All food has a limited shelf life which will vary depending on the type of food, how it is packaged and how carefully it is transported and stored.
The storage life of food products is influenced by many factors, including:
- microbial growth
- chemical changes such as a slow development of brown colour and/or flavour changes
- rancidity in fats
- water uptake or loss (can affect texture or other food attributes)
- warm storage
- bright light
- high humidity
The environmental conditions under which food is stored also influence storage life. Water uptake or loss can affect texture and other food attributes. Warm storage temperatures, bright light, air (containing oxygen), and high humidity all shorten storage life – and ultimately affect your product quality, price and marketability.
Appropriate packaging and refrigeration can substantially reduce the rate at which food will deteriorate. Low temperatures slow the growth of microorganisms and the rate of chemical (including enzymic) changes in food.
Many factors are critical in maximising shelf life, such as ingredient selection, processing techniques and packaging, as well as handling practices, storage protocols and cold chain transport solutions.
It is important to check that your storage room or refrigerator is operating correctly. Your thermometer should show a temperature below 5°C in the main section of the refrigerator.
Avoid crowding stored products in the refrigerator, ensure good air circulation around each item. Proper storage not only keeps your products in good condition and safe from the growth of food poisoning bacteria, but saves you money because it reduces waste.
The responsibility of determining the shelf life of a food, and thus its best-before or use-by date, lies with the manufacturer/packer.
The most direct way of doing this is to conduct properly constructed storage trials under realistic, defined conditions. This may not be possible for smaller manufacturers, in particular those just entering the market so you may need to call on the services of a specialist to complete this process. It is essential to test shelf life and have your testing data and evidence available to reduce your business risk and to present to potential customers for your product, as without it, some customers will simply refuse to stock your product.
Retailers may also have their own demands about shelf life of particular product categories especially those with a relatively short shelf life.
In South Australia, the South Australian Research and Development Institute (SARDI) employs food technologists who provide a service to South Australian food businesses using a range of methods and models to investigate shelf life and use-by dates.
It is an offence to sell a packaged food past its use-by date and this form of date marking is tied to food safety. There are two types of date marking of foods in Australia. These are ‘best-before’ and ‘use-by’. The length of time used to calculate these dates is determined by how long it takes for the product to begin to deteriorate or to become less nutritious or unsafe. There is also an option to date mark bread with a shelf life of less than seven days with a ‘baked-on’ or ‘baked-for’ date.
The legal requirement for manufacturers of packaged foods to open date mark foods was introduced in Australia in 1978. This followed similar moves internationally and the publication of a standard by the Codex Committee on Food Labelling. It was argued by consumer groups that with the rapid changes occurring in food manufacturing, packaging and retailing, consumers could no longer rely on traditional wisdom and habits to dictate how long a food may be stored.