Edible oil is used in preparation of all sorts of food all over the world. It is refined using chemical process. It is important that the consumers should be aware of process as well as chemicals used. Our test results of using some of the chemicals in Nigeria proved that hexane used in the process was having excessive benzene content and that is carcinogenic. We decided to write and make the general public aware of the situation. We are providing guidelines to edible oil industry to select the right product and process to alleviate the health damage that may be caused by using hexane that is not edible grade. Wrong product used can cause serious health problems.

The edible oil we consume for daily food process is refined by a simple chemical process. We have to be careful about the process and the chemicals used in extracting oil. Wrong chemicals and processes may lead to production edible oil which can cause health hazards and considerable after effects. It is important that the general public, consumers of the edible oil would be aware and insist on buying the right product.

We consume 14—20% edible oil in daily food preparations and readymade packaged foods.

There are many different kinds of commercially refined vegetable based oils, including canola or rapeseed oil, soybean oil, canola oil, corn oil, sunflower oil, safflower oil, and peanut oil. In Nigeria being the palm oil producer country the cheapest and widely accepted cooking oil is palm oil.

Refined cooking oils are made by highly intensive mechanical and chemical processes to extract the oil from the seeds. Oil seeds are gathered and then seeds are husked and cleaned of dirt and dust, then crushed. The crushed seeds are then heated to temperatures between 110˚ and 180˚ centigrade in a steam bath to start the oil extraction process. The seeds are put through a high volume press which uses high heat and friction to press the oil from the seed pulp. The seed pulp and oil are then put through a hexane solvent bath and steamed again to squeeze out more oil.

Now the seed and oil mixture is put through a centrifuge and phosphate is added to begin the separation of the oil and seed residues. After solvent extraction, the crude oil is separated and the solvent is evaporated and recovered. The seed pulp residues are conditioned and reprocessed to make by-products such as animal feed.

The crude vegetable oil can then be put through further refining techniques including degumming, neutralization and bleaching:

Water degumming: In this process, water is added to the oil. After a certain reaction period the hydrated phosphatides can be separated either by decantation (settling) or continuously by means of centrifuges. In this process, a large part of water soluble and even a small proportion of the non-water soluble phophatides are removed. The extracted gums can be processed into lecithin for food, feed or for technical purposes.

Neutralization: Any free fatty acids, phospholipids, pigments, and waxes in the extracted oil promote fat oxidation and lead to undesirable colors and odors in the final products. These impurities are removed by treating the oil with caustic soda (sodium hydroxide) or soda ash (sodium carbonate). The impurities settle to the bottom and are drawn off. The refined oils are lighter in color, less viscous, and more susceptible to oxidation.

Bleaching: The major purpose of bleaching is the removal of off colored materials in the oil. The heated oil is treated with various bleaching agents such as fuller’s earth, activated carbon, or activated clays. Many impurities, including chlorophyll and carotenoid pigments, are absorbed by this process and removed by filtration. However, bleaching also promotes fat oxidation since some natural antioxidants and nutrients are removed along with the impurities.

Deodorization is the final step in the refining of vegetable oils. Pressurize steam at extremely high temps (500˚centigrade or more) is used to remove volatile compounds which would cause off odors and tastes in the final product. The oil produced is referred to as “refined oil” and is ready to be consumed or for the manufacture of other products. A light solution of citric acid is often added during this step to inactivate any metals such as iron or copper present in the final product.

In Nigeria most of the vegetable cooking oil came into the market is simply solvent extracted palm oil. The biggest health hazards observed and heard is the usage of straight run gasoline (SRG) which is petroleum refinery waste. SRG is used in place of Hexane as the solvent extraction medium since it is cheap in comparison to HEXANE. SRG is complex mixture of aliphatic and aromatic hydrocarbons C4-C10. It contains the isomers and derivatives of butane to decane and also sulphur. All these chemicals are extremely carcinogenic and hazardous for human health. Since SRG is not well defined molecule it also contains the free radicles and complex polymerized hydrocarbons which can react with Oil molecule and stay with the refined oil and thereby make the oil poisonous for human health. The complete separation of these molecules in distillation process is not possible due to variable boiling points. Still due to economical reason it was used for the process of edible oil refining.

Hexane is the well-defined molecule with defined boiling point and thereby more control on the distillation process. Also food grade Hexane which is utilized globally for edible oil refining is free from Sulphur, free radicles and other aromatic and aliphatic petrochemical derivatives. Hence is it most suitable for oil extraction and refining process.

Regulating the products that are being used in oil extraction is the responsibility of respective government agencies. We urge the governmental body would take notice of the above technical requirements and make sure that our edible oil refining companies will use the right chemicals.

As a health conscious consumer you should insist that petrochemical impurities free Hexane to be used in your oil refining which is globally standardized product. Previously there were rumors that hexane was not available locally and hence some of the edible oil refining companies used Straight Run Gasoline (SRG). But now HEXANE is available in large quantities for distribution by reputed local company. So, next time when you are buying our jerry can of oil make sure that you will buy oil that gives you a chemical free healthy wholesome food.

There are no specific regulations to clearly label the details, it is very difficult or almost impossible for the consumers of the edible oil to understand the contents of the edible oil. Hence it is important that this problem is addressed at the manufacturing or the process level by the local regulatory authorities. Local regulatory authorities should audit the manufacturing and bill of materials in the consumption process and approve the products.

Maduagwu is CEO at Andra Industries Nigeria Limited, Kulkarni is an industrial engineer, Anand works for a marketing and distribution company in Houston, USA while Meshram has M.Sc is head of the Chemicals Business Division for TATA International, Lagos, Nigeria.


Source: The Guardian Newspaper