Notes

Jun 06

Manufacture of edible oil: Solvent extraction

Material containing low amount of oil such as oilseed cake (meal) and rice bran are suitable for solvent extraction. Hexane is most widely used solvent and this process can extract oil form feed until oil present in feed is reduced to 0.5 % or less.

 

Perforated basket attached in conveyor belts holds the feed. Fresh warm solvent is sprayed from the top. Hexane is used as solvent whose boiling point is nearly 60°C. The basket moves up carrying the feed which is extracted through screen at the bottom of basket. The residue is treated with fresh solvent and finally defatted cake is obtained. The half miscella is recirculated through pump and again comes in contact with solvent. The full miscella is evaporated, refined, bleached and deodorized to obtain refined bleached and deodorized (RBD) oil.

 

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Jun 06

Manufacture of edible oil: Screw press method

Extraction of fat from different sources like oilseeds, nuts, oil containing fruits, animal fat are different and use different techniques.

  1. Animal fat is extracted by rendering technique that uses heating (moist/dry) fatty tissue.
  2. Oil from oilseeds and nuts is extracted by using mechanical expellers (screw press) that can extract 90 – 95 % oil in seed.
  3. Oil from oil cakes and bran is extracted by solvent extraction using hexane as solvent.
  4. Oil from flesh of fruits is extracted by using hot water extraction technique where flesh of fruit is macerated in hot water and extracted oil can be recovered by settling or centrifugation method.

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Jun 04

How mixtures can be separated on basis of relative volatility?

When a liquid mixtures is heated in a closed container, the mixture boils and starts forming vapor. The vapor will have different composition compared to the liquid. The vapors are obviously richer in more volatile component. If such vapors are collected and condensed, the condensed liquid will have different composition form original mixture and is richer in high volatile component. Read more

Jun 02

Relative Volatility

In order to separate binary mixtures using distillation process, there must be differences in volatilities of the components. The greater the difference, the easier it is to do so. A measure for this is termed relative volatility. Volatility is a way of expressing relationship between components of vapor Ya and that of liquid Xa in equilibrium. It is defined as ratio of partial pressure of component to mole fraction of component in liquid.

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