Abstract
This study investigated the effect of initial contamination levels, biofilm maturity and presence of salt and fatty food soils on desiccation survival of Listeria monocytogenes on stainless steel (SS) coupons. L. monocytogenes cultures grown (at 15 degrees C for 48 h) in Tryptic Soy Broth with 1% glucose (TSB-glu) containing either 0.5 or 5% (w/v) NaCl were re-suspended in TSB-glu containing either 0.5 or 5% NaCl and used to contaminate SS coupons at levels of 3.5, 5.5, and 7.5 log CFU/cm(2). Desiccation (at 15 degrees C for 20 days, 43% RH) commenced immediately (non-biofilm) or following biofilm formation (at 15 degrees C for 48 h, 100% RH). To study the impact of food lipids, non-biofilm L. monocytogenes cells were suspended in TSB-glu containing either canola oil (5-10%) or lard (20-60%) and desiccated as above on SS coupons. Following desiccation for 20 days, survivors decreased by 1.4-3.7 log CFU/cm(2) for non-biofilm L. monocytogenes cells. The contamination level had no significant (p > 0.05) effect on survival kinetics. SEM micrographs showed mature biofilms on coupons initially contaminated with 5.5 and 7.5 log CFU/cm(2). Mature biofilm cells were significantly (p <0.05) more desiccation resistant than cells in immature biofilms formed by the lowest contamination level. Besides biofilm maturity/formation, previous osmoadaptation, exposure to lard (20-60%) or salt (5%) during desiccation significantly (p <0.05) increased the bacterium's survival. In conclusion, L. monocytogenes desiccation survival can be greatly reduced by preventing presence of mature biofilms and salty or fatty soils on food contact surfaces. (C) 2013 Elsevier Ltd. All rights reserved.
Original language | English |
---|---|
Journal | Food Microbiology |
Volume | 36 |
Issue number | 1 |
Pages (from-to) | 46-56 |
ISSN | 0740-0020 |
DOIs | |
Publication status | Published - 2013 |
Externally published | Yes |
Keywords
- Food Science
- Microbiology
- Biofilm
- Desiccation
- Food lipid soils
- Listeria monocytogenes
- Non-linear inactivation
- Osmotic stress
- SEM
- Stainless steel
- fat
- sodium chloride
- stainless steel
- article
- biofilm
- biological model
- chemistry
- desiccation
- drug effect
- equipment
- equipment contamination
- fast food
- food contamination
- food storage
- growth, development and aging
- microbial viability
- microbiology
- physiology
- Biofilms
- Equipment Contamination
- Fast Foods
- Fats
- Food Contamination
- Food Storage
- Microbial Viability
- Models, Biological
- Sodium Chloride
- Stainless Steel
- Bacteria (microorganisms)
- Brassica napus var. napus
- BIOTECHNOLOGY
- FOOD
- MICROBIOLOGY
- FOODBORNE PATHOGENS
- EXTRACELLULAR DNA
- SODIUM-CHLORIDE
- ATTACHMENT
- SALMONELLA
- MODEL
- TEMPERATURE
- STRAINS
- STRESS
- SPP.
- biofilm maturity
- desiccation species survival
- fatty food soil
- food grade stainless steel surface
- food processing industry
- initial contamination level
- lard exposure
- osmoadaptation
- salt food soil
- Eubacteria Bacteria Microorganisms (Bacteria, Eubacteria, Microorganisms) - Regular Nonsporing Gram-Positive Rods [07830] Listeria monocytogenes species contaminant
- canola oil
- food lipids
- glucose 58367-01-4
- sodium chloride 7647-14-5
- 10068, Biochemistry studies - Carbohydrates
- 13502, Food technology - General and methods
- 31000, Physiology and biochemistry of bacteria
- 32500, Tissue culture, apparatus, methods and media
- cell culture laboratory techniques, culturing techniques
- tryptic soy broth laboratory equipment
- Foods
- 12597-68-1 Stainless Steel
- 7647-14-5 Sodium Chloride
- BIOFILMS
- CONTAMINATION
- DRYING
- FOOD SAFETY
- LARD
- LISTERIA
- LISTERIA MONOCYTOGENES
- MICROBIAL CONTAMINATION
- MICROORGANISMS
- RAPESEED OILS
- SALTS
- STAINLESS STEEL
- STEEL
- SURFACES
- Hygiene and toxicology
- Microbiological aspects