Affiliation:
1. Department of Food Science and Technology, University of Tennessee, Knoxville, Tennessee, USA
Abstract
ABSTRACT
Essential oils are marginally soluble in water, making it challenging to evenly disperse them in foods and resulting in an increased tendency to bind with food lipids and proteins, resulting in lowered antimicrobial efficacy. In the current study, free and nano-dispersed (ND) thymol were compared in terms of their antimicrobial efficacies against
Escherichia coli
O157:H7 ATCC 43889 and 43894 and
Listeria monocytogenes
strains Scott A and 101 in apple cider and 2% reduced-fat milk. Apple cider was adjusted to pHs 5.5 and 3.5, and antimicrobial tests were performed at 0.3-, 0.5-, 0.75-, and 1.0-g/liter thymol concentrations at 35, 32, 25, and 4°C. Overall, 0.5 and 1.0 g/liter thymol in nano-dispersion and along with free thymol were inhibitory and bactericidal, respectively, against bacterial strains under all treatment conditions. At pH 5.5, 0.5 g/liter ND thymol was bacteriostatic against
L. monocytogenes
and
E. coli
for up to 48 h. At pH 3.5,
L. monocytogenes
controls did not survive beyond 12 h but
E. coli
survived and was inhibited by 0.5 g/liter ND thymol after 12 and 48 h in apple cider.
E. coli
strains were significantly sensitive to 4°C and pH 3.5 (
P
< 0.05). When bacteria were tested in 2% reduced-fat milk at 35 or 32°C, ND and free thymol demonstrated inhibition at 4.5 g/liter. Thus, the current technology seems to be promising and novel, enabling thymol-containing nano-dispersions that are not only transparent but also effective against pathogens in food applications, especially in clear beverages.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
94 articles.
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