Inactivation of Salmonella enterica on tomato stem scars by antimicrobial solutions and vacuum perfusion.
A study was conducted to identify sanitizing solutions effective at inactivating ca. 5logCFU of Salmonella enterica inoculated onto the stem scar of red round tomatoes during two-minute immersion treatments. Sixty-three antimicrobial combinations were tested. Vacuum perfusion was applied to tomatoes during selected treatments to promote infiltration of sanitizer into porous tomato stem scar tissue. Red round tomatoes were inoculated to ca. 6.9logCFU/stem scar with a four-serovar composite of Salmonella enterica, air dried, and tomatoes were immersed in circulating sanitizing solutions for 120s at ca. 22°C. Stem scars were aseptically excised, macerated in DE neutralizing broth, and the homogenate was spiral plated. Twenty-four washes inactivated ≥3.0logCFU/stem scar. Seven treatments reduced ≥4.8 log (viz., 40% EtOH, sulfuric acid, and organic acid combinations). LogCFU/stem scar reductions for various sanitizers are listed in parenthesis, as follows: 90ppm peroxyacetic acid (1.31), 200ppm chlorine (1.53), 190ppm chlorine+15″ Hg vacuum perfusion (2.23), 0.2N sodium hydroxide (NaOH) (3.78), 2% total of lactic+acetic acid (4.35), 3% total of phosphoric+lactic acids (4.51), and 40% ethanol (4.81). Solutions that achieved ≥4.95 log reductions were 5.1% total of lactic+acetic+levulinic acids, 49% ethanol, 6% total of lactic+acetic acids, and a 0.2M H(2)SO(4) (sulfuric acid) solution. The use of vacuum perfusion with 200ppm chlorine increased inactivation by 0.7logCFU over chlorine alone, however, P>0.05. Results from this study provide tomato processers with some sanitization options effective at inactivating Salmonella from the stem scars of tomatoes. These results may also help processors and scientists design future decontamination studies by incorporating combinations of these chemical treatments.
Food Safety and Intervention Technologies Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038-8551, USA. joshua.gurtler@ars.usda.gov
Joshua B
JB
Gurtler
Amanda M
AM
Smelser
Brendan A
BA
Niemira
Tony Z
TZ
Jin
Xianghe
X
Yan
David J
DJ
Geveke
D000890:Anti-Infective Agents / Q000494:pharmacology; D002713:Chlorine / Q000494:pharmacology; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D005506:Food Contamination / Q000517:prevention & control*; D018551:Solanum lycopersicum / Q000382:microbiology*; D018547:Plant Stems; D012475:Salmonella / Q000187:drug effects; D019779:Salmonella enterica / Q000187:drug effects* / Q000254:growth & development; D014618:Vacuum
D000890:Anti-Infective Agents; D004202:Disinfectants; D002713:Chlorine