By Martin George - 27 June 2014

Verification is a key requirement for safe food production and confirms that a food safety system based around HACCP is working effectively. Guidelines on the application of the principles of HACCP tell us that validation activities are used to support the principle of verification. This is particularly true in the heat preserved foods sector, where the degree of thermal process has a direct bearing on the safety and quality of the food. However, validation of the heat treatment is becoming an increasingly difficult challenge - there is today an extensive and ever-growing range of food products preserved by means of thermal technologies, from full sterilisation to milder pasteurisation or cook-chill/freeze heat treatments. There is also a range of thermal process equipment used in manufacturing, such as continuous flow heating and cooling systems, hot-fill processes and even alternative technologies such as microwave, radio-frequency, and ohmic heating. It really is a considerable challenge to the food processor to prove the safety of the food product. A golden rule is that validation is a continuous exercise, ongoing throughout production, to demonstrate due diligence by the food manufacturer.

Among the things that those undertaking heat processing need knowledge of or help with are:

• microbial risks, product and packaging characteristics, critical factors, commercial equipment, and manufacturing procedures, and their effects on the delivery of a thermal process and maintenance of product sterility
• applicable regulations and codes of practice
• underlying principles, process calculations, analysis and evaluation tools
• appropriate design and methods of conducting thermal processing studies. Examples include heat penetration, temperature and heat transfer distribution studies, thermal–death–time experiments, and process validation and verification studies
• analysis of data generated by scientific studies, and evaluation of the effectiveness of a thermal processing and packaging system to ensure safe and commercially sterile products
• identification and evaluation of process deviations and spoilage incidents;
• documentation of process establishment methods and results, and communication of thermal process requirements and recommendations.

One of the most demanding challenges facing a food processor is to establish appropriate documentation regarding the processing equipment used for thermal processing studies. A useful tool is an 'equipment survey' and this can be helpful in documenting study test conditions, as well as helping plant management realize that other factors may have an effect on processing operations. Surveys should be periodically performed on all equipment to ensure that they remain consistently and properly installed to previously documented conditions. These may also be an important part of a plant's change control program. The USDA requires annual surveys or audits of retort systems, and others may follow this lead. Often, an independent check of the equipment, process conditions and factory environment can lead to a 'quick fix' of potential problems!

Our expertise in processing technology, process microbiology, packaging, chemistry, sensory science and legislation means that we can offer food manufacturers a really powerful support service in thermal process validation.

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