Exercise 1. Read and translate the following word without a dictionary.
Distill - distillation, neutral – neutralize - neutralization, delicately, deodorize – deodorization, margarine, deodorization technology, guarantee, apparatus, vacuum, cosmetics, physical method.
Reading. Read the text and say what are the stages in the deodorizing process.
Most oils, even after refining, have characteristic flavours and odours. The deodorization process consists of blowing steam through heated fat held under a high vacuum. Small quantities of volatile components, responsible for tastes and odours, distill, leaving a neutral, virtually odourless fat that is suitable for the manufacture of bland shortening or delicately flavoured margarine. Originally, deodorization was a batch
process, but increasingly, continuous systems are being used in which hot fat flows through an evacuated column countercurrent to the upward passage of steam. In Europe, a deodorization temperature of 1750-2050 C is common, but in the United States, higher temperatures of 2350-2500 C are usually employed.
There are different types of deodorization technologies, but the aim is always to guarantee the best possible contact between oil and steam, to reach the optimum level of efficiency. The process may operate continuously, semi-continuously or in batches. The choice of the equipment depends on the application, the type of oil, the required amount of product changes per day, etc... Each type of equipment is somewhere the best option for a given application.
Conventionally, the three stages in the deodorising process are:
- deaeration-heating: the bleached oil is first deaerated under vacuum before heating by heat exchange with the deodorised oil;
- deodorisation-steam stripping: the deodoriser operates at a pressure of about 3 mbar and is equipped with a series of steam injection devices, which guarantee intensive agitation in each spot of the deodoriser and even steam distribution on the oil surface;
- heat recovery-cooling: the oil is cooled under vacuum, by mere heat exchange.
There are machines that combine neutralization by distillation and deodorizing of the oil which allow to produce refined and deodorized vegetable oils. Specific feature
of the apparatus (Figure 61) is that the neutralization of odors and taste is achieved by physical method, without any using any chemical substances, such as alkali. Neutralization process is combined with deodorization and is effected in one tower.
Neutralization and deodorization of the oil in the apparatus are effected by way of evaporation of fatty acids and odours at the high temperature and low pressure. The oil is heated in two steps. The oil from the initial product tank passes through the first heater and is fed to the deaerator-drier unit where the excessive moisture is vacuum-dried. Further the oil is passed through the second heater and is fed to the deodorizing tower where it is deodorized and refined. Subsequently the oil from the tower is fed to the cooler from which it is discharged to the tank for ready product. The cooler is cooled with running water. Residue (fatty acids), usually 3 to 5% of the initial oil volume are collected in a storage tank and may subsequently be utilized in manufacture of soap or cosmetics.
Figure 61. Machine for oil refining and deodorization.
Exercise 2. Answer the following questions. 1. When is deodorization applied?
2. What are its essential stages?
3. What factors does the choice of deodorization equipment depend on? 4. What extracted oil processing technique is the most expensive?
Exercise 3. Complete each sentence with a word or phrase from the box.
deodorization process steam injection devices evacuated column
heat recovery cooling deaerator-drier
1. A process of cooling the oil under vacuum by mere heat exchange is called ___. 2. The ___ consists of blowing steam through heated fat held under a high vacuum. 3. The ___is a unit where the excessive moisture is vacuum-dried.
4. ___ guarantee intensive agitation in each spot of the deodoriser and even steam distribution on the oil surface.
5. Deodorization is a continuous process in which hot fat flows through an ___ countercurrent to the upward passage of steam.
Exercise 4. Each sentence has a word or phrase underlined. Below each sentence are four words or phrases. You are to choose the one word or phrase which would best keep the meaning of the original sentence if it were substituted for the underlined word.
1. Extracted from flaxseed, linseed oil is the principal source of drying oil for paint. a) Derived; b)Differentiated; c)Detached; d)Descended.
2. The fragrance of oil depends on extraction method.
a) bark; b)hardness; c)scent; d)texture. 3. The number of vegetables is greater than that of all oilseed crops.
a) exceeds; b)equals; c)augments; d)predicts. 4. The extractor circles around a stationary axis.
a) expands; b)rotates; c)accelerates; d)vibrates.
5. The perpetual motion of the extractor creates favourable conditions for the efficient solvent extraction.
a) ancient; b)rhythmic; c)leisurely; d)constant.
Exercise 5. Read the text describing production process of machine for oil hydration. Fill in the spaces with the correct number of the unit.
The machine for oil hydration (Figure 62) consists of the following units:
· deaerator-drier ( ) for removal of air and moisture from the oil
· mixer for mixing oil and water ( )
· coagulator which performs flocculation of phosphatides and proteins and thus speeds-up their deposition ( )
The apparatus works as follows: the oil heated in the heat exchanger of the
mixer is mixed with the preliminary heated water. The resulting water-in-oil emulsion is fed to the coagulator where it is slowly stirred and phosphatides and proteins contained in the oil are coagulated (large flocs are formed). The mixture containing flocculated phosphatides and proteins is fed to the settling tank. For the hydration process on a continuous basis three settling tanks are necessary: first tank to receive the oil, second tank for oil settling; from the third tank the oil is fed to the filter press and deaerator-drier and discharged to the storage tank.
Exercise 6. Match the terms on the left with the statements on the right.