Food Protection Trends - May/June 2014 - 132

PEER-REVIEWED ARTICLE

Frederick Breidt,*1 Kathryn Kay,2
Jason Osborne,3 Barbara Ingham4
and Fletcher Arritt2

Food Protection Trends, Vol 34, No. 3, p.132-138
International Association for Food Protection
6200 Aurora Ave., Suite 200W, Des Moines, IA 50322-2864

USDA-ARS Food Science Research Unit, 322 Schaub
Hall, Box 7624, North Carolina State University, Raleigh,
NC 27695, USA

Dept. of Food, Bioprocessing and Nutrition Sciences,
400 Sullivan Drive, North Carolina State University,
Raleigh, NC 27695, USA

Dept. of Statistics, 2311 Stinson Drive, Box 8203, North
Carolina State University, Raleigh, NC 27695, USA

Dept. of Food Science, 1605 Linden Drive, University
of Wisconsin, Madison, WI 53706, USA

Mention of a trademark or proprietary product does not
constitute a guarantee or warranty of the product by
the U. S. Department of Agriculture or North Carolina
Agricultural Research Service, nor does it imply approval
to the exclusion of other products that may be suitable.

Thermal Processing of Acidified Foods
with pH 4.1 to pH 4.6
INTRODUCTION

ABSTRACT

helf-stable acidified foods with a pH at or below
4.6 must be processed to achieve a 5-log
reduction for vegetative bacterial pathogens.
Published research does not exist to adequately
support the Food and Drug Administration process
filings for products with pH 4.1-4.6 or to define critical
limits for acid and acidified foods with pH values in this
range. Using a non-inhibitory vegetable-based medium, we
developed models and data for the thermal destruction
of acid-resistant vegetative microbial pathogens,
including 5-strain cocktails of Escherichia coli O157:H7,
Salmonella enterica, and Listeria monocytogenes in
acidified foods with pH values of 4.1 to 4.6. Under the
experimental conditions, Listeria monocytogenes was
the most heat- and acid-resistant pathogen. A z-value of
16.7°F, an F-value (at 160°F) of 5.6 min, and a table of
recommended processing conditions were estimated from
the thermal processing data. This work addresses a lack
of documentation that is challenging to all areas of the
industry, especially small processors.

ll processors of acidified and low-acid canned
foods must register with the Food and Drug
Administration (FDA) and file scheduled processes
for each product that they manufacture. These process
filings must be supported by research that substantiates
the lethality of the scheduled process for microbial
pathogens. For acidified foods with a pH of 4.1 or lower,
research has defined heat processing conditions that
ensure a 5-log reduction of the pathogens of concern,
Escherichia coli O157:H7, Salmonella enterica and
Listeria monocytogenes (3, 5). These data identify the
holding time at the recommended temperature for the
"cold spot" in the product container, as defined by a
process authority. However, no published peer-reviewed
documented research exists to support FDA process
filings for processing acidified food products with pH
4.1-4.6. This lack of documentation is challenging to
all areas of the industry but especially so for small food
processors that lack the resources to support challenge
studies conducted by private laboratories.

* Corresponding author: Phone: +1 919.513.0186; Fax: +1 919.513.0180; E-mail: fred.breidt@ars.usda.gov

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