Modified atmosphere

Modified atmosphere is a way to preserve food operating on the atmosphere around it. Salad crops which are notoriously difficult to preserve are now being packaged in sealed bags with an atmosphere modified to reduce the oxygen (O2) concentration and increase the carbon dioxide (CO2) concentration. There is concern that although salad vegetables retain their appearance and texture in such conditions, this method of preservation may not retain nutrients, especially vitamins.

Grains may be preserved using carbon dioxide. A block of dry ice is placed in the bottom and the can is filled with grain. The can is then "burped" of excess gas. The carbon dioxide from the sublimation of the dry ice prevents insects, mold, and oxidation from damaging the grain. Grain stored in this way can remain edible for five years.

Nitrogen gas (N2) at concentrations of 98% or higher is also used effectively to kill insects in grain through hypoxia. However, carbon dioxide has an advantage in this respect as it kills organisms through both hypoxia and hypercarbia, requiring concentrations of only 80%, or so. This makes carbon dioxide preferable for fumigation in situations where a hermetic seal cannot be maintained.

Many root vegetables are very resistant to spoilage and require no other preservation other than storage in cool dark conditions, usually in field clamps.

Some foods, such as many traditional cheeses, will keep for a long time without use of any special procedures. The preservation occurs because of the presence in very high numbers of beneficial bacteria or fungi which use their own biological defences to prevent other organisms gaining a foot-hold.

b) Find the meaning of the English words or word combinations:

edible	избыток газа
fumigation	предпочтительный
dry ice	сохранять питательные вещества
sealed bags	кислородная недостаточность
beneficial bacteria	содержание углеводорода
preferable	обеззараживание
hypoxia	благотворные бактерии
retain nutrients	сухой лёд
excess gas	герметичные пакеты
carbon dioxide concentration	съедобный, годный в пищу

с) Compose the sentences from the given words. Be atentive! There can be odd words.

1. to preserve, are, crops, sealed, the oxygen, with, Salad, an atmosphere, packaged in, to reduce, bags, concentration, modified.

2. bottom, of, placed, dry, the, a block, is, ice, in.

3. is, to, grain, used, insects, gas, in, kill, Nitrogen, effectively.

4. require, dark, vegetables, conditions, Many , in, storage, cool, root.

5. a long time, of, keep, presence, for, bacteria, the, of, beneficial, will, because, Cheeses.

VIII. Fill in the blanks with appropriate words or word combinations according to the delivered texts and translate them:

1. Preservation usually involves preventing the growth of …, … and other micro-organisms.

2. Vacuum-packing stores food in …, usually in an air-tight bag or bottle.

3. Canning involves cooking fruits or vegetables, … them in sterile cans, and … the containers to kill or weaken any remaining bacteria as a form of pasteurization.

4. Drying reduces … sufficiently to delay or prevent bacterial growth.

5. … draws moisture from the meat through a process of osmosis.

6. Lack of quality control in the canning process may allow … or ….

7. Some preservation methods require the food to be … after treatment to prevent … with microbes.

8. Sugar is used to preserve fruits, either in … with fruit in ….

9. Food may be preserved by cooking in a material that … to form a gel.

10. Cold stores provide large volume, … for strategic food stocks.

11. The use of sugar is often combined with … for preservation of luxury products.

12. … is the process of stewing the meat in a covered earthenware jug or casserole.

13. The combination of … and the addition of … from the smoke preserves the food.

14. … is a method of preserving food by placing it in brine, vinegar, ethanol, and vegetable oil.

15. Irradiation is the treatment of food with … or … to kill bacteria and mold and may be combined with … .

9. Tell in short about food preservation and its methods.

10. Skim through the text and say in one sentence what the message of the text is. Answer the questions which follow the text.

A commodity is something that is relatively easily traded, that can be physically delivered, and that can be stored for a reasonable period of time. It is a characteristic of commodities that prices are determined on the basis of an active market, rather than by the supplier (or other seller) on a "cost-plus" basis. Examples of commodities include not only minerals and agricultural products such as iron ore, crude oil, ethanol, sugar, coffee, aluminium, rice, wheat, gold, diamonds, or silver, but also so-called "commoditized" products such as personal computers.

In the original and simplified sense, commodities were things of value, of uniform quality, that were produced in large quantities by many different producers; the items from each different producer are considered equivalent. It is the contract and this underlying standard that define the commodity, not any quality inherent in the product.

* * *

1. Can a commodity be stored for a reasonable period of time?

2. What are prices of commodities determined on?

3. What is an example of so-called "commoditized" products?

4. What defines the commodity?

24