Product reheating

Optimising quality in product reheating

By Greg Hooper - 28 October 2014

Reheating instructions on product labels are developed from a 'safety first' viewpoint, but there is much that can be done to optimise quality without compromising on safety. The overall objective of reheating is to provide enough heat to ensure food safety, without overheating the product or packaging.

Product and packaging design are fundamental to optimising final product quality, but so too are the instructions actually given to the consumer. Product formulation and design and reheating instructions are quite intimately linked. The quality of the best–designed product will be limited by the producer having investigated the best way to reheat the product. This is especially true for microwave–reheated products.

The requirements of re–heating (or cooking), in terms of the temperature required to give both an assurance of food safety and palatability in the food, depend very much on the food itself, the storage conditions, the packaging used to hold and protect the food, and the mode of heating (e.g. microwave, grilling, conventional oven).

The target temperature aimed for at the end of the re–heating process depends on whether the food can be classed as safe to eat without further thermal treatment (such as some bakery goods, or canned foods) or whether the food requires reheating to kill any possible food poisoning bacteria that may have re–contaminated or grown on the food prior to the re–heating process.

As a rule of thumb, minimising the amount of heating (time and temperature) required will optimise quality. This can be facilitated by ensuring, as far as is possible, that all parts of the product attain the required temperature at the same time. The way that individual components are arranged in a product can help in this, particularly in microwave–reheated foods. Reducing the thickness of food will also help to ensure shorter heating times.

In preparing reheating instructions, it is important to make them clear and simple to follow, as well as appropriate. The instructions should be chosen to give minimum nutrient loss (for example by using the smallest amounts of water when boiling vegetables). Inadequate cooking instructions may leave the product under or overheated. Underheating could lead to the product being insufficiently warm to be palatable or worse, cause possible food poisoning issues. Overheating may result in the product quality being deemed unacceptable by the consumer or cause possible issues with chemical contamination of the food (migration) caused by the breakdown of the packaging if the temperature limit (of the packaging) is exceeded. Exceeding the temperature limit of the packaging is more common than expected with microwave foods.

The development of instructions using appropriate appliances and considering re–heating prior to or during the development of a food product can have huge advantages compared to just applying re–heating instructions as an afterthought. Product quality, shorter re–heating times and less energy required during the heating process are all benefits of better re–heating design, planning and development. We offer an instruction development service that can optimise the quality of cooked or re–heated foods, but always focuses of product and packaging safety. If you would like to know more about the services offer, please give me a call.

Remember that 'product instructions' are the last crucial stage in the handling of a product prior to consumption. Get it wrong and all the work gone into designing and marketing the product will be wasted and, worse still, could result in product recall or food poisoning incidents.

*A more detailed report on the importance of reheating instructions is available as a free white paper. For a copy, send an e–mail to with the subject line: send reheating

Greg Hooper, Microwave and Thermal Process Specialists
+44(0)1386 842039

Greg Hooper

About Greg Hooper

Greg Hooper works in the Process Innovation Group at Campden BRI. He joined Campden BRI in 1990 having gained a BSc in Applied Science (Physics and Chemistry) from Sheffield City Polytechnic.

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