Notes on the text:

1. cut-отруб

2. proteolytic enzyme - протеолитический фермент

3. to involve - включать в себя

4. to inject - впрыскивать, вводить

5. dish - блюдо

6. gravy - мясной соус

7. commercial - промышленный

8. shelf-life - срок хранения

9. luncheon meat-мясо (консервированное) для завтрака

2. Why fish go bad

As soon as a fish dies, spoilage begins. Spoilage is a result of a whole series of complicated changes brought about in the dead fish by its own enzymes, by chemical action and by bacteria. It is necessary to understand something of the way in which these changes take place in order to make the fullest use of chilling of keeping them in check.

An important series of changes is brought about by the enzymes of the living fish which remain active after its death. They are particularly involved in the flavour changes that take place during the first few days of storage, before bacterial spoilage has become marked.

Millions of bacteria, many of them potential spoilers, are present in the surface slime, on the gills and in the intestines of the living fish. They do no harm because the natural resistance of a healthy fish keeps them at bay. Soon after the fish dies, however, bacteria begin to invade the tissues through the gills, along blood vessels, and directly through the skin and the lining of the belly cavity.

In addition to bacterial and enzymatic changes, chemical changes involving oxygen from the air and the fat in the flesh of species such as tuna and mackerel can produce rancid odours and flavours.

Thus, spoilage is a natural process once the fish dies, but chilling can slow down this process and prolong the shelf life of fish as food.

Effect of temperature on spoilage. There are three important ways of preventing fish going bad too quickly – care, cleanliness and cooling. Care in handling is essential because unnecessary damage can provide access through cuts and wounds for the spoilage bacteria, thus hastening their effect on the flesh. Cleanliness is important in two ways: 1) the natural sources of bacteria can largely be removed soon after the fish is captured by taking out the guts and washing off the slime from the surface of the fish; 2) the chances of contamination can be kept to a minimum by ensuring the fish is always handled in a hygienic manner. But most important of all, the fish must be chilled quickly and kept chilled.

The speed with which bacteria grow depends on temperature. Indeed, temperature is the most important factor controlling the speed at which fish go bad. The higher the temperature, the faster the bacteria multiply, using the flesh of the dead fish as food. When the temperature is sufficiently low, bacterial action can be stopped altogether; frozen fish stored at a very low temperature, for example -30°C, will remain wholesome for a very long time because bacteria are either killed or completely inactive at this temperature, and other forms of spoilage progress only very slowly. But, even at -10°C, some kinds of bacteria can still grow, although only a very slow rate. Therefore for long-term storage, of many weeks or months, freezing and cold storage are necessary.

It is not possible to keep unfrozen fish at a temperature low enough to stop bacterial action completely, because fish begin to freeze at about -1°C. however, it is desirable to keep the temperature of unfrozen fish as close to that level as possible in order to reduce spoilage; the easiest and best way of doing this is to use plenty of ice which, when made from clean fresh water, melts at 0°C.

At temperatures not much above that of melting ice, bacteria become much more active and fish consequently goes bad more quickly. For example, fish with a storage life of 15 days at 0°C will keep for 6 days at 5°C and only about 2 days at 15°C before becoming unacceptable.

Notes on the text:

1. complicated – сложный

2. enzyme – энзим, фермент

3. chilling – охлаждение

4. involve – вовлекать

5. intestines – кишки, кишечник

6. invade – проникать

7. mackerel – скумбрия

8. prolong – продлить

9. prevent – предотвращать

10. access – доступ

11. contamination – загрязнение