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Microwave From December 2018 newsletter

BRC Issue 8 - on pack instruction validation

The new BRC Issue 8 clause 5.2.5 relates to ensuring safe cooking (heating) instruction validation. Instruction validation is the use of a methodology, procedure or protocol to help ensure that the cooking or heating instructions for a food product are developed and tested to achieve a ‘safely’ heated product, of acceptable quality, for consumers to eat.


Why is heating foods important?


Food is heated primarily to kill pathogenic bacteria (so that it is safe to eat) and to make it more palatable. One of the more temperature tolerant pathogenic organisms able to grow at low temperatures is Listeria monocytogenes. The destruction of this bacterium requires a sufficient thermal process - meaning a combination of time and temperature - to kill it. The higher the temperature the bacteria are subjected to, the greater the killing effect. Similarly, the longer the time at a temperature the greater the killing effect.


Why should equipment be calibrated?


Any devices used to measure temperature of a thermal process need to be calibrated on a regular basis against a UKAS certified reference thermometer. It’s also crucial to calibrate all appliances used for instruction development (e.g. ovens, microwaves, grills and hobs) as it is important that the cooking environment (temperature or heat output) of the heating appliance is known and representative of consumers’ appliances, and that it is operated consistently.


Which samples should be tested?


Instruction validation should be performed to ensure the instructions will allow the delivery of the required minimum thermal process using ‘worst case’ samples. Worst case samples are those defined as taking longest to heat. If trials are performed using ‘average’ or ‘mean’ samples then the worst-case samples would be unlikely to achieve the minimum safe thermal process. So, samples chosen for testing should be selected to have:



Every different product within a range should be tested as even slight variations may alter the cooking time required. For example, it is not acceptable to develop instructions for a soup and use these instructions for different soups without full testing. Likewise, any changes to a product, such as recipe or packaging, would necessitate further instruction validation testing.


Several (worst case) replicates need to be performed in each appliance to help ensure the attainment of reproducible results. We suggest a minimum of five are performed in each appliance. For example, if oven cooking is given as an instruction, a minimum of five ‘successful’ replicate tests should be performed in each oven type (gas, electric and fan-assisted) i.e. a minimum of fifteen trials. The term ‘successful’ refers to samples shown to receive the required minimum thermal process.


It is crucial that the cold spot (slowest heating location) is identified and the temperature at this location measured. Cold spots can be notoriously difficult to locate, especially with microwave heated foods (cold spots can be anywhere within the product - even at the surface) so thorough and careful temperature probing is necessary.


How should validation trials be recorded?


All information related to instruction validation trials should be recorded and retained for at least the life of the product. This provides evidence that trials were performed for due diligence reasons, but it can also build a reference database of products and suitable instructions (and a starting point for future instruction validation trials).


Contact: Greg Hooper
+44(0)1386 842039
greg.hooper@campdenbri.co.uk


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