You are here

NCCEH Student Project Award 2013 - T Chu

The Hot Lunch Dilemma: Evaluation Heat Retention Ability of Insulated Container with Macaroni and Cheese

T Chu
BC Institute of Technology: Environmental Health

More child care facilities are refraining from helping children to microwave their lunches because of inadequate staffing and time. As a result, parents have to pack hot lunches using thermal insulated containers. For food safety purposes, the temperature of food should be kept above 60˚C or below 4˚C. Improper hot holding temperature (i.e. 4˚C to 60˚C) can provide an ideal condition for bacteria to thrive and can possibly lead to foodborne illnesses in children.

The true heat retention ability of insulated containers has rarely been studied and tested. Information on proper use is also not comprehensive. When children are sent to school with lunch packed in a thermal container, there is typically a period of five to six hours from preparation of food to actual consumption of it. Food inside can therefore possibly be held at inadequate temperature within that period of time. The purpose of the study was to monitor the temperature changes of macaroni and cheese that was packed in three commonly used thermal containers over six hours. Whether preheating those containers with boiling water would result in increased heat retention abilities was also assessed.

Using SmartButton, a temperature data logger, the temperature change of macaroni and cheese over six hours was collected thirty times from each preheated thermal container and another thirty times from each non-preheated thermal container. Data collected was analyzed to generate descriptive and inferential outputs. The results showed that none of the containers can keep food hot above 60˚C for more than three hours whether subjected to preheating with boiling water or not (p=0.000). Regardless, results indicated that preheating the container provided an extra level of food safety by slightly enhancing the heat retention abilities for all containers. Based on these results, parents must preheat thermal containers when preparing lunches for their children and child care facilities should arrange lunch hour to be at an earlier time to provide an extra level of food safety by limiting potential bacterial growth within the food.