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conferenceseries.com
October 27-29, 2016 Rome, Italy
15th International Conference on
Food Processing & Technology
Volume 7, Issue 12 (Suppl) J Food Process Technol 2016
ISSN: 2157-7110 JFPT, an open access journal Food Technology 2016
October 27-29, 2016
Inhibition of Listeria monocytogenes in hot dogs by surface application of freeze-dried bacteriocin-containing
powders from lactic acid bacteria
Gulhan Unlu1,2, Barbara Nielsen1 and Claudia Ionita1,3
1University of Idaho, USA
2Washington State University, USA
3Clemson University, USA
Six lactic acid bacteria (LAB) strains, Lactococcus lactis BFE 920, L. lactis subsp. lactis ATCC 11454, L. lactis subsp. cremoris
ATCC 14365, Lactobacillus curvatus L442, Lact. curvatus LTH 1174, and Lact. bavaricus MN, were grown in cheddar cheese
whey supplemented with complex nutrient sources. Cell-free culture supernatants were freeze-dried and the resulting bacteriocin-
containing powders were applied on the surface of hot dogs that were inoculated (~ 4 log cfu/hot dog) with a five-strain Listeria
monocytogenes cocktail. Hot dogs were vacuum sealed and stored at 4°C for 4 weeks. L. monocytogenes was enumerated, using both
Tryptic Soy Agar (TSA) and Oxford Listeria Agar (OXA), on day 0 and at 1, 2, 3, and 4 weeks of the refrigerated storage. In hot dogs
containing only the L. monocytogenes inoculum, L. monocytogenes counts increased from 4 log cfu/hot dog up to 7 log cfu/hot dog.
All samples containing freeze-dried bacteriocin-containing powders exhibited significantly lowered (P < 0.05) L. monocytogenes
populations on the surface of hot dogs throughout the 4-week study except for bavaricin MN powder. Bacterial counts on hot dogs
packed without any powder were statistically equal on day 0 when enumerated on OXA. Freeze-dried bacteriocin-containing powders
from L curvatus L442 and L. lactis subsp. cremoris ATCC 14365 decreased L. monocytogenes populations on the surface of hot dogs
by greater than 2 log cfu/hot dog throughout the 4-week study. For the powdered bacteriocin preparations from L lactis BFE 920, L.
lactis subsp. lactis ATCC 11454, and L. curvatus LTH 1174, L. monocytogenes populations were determined to be approximately 3-log
cfu/hot dog after 4 weeks of storage.
Biography
Gulhan Unlu is an Associate Professor within the School of Food Science at the University of Idaho and Washington State University. Her research interests
include food microbiology, dairy microbiology, food biotechnology, microbial food safety, food bio-preservation, bioactive packaging of foods, functional foods, and
bioconversion of agricultural and industrial waste into value-added products. She is an alumna (2012-2013) of The Fulbright US Scholar Program. She is an active
member of the Institute of Food Technologists (IFT) and served as the Chair for the Biotechnology Division of the IFT (2014-2015). She serves on the Editorial
Board of Probiotics and Antimicrobial Proteins.
Gulhan Unlu et al., J Food Process Technol 2016, 7:12 (Suppl)