III.3. Prevention of spoilage of fish after processing

Although the spoilage process of fresh fish can be inhibited through various curing methods, cured products may still become inedible due to other causes such as mould or insect attack. The subject of losses in cured fish has been reviewed in detail by FAO (1981). It is hoped that the research and development programme recommended in the FAO study will yield improved techniques and reduced losses.

The storage life of cured fish will depend on the adopted curing methods and packaging. Cooking inhibits spoilage by destroying bacteria and preventing certain chemical changes. Tropical fish cook at temperatures over 50° C, although higher temperatures are usually used to reduce the time required to complete the process. Boiling fish in water for a few minutes is, for example, a popular process in South-East Asia. It must be stressed, however, that the preservation of fish due to cooking alone is short term unless recontamination by bacteria is prevented by canning or a similar process. Canned fish can be kept for a long time but the process is expensive and may not be suitable if retail prices are to be kept low. Cooked fish, such as boiled or hot-smoked products, must also be salted and/or dried if a storage life of more than two days at tropical temperatures is required.

The storage life of cured fish may be increased if the following measures were adopted:

- To ensure sufficient drying of the fish in order to avoid attacks by certain bacteria or moulds during storage.

- To use appropriate packaging, and to store packaged goods in cool storage areas protected from dust, insects, etc.

- To avoid excessive smoking and drying of fish if losses are to be avoided through the breaking of fish into small pieces.

- In general, it would be useful to process the right amounts of fish at a time, so that the whole output can be sold within the estimated storage life of the processed fish. It would not make sense to process much more than can be marketed within a given period of time, and have the surplus thrown away because it is not anymore fit for consumption.

More information on the various measures needed to prevent the early spoilage of fish will be further elaborated in the following chapters.