Factors affecting shelf-life

1. Raw materials

  • If incorporated into another product without being processed or significantly changed (e.g. chilled ham placed on a chilled raw pizza or included in a sandwich), the life of the final product should not exceed the life declared for the raw material.
  • If a raw material is changed during processing (e.g. by being cooked) or if the storage requirements change (e.g. chilled raw material but frozen final product) the life given to the final product should be re-assessed.
  • The food safety controls used to set the raw material life should be understood to ensure that any impact a change may have is understood. Examples are:
    • if a raw material has a long shelf life due to being very dry (low Aw) and it is then added to a wetter product (higher Aw), the shelf life is likely to reduce.
    • if packed in Modified Atmosphere Packaging (MAP), the shelf life only applies whilst the packaging remains sealed and the shelf life may significantly reduce when the package is opened e.g. a bag of salad is opened and the salad added to a sandwich. Even if MAP has not been employed, fresh produce will naturally modify the atmosphere in the pack and so again opening the pack may have an impact on the remaining life.

2. Product description

The type of recipe (e.g. sliced honey roast ham) is not sufficient information on which to base the shelf-life of a product and therefore it is inadvisable to simply copy the life assigned to someone else’s product or from a similar in-house recipe. For products where Listeria monocytogenes is a hazard, shelf life must be established according to Annex II of Commission Regulation (EC) 2073/2005 on Microbiological Criteria for Foodstuffs as amended. FSA Guidance on EC Regulation 2073/2005 as amended by EU Regulation 1441/2007 is also available.

  • Controls used in a designated ingredient to ensure food safety such as pH, type of acid, preservative, water activity and humectant may be specific to that ingredient and may not be of the same type, added in the same quantity or may not be present at all in similar ingredients. Once combined in a recipe, their effectiveness may also be reduced or increased on interaction with other ingredients.
  • The mix and quantity of ingredients used in the recipe may also affect parameters such as leaching of colour in layered product or the rate of fat oxidation, which in turn can influence consumer acceptance and therefore the shelf life of the product.

3. Type of packaging

  • Use of MAP for the food being produced may enable a longer shelf-life to be assigned than would otherwise be possible.
  • Vacuum packaging can extend product life by removing all air from a package which is then sealed. The removal of the air is the key factor for preservation in these products although it should be noted that for some chilled foods this can increase the risk from some types of food poisoning bacteria, e.g. Clostridium botulinum, that will only grow in the absence of oxygen and in such cases additional controls will be required to be used in combination.
  • ‘Active’ packaging materials in the form of sachets or altered packaging materials may be used to extend life either by adding or removing gases (e.g. oxygen) from a pack over life or by controlling the rate at which certain gases can pass through the film.
  • Different packaging materials may react differently on contact with food and consideration should be given to potential migration of chemicals from different packaging materials over time.
  • ‘Secondary’ and ‘tertiary or transport’ packaging must not be ignored for these will often be designed to protect the primary packaging in direct contact with the food e.g. glass jars are designed to protect the food whilst the tertiary and secondary packaging are designed to protect the glass jar during its journey along the rest of the supply chain. Knowledge of the supply chain and handling requirements will be needed to ensure that external packaging carries sufficient information to ensure the primary pack and product is stored and handled correctly.

4. Temperature

  • The temperature to which foods are exposed may greatly affect the length of time that a food remains safe or of a suitable quality for consumption. Selection of the most appropriate temperature regimes and applying them consistently is therefore extremely important not just for finished product but also during preparation.
  • Consideration must be given to what can reasonably be expected to happen once the food has left your control and it should be noted that allowing for ‘abuse’ or mishandling is a legal requirement under the Consumer Rights Act 2015, the commentary for which states:
    ‘the test of whether or not the quality of the goods is satisfactory is determined by what a reasonable person would consider satisfactory for the goods in question, taking into consideration all relevant circumstances…’
    Therefore, while instruction may be given for a food to be stored at +5oC or below, as it is reasonable to expect higher temperatures to occur in a consumer’s car and that the food will actually be held at below +8oC due to the normal operating temperature of a domestic fridge, these temperatures must be allowed for when setting the shelf-life. In some cases, the difference between the safe shelf life that can be obtained under ideal conditions and the shorter shelf life that occurs when allowing for such abuse is referred to as a ‘buffer’. However, it is advisable instead to think of this as a safety zone designed to protect both the consumer and the manufacturer or seller of the food.
  • If food is exported, do not assume that your product will be handled or stored under the same conditions as in your own country. The business to consumer supply chain should be considered in setting the appropriate shelf life. This will require investigation.

5. Hygiene

Product design and assessment in isolation does not provide enough information to enable the setting of shelf-life in relation to food safety. It is therefore important to consider:

  • Building design
    The environment used for storing and handling both foods and food contact packaging will commonly range from a high risk environment where the aim is to prevent contamination from micro-organisms to a low risk area where the aim is to minimise the growth and contamination of micro-organisms. In some cases, there may even be ‘zero care’ environments such as outside catering. Clearly the lower the level of control achieved, the greater the risk of contamination that could immediately, or after a period of time, create a food safety problem.
  • Process design
    Bacteria are highly unlikely to be completely absent from anything other than highly specialised food production areas or types of foods (e.g. NASA’s meals for astronauts) and so it is important to build up a clear picture of where bacteria may exist, how quickly numbers increase and how they might contaminate the food. The effectiveness of cleaning, the length of time equipment is used before being cleaned and the sources of bacteria should therefore be carefully assessed. It is advisable to make use of laboratory testing to analyse findings and validate hygiene programs.
  • Equipment design and storage
    • The harder equipment is to clean and the longer it takes to clean, the less likely it is to be cleaned and disinfected effectively.
    • It is unlikely that equipment will remain in a hygienic condition indefinitely without specific controls being applied. The frequency of use and the controls in place to prevent recontamination of clean equipment should therefore be understood before deciding upon the shelf-life to apply.

6. Expected usage after opening

Different foods can be expected to be used in different ways from a packet of cereal being opened and lasting a number of weeks to an ice cream lolly that is likely to be consumed immediately on opening.

  • Where there is any likelihood of a foodstuff not being consumed immediately on opening, this secondary or open life must also be allowed for taking into account all of the factors described above in relation to the food and the consumer’s environment such as a domestic kitchen.
  • It is a legal requirement to provide the consumer with any special instructions ‘if they will need them to use the food appropriately’1. This includes instructions on preparation such as defrosting or cooking, how to store the food once the package is opened, or to consume immediately.

1Defra Guidance on Food labelling: giving food information to consumers (June 2015)

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Last reviewed: 05 Jun 2018