Understanding Trans-Fat To be Free From it
Monday, November 8th, 2021
Oils and fats are triglycerides, comprised of a glycerol back bone bonded with three fatty acid chains – saturated or unsaturated. Unsaturated fatty acids in vegetable sources are solely cis-isomers, while trans-isomers are present naturally in a small percentage in animal sources.
By Dr. LaiYee, Lee – Futura Ingredients
The malicious trans fats widely spoken of are the trans isomers obtained from altering liquid vegetable oil through a partial hydrogenation process. Hydrogenation is a chemical process to reduce the degree of unsaturation in oils and fats by adding hydrogen atoms to the unsaturated bonds. Essentially all unsaturated fatty acids are converted to fully saturated format in fully hydrogenated fat. However, oils and fats that has undergone a partial hydrogenation process would have the positional isomers present. These man-made trans fats are widely used in margarines and shortenings to impart desired characteristics which mimics animal fats, which were the traditional fat sources. Another contributing factor to the significance of trans fats is the shift from animal to vegetable based fat; where trans fats appeared to be a more stable form of unsaturated fat against oxidation and rancidity, and were earlier thought to be healthier than saturated fat.
Man-made trans fats, also known as partially hydrogenated oil (PHO), are now known as the worst fat source contributor toward cardiovascular diseases. Malaysia has set a maximum of 2% trans fats in oil and fats products since 2003. Thailand is the first country in ASEAN to ban trans fats since 2019, while Singapore joins to ban trans fats from June 2021. Many countries have in turn taken initiatives in joining the World Health Organisation’s REPLACE programme, which is a 5-year action plan launched in 2018, to achieve global elimination of man-made trans fats from the food supply chain.
Nonetheless, the elimination of trans fats results in a need for functionality replacements in food formulations. Some of the options available are palm oil, structured oil and interesterified oil. Palm oil – derived from oil palm fruit, is a natural triglyceride. It is the most consumed vegetable oil, and also the most divisive vegetable oil due to issues surrounding environmental sustainability, i.e. deforestation leading to biodiversity lost and climate change.
For almost two decades now, the palm industry has adhered to the principles of the Roundtable on Sustainable Palm Oil (RSPO) to promote the use of sustainable palm oil. One of its key principles is to ensure no primary forests or high conservation value areas are sacrificed for new oil palm plantations. In general, RSPO certified palm oil is produced with actions taken to mitigate any possible negative impact to the environment, and balancing the needs of local communities to sustain their livelihoods. It is important to note that sustainability issues surrounding palm are also applicable to other oil crops, which are often out of the media glare. It is only fair when the environmental impact of the cultivation of all edible oil crops are compared side by side for consumers to conclude if palm is that pernicious to the environment. For example, palm is the most efficient oil crop among the four major oil crops – palm, soya bean, rapeseed and sunflower seed. Oil palm trees provide the highest yield of oil per hectare, between 4-6 MT/ha, as compared to the other three oil crops that yield less than 1 MT/ha.
Comparing global top two edible oils: palm and soya bean – palm oil has fatty acid composition that is more saturated as compared to soya bean oil. The two major fatty acid chains in palm oil is palmitic acid (C16:0 at 39.3 – 47.5%), followed by oleic acid (C18:1 at 36 – 44%); while in soya bean oil, they are the linoleic acid (C18:2 at 48 – 59%) and oleic acid (C18:1 at 17 – 30%). As such, palm oil has a fair portion between saturated and unsaturated fatty acid chains carrying characteristics lacking in highly unsaturated soya bean oil, or any other soft oils, and therefore palm oil has better stability over time. As a result, palm oil – with its original fatty acid composition – is one of the best options to replace man-made trans fats in the food supply chain.
There has been a misconception that consuming palm oil causes cardiovascular diseases because of its high degree of saturation. The three fatty acid chains bonded to glycerol in triglycerides are referred according to their stereospecific number (sn) -1, -2 and -3 (Figure 1). Liquid vegetable oils has its sn-2 typically attached with unsaturated fatty acids. Palm oil, also has its sn-2 attached with its main unsaturated fatty acid, i.e. oleic acid, although it is higher in degree of saturation. Fatty acid sn-1 and sn-3 in triglycerides are typically hydrolysed and absorbed as free fatty acid and metabolised independently; while fatty acid sn-2 remained attached to the glycerol backbone and absorbed into the body. Studies have shown that palm oil does not alter blood lipid profile. It is therefore improper to group palm oil with traditional sources of saturated fats.
Figure 1: Triglyceride structure showing the stereospecific numbering of sn-1, sn-2 and sn-3
We see man-made trans fats with its limit capped or banned for use as an ingredient directly into food formulations. However, there has yet a law that regulate the use of trans fats in the making of food additives, especially those of oils and fats origin, for instance, food emulsifiers. Traditional oils and fats sources for food emulsifiers are animal origin, which has shifted to vegetable oil almost completely since 1980s. Food emulsifiers are ubiquitous in food products; for instances, in baked goods, i.e. breads and rolls; oils and fats products, i.e. margarines, spreads and shortenings.
In bakery applications, particularly breads, the functionalities and effectiveness of emulsifiers are affected by its dispersibility. The dispersibility of emulsifiers is influenced by the balance between particle size and degree of unsaturation. The industry uses monoglycerides in bread for its crumb softening effect, and the degree of crumb softening depends greatly on how well monoglycerides are dispersed within the dough matrix. Fully saturated monoglycerides in a finer particle size improves dispersibility, but comes with handling challenges, such as dustiness causing environmental hazard to operators.
The other way to improve dispersibility is to increase the unsaturation level of monoglycerides, hence lowering its surface tension for better dispersion within the dough matrix. This however, would lower the melting point of the monoglyceride which in turn may lead to high tendency of the monoglyceride to form lumps, especially in hot climates. The use of trans fats in the making of unsaturated monoglycerides is one of the ways to increase the product’s melting characteristics and its robustness against caking, hence gives better dispersibility. Nonetheless, new technology in designing emulsifiers with superior powder properties and therefore good dispersibility without the man-made trans fats are now available.
As the configuration of trans fatty acids does not have the “kink” like its cis-counterpart (Figure 2) it aligns itself better along other fat crystals imparting good fat crystallisation effect particularly in oils and fats products. Now that trans fats as an ingredient is phased out, attention is shifted to the use of saturated fats, interesterified fats, and emulsifiers in replacing trans fats functionalities. Emulsifiers like trans fats based monoglycerides could be an option; nonetheless, there are other options with various fatty acid compositions, for examples, the fully saturated monoglycerides, and the trans fats free unsaturated monoglycerides – used in combination at times for synergistic effects.
Food formulators that are inclined to replace both trans fats and saturated fats now have the option of applying oleogels in their formulations. Oleogels are edible liquid vegetable oils structured with gelators such as low molecular weight gelators, i.e. emulsifiers and fatty acids; and polymeric gelators, i.e. natural wax. Emulsifiers like monoglycerides are great examples to be used in creating suitable oleogels through Pickering and network stabilisation mechanism. Other emulsifiers examples that help in stable olegels formation are the polyglycerol esters, sorbitan esters and lecithins.
Figure 2: Configuration of cis- and trans-fatty acids of C18:1
Regulatory bodies of many countries have taken the initiatives to join the WHO action to eliminate man-made trans fats in the food supply chain – at the macro level. Trans fats as raw materials to make food ingredients or additives remains a possibility for trans fats to appear in food products. For this reason, ingredients and additives manufacturers together with food formulators’ are integral part of the chain to achieve the global goal of zero trans fats. Futura Ingredients takes great pride in contributing to the sustainable future of food. The latest addition to our product portfolio is the Ekömul NEXT series, the next generation crumb softener, designed with superior crumb softening effect and excellent powder flowability – with zero trans fats.
Reach out to Futura Ingredients for our comprehensive range of emulsifiers – including trans fats free and palm RSPO options.
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