Texts for home-reading (II course)

TENDERIZED FRESH MEATS

Enzyme tenderization of fresh meats particularly of certain beef cuts,¹ has been a long practice. A proteolytic enzyme² such as pa­paya is usually used. The meat products are dipped in enzyme solu­tion and then frozen. Another tenderizing process involves³ injecting⁴ an enzyme solution into the blood stream of the animal before slaughtering it.

Many frozen meats fall in the category of processed meat prod­ucts. The cooking and rapid freezing of certain meat dishes⁵ is a well-established practice. Generally the precooked meat items hold up^ better in frozen storage if they are covered with gravy.⁶

Canned meats are meats that are preserved by heat sterilization while enclosed in cans or glass jars. They may or may not be pre­cooked prior to being placed in the container. If finely divided ma­terials are to be processed and if it is desirable that they remain in this finely divided state, it is necessary that these items be precooked prior to being placed in the container. The containers are processed at 104.4 - 126.7°C for periods of time sufficient to inactivate most bacteria. This kind of treatment results in a commercially⁷ sterile product.The shelf-life⁸ of these items is very long. Certain canned meats are produced without inducing complete sterility. These include items such as canned hams, luncheon meat,⁹ etc. These items are generally reacted with curing ingredients and then processed to tem­peratures of approximately 71.1°C while in the can. Such items gene­rally require storage at refrigeration temperatures of 4.4 - 10°C and are very stable at these temperatures, having shelf-life of approxi­mately 2-3 years or longer.

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

 

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

 

CHILLED FISH

The chilling of fish is a process by which the temperature of fish is reduced close to (but not below) freezing point. It delays the biochemical and bacteriological processes in fish and consequently prolongs the storage life of fish products.

Fresh fish or fish products that have been exposed to cold until they are near freezing point are called chilled. The biochemical and bacteriological processes in them are merely delayed, and not stopped; their storage life is therefore prolonged and will last so long as spoilage has not become sufficiently far advanced to impair their value as food. The storage life of a chilled product depends mainly on the quality of the raw fish, on the method and duration of chilling, and the conditions of storage.

The freezing point for fish is between –0.6°C and -2°C, depending on the species and on the concentration of intercellular fluid. It is usually taken as –1°C. During chilling the heat transfer between the food product and the coolant is often is accompanied by weight transfer (e.g. through evaporation from the surface with air chilling); chilling must therefore be regarded as a complex process of heat and mass transfer.

The important considerations in preparing good quality chilled fish products are the biochemical and physical changes in the fish during chilling time, the temperature conditions, the chilling time, and the equipment and technology used.

Before chilling the fish are graded for species and size, their quality must conform to the technical requirements and is determined both by organoleptic signs and by physical and chemical information derived from laboratory analysis of specimens or by other means. Fish to be processed into frozen fillets or to be delivered in ice to the consumer may be live or dead, but must be absolutely fresh.

Changes occurring during chilling. During chilling important physical and biochemical changes take place in the product. The physical changes generally entail an increase in the density of tissues and in the viscosity of tissue juices and blood, and a loss in the weight due to partial evaporation of moisture from the surface desiccation during air chilling. The extent of desiccation depends on the properties of the product and coolant and on the conditions of chilling. The main properties of the product on which desiccation depends are its specific gravity, the size of the individual fish, and the type of packaging during chilling and storage.

The more water there is in the product, the more moisture will evaporate from the fish; lean fish consequently is more subject to dehydration than fatty, which contains relatively less water. The subcutaneous layer of fat offers protection against evaporation from the tissues. Products with a higher specific gravity contain more organic matter and therefore relatively less water. The evaporation surface depends on the size of the individual fish. Depending on its properties the packaging may offer complete protection against evaporation, or may impede and delay the process; but if it is hydroscopic, it will absorb moisture from the fish.

Chilling time. The chilling time of fish and other marine products depends on their properties of the coolant, and the conditions under which the process takes place (cross-section of the product, thermal efficiency, specific gravity, temperature of the coolant, type of motion and velocity of the coolant, humidity, heat transfer coefficient from product to coolant).

Fish chilling practice. The methods employed for chilling fish and other fishery products are very varied, but may be divided into two groups according to the type of coolant: a) methods of chilling in a homogeneous coolant (as when fish are chilled in cold liquid, for example), and b) methods of chilling in heterogeneous coolant (for instance in ice).

Fish are very seldom air-cooled at a temperature of -2° to – 3°C, because they chill slowly in air and deteriorate in appearance both while being chilled and during subsequent storage. The most used commercial methods of chilling are by immersion in a cold liquid, by spraying with cold brine, or by packing in crushed ice. Of these three methods the least used is brine-spraying, and the most used is chilling in crushed ice. The method of chilling in liquid is to immerse the raw fish in the cold liquid (fresh water, brine or sea water). fresh water, which freezes at 0°C, can only be used if the fish are to be lightly chilled. To chill fish thoroughly down to 0°C or –1°C, it is necessary to use either brine (for example a 2 per cent solution of sodium chloride) or sea water, both of which have a freezing point below 0°C, and can be kept at a temperature within – 3° and - 4°C throughout the chilling process. It goes without saying that, since the fish are in direct contact with the liquid during chilling, the solution must be perfectly harmless to man.

 

Notes on the text:

1. that have been exposed to cold until they are near freezing point – которые охлаждены почти до точки замерзания

2. storage life – продолжительность хранения

3. to impair their value – чтобы ухудшить их пищевые качества

4. intercellular fluid – внутриклеточный сок

5. heat transfer – теплообмен

6. weight transfer – массообмен

7. by spraying with cold brine – орошением холодным рассолом

 

HANGING

The split fish have to be stretched out somehow so as to ensure thorough exposure to the smoke, and practice varies considerably from place to place. Typical methods are handing on pairs of hooks, nailed at regular intervals along a wooden “tenter” stick or threading through the “lugs” on pointed metal “speats”. In the case of large “finnans”, a loose hook is sometimes clipped onto the projecting backbone in order to prevent the soft flesh of the “lugs” from tearing under the weight of the fish. Fillets tend to tear if hung by hooks through the flesh. They laid over either pairs of wooden strips or a metal loop, sometimes closed at both ends. “Reds” and bloaters are “speated” through the gill and mouth with wooden or metal rods, and sprats, when hot-smoked for canning as “sardines” are threaded the eyes on thin “speats”. Buckling with heads on are sometimes threaded in pairs on sticks. If smoked after beheading, they can be speated through the thickets part, or else suspended by a clip on the tail, although in this case any roe is liable to drop out of the fish, and liquid exuding during the cooking process drips onto the fish below, leaving unsightly stains. Predrying such hotsmoked fish for a period of half an hour or so at fairly low temperature, not above about 40°C is desirable for its effect on toughening the flesh so that it is not so unduly softened as to tear during the subsequent stage of cooking at higher temperatures. “Arbroath smokies”, which are headed and hot smoked, are tied in pairs with string. Sticks can be inserted in the gut cavities to keep the fish open and thus ensure through exposure to the smoke. Large whole split fish, such as salmon, are suspended by the tail and kept flat open during smoking by means of steaks or metal skewers threaded through the flesh. Salmon fillets are suspended by a loop of twine through a hole made in the “lug” gust under the “shoulder lone”. Many of those devices leave unsightly holes in the fish, and wooden tenter sticks, metal speats, etc., are difficult to keep clean. Fillets have wet, unsmoked patches where they touch the stick. Furthermore, the operation of hanging and unbanging is manually laborious, particularly with small fish. Only in Norway has any attempt been made to mechanize the threading on rods of even such tiny fish as sprat and immature herring.

Fish can be smoked satisfactorily on wire gauze trays, provided that the mean does not mark the skin or flesh excessively, and this practice is quite normal in North America, the fish hewing tilted a little so that smoke rising upward contacts both sides. With a mechanical kiln delivering horizontal flow of smoke, tray smoking seems just as convenient as hanging vertically, and more easily adaptable to mechanization.

 

Notes on the text:

1. hang (hung) – вешать

2. ensure – убеждаться

3. considerable – значительный

4. thread – нить

5. backbone – позвоночник, хребет

6. back – обратно

7. bone – кость

8. tear – рваться

9. loop – петля

10. gill – жабры

11. can – мочь

12. suspend – подвешивать

13. tail – хвост

14. roe – икра, молоки

15. stain – пятно

16. device – прибор

17. attempt – попытка

 

FOOD PRESERVATION

Though some foods, such as rice, wheat and other cereals can be stored for years before they deteriorate, other foods, such as fish and meat, normally deteriorate quickly. For different types of food different methods of preservation are suitable.

The traditional methods of drying, smoking, salting or pickling food were widely used long before it was known why these methods were effective. It is now known that the processes of decay are accelerated by enzymes already present in the food and by bacteria or other microorganisms which may be already present or may come from external sources. To preserve food from decay, it is necessary either to destroy the bacteria or to create an environment in which cannot multiply and enzymes are inactivated. Bacteria can be destroyed by heat and be inactivated by dehydration. Enzymes can be inactivated by cold or by reducing the moisture content.

The moisture content of food can be reduced by drying in the sun or by other means fish suspended over smoking fire is partly dried and the smoke also has bactericidal properties. Salt and vinegar are also effective preservations, which is based on some physical principles.

Heat can be used to destroy bacteria and stop enzymic activity in food. The food is sealed in a can so that bacteria couldn’t come from the external sources. The can is then heated to a temperature sufficient to sterilize the contents. The length of time and the temperature required for sterilization depend on the product and on the type of bacteria to be destroyed.

It is important that the contents of the can are heated uniformly. The exact temperature can be controlled by means and the thermo-couple inserved into a can.

 

Notes on the text:

1. cereals – зерновые

2. preservation – сохранение, консервирование

3. to store - хранить, сохранять

4. deteriorate - портить(ся)

5. suitable – подходящий

6. drying – вяление

7. smoking – копчение

8. pickling – маринование

9. decay – гнить, разлагаться

10. enzyme – фермент

11. environment – среда

12. multiply – увеличивать, размножать(ся)

13. dehydration – обезвоживание

14. moisture – влага

15. to suspend – подвешивать

16. content – содержание

MARINE POLLUTION PREVENTION

Civilization has its sunny and cloudy sides. The vessel traffic in the World Ocean is constantly growing; as a result the risk of marine pollution is greatly increasing. The pollution of the sea has reached a very dangerous level and presents a serious threat to sea life and to the whole mankind. Marine pollution protection has become a global problem. We cannot stop progress but we can and must unite our efforts in protecting our planet.

That’s why in 1973 the International conference adopted the Convention for the Prevention of pollution of the Sea by Oil. According to it ships should be equipped with technical facilities that prevent the possibility of discharging waters containing oil or oil products into the sea. If a ship notices an oil slick the captain should immediately inform the authorities about it. No matter how that oil has spilled into the sea, the inspectors have to make up a violation report.

In this case it is very important for the ship to prove that they haven’t discharged any oil products overboard. They must show that the bilge water passes through a separator, that it is registered in the Oil Record Book. They must also prove that they have not violated the international Convention for the Prevention of Pollution of the Sea by Oil. They should also settle the matter with another ship in the vicinity.

On board every ship there must be a sewage treatment plant. It operates continuously during the ship’s stay in a port and in areas closed to discharge of sewage. The ship must be equipped with a system to comminute and disinfect the sewage. All the sewage is collected in the sewage tank. It is allowed to discharge overboard waters from sewage system at full speed when the ship is more than 300 miles off the coast.

The crewmen should also be informed of the Regulation according to which the disposal of all kinds of plastics into the sea is prohibited.

Food wastes should be stored in special receptacles and in the port dry rubbish and garbage should be taken away by ash-boats.

Unfortunately, these days a threat to sea life is still growing. Fish may no longer be healthy food. Studies show that parts of the North Sea contain pesticides, oil and poisonous metals such as cadmium, some of which has found its way into the liver tissue if fish. This could affect products such as cod liver oil.

 

Notes on the text:

1. traffic – движение

2. threat – угроза

3. facilities – средства

4. slick – пятно

5. violation – нарушение

6. bilge water – трюмная вода

7. sewage – сточные воды

 

DRYING OF FISH

Drying after salting is one of the oldest ways of preserving fish which gives a product a long storage life. Both mechanical and natural drying are used. Fish that is dried naturally becomes desiccated and undergoes complicated biochemical protein changes as a result of which it loses its raw flavour. It can then be eaten as it is, without cooking.

The curing of smelt and other small fish by hot drying is a widespread and commercially important method of processing. In recent years vacuum drying has been used more and more. There is drying under natural conditions. Fish dried at a temperature hot exceeding 35 C, give a tasty and valuable product. The fish are usually hund on racks in the open air in warm and dry weather, or are dried in special chambers.

The drying process consists of a gradual loss of weight moisture evaporation. At the same time, complex biochemical processes take place.

To insure uniform salting and drying the fish are first graded for size, then fed into the salting vat, natural 20 per cent brine is poured. Salting time depends on the size and temperature of the fish.

Pacific salmon cured fillets are processed only from the highest quality fresh fish. The fish are dressed by cutting the belly away from the back. The fish is then washed, and slime scrubbed away with a brush. After gutting and washing the prices are salted in vats.

After six days the fish is immersed some hours and hung on racks, they take about a mouth to dry.

Notes on the text:

1. drying – вяление

2. desiccate – высыхать

3. raw – сырой

4. rack – жердь

5. vat – чан, бак

6. cured fillet – вяленый балык