In October 2009 the Department of Health met industry players and academics to discuss its plans to draft regulations to reduce the levels of unhealthy trans fats in all processed and prepared foods.
The law will affect all manufactured and prepackaged food sold in SA as well as food prepared by restaurants and fast food outlets.
Why such extreme measures? Trans fats are of particular use to the food industry because they have a higher melting point than cis unsaturated fats, increasing shelf-life and also improving flavour stability of foods. However, research has proved unequivocally that, unlike other unsaturated fatty acids which protect against heart disease, trans fatty acids do the opposite, and their effects on the cardiovascular system are even worse than those of saturated fats.
The legislation is imminent and, according to sources, the DoH is under pressure to legislate as soon as possible. The amount of trans fats that will be allowed in products is expected to be between 1-2% but this has not been finalised. Fats and oils specialist, Hudson & Knight facilitated a workshop in Gauteng late last year for interested parties and customers. Nina van Heerden, Head of the Innovation Centre for Africa at Hudson & Knight, says that it’s critical that the industry has time to prepare and is ready for the legislation when it comes to pass.
What are trans fats?
Trans fat is the common name for unsaturated fat with transisomer fatty acid(s). These unsaturated fatty acids contain at least one double bond in the trans configuration, as opposed to the cis configuration ordinarily found in nature.
The main source of synthetic trans fatty acids is hydrogenation. This is an industrial process in which oil is heated to a high temperature (typically 260-270ºC) under pressure and – in the presence of a metal catalyst such as nickel, Rayner’s nickel (a nickel / aluminium alloy) platinum, palladium or cobalt – hydrogen is introduced. The hydrogen is absorbed into the fat molecules, changing its molecular structure and its chemical composition as it converts the unsaturated oil to a more saturated form.
This transforms the oil, naturally liquid at room temperature, into a hard or semi-hard grey-white fatty substance. This ‘partially hydrogenated vegetable oil’ is virtually flavourless and has excellent keeping properties, making it an ideal feedstock for the food industry. In particular, unstable components such as the omega-3 fatty acid alpha-linolenic acid (ALA), prone to oxidation and rancidity, are preferentially hydrogenated by the process into more saturated and stable forms.
However hydrogenation, as well as making fats more saturated, also causes geometric isomerisation in unsaturated vegetable oils such as soy, corn or canola / rapeseed oils ie. the fat molecules change from one shape to another, such as from the cis to the trans configuration. This is partly the result of high temperature, but also the result of direct molecular excitation during hydrogenation, for example when ALA is hydrogenated to linoleic acid, or when linoleic acid is hydrogenated to oleic /elaidic acid.
The formation of trans isomers of fatty acids during partial hydrogenation was originally an accidental side effect. However in the 1980s the food industry began to selectively hydrogenate oils to produce a high fraction of elaidic acid, the trans isomer of oleic acid. This is because elaidic acid melts at mouth temperature, giving a luxurious sensation in the mouth. If fully hydrogenated to stearic acid, the result is a hard, waxy fat.
‘Heart attack in a box’
While at one time it may have seemed a panacea for the food industry, there is no arguing anymore: trans fats are bad for one’s health. Most convincingly, there is a direct, proven relationship between diets high in trans fats and LDL (‘bad’) cholesterol levels and, therefore, an increased risk of coronary heart disease – a leading cause of death. The Nurse’s Health Study which studied 120 000 nurses in the US gives the most convincing evidence.
The results led the New England
Journal of Medicine to conclude in 2006 that ‘On a per-calorie basis, trans fats appear to increase the risk of CHD more than any other macronutrient, conferring a substantially increased risk at low levels of consumption (1-3% of total energy intake).’ The study estimated that between 30 000 and 100 000 cardiac deaths per year in the United States are attributable to the consumption of trans fats.
The National Academy of Science (NAS ) which advises the US and Canadian governments on matters of nutritional science for public policy also concluded that there is no safe level of trans fat consumption because any incremental increase in trans fat intake increases the risk of CHD.
In a presentation given at the workshop hosted by Hudson & Knight, Dr Carl Albrecht from CANSA emphasised that TFA's trigger systemic inflammation. ‘Systemic inflammation is a precursor for various chronic diseases of lifestyle. It is viewed internationally as one of the best markers of human health,’ he said. Put simply, saturated fats and TFA s cause ‘logjams’ in cell membranes, contributing to inflammation. Systemic inflammation is a precursor for coronary heart disease, diabetes and is associated with an increased risk for breast and prostate cancer. On the other hand, beneficial fats such as Omega 3, break down so-called ‘logjams’, preventing inflammation. While there has not been scientific consensus that they are directly to blame, TFA s have been implicated in various types of cancers, Alzheimer’s disease, obesity, liver dysfunction and infertility.
Albrecht is an outspoken proponent of the government’s desire to restrict TFA s. ‘There is general international consensus, supported by copious peer–review data, that TFA s are a threat to human health. They should be removed from food.’
Clarity or confusion?
South Africa is planning to use Danish legislation as a starting point, but is willing to consider all available models to best formulate an effective law. Denmark was the first country to legislate against TFA s in 2003. It’s important to note that its definition of trans fats excludes naturally occurring ruminant TFA s. Challenges include distinguishing between ruminant and non-ruminant TFA s when analyzing food samples, enforcement and the fact that there is no food composition data available on TFA s anywhere in the world. Questions still exist as to how laboratories will analyse samples. Both locally produced food as well as imported food will be affected by the legislation, which will form part of the FCD Act.
According to the DoH, pre-packed imported foodstuffs will be sampled at point of entry. Sampling will occur at point of production (sampling of product at manufacturing level) and ingoing ingredients. Therefore, manufacturers will be held responsible and not retailers.
The draft will be made available for public comment and the DoH has committed to consulting with the necessary stakeholders and experts.
Alternatives
Dr. Martijn Zieverink, a chemical engineer specialising in fat hydrogenation from Unimills, (a Dutch-based company owned by Sime Darby, like Hudson & Knight) briefed both the DoH and the Hudson & Knight industry workshop on alternatives available to partial hydrogenation.
‘Oils and fats are modified for a number of reasons,’ he explained, ‘to change chemical behaviour, especially for oxidative stability; to change physical behaviour such as melting point, rate of crystallization and flavour; or to accommodate a functional specification demanded by final product, such as margarine, frying oil, coating fat, cocoa butter replacer.’
Major fat modification technologies include:
Hydrogenation:
Partial hydrogenation increases the amount of trans fat for better functionality. It can be used to change liquid oils to solid fats; to obtain specific melting characteristics and, of course, to increase the oxidative stability of a product. Full hydrogenation is only used to make saturated fats.
Dry fractionation of tropical fats allows the separation of fats into a more liquid and a more solid phase. Then fats are cooled until crystals form. Using dry fractionation, palm oil, for example, can be formed into olein, stearin, super olein, mid fraction, soft stearin and super stearin.
Interesterification seems to be the method of choice in Europe. Interesterification changes the melting behaviour of fat by changing the position (randomisation) of fatty acids on glycerol backbone. It can be achieved in both a chemical or enzymatic fashion.
Unilever, as a whole, switched to interesterification in the 1990s as the deleterious health effects of trans fats became clear. Zieverink says that up to 25% of products processed by Unimills currently are interesterified, with enzymatic interesterification becoming more popular.
Zieverink gave the following estimates of cost increases associated with each modification technology: pure refinement implies 100% increase; partial hydrogenation 150% increase; full hydrogenation 180% increase; chemical interesterification 230% increase; enzymatic interesterification: 250% increase. It’s clear to see from these cost estimates why partial hydrogenation has been so popular in the past.
Zieverink emphasized that all fatty acids should not simply be vilified, but each should be assessed based on their own characteristics and health effects, good or bad. In addition, he says: ‘We should not be condemning the process of partial hydrogenation as bad or unhealthy – it’s perfectly safe as a process –, but we should be looking at the final product created.’
From a product development point of view, significant reduction or removal of trans fats most often implies an increase in saturated fat levels, which are more challenging to decrease. Saturated fats also carry considerable health risks. Butter, for example, while only containing 6% trans fats, has a saturated fat content of a 80%!
History of partial hydrogenation
Nobel laureate Paul Sabatier worked in the late 1890s to develop the chemistry of hydrogenation, which formed the basis of the margarine, oil hydrogenation, and synthetic methanol industries. While Sabatier only considered hydrogenation of vapours, the German chemist Wilhelm Normann showed in 1901 that liquid oils could be hydrogenated, and patented the process in 1902. During the years 1905–1910, Normann built a fat hardening facility in the Herford company, Germany. At the same time the invention was extended to a large scale plant in Warrington, England at Joseph Crosfield & Sons. It took only two years until the hardened fat could be successfully produced in the plant in Warrington, commencing production in the autumn of 1909.
The initial year’s production totaled nearly 3000 tonnes. In 1909, Procter & Gamble acquired the US rights to the Normann patent. P&G then hired chemist E. C. Kayser to develop an industrial process for the hydrogenation of cottonseed oil. Initially the intention was to make a cheap replacement for the animal based tallow used in candles. But in 1911 P&G, noticing that the hydrogenated oil looked and behaved like lard, began to sell it as a lard substitute under the brand name of Crisco. Further success came from the marketing technique of giving away free cookbooks in which every recipe called for Crisco.
Hydrogenated fats became more established in the 1930s, due to their lower cost. Their use rapidly increased during World War II when people turned to margarine and vegetable shortenings as alternatives to butter, which was subject to rationing. They received a further boost in the late 1980s: health concern focused on saturated fats, which were widely vilified as extremely unhealthy. Meanwhile margarines containing hydrogenated vegetable oils were promoted to consumers as a ‘healthier’ alternative, replacing butter and other animal fats, as well as more saturated tropical vegetable oils such as palm and coconut.
Another factor was the growth of vegetarianism:
Manufacturers of biscuits, for example, were worried about loss of market share as vegetarians avoided products which contained ‘animal fat’ as shown in the ingredients list.
Sources:
For more information, contact Nina van Heerden at Hudson & Knight or consult
the comprehensive knowledge base online, used extensively for this article at
The Campaign against trans fats in foods www.tfX.org.uk
Hudson and Knight: T +27 (0) 11 898 5317
