Palm oil is ubiquitous in food products, found in everything from ice cream to instant noodles. It was once a relatively rare ingredient, but food formulators have made a wholesale shift to palm oil, says Alejandro Marangoni, professor and Canada Research Chair in Food, Health and Aging at the University of Guelph. That’s because it’s inexpensive and was thought to be a healthier alternative to trans fats. “All the fat used in our food supply went from the partially hydrogenated fat to palm oil. And why not? There’s a lot of it around, and the price is very low,” says Marangoni. “Yes, it’s high in saturated fat, but you need to have some crystalline material in order to create structure.”
Apart from palm oil’s high saturated fat levels, it presents another big problem: it’s environmentally unsustainable. Yet, says Marangoni, there isn’t a suitable, hard, plant-based fat replacement available that’s healthier, as inexpensive as palm oil, and sustainable. “So what can we do in order to address the sustainability problem, and what can we do at the same time to address this decreased saturated fat problem?” he asks. Marangoni and his colleagues set out to find a solution.
They found that by using enzymatic glycerolysis with cottonseed oil, they could convert the oil into a fat. They mixed the oil with glycerol or glycerine and catalyzed it using an enzyme (in this case, Candida antarctica lipase B). The ensuing reaction converts triacylglycerol into partial glycerides—monoacylglycerols and diacylglycerols, which both have higher melting points than triglycerides. Marangoni says it is “actually a very simple reaction.” The findings were published in Nature Food.
The fatty acid composition remains the same, says Marangoni—the cottonseed oil is still cottonseed oil. “But instead of having 100% triglycerides, you now have something like 50% diglycerides, 30% monoglycerides, and 20% triglycerides,” he says. “By doing that, you’ve raised the melting point of the constituent molecules, and now you have converted an oil into fat.”
The researchers then experimented with oils with different fatty acid compositions: tigernut, peanut, olive, soybean, canola, high oleic canola, sesame, and high oleic algal oil. “We just tried out every oil we could get our hands on,” says Marangoni. These findings were published in Current Research in Food Science.
The surprising favorite, says Marangoni, was tigernut oil because it changed so nicely from a liquid to a solid. It made a margarine comparable to commercial margarine because the solid fat increased significantly due to the glycerolysis reaction. Cottonseed oil is another oil that structures heavily—i.e., it has a high level of saturated fatty acids, which makes for better crystalline mass and structure—and doesn’t melt until 50˚C. Oils with greater than 10% saturated fat and a lot of oleic acid had the most solid fat increase post-glycerolysis.
According to the researchers, this is the first time this process has been used to create food fats. Marangoni and his colleagues are investigating the molecular reasons for these changes, but, he says, “it was unexpected that just by converting them from triglycerides to partial glycerides, it would structure so well.”
Plant-based products are the obvious market for these new fats, which can tout health benefits and environmental sustainability. Products that are marketed as green can’t contain palm oil, given its reputation and the current lack of legitimately sustainable plantations. Coconut oil, a common ingredient in alt-meat products, is expensive and isn’t great for the environment. “There’s a big push these days to try to find either another alternative or a replacement for coconut [oil],” Marangoni points out.
Because the method detailed in this research allows for different oils to be modified according to need, it holds promise for a new generation of fats. “This is an interesting option that we haven’t had,” says Marangoni. “You’re really troubled if you’d want to take palm oil out of the food supply. It’s everywhere.”