10 Chilled and frozen storage Theoretically, there are clear differences between the environmental con- ditions required for cooling, which is a heat removal/'temperature reduction process, and those required for storage where the aim is to maintain a set product temperature. However, in many air-based systems, cooling and storage take place in the same chamber and even where two separate facil- ities are used, in many cases not all the required heat is removed in the cooling phase. This failure to remove the required heat can be due to a number of causes insufficient time allowed insufficient refrigeration capacity to cater for high initial product load overloading variability in size of products incorrect environmental conditions. Extensive data are available on the optimum storage conditions and attainable chilled and frozen storage lives for many products(IIr, 2000; IIR, 1986; ASHRAE, 1998) torage life terms There are a wide range of rather confusing definitions used to define sto life. The EC directive( Commission of the European Community states simply that frozen storage must preserve the intrinsic characteristics of the food. Although this is probably every food technologists aim, many different criteria can be used to measure these characteristics. The Iir10 Chilled and frozen storage Theoretically, there are clear differences between the environmental con￾ditions required for cooling, which is a heat removal/temperature reduction process, and those required for storage where the aim is to maintain a set product temperature. However, in many air-based systems, cooling and storage take place in the same chamber and even where two separate facil￾ities are used, in many cases not all the required heat is removed in the cooling phase. This failure to remove the required heat can be due to a number of causes: • insufficient time allowed • insufficient refrigeration capacity to cater for high initial product load • overloading • variability in size of products • incorrect environmental conditions. Extensive data are available on the optimum storage conditions and attainable chilled and frozen storage lives for many products (IIR, 2000; IIR, 1986; ASHRAE, 1998). 10.1 Storage life terms There are a wide range of rather confusing definitions used to define storage life. The EC directive (Commission of the European Community, 1989) states simply that frozen storage must ‘preserve the intrinsic characteristics’ of the food. Although this is probably every food technologist’s aim, many different criteria can be used to measure these characteristics. The IIR