Inactivation of Listeria monocytogenes in raw fruits by enterocin AS-48.
The purpose of this study was to determine the effect of enterocin AS-48 on Listeria monocytogenes CECT 4032 in fruits and fruit juice. Fruits were contaminated with a L. monocytogenes cell suspension, washed with enterocin AS-48 (25 microg/ml) or with sterile distilled water as control, and stored at different temperatures (-20, 6, 15, 22 degrees C). Washing treatments significantly inhibited or completely inactivated L. monocytogenes in strawberries, raspberries, and blackberries stored at 15 and 22 degrees C for up to 2 days and in blackberries and strawberries at 6 degrees C for up to 7 days. Washing treatments with enterocin AS-48 also reduced viable counts in sliced melon, watermelon, pear, and kiwi but did not avoid proliferation of survivors during storage at 15 and 22 degrees C. Added enterocin (25 microg/ml) completely inactivated L. monocytogenes in watermelon juice within 24 h. To enhance the antilisterial activity of treatments, enterocin AS-48 was tested in combination with other antimicrobial substances on sliced melon stored at 22 degrees C. The combinations of enterocin AS-48 and trisodium trimetaphosphate, sodium lactate, lactic acid, polyphosphoric acid, carvacrol, hydrocinnamic acid, p-hydroxybenzoic acid, n-propyl p-hydroxybenzoate, or 2-nitropropanol showed increased antilisterial activities compared with each antimicrobial tested separately. Washing treatments with enterocin AS-48 in combination with 12 mM carvacrol, as well as with 100 mM n-propyl p-hydroxybenzoate, avoided regrowth of Listeria during storage at 22 degrees C. Results from this study indicate that enterocin AS-48 alone or in combination with other preservatives could serve as an additional hurdle against L. monocytogenes in fruits and fruit juices.
Molinos
Antonio Cobo
AC
Area de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071-Jaén, Spain.
Abriouel
Hikmate
H
Ben Omar
Nabil
N
Lucas
Rosario
R
Valdivia
Eva
E
Gálvez
Antonio
A
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001430:Bacteriocins / Q000494:pharmacology*; D001628:Beverages / Q000382:microbiology; D015169:Colony Count, Microbial; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005519:Food Preservation; D005638:Fruit / Q000382:microbiology*; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D013696:Temperature; D013997:Time Factors
D000900:Anti-Bacterial Agents; D001430:Bacteriocins; C466236:enterocin AS-48, Enterococcus faecalis