Efficacy of Cooling Beef Taco Meat and Steamed Rice in United States School Foodservice Operations

doi:10.4236/fns.2013.47094

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Food and Nutrition Sciences, 2013, 4, 735-740

http://dx.doi.org/10.4236/fns.2013.47094 Published Online July 2013 (http://www.scirp.org/journal/fns)

Efficacy of Cooling Beef Taco Meat and Steamed Rice in

United States School Foodservice Operations*

David A. Olds1#, Kevin R. Roberts2, Kevin L. Sauer2, Jeannie Sneed2, Carol W. Shanklin3

1Department of Family and Consumer Sciences, Bradley University, Peoria, USA; 2The Center of Excellence for Food Safety Re-

search in Child Nutrition Programs, Department of Hospitality Management and Dietetics, Kansas State University, Manhattan, USA;

3Graduate School & the Center of Excellence for Food Safety Research in Child Nutrition Programs, Department of Hospitality

Management and Dietetics, Kansas State University, Manhattan, USA.

Email: #[email protected]

Received May 9th, 2013; revised June 9th, 2013; accepted June 16th, 2013

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Food is frequently cooked, cooled and reheated for service at a later time in schools and other foodservice op erations in

the United States [US]. Inadequate cooling of food has been associated with foodborne illness. The purpose of this

study was to determine if practices commonly used in school foodservice to cool beef taco meat and steamed rice would

meet US Food and Drug Administration [FDA] 2009 Food Code standards. Prepared products cooled at 5.08 cm and

7.62 cm depths in stainless steel counter pans were placed uncovered in a walk-in refrigerator, a walk-in freezer (beef

taco meat only), and a walk-in refrigerator with an ice water bath. Data were analyzed using descriptive statistics, in-

cluding mean times and temperatures, with standard deviations. Cooling beef taco meat in a walk-in freezer at a depth

of two inches and cooling steamed rice in a walk-in refrigerator at a depth of two inches with an ice water bath were the

only methods that met both FDA Food Code time and temperature standards. Results suggest that challenges and risks

exist with common methods used to cool food, especially if food volume is not reduced before cooling. Specific proto-

cols for cooling procedures based on types of food and equipment are needed. These findings and recommendations are

important for foodservice professionals who oversee food services and cooling practices in schools and other opera-

tions.

Keywords: Cooling; Schools; Foodservice; FDA; Food Code

1. Introduction

Approximately 12.1 million children are served breakfast

in schools each day [1] and over 31 million children are

served daily in the United States [US] National School

Lunch Program [2]. Due to the large numbers of children

served, food safety is paramount. To improve food safety,

the Child Nutrition and WIC [Women, Infants, and Chil-

dren] Reauthorization Act of 2004 required all schools to

have a food safety program based on Hazard Analysis

Critical Control Point [HACCP] principles [3].

When planning food safety programs, school foodser-

vice directors identified cooling as a potential critical

control point that needed attention. Between 1961 and

1982, inadequate cooling of food was the leading con-

tributing factor in 1918 cases of C. perfringens food-

borne illness outbreaks in the US [4]. The Centers for

Disease Control and Prevention [CDC] estimated that C.

perfringens bacteria, a bacteria often associated with im-

proper food temperatures, accounted for 10% of the 9.4

million cases of foodborne illness that occur annually in

the US [5]. The US General Accounting Office [6] re-

ported 447,483 cases of foodborne illness and 15,831

foodborne outbreaks be tween 1973 and 199 9, resu lting in

20,119 hospitalizations and 457 fatalities. From 1973 to

1997, 604 foodborne disease outbreaks were reported in

US schools, a median of 25 per year [7]. From 1990 to

1999, improper cooling was identified in five of 19 out-

breaks in school foodservice operations [6]. Inadequate

or “slow” cooling of food prepared on school premises

was ranked third in the top 10 reportedcontributingfac-

torsin16of 298 school-associated foodborne outbreaks

from 1998-2006 [8].

Krishnamurthy and Sneed [9] reported that 78% of

surveyed school f oodservice directors cooled leftovers to

*Authors declare no conflict of int erest.

#Corresponding author.

Efficacy of Cooling Beef Taco Meat and Steamed Rice in United States School Foodservice Operations

736

reheat and serve at another meal. Foods often cooled in

more than half of all schools included taco meat, turkey

(whole or roasts), and ch ili. Cooling most often was done

in walk-in refrigerators or walk-in freezers, and few fa-

cilities (8%) had blast chillers to speed the cooling proc-

ess. The majority of schools did not monitor product

temperatures during the cooling process. These findings

in schools are consistent with a recent study that found

that many restaurants do not verify cooling, do not moni-

tor time and temperature during cooling, and do not cali-

brate thermometers [10].

Cooling standards in the 2009 US Food and Drug Ad-

ministration [FDA] Food Code specify that cooked po-

tentially hazardous food shall be cooled within two hours

from 57.2˚C to 21.1˚C and within a total of six hours

from 57.2˚C to 5˚C or less [11]. The FDA considers

cooling to be a critical control point, “a point or proce-

dure in a specific food system where loss of control may

result in an unacceptable health risk” [11]. The 2009

FDA Food Code outlines acceptable cooling methods

based upon the type of food product to be cooled. These

cooling methods include placing food in shallow pans,

portioning food into thinner or smaller amounts, em-

ploying the use of specialized equipment to cool food

rapidly, stirring food in a container placed in an ice water

bath, utilizing containers that allow heat transfer, adding

ice to the food product, or other methods that facilitate

the cooling process [11]. The 2009 FDA Food Code

identifies methods used to meet cooling standards, but it

does not specify procedures for monitoring cooling or

provide guidelines for foodservice operators or inspec-

tors to verify if cooling standards are being met. Snyder

and Labalestra [12] stated that health departments have

not conducted cooling studies to verify the FDA cooling

standard in retail foodservice.

Previous research has established that challenges exist

to achieving FDA Food Code standards for cooling bulk

foods [12-15]. Research by Roberts et al. [13] examined

the efficacy of various cooling methods for liquid foods.

When comparing 5.08 cm and 7.62 cm depths of chili

and tomato sauce cooled in a walk-in refrigerator and

freezer, only products cooled at a 5.08 cm depth in a

freezer met FDA Food Code standards. The use of an ice

water bath decreased the initial cooling time of products

in a refrigerator, but the ice water bath was not changed

during the cooling process because typical school cooling

processes were being replicated. Although rapid cooling

of food is a known preventative measure to outbreaks of

foodborne illness, limited in formation exists about which

cooling methods meet FDA Food Code standards in

foodservice operations.

The purpose of this study was to determine if cooling

practices commonly used in school foodservice opera-

tions in the US to cool beef taco meat and rice would

meet FDA Food Code standards. Cooling practices ex-

amined included 5.08 cm and 7.62 cm depths of products

cooled in a walk-in refrigerator, walk-in freezer, and an

ice water bath combined with the walk-in refrigerator.

2. Methodology

2.1. Sample

United States Department of Agriculture [USDA] recipes

for schools, available online on the National Food service

Management Institute’s website [16], were used to pre-

pare two products: “Beef or Pork Taco”, USDA Recipe

D-13 (hereafter referred to as beef taco meat); and “ Coo k-

ing Rice”, USDA Recipe B-03 (hereafter referred to as

steamed rice). Beef taco meat and steamed rice represent

two food items that are prepared and cooled in the Na-

tional School Lunch Program [9]. Beef taco meat was

prepared in a stand ard steam-jacketed kettle an d steamed

rice was prepared in a standard convection steamer. Both

pieces of equipment are often used in school foodservice.

2.2. Cooling Procedures

Three replications w ere conducted for each cooling m e t h od

tested and three identically prepared and portioned food

product samples were used in each replication. The mean

cooling curves for each method and product tested were

determined. Prior studies demonstrated that covered food

products cooled slower than uncovered products [14,17].

Based on these findings, all food products tested were

left uncovered during cooling.

Table 1 outlines the cooling methods. Cooling times

and temperatures were logged at one minute intervals

during testing using Comark RF512 wireless temperature

transmitters (Comark Instruments, Beaverton, Oregon,

USA) in conjunction with a Comark RF500A wireless

monitoring gateway. A Comark RFAX100D thermistor

was fixed in the geometric center of food products tested

in 15.08 cm × 50.8 cm stainless steel pans. Probes were

fixed at 2.54 cm depths for food products tested at 5.08

cm product depths and at 3.81 cm depths for food prod-

ucts tested at 7.62 cm depths.

Prior to each replication, food products were prepared

and portioned identically. An insert pan containing an ice

water bath was used for replicates using the ice water

bath method. For ice water bath replicates, pans of food

product were lowered into insert pans (15.08 cm × 50.8

cm × 10.16 cm insert pans and 15.08 cm × 50.8 cm ×

15.24 cm insert pans for 5.08 cm and 7.62 cm cooling

methods, respectively) containing ice water (2:1 cubed

ice to cold tap water ratio), which contacted the bottom

and sides of the hot pans completely. Immediately fol-

lowing ice water bath insertion, replicates were placed in

a walk-in refrigerator for the remainder of the cooling

Efficacy of Cooling Beef Taco Meat and Steamed Rice in United States School Foodservice Operations

737

Table 1. Mean cooling times for beef taco meat and steamed rice using differing product depths and cooling methods.

Mean Cooling Time (hr:min) ± SD1

Food Product Product Depth Cooling Method 57.2˚C - 21.1˚C 57.2˚C - 5˚C

Beef Taco Meat 5.08 cm Walk-in freezer 1:47 ± 0:14 3:19 ± 0:24

Beef Taco Meat 5.08 cm Ice water bath in walk-in re frigerator 1:05 ± 0:06 7:30 ± 1:34

Beef Taco Meat 5.08 cm Walk-in refrigerator 3:01 ± 0:18 9:19 ± 1:01

Beef Taco Meat 7.62 cm Walk-in freezer 3:04 ± 0:19 5:22 ± 0:31

Beef Taco Meat 7.62 cm Ice water bath in walk-in ref rigerator 3:00 ± 0:17 15:48 ± 1:08

Beef Taco Meat 7.62 cm Walk-in ref rigerator 4:55 ± 0:14 15:24 ± 0:34

Steamed Rice2 5.08 cm Ice water bath in walk-in refrigerator 1:04 ± 0:05 3:04 ± 0:13

Steamed Rice 5.08 cm Walk-in refrigerator 3:18 ± 0:17 9:55 ± 0:53

Steamed Rice 7.62 cm Ice water bath i n walk-in refrigerator 2:02 ± 0:11 7:11 ± 1:15

Steamed Rice 7.62 cm Walk-in refrigerator 4:32 ± 0:18 13:37 ± 0:40

FDA 2009 FOOD CO DE COOLING STANDARDS3 2:00 6:00

1Standard deviation; 2Steamed rice was not tested in a walk-in freezer because this method is not commonly used in United States [US] school foodservice

operations; 3US Food and Drug Administration [FDA].

process. The ice water bath was not replaced during the

cooling process to simulate food handling procedures

previously observed in foodservice operations [18]. For

each replication, a maximum of four pans was placed in

the walk-in refrigerator or walk-in freezer during testing.

Following placement of food products into the walk-in

refrigerator/freezer, doors were securely locked and re-

mained closed until the cooling process had co ncluded.

3. Results and Discussion

Average cooling curves for beef taco meat and steamed

rice cooling methods are shown in Figures 1 and 2, re-

spectively. The only cooling method for the beef taco

meat that met both FDA standards (food product cooled

from 57.2˚C to 21.1˚C within two hours and 57.2˚C to

5˚C within a total of six hours) was when the product

was at a 5.08 cm depth and cooled in a walk-in freezer.

The only steamed rice method that met both FDA stan-

dards was when the product was cooled in an ice water

bath placed in a walk-in refrigerator at a 5.08 cm product

depth. Interestingly, the steamed rice cooled at a 5.08 cm

depth in an ice water bath met FDA standards while beef

taco meat cooled using the same method did not, illus-

trating that the physical nature of the product being

cooled impacts the cooling process. Steamed rice was not

tested in a walk-in freezer because this cooling method is

not commonly used in foodservice operations. It is rec-

ommended that steamed rice be cooled rapidly at a 5.08

cm depth or less using an ice water bath in a walk-in re-

frigerator to ensure that FDA standards are met.

Beef taco meat cooled using an ice water bath in the

walk-in refrigerator at a 5.08 cm depth met the first FDA

2009 Food Code standard (57.2˚C to 21.1˚C within two

hours), but failed to cool from 57.2˚C to 5˚C within a

total of six hours. Beef taco meat cooled in the walk-in

freezer at a 7.62 cm depth failed to meet the first FDA

standard of 57.2˚C to 21.1˚C within two hours, but did

cool from 57.2˚C to 5˚C within the required six hours.

Neither food product cooled within the recommended

FDA standards using the walk-in refrigerator or the ice

water bath in the walk-in refrigerator at 7.62 cm depths.

For all cooling methods, each food product required a

longer cooling time at 7.62 cm depths than at 5.08 cm

depths. None of the 7.62 cm cooling methods tested on

either food product met both FDA 2009 Food Code time

and temperature cooling standards. The method taking

the longest time to cool was the beef taco meat in an ice

water bath in a walk-in refrigerator at a 7.62 cm depth.

This product required longer than the same 7.62 cm

depth of beef taco meat in a walk-in refrigerator without

the ice water bath. The use of an ice water bath did in-

crease the cooling rate of beef taco meat from 57.2˚C to

21.1˚C, however, once the ice had melted, the additional

volume of warmed water inhibited rapid cooling com-

pared to the same product tested in the walk-in refrigera-

tor without an ice water bath at the same 7.62 cm depth.

Ice water baths speed the cooling process, but if they are

not changed once the ice has melted, it can actually in-

crease the overall cooling time. This study was designed

to simulate practices in schools, where employees leave

work after food production has concluded, thus being

unable to actively cool or monitor food products. There-

fore, ice water bath insert pans were not changed and

remained in place throughout all ice water bath replica-

tions.

4. Conclusions

Results show that cooling food properly is difficult and

may pose a food safety risk, especially if the volume of

food is not greatly reduced before cooling. Previous

Efficacy of Cooling Beef Taco Meat and Steamed Rice in United States School Foodservice Operations

738

Figure 1. Cooling curves for cooling beef taco meat.

Figure 2. Cooling curves for cooling steamed rice.

Efficacy of Cooling Beef Taco Meat and Steamed Rice in United States School Foodservice Operations 739

research demonstrated that blast chillers, which use for-

ced air, can effectively cool foods to FDA 2009 Food

Code standards [15]. However, blast chillers are expen-

sive and the financial resources may not be available in

many school foodservice operations to purchase them

even though the need for rapid cooling equipment exists.

This is supported by findings of Krishnamurthy and

Sneed [9] who surveyed 411 school foodservice direc-

tors/managers and found that only 8% of those opera-

tions had blast chillers available.

Foodservice operations require economical methods to

safely cool a wide variety of foods. Managers faced with

limited financial resources rely on refrigerators, freezers,

or ice water baths as practical means to safely cool food

products of 5.08 cm depths or less. However, freezers

may not be suitable if there is insufficient time to reheat

frozen food in time for service following cooling. As

shown in this study, ice water baths are suitable for po-

rous foods, such as rice, but are not suitable for denser

foods that do not permit cool air to penetrate the food

product and promote heat transfer. School foodservice

personnel may not distinguish between products that

should be cooled with ice water baths versus other

methods. Cooling foods in freezers may pose a challenge

if adequate space do es not exist to accommod ate cooling

along with regular and safe storage of frozen food prod-

ucts.

Specific recommendations for cooling procedures bas ed

on specific types of food and equipment should be de-

veloped and shared with foodservice managers in all

types of foodservice operations. These managers need to

monitor cooling times and temperatures to ensure that

cooling practices are effective for their operation based

on food, equipment, load of the cooling unit, and other

factors that influence cooling.

Future research should further explore the recom-

mended cooling methods in the FDA 2009 Food Code.

Specific instructions, based on sound science and re-

search, should be provided to foodservice operators who

wish to cool large amounts of food product. For example,

the current code recommends cooling food in an ice wa-

ter bath while stirring. However, specific information

about how often the product should be stirred and the

maximum depth needed to cool the food properly should

also be provided.

FDA Food Code standards for time and temperature

could be validated for microbiological growth of patho-

gens in environments that more closely simulate food

production in school foodservice operations. This study

found that barriers exist to proper food cooling even un-

der best-case scenarios. Further research is suggested to

determine which cooling methods could be effectively

implemented in foodservice operations, while also meet-

ing FDA 2009 Food Code standards to cool cooked po-

tentially hazardous food. Recommended cooling proce-

dures should be added to the USDA standardized recipes

and to policy and procedures manuals within each school

and/or district.

Results of this study can be applied to any foodservice

operation. Food service professionals in restaurants, medi-

cal centers, long-term care and assisted living facilities,

and college and universities can implement recommen-

dations to improve cooling in those operations.

5. Acknowledgements

This research project was conducted at Kansas State

University and was federally funded, in part, by the US

Department of Agriculture [USDA]. This research does

not necessarily reflect the views or policies of the USDA,

nor do mentions of organizations, commercial products,

or trade names within this publication suggest or imply

endorsement by the United States Government.

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