III.2. Prevention of spoilage of fish during processing

A number of measures may be adopted in order to minimise the spoilage of fish during processing. They may include the following:

- To keep all tools, fish boxes, boat holds, cutting tables etc. clean by washing with clean water. Where drinking water is available, to use it to wash the fish before and during processing, for example, after gutting or splitting the fish.

- To prevent fish offal (guts, heads, gills, etc.) from coming into contact with cleaned fish. Also, the fish working area should be cleaned regularly, at least once a day by removing all offal and dirt which might contain bacteria or attract insect pests such as flies. All offal should be removed from the working site. It may be used as fertiliser, or buried. It should not be thrown into the water near the work site as this practice fouls the water and may attract insects.

- To ensure that high standards of personal hygiene are maintained. Fish processors are handling food, and hands should always be washed before starting work and particularly after visiting the toilet. People who have infected wounds, stomach complaints or any contagious disease, should not be allowed to handle the fish.

- To ensure speed during processing. The longer the time required by processing, the greater the amount of spoilage which will occur before processing is completed.

- If possible, to keep fish in boxes and off the ground. Work, such as cutting fish prior to salting or drying, must be carried out on tables, not on the ground where the fish will become dirty and pick up bacteria.

- To protect the fish from rain and to use salt during drying in order to avoid the spoilage of fish through bacterial, mould or insect attack.

- To use well-designed smoking kilns or ovens in order to avoid the over-cooking of fish which may catch fire or become excessively brittle.

- To protect the fish against insect infestation during processing. Blow-flies lay their eggs in the fish while they are still moist and the larvae eat the flesh. Beetles, such as the hide beetle, lay eggs in the fish as they are drying and the larvae eat the flesh even when it is quite dry. Damage can be reduced by ensuring that processing waste is properly disposed of so that there are no places for insect to breed. Using better salting techniques may help since insect larvae are not attracted by heavily salted fish. Techniques which speed the drying process are useful in countering blowflies. Temperatures in excess of 45°C decrease infestation by fly larvae although 20 hours at this temperature is required for complete de-infestation. Fumigation or heat treatment such as resmoking can be used to kill beetle pests. 40 minutes at 70° C is generally sufficient to kill insects in a dried product.