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conferenceseries

.com

October 27-29, 2016 Rome, Italy

15

th

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 Unlu

1,2

, Barbara Nielsen

1

and

Claudia Ionita

1,3

1

University of Idaho, USA

2

Washington State University, USA

3

Clemson University, USA

S

ix 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@uidaho.edu

Gulhan Unlu et al., J Food Process Technol 2016, 7:12 (Suppl)

http://dx.doi.org/10.4172/2157-7110.C1.056