Processing healthy fats and oils
the right way
For a long time, lipids were thought to cause weight gain and, as such, avoiding them was recommended. Numerous studies have recently shown, though, that this is not entirely true; certain fats and oils are actually needed to maintain a healthy body and mind.
Unsaturated fatty acids may be the most popular example. And although lipids are incorporated into many different food applications, processing them can be challenging: it is important to remove contaminants and residues, optimise their properties (according to the intended use) and source them sustainably. At the same time, both consumer preferences and legal requirements must be met and observed.
Omega-3 enriched foods and beverages are in high demand, including smoothies, bars, lemonades, and dairy products, to name a few. Partially driven by positive media coverage, this trend is supported by studies that show that babies and small children particularly benefit from essential fatty acids (EFAs). In the EU, for instance, the fatty acid DHA (docosahexaenoic acid) must now be included in infant formulas (Fig.1). And although the most common source of omega-3 is still fish, oils from microalgae or land plants such as flax or thistles are becoming more popular. At the same time, expectations of transparency and high quality pose a dilemma for suppliers: there are no 100% pure oils on the market. As contaminants are often apolar substances, just like fats and oils, they can accumulate in the source material — from the crops and plants to raw oil — during processing until it’s finally integrated into the application. As a specialist in oil and fat processing, the Swiss company Nutriswiss knows that obtaining high-purity products is possible, even when the oils are highly sensitive and unstable because of a high omega-3 content.
Essential fatty acids: “good” fats
As the body can’t actually synthesise highly unsaturated fatty acids, they have to be consumed or obtained by supplementation. The World Health Organization (WHO) recommends 1–2 servings of fish per week or an equivalent substitute that delivers 200–500 mg of EPA (eicosapentaenoic acid) and DHA. Long-chain omega-3 fatty acids play an important role in brain growth and development, blood pressure regulation, kidney function, blood clotting and numerous inflammatory and immunological reactions. A recent study showed that omega-3s can protect the brain from the damage caused by inhaled particulate matter. As a component of cell membranes, the unsaturated fatty acids in breast milk, especially DHA, are important for healthy eye and brain development, especially during the first two years of life. Accordingly, children who are not breastfed must be supplemented with these important micro-nutrients.
Although EPA and DHA are found in fatty fish, the omega-3 fatty acid extracted from plants is ALA (alpha-linolenic acid), which must first be metabolised by the body into EPA and DHA. The only non-animal source is oil from microalgae, which is regarded as an environmentally friendly alternative to fish oil as the fast-growing microalgae can be cultivated. However, one thing applies to all omega-3 oils: they require customised treatments and a higher degree of care than ordinary oils to preserve their essential fatty acids, micronutrients and vitamins.
High-purity oil and its hurdles
Most food operators are extremely well informed about the hurdles that must be overcome when using oils containing polyunsaturated fatty acids such as omega-3 and omega-6. The chemical structure of omega-3 (DHA) and omega-6 (ARA or arachidonic acid) fatty acids contain several double bonds, which is why they react with ambient air very quickly. When they come into contact with atmospheric oxygen, undesirable oxidation products such as hydroperoxides and secondary degradation products such as ketones and aldehydes are formed. The consequences manifest themselves as off notes, an unappealing smell and taste, especially with fish oils, and a dark colour. But it’s not just sensory properties that make a good omega-3 oil, purity is also crucial.
In addition to this — as their long-term effects on human health become better understood — the detection limits for food contaminants continue to improve, which poses increasing challenges for processors and users of edible oils and fats. Increasingly precise analytical methods, together with the results of numerous studies, have led to lower levels of legally permitted amounts of residues in products destined for the EU market. For products such as baby foods, for example, the EU Commission has now set strict new limits for trans fats, plasticisers, glycidyl fatty acids esters and 3-MCPD. Plus, in February 2021, lower limits for plant protection product-derived residues will also come into force for infant formulas. That’s good news — but current processes used to purify non-critical oils would also impair the valuable fatty acids.
The classic way to clean contaminated crude oil is to use a physical refining process that involves high temperatures (230–270 °C). In a semi-continuous batch process, the crude oils are degummed and bleached before any free fatty acids are removed via steam distillation. In the bleaching process, heavy polycyclic hydrocarbons, dyes and oxidative degradation products adhere to auxiliary materials and can then be filtered out. Molecules with organoleptic properties such as aldehydes and ketones are removed during the final deodorisation process, as are pesticides and light polycyclic hydrocarbons.
The end product is tasteless and odourless, durable and oxidation resistant. Before the final desodoration, the oils can be hydrogenated, transesterified or mixed with other components in different modification steps, depending on the intended use. If the oil to be refined shows only a low level of contamination in the initial laboratory test, an alkaline process can be used as an alternative. Here, the free fatty acids are saponified and then separated. In this process, the risk of undesirable process contaminants such as
3-MCPD or glycidol fatty acid esters being formed owing to high temperatures is much lower.
Setting new standards: Short Path Distillation
Nutriswiss is already prepared for stricter limit values by offering customers a new process technology based on Short Path Distillation (SPD). In the future, it is predicted to be the method of choice for difficult-to-process raw materials, such as when the crude oil is heavily contaminated, the oxidation process is at an advanced stage or the end product must be extremely pure for use in baby foods or pharmaceutical products, for example. This technology is a particularly gentle thermal separation process and has already been established for years in fish oil processing (Fig.2).
In numerous preliminary tests, Nutriswiss has determined — together with the independent German Fresenius Institute — the chain length of the impurities that can be removed from mineral oil. They also examined how low temperatures improve the preservation of micronutrients. In the end, a plant concept was developed with which contaminants can be removed without creating new ones. This concept is suitable for a wide range of edible oils, palm oil and omega-3 oils from a variety of raw materials. Owing to the use of a finely controlled vacuum (with a pressure of less than 0.01 mbar) and short residence times, the amount of thermal stress experienced by the raw material is minimised, which prevents the formation of process contaminants such as 3-MCPD or glycidyl fatty acid esters and maximises the yield of, for example, omega-3 fatty acids. At the same time, free fatty acids, plasticisers and pesticides are removed to an extent that is not possible with any other conventional technology. In fat blends for infant nutrition, the composition of omega-3 and omega-6 fatty acids can be specifically adjusted. This also has a beneficial effect on the organo-leptic properties of the end product.
Preserving micronutrients with SPD
Studies by independent food laboratories such as the Fresenius Institute show that MOSH/MOAH levels can be reduced by up to 80%. In addition, the content of high molecular weight pesticides can be reduced by up to 90%, micronutrients are preserved, plasticisers such as DEHP are 100% degraded and, in the case of extremely contaminated oils, although tocopherols (vitamin E) are distilled off during processing, they can be added back to the purified oil at the end. Nutriswiss Managing Director Michel Burla comments: “Our new plant is a game changer in edible oil refining and enables completely new applications with exceptional quality. The isolation of certain fatty acids, the enrichment with valuable essential fatty acids or the targeted use of free fatty acids are only three examples of what we will soon be able to offer our customers.”
Quality begins with cultivation
The quality of almost all raw materials, including vegetable fats, begins at the cultivation stage. Pollutants regularly enter plants and their oilseeds during cultivation. Whether from weathered rocks, volcanic eruptions, mining, industry or agriculture, they can be found in atmospheric dust particles, in rainwater, in the soil and even in fertilisers. Furthermore, it is a known fact that conventional approaches to plant protection and parasite control often involve synthetic pesticides, herbicides or fungicides. Some pesticides, such as kerosene oils, are even permitted in organic farming. However, because they are apolar substances and fat-soluble, they can accumulate in plants and crops. Other factors can also affect plant raw materials during harvesting. They can easily absorb contaminants from the environment, such as mineral oil hydrocarbons (MOSH/MOAH), which originate, for example, from exhaust gases or jute or sisal sacks that have been impregnated with mineral batching oil. And, during preprocessing in the fields and production facilities, food might come into contact with technical oils or additives that are needed to operate machinery. As a result, despite numerous regulations, maximum limit values are repeatedly exceeded.
Supply chain is key
Transportation, whether thousands of nautical miles or just a few road kilometres, always presents a contamination risk for crude oil. In conventional logistical chains, each kilo of raw material of crude oil can be reloaded or pumped up to six times during transit, which raises the risk of contamination with foreign bodies. In ocean freight traffic, only the last three shipments are globally regulated. As such, the composition of a tanker’s cargo or the hygienic conditions of its containers cannot be guaranteed. Nutriswiss minimises the risk of contamination by using its own tracked food-grade containers. They are loaded after the harvest, sealed and only opened when they reach the refinery (Fig.3)
Viewed as a whole, the much maligned MOSH/MOAH could — hypothetically — have already been included at the cultivation stage and during transportation. A challenge when refining fats and oils is the high temperatures required, at which harmful trans fatty acids (TFAs) and chlorinated fatty acid esters, for example 3-MCPD, can form. Put simply: the purification of crude oils poses certain problems … but these can be overcome with the help of particularly gentle process conditions and state-of-the-art technology. Not to mention a raw material management system in which nothing is left to chance.
The vegetable oil trends
Also high on the ecological agenda are cultivation conditions and the environmental consequences of resource-intensive farming. Palm oil has been discussed in this context for years. A nutritionally and economically interesting alternative is rapeseed oil. Its ratio of omega-6 to omega-3 fatty acids is almost perfect and less than 5:1. And, compared with other vegetable oils, it has a very low potential for the formation of MCPD and glycidol esters, which is particularly advantageous when used for frying. In addition, it is also stable to oxidation: if it comes into contact with oxygen during prolonged storage, comparatively few triglyceride monohydroperoxides, aldehydes and ketones are formed. Replacing palm oil and palm oil fractions in confectionery, bakery products (especially puff pastry), spreads, marinade oils or popular nut nougat creams is a demanding task. In addition to pure rapeseed oil, completely hardened rapeseed oil and, if necessary, additional coconut fat must be used. Modern processes saturate almost all unsaturated fatty acids and the trans fatty acid content drops below 1%. Michel Burla comments: “There are alternatives to palm oil. We offer them and our customers use them. Perhaps the greatest challenge is getting chocolate to melt properly. We often work with a combination of cocoa butter and other oils, but this is sometimes only cost-effective with branded products.”
Armed against food fraud
In addition to the harmful substances that are already critical during cultivation, another risk factor is becoming increasingly important: food adulteration. The growing global demand for natural food has led to a boom in falsified food. One of the best-known examples of food fraud is olive oil that is wrongly declared or blended with other oils … but sold as pure virgin olive oil.
To rule out risks such as these from the outset, Nutriswiss takes its own approach to raw material sourcing. Here, it’s not the price that counts, but quality, sustainability and social responsibility. Around 30% of the crude oil processed by Nutriswiss comes from Swiss oil mills, the other 70% comes mainly from tropical regions. Palm oil and palm oil fractions from conventional and organic farming, rapeseed oil and rapeseed HOLL (High Oleic, Low Linolenic), GMO-free soybean oil and sunflower oil (also HO) are part of the standard range, as well as coconut oil, for which there is no globally valid sustainability index (Nutriswiss therefore uses its own defined standards and controls when purchasing). Cocoa butter, shea butter and medium-chain MCT fats are also on the product list.
Highest product safety and quality
Nutriswiss, the Swiss market leader for special and organic edible oils, purifies, neutralises, bleaches, filters, deodorises, modifies and mixes crude oils from a wide range of sources. They have established an expansive network of contract farming associations and sourcing practices to ensure the best possible standards. Working with both conventional and organic producers, both locally and internationally, the company has been able to implement its own standards and controls. Not only does this promote long-term relationships with suppliers, it also provides valuable insight into raw material design and quality. Nutriswiss offers both the contract refining of provided raw materials and access to its own supply chain. Behaviours such as having an independent inspector visit the plantation to review the raw material before it’s loaded into the company’s own ISO-certified containers is a critical part of supply chain security. Similarly, ensuring that the containers are sealed and only opened again when they reach their destination — all the while tracked in real-time by satellite — means that the risk of contamination in transit from the country of origin to the processing plant is virtually eliminated.
1 www.who.int/nutrition/topics/5_population_nutrient/en/index13.html (latest access: 12 October 2020).
2 Cheng Chen et al. (2020): Erythrocyte omega-3 index, ambient fine particles exposure and brain aging, Neurology Vol. 95 (8). https://n.neurology.org/ content/95/8/e995. (Latest access 12 October 2020)