This guidance document is intended to help food operators who process, prepare and handle food to
determine the shelf life of their food products and to apply appropriate date marking. It describes:
- how shelf life is defined;
- the causes of food deterioration and spoilage;
- why food may become unsafe during storage;
- how to decide whether a ‘best-before’ or ‘use-by’ date mark is required;
- the information needed to work out what the shelf life is; and
- how to ensure the safety of chilled foods.
The shelf life of many foods can be extended through various means including chilled storage. Low
temperatures slow down chemical changes and growth of many spoilage and pathogenic microorganisms (bacteria, yeasts and moulds) and any toxin formation. However some pathogenic bacteria are able to grow at the low temperatures used for refrigeration and chilled storage. These are referred to as cold-tolerant bacteria.
The type and length of storage may provide the suitable conditions and time for the cold-tolerant bacteria to grow in number so that the food becomes unsafe after a period of time, even if low numbers are present after manufacture. This will impact on the shelf life and safety of the food especially where the food is considered to be ready-to-eat. Ready-to-eat foods are those foods where there is no further processing that will reduce or eliminate harmful microorganisms before consumption.
The focus of this guidance document is therefore on determining the shelf life of chilled ready-to-eat foods.
This guidance document may provide some useful information for manufacturers and processors of other foods.
In this guidance document for any references to sections included refer to sections in this guidance document unless it is otherwise stated.
Ministry for Primary Industries