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RED ALERT FOR THE EDIBLE OIL INDUSTRY – DR. C. POHL 

The South African Fryer Oil Initiative has its roots in the Lipid Biotechnology group of the Department Microbiology and Biochemistry. One of the interests of this group is the biological oxidation of lipids. In 1988 they discovered the when the fatty acid arachidonic acid was fed to a yeast, it was oxidise to a novel 3 – hydroxy-fatty acid. A 3-hydroxy-fatty acid has a carbon chain and on the 3rd carbon from the carboxylic acid group has a hydroxy group. These compounds have shown to be biologically active in humans.

From the biological oxidations our interests spread to auto-oxidation. A classical example of this is what happens when food is fried in oil. Water released from the food is involved in the hydrolysis of triacylglycerols (the main component of oils) to di-acylglycerols, mono-acylglycerols and free fatty acids. These are all polar compounds. The free fatty acids. These are all polar compounds. The free fatty acids may react with metals present in the food or spices and form soaps. Thermal oxidation results in the formation of free radical, peroxides, aldehydes and hydrocarbons and eventually, through quenching polymers are formed. The longer an oils is used, the more of these oxidation products are formed. This leads to over-oxidation. The causes of over-oxidation are high temperatures, prolonged heating, repeat usage and incorrect topping up practices. Up to 200 different compounds with possible health implications may be formed. The health dangers of these over-oxidized oils include diarrhea, problems with reproduction, enlargement of the liver, spleen, athrosclerosis and oxidative stress is one of the factors that may play a role in the progression of HIV to AIDS. This is all part of a viscous cycle, since the more an oil is broken down; the easier it is absorbed by food. Because of these health dangers, several European countries have strict laws and regulations regarding the use of oil for food preparation. 

Why are we interested in abused oil in South Africa? Three main events occurred. The first was a claim by a company in August 1993 that they can clean dark, dirty used oil so that it is even better than unused oil. This is impossible, since once an oil has started breaking down, it is not possible to restore the triacylglycerols with normal refining processes. We also saw indiscriminate cleaning of oil with bleach and lime. This oil was again used for the frying of food. 

In 1994, we conducted a survey together with the Department of Health in Bloemfontein. 54 oils samples were drawn from the formal sector in Bloemfontein and analyzed for polar compounds according to internationally accepted methods. The samples could be divided into three groups. The 1st group, containing 69% of the samples had a polar compound content of 30%. The second group, consisting of 20% of the samples contained between 30-50% polar compounds and the 3rd group of 11% of the samples contained more than 50% polar compounds. The last 2 groups are well above the limit of 25% set as a save standard. What was most alarming, however was the fact that, 88% of the establishment were selling these oils to their workers for further use in food preparation. Since then the work of SAFOI has led to the following events: in 1994 a release was made to the press in order to inform the public of the issue. In 1995 we received FLAG approval for the legislation and Draft regulations were published in 1995. This was followed by the first National Symposium on Abused Cooking Oil where Elto’s were made aware of the problem. The EHO’s were mobilized to draw samples from frying establishment all over South Africa. These samples were analyzed by the Forensic Laboratory in Pretoria. Final regulations were published in 1996 and this was followed by the Second National Symposium on Abused Cooking Oil. Here the EHO’s were given the opportunity to give feedback on their awareness programmes. The final regulations state that an oil or fat used in the frying of food is deemed hazardous to human health if it contains more than 16% polymerized triglycerides and/or 25% polar compounds. With this regulations South Africa joins other countries in their concern with quality of frying oil. 

During the last 3 years, however, we noticed a problem with the quality of the new, unused oil. Although this is not a statistically representative study, an increase was observed in the average percentage polymerized triglycerides in new oil over the last 3 years. This indicates that there are malpractices occurring and that either old oils are being mixed with new oils and resold as new, unused oil; or that the refining process is not effective. This has resulted in the Oil Seed Board commissioning a base line study. We can say that South African produces oils that are comparable to the best in the world. This can be seen by the fact that the upper control limit for the percentage polymerized triglycerides in new, unused oils is less than 2,5%. However, there are certain samples that are well above this limit. 

There does, however, seem to be a light at the end of the tunnel. Recent results do indicate an improvement in the average percentage polymerized triglycerides especially in the samples from KwaZulu/Natal. 

In order for us to achieve our aims of terminating the abuse of frying oils and to develop effective waste management procedures we propose a total quality management programme. This total process will rely on several quality control steps from the production of crude oil from seed, the refining process and the eventual use of oil for frying. It will also be necessary to have quality control steps in the impact of crude and refined oil that has reached the end of its life to the Oleo-chemical Industry.

 

 

 

 

 

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