Food spoilage and the rate of which it does so varies from product to product. Most foods change progressively during storage, and these changes in most cases render the food less attractive and palatable – ultimately ending up unfit for consumption. In her latest blog, Zarina Mohd, process manager at Integrated Food Projects takes a look at how the ‘spoilage qualities’ of a food product affect its shelf life and what food manufacturers can do to extend this.
The safety standard of our food is not only fundamental for public consumption, but it is a legal requirement too. Once food has been stored for a certain period, one or more quality attributes of a food may reach an undesirable state. At that time, the food is considered unsuitable for consumption, reaching the end of its shelf-life. This is usually at a point where it will likely be rejected by the customer or become harmful to the person consuming them.
Physical, chemical and microbiological changes are the leading causes of food deterioration. Physical changes are caused by mishandling of foods during harvesting, processing and distribution. The most important chemical changes in foods are associated with oxidative reactions, enzymic action and non-enzymic browning, which cause products to deteriorate. Microbial growth in food results in spoilage with the development of undesirable sensory characteristics and in certain cases the food may even become unsafe for consumption.
There are various measures that are used to minimize or prevent microbial growth in foods, including altering the temperature to slow the growth process or to destroy the microbes, removing water; or controlling the environmental gases and pH level.
The responsibility for determining food shelf-life lies with the manufacturer. Food that’s marked with a ‘use by’ date is highly perishable and constitutes an immediate danger to human health after the expiry date. The ‘best before’ date on packaging is the date up to and including when the food will retain its specific properties, providing it has been stored properly. Food may still be edible after that, but its appearance and quality could suffer. Clear storage instructions are required alongside the ‘best before’ date if the food is to be enjoyed at its best. It is the manufacturer’s responsibility to decide whether a ‘use by’ or ‘best before’ date is the appropriate indication for the consumer.
Food shelf-life determination is often subjective, so a trained assessor can be brought in to judge the appearance, smell, texture and flavour of food products. Consumer panels producing statistically analysed results can also give the best measure of storage changes and acceptability. The determination of a new product requires storage for significant periods and includes samples from early development stages as well as initial production runs. A direct way of determining shelf-life is to conduct storage trials under defined conditions that mimic the experience during storage, distribution, retail display and consumer use. This direct approach may be unacceptable if the extended shelf-life is too long. Accelerated shelf-life determination (ASLD) is often used to shorten the time required to estimate a shelf-life which can otherwise take a very long time. The most common form is storing food at an elevated temperature; however, the results must be interpreted carefully, based on detailed product knowledge and sound scientific principles.
Shelf-life determination should consider all stages during the manufacture of a food product, including information and data about the raw materials used, product composition and formulation, product assembly and processing techniques. The principles of HACCP are equally applicable to the identification of hazards that reduce shelf-life and the management of CCP’s associated with them.
There is also an environmental consideration on the of shelf life of food products. Growing, processing, packaging and transporting the food we eat all contributes to climate change. Expiry dates on product packaging is a key contributor to food waste as it is not possible for retailers to sell products after their ‘use by’ date. Consumers tend to lack an understanding of food quality – leading to a high percentage of food waste, with consumers erring on the side of caution and throwing away perfectly edible food. Extending the shelf-life of a perishable product by just one day can reduce tonnages of food waste in a year. The extension of shelf-life is critical to attract consumers, giving them a larger window to consume the product. The food industry is constantly working on new technologies and safe methods to lengthen the shelf-life of foods.
Knowledge on factors affecting shelf-life is important to all involved in the manufacture, processing, distribution, sale and consumption of food products. Food safety and product shelf-life are inextricably linked; and a proper evaluation of shelf-life must be grounded on sound scientific principles, supported by up-to-date techniques in food science and technology. Reducing food waste is good for the economy, good for food security and good for the environment. It’s important for consumers to be educated on the impact of their behaviour in terms of buying, preparing and storing food in order to reduce their own environmental impact.
The shelf-life of foods is a multi- disciplinary effort throughout the entire supply chain, and the determination starts with the careful application of good practices in food manufacture and processing.
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