Large foodservice operations, such as cruise ships, schools and staff canteens, know only too well the importance of safe hot holding. When substantial volumes of cooked food are prepared in advance for a buffet that will remain open for an extended period, the conditions are ripe for harmful bacteria to flourish.
Potentially lethal pathogens multiply with abandon in the so-called ‘Danger Zone’ between 5°C (40°F) and 63°C (140°F).
Hot Holding is the process of keeping the cooked food at a safe temperature while it is ready for service. Guidelines for hot holding are established in the Food Safety Regulations 1995 and similar legislation.
What is the issue?
Cooked food may present considerable food poisoning risks without showing any visible signs of contamination. It may look fresh, carry no unpleasant aroma, and even taste perfectly normal. But above 5°C, bacteria are primed to multiply. The only safe response is either to chill cooked food for later use, or maintain the temperature above 63°C.
Foodservice operators should use dedicated equipment designed for the sole purpose of hot holding. Typically, these come in the form of a soup kettle for liquids and sauces, or a Bain Marie for anything from scrambled eggs to stews. These kitchen utensils use a combination of direct heat and steam to maintain a consistent temperature.
The hot holding equipment should be switched on in advance of food transfer, or pre-heated. Only hot, cooked food should be transferred for hot holding. Because these utensils apply a gentle heat, they cannot be used as a slow cooker to raise the temperature gradually.
Since one of the aspects of food service where hot holding is concerned is the rotation of shifts, it is vital that the temperature of the food is recorded regularly with a temperature probe, and displayed in a prominent place. Stir sauces and stews regularly to distribute the heat evenly, and measure the core temperature with a probe. This temperature should be recorded on a log that incoming shifts can consult easily.
Limits of Hot Holding
However gentle the heat that is applied in hot holding, the process will inevitably cause sauces to thicken and proteins to toughen or dry out over time. For this reason (not to mention the safety concerns), hot holding should ideally not be used for longer than an hour. The maximum time limit should be displayed in the hot holding area.
If reheating food for hot holding, for example in the microwave, best practice is to bring the internal temperature up to 75°C (165F) for at least 15 seconds to compensate for uneven heat distribution. The only exception where the temperature is concerned is for properly cooked roasts. These can be held under a gentle heat source at a temperature no lower than 54°C (130F°).
If hot holding equipment or sufficient supervision is not available, standard food safety guidelines apply.
Food under 63°C (145°F) for 2 hours or above 8°C (46°F) must be discarded.