PROCESS CONTROL
By Brian A. Nummer, Ph.D.
Cook-chill Reduced-oxygen Packaging in
Retail and Foodservice
Operations
lead to product quality loss. After cooking and while hot (at least 135 °F), foods
are pumped or placed into impermeable
bags. Air is expelled, and the bags are
sealed. Bags are rapidly chilled and then
placed into a refrigerator or freezer for
storage until use.
Increasingly, retail and foodservice oper- ators are turning to food technology to
save time and money and to increase
food quality. One of those technologies
is cook-chill processing. Cook-chill is a
process where foods are cooked, bagged and rapidly chilled to ex-
tend shelf life. Alternatively, foods can be bagged, cooked in the bag
and chilled, termed “sous vide.” Bagged foods are held refrigerated
for a limited shelf life. Some of the benefits of the cook-chill process
include increases in shelf life, consistency, portion control and quality
of foods.
The cook-chill process also decreases labor, product handling and chances of
cross-contamination of foods. Regulations for cook-chill processing in retail or
foodservice operations are specified in
the 2009 Food Code in 3-502.11.D and
3-502.12. Additional guidelines are
found in Annex 3 §3-502.12 and Annex
6. 2 of the Food Code.
A typical cook-chill process starts with
assembling ingredients, followed by
cooking. Cooking reduces or eliminates
vegetative disease-causing microorganisms, reduces spoilage microorganisms
and inactivates food enzymes that can
Cook
Chill
Cook-chill Process Food
Safety Concerns
The cooking step employed in cook-chill processing will not effectively destroy bacterial spores. Spores from the
genera Clostridium and Bacillus can survive and cause foodborne illness. Therefore, special attention must be given to a
proper rapid-cooling procedure to prevent the growth and toxin formation of
these bacteria (Table 1). Secondly, bagging cook-chill foods creates a reduced-oxygen atmosphere, which is a
requirement for the growth of
Clostridium bacteria. Bagging and handling after
cooking may provide an opportunity for
cross-contamination with illness-causing
bacteria. Lastly, some of these bacteria
can grow slowly at refrigeration temperatures. These are described as psychrotropic and include some strains of
Clostridium botulinum and all strains of
Listeria monocytogenes. These two bacteria
are considered the primary microbiological hazards in the cook-chill process.
The U.S. Food and Drug Administration (FDA) has recognized these hazards
since the earliest versions of the Food
Code in 1993. Earlier versions of Annex
6 specified that all operations using reduced-oxygen packaging, including
cook-chill processing, were required to
obtain a variance from their regulatory
authority if refrigeration was the only
Table 1: Cook-chill Food Safety Concerns
Spoilage organism competition reduced; Clostridium botulinum
survives normal cooking temperatures
Bag Creates reduced oxygen environment; may contaminate after
cooking with Listeria monocytogenes (not a concern if foods are bagged
prior to cooking)
Both C. botulinum psychrotropic strains and L. monocytogenes grow
slowly under refrigeration; extended shelf life may allow growth or
toxin formation; potential for temperature abuse and greater risk of
growth
