edible oil processing

1. Processing of edible
Oil and Fat

2. REFINING
• Refining produces an edible oil with characteristics that consumers desire
such as bland flavor and odor, clear appearance, light color, stability to
oxidation and suitability for frying.
• In a refining process comprising the following steps:
1. Lecithin removal
2. Degumming
3. Free fatty acid removal
4. Bleaching
5. Deodorization

3. • The following precautionary measures are taken during refining in
order to avoid undesirable autoxidation and polymerization reactions:
1. Absence of oxygen
2. Avoidance of heavy metal contaminations
3. Maintaining the processing temperature as low and duration as
short as possible.

4. 1.Removal of lecithin
• This processing step is special importance for soybean oils .
• Water (2-3%) is added to crude oil, thereby enriching the
phospholipids in the oil/water interface.
• The emulsion thus formed is heated up to 80 °∁ and then separated
or clarified by centrifugation.

5. 2.Degumming
• Finely dispersed protein and carbohydrate are coagulated in oil by
addition of phosphoric acid ( 0.1 % of oil weight ).
• A filtering aid is then added and the oil is clarified by filteration.

6. 3.Removal of Free Fatty Acids
( deacidification )
• The removal of fatty acids with 15 % sodium hydroxide (alkali refining)
is most frequently used method.
• Technically , this is not very simple since fat hydrolysis has to be
avoided and , moreover , the sodium soap which tends to forms
stable emulsions , has to be washed out by hot water.
• After vacuum drying , the fat or oil may contain only about 0.05 %
free fatty acids and 60 to 70 ppm of sodium soaps.
• When fat or oil is treated with diluted phosphoric acid , the content of
sodium soaps decreases to 20 ppm and part of the trace heavy-metal
ions is removed.

7. 4.Bleaching
• In order to remove the plant pigment (chlorophyll , carotenoids ) and
autoxidation products, the fat or oil is stirred for 30 min in the
presence of Al-silicates ( bleaching or Fuller’s earth ) in a vacuum at
90°∁.
• The bleached oil is removed from the adsorbent by filteration .
• The retained by the absorbent can be recovered by hexane extraction
and recycled into refining process.

8. 5.Deodorization
• Deodorization is esentially vacuum steam distillation ( 190-230°∁ ,
0.5-10 mbar ) .
• The volatile compounds , together with undesirable odorants present
in the fat or oil , are separated in refining steps
• Deodorization takes place min 20 in to 6 h depending on the type of
fat or oil and the content of volatile compounds.

9. THANK YOU