have resulted in outbreaks and recalls, but researchers are limited in their abilities to investigate solutions. Methods used in most laboratory studies do not accurately reflect the route of contamination or har...

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Main Authors: Manita Adhikari, Kavita Patil, Jennifer C. Acuff
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:Journal of Food Protection
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Online Access:http://www.sciencedirect.com/science/article/pii/S0362028X25000092
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author Manita Adhikari
Kavita Patil
Jennifer C. Acuff
author_facet Manita Adhikari
Kavita Patil
Jennifer C. Acuff
author_sort Manita Adhikari
collection DOAJ
description Pathogen contamination and harborage in low-moisture food (LMF) processing environments have resulted in outbreaks and recalls, but researchers are limited in their abilities to investigate solutions. Methods used in most laboratory studies do not accurately reflect the route of contamination or harborage of pathogens in LMF environments, which complicates studying of sanitation methods. Inoculation methods were compared to establish low-moisture food persistent bacterial populations (LMF PBPs) that realistically reflect populations found in LMF environments. Culture-preparation techniques, food matrices, and ratios of nutrient to moisture were compared for their impacts on Salmonella Tennessee survival. A slurry method with 0.5 mL of culture to 0.4 g (NFDM) was easiest to form, inoculate, and process for further investigation, as was more consistent than other methods. With the chosen technique, LMF PBPs of Salmonella Tennessee (0.5: 0.4 [mL Salmonella Tennessee to g Powder]) with different powders (NFDM, peanut butter powder [PB], chicken powder [CP] and silicon dioxide [SiO2]) were made using lawn-based and broth-based cultures and distributed evenly on sterilized stainless-steel coupons to compare the impacts of preparation and food matrix on survival. Coupons stored at 22–25 °C and 50% relative humidity (RH) were assessed on 0, 1, 3, 5, and 7 days. Matrices and culture preparation showed significant differences (p ≤ 0.05). Salmonella LMF PBP derived from bacterial lawns demonstrated higher initial populations (10.1 ± 0.0 log CFU/cm2) compared to the broth cultures (8.2 ± 0.2 log CFU/cm2). Salmonella LMF PBP reductions were lower for the lawn-prepared cultures (0.3–2.7 log CFU/cm2) compared to broth-based cultures (1.0–5.1 log CFU/cm2) for all food matrices. Salmonella in LMF PBP with SiO2 (2.7–5.1 log CFU/cm2) reduced significantly more than in other food matrices (0.7–2.2 log CFU/cm2) and Sal without a matrix (0.3–1.5 log CFU/cm2) for both culturing methods.
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publishDate 2025-02-01
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spelling doaj-art-5bdea0f52afd46cf9f3c995d1ab24be92025-02-06T05:11:02ZengElsevierJournal of Food Protection0362-028X2025-02-01883100457Dried and Tested: Inoculation Method Impacts Low-Moisture Food Persistent Bacterial PopulationsManita Adhikari0Kavita Patil1Jennifer C. Acuff2Department of Food Science, University of Arkansas System Division of Agriculture Fayetteville Arkansas USADepartment of Food Science, University of Arkansas System Division of Agriculture Fayetteville Arkansas USACorresponding author.; Department of Food Science, University of Arkansas System Division of Agriculture Fayetteville Arkansas USAPathogen contamination and harborage in low-moisture food (LMF) processing environments have resulted in outbreaks and recalls, but researchers are limited in their abilities to investigate solutions. Methods used in most laboratory studies do not accurately reflect the route of contamination or harborage of pathogens in LMF environments, which complicates studying of sanitation methods. Inoculation methods were compared to establish low-moisture food persistent bacterial populations (LMF PBPs) that realistically reflect populations found in LMF environments. Culture-preparation techniques, food matrices, and ratios of nutrient to moisture were compared for their impacts on Salmonella Tennessee survival. A slurry method with 0.5 mL of culture to 0.4 g (NFDM) was easiest to form, inoculate, and process for further investigation, as was more consistent than other methods. With the chosen technique, LMF PBPs of Salmonella Tennessee (0.5: 0.4 [mL Salmonella Tennessee to g Powder]) with different powders (NFDM, peanut butter powder [PB], chicken powder [CP] and silicon dioxide [SiO2]) were made using lawn-based and broth-based cultures and distributed evenly on sterilized stainless-steel coupons to compare the impacts of preparation and food matrix on survival. Coupons stored at 22–25 °C and 50% relative humidity (RH) were assessed on 0, 1, 3, 5, and 7 days. Matrices and culture preparation showed significant differences (p ≤ 0.05). Salmonella LMF PBP derived from bacterial lawns demonstrated higher initial populations (10.1 ± 0.0 log CFU/cm2) compared to the broth cultures (8.2 ± 0.2 log CFU/cm2). Salmonella LMF PBP reductions were lower for the lawn-prepared cultures (0.3–2.7 log CFU/cm2) compared to broth-based cultures (1.0–5.1 log CFU/cm2) for all food matrices. Salmonella in LMF PBP with SiO2 (2.7–5.1 log CFU/cm2) reduced significantly more than in other food matrices (0.7–2.2 log CFU/cm2) and Sal without a matrix (0.3–1.5 log CFU/cm2) for both culturing methods.http://www.sciencedirect.com/science/article/pii/S0362028X25000092HarborageHygieneLow-water activitySalmonella
spellingShingle Manita Adhikari
Kavita Patil
Jennifer C. Acuff
Dried and Tested: Inoculation Method Impacts Low-Moisture Food Persistent Bacterial Populations
Journal of Food Protection
Harborage
Hygiene
Low-water activity
Salmonella
title Dried and Tested: Inoculation Method Impacts Low-Moisture Food Persistent Bacterial Populations
title_full Dried and Tested: Inoculation Method Impacts Low-Moisture Food Persistent Bacterial Populations
title_fullStr Dried and Tested: Inoculation Method Impacts Low-Moisture Food Persistent Bacterial Populations
title_full_unstemmed Dried and Tested: Inoculation Method Impacts Low-Moisture Food Persistent Bacterial Populations
title_short Dried and Tested: Inoculation Method Impacts Low-Moisture Food Persistent Bacterial Populations
title_sort dried and tested inoculation method impacts low moisture food persistent bacterial populations
topic Harborage
Hygiene
Low-water activity
Salmonella
url http://www.sciencedirect.com/science/article/pii/S0362028X25000092
work_keys_str_mv AT manitaadhikari driedandtestedinoculationmethodimpactslowmoisturefoodpersistentbacterialpopulations
AT kavitapatil driedandtestedinoculationmethodimpactslowmoisturefoodpersistentbacterialpopulations
AT jennifercacuff driedandtestedinoculationmethodimpactslowmoisturefoodpersistentbacterialpopulations