By-products of the fishery industries

By-products include fish oil used both industrially and for feeding purposes, liver oil used medicinally, fish meal, fish glue and isinglass.

Fish oils. Fish oils are liquid fats and consist chiefly of various proportions of glycerides and saturated and unsaturated fatty acids. Fish oils are obtained from oil parts of fish, whereas the fish liver oils are prepared from the livers only. Increasing interest in fresh liver oils as concentrated sources of vitamins A and D has led to a rather general use of many types of fish livers for this purpose.

Although many liver oils have been examined from time to time the only one that is of commercial importance is that of the cod, of which enormous quantities are produced. The great importance of cod liver oil lies in its value as a curative agent in those diseases which аre caused either directly or indirectly by malnutrition.

Since the nutritive and therapeutic properties of cod liver oil is due to its content of the vitamins A and D, it is necessary to use special precautions not to destroy these components during the preparation, refining and storage of the oil.

Blubber oils from marine mammals. Seal oil is obtained from the blubber of various species of seal. Whale oil is extracted from the blubber of various species of whale. The first operation consists in stripping the blubbers from the dead whale; huge pieces аre put through the chopping machine, taken up by an elevator and dropped into the cooker. Steam is turned on and after a sufficient period, generally six to eight hours the oil runs off through a system of separating tanks to get rid of the free water, then into the store tanks.

Fish meal. Fish meal is highly concentrated, nutritious feed supplement consisting principally of high-quality proteins, minerals and B-complex vitamins. It is obtained through the fish reduction process which consists essentially of grinding, cooking, pressing, and drying of fish scrap obtained from filleting or canning operation or by processing whole fish as herring, capelin, and pilchards. The moisture content of the resultant scrap must be 50–60 per cent. In the continuous drying drum the moisture content is reduced to 8–10 per cent.

From the drying drum the material is fed to the hacking device then for sieving, and to the magnetic trapping device.

Fish meal possesses exceptionally good nutritional value. It furnishes, in concentrated form, high quality proteins which contain all of the essential amino acids and it is particularly high in lysine. It furnishes some of the B-complex vitamins, namely, riboflavin, niacin, pentothenic acid, choline, and B12.

Fish meal is high in mineral content ranging about 35 per cent for a high protein meal to about 12per cent for a low protein meal. It is particularly high in bone and tooth building minerals, i. e. calcium and phosphorus. It also contains most of the minerals that are necessary for building up or maintaining the animal body, namely, copper, and some traceelements.

Fishglue and isinglass. Practically all of the glue manufactured today are made from the waste products of fish especially from the sounds (bladders) and scale. The glue stock must be freed from salt or freshened before being made into glue. And then after special treatment with alkali and saline acid it is cooked at 70–80 degree C. Isinglass is an excellentraw material for producing fish gelatin.

Exercise 4. Find the Russian equivalents for the following:

liquid fats, nutritional value, special treatment, the magnetic trapping device, the continuous drying drum, an excellentraw material, the hacking device, traceelements, to be particularly high in, after special treatment, the fish reduction process, a system of separating tanks.

Exercise 5. Find the English equivalents for the following:

производство рыбного желатина, исключительная пищевая ценность, дробилка, на просеивание, мука с высоким содержанием белковых веществ, мука с низким содержанием белковых веществ, магнитная ловушка, клеевое сырье, микроэлементы, добавка в корм, недостаточное питание, морские млекопитающие, дезинтегратор, иметь промышленное значение.

Exercise 6. Complete the sentences using information from the text:

1. Fish meal possesses exceptionally…

2. Isinglass is an excellentraw material for…

3. Fish meal is high in…

4. The great importance of cod liver oil lies in…

5. Fish oils are obtained from…

6. The moisture content of the resultant scrap…

7. Fish meal is highly concentrated, nutritious feed supplement…

Exercise 7. Fill in the blanks with prepositions from, of, for, with, by, to, in, into, on, at, through:

1. Fish meal is high … mineral content.

2. Practically all … the glue manufactured today are made … the waste products.

3. … special treatment … alkali and saline acid it is cooked … 70–80 °C.

4. It also contains most … the minerals that are necessary … building up and maintaining the animal body.

5. Huge pieces аre put … the chopping machine, taken up … an elevator and dropped … the cooker.

Exercise 8. Say if the sentences are true or false using the information from the text:

1. The great importance of cod liver oil lies in its value as a curative agent.

2. Practically all of the glue manufactured today are made from the high quality fish.

3. From the drying drum the material is fed to the magnetic trapping device.

4. The glue stock must be freed from minerals and freshened before being made into glue.

5. Fish oils are liquid fats and consist chiefly of various proportions of glycerides and saturated and unsaturated fatty acids.

6. In the continuous drying drum the moisture content is reduced to 20–30 per cent.

7. Isinglass is highly concentrated, nutritious feed supplement consisting principally of high-quality proteins, minerals and B-complex vitamins.

Exercise 9. Put the verbs in the brackets into the correct tense and form:

1. The factories (to mount) the new modern equipment for fish meal production recently.

2. The lowest price for fish oil (to cause) by rather large by-catch of fish last year.

3. Potential customers (to recommend) to pay great attention to the quality of the product.

4. The company (to use) this new technological method already for six months.

5. Fish meal (to know) to possess exceptionally good nutritional value.

Exercise 10. Answer the following questions:

1. Where are by-products used?

2. Why are they important?

3. What by-products are usually produced?

4. How is fish meal produced?

5. What devices are used for its production?

6. What minerals does it contain?

7. What is fish meal used for?

8. What is the difference between fish oil and cod liver oil?

9. What is the importance of cod liver oil?

10. What by-products are produced from waste products of fish?