Who doesn’t enjoy eating French fries or potato chips from time to time? After all, frying is one of the oldest and most popular forms of cooking. It gives food that taste, colour and texture we love so much.
Of course, most fried food is not exactly what you could call “healthy”. Partially hydrogenated oils have long been widely used in the food industry because of their ability to withstand high heat and remain stable over time. In other words, these oils degrade very slowly, which protects the organoleptic qualities of the foods that are fried in them. However, these oils also happen to be largely responsible for the trans fats found in our diet. Since 2005, nutritional labels on food products in Canada have been required to list their trans fats content.
Problems linked to trans fats
So what’s the problem with trans fats?
Excessive consumption of trans fats has been shown to raise the bad cholesterol in our blood and increase our risk of cardiovascular disease. But what about saturated and partially hydrogenated fats? These fats are also known to increase our risk of cardiovascular disease.
The double bond that unites two carbon atoms in a fatty acid molecule can exist in two forms. On the one hand, there are cis bonds, where the functional groups are located on the same side of the double bond; in trans bonds, the functional groups are on both sides. Both forms are found in unsaturated fatty acids, but because of their configuration, they behave in the body in the same way as saturated fatty acids.
So how do unsaturated fats become trans fats?
First it’s important to understand that trans fatty acids come from two sources.
On the one hand, there are naturally-occurring trans fats, which are derived from a bacterial transformation of unsaturated fatty acids in the first stomach of ruminants such as cattle. This is why trans fat is found in dairy products. Most animal fats are saturated fats (think tallow from beef and lard from pork, which are fats in solid form)
On the other hand are industrially produced trans fats, which are formed during manufacturing, primarily by partially hydrogenating oils. This is the process that allows vegetable oils to solidify. Unfortunately, the phenomenon of hydrogenating the oils used in frying simply occurs when the oil is repeatedly heated to a very high temperature. Under the effect of this heat, the cis fatty acid chains becomes trans.
Industrial saturated fats, meanwhile, have long been found in margarines. We used to completely hydrogenate natural unsaturated oils, which solidified them. But because the hydrogenation reaction was not perfectly complete, trans bonds were formed. For a long time now, margarine has therefore been a source of trans fat.
In the U.S., the food industry has until June 2018 to eliminate all sources of trans fat from their products. Canada will be banning trans fats in September 2018 . But whether it’s mandatory or simply because trans fats get such bad press, the industry will have no choice but to turn to vegetable oils – the so-called “non-trans fats”.
Vegetable oils are known as being monounsaturated or polyunsaturated; in other words, cis-form fatty acids. Because they do not raise bad cholesterol in the blood, these cis fats lower the risk of heart disease and are known as the “good” fats. They’re also known as Omega-3, -6 and -9.
The industry has already begun to use non-trans fats, but this shift has created its own new set of problems. Compared to the previously used partially hydrogenated oils (trans fats) or saturated fats, these monounsaturated and polyunsaturated oils are less stable and therefore more likely to rapidly degrade.
Problems linked to non-trans fats
Oils used for frying need to be able to withstand high heat. Although oils rich in monounsaturated fatty acids and Omega-9 have a good heat resistance and a neutral taste, they are also expensive and therefore the least used. For example, olive oil is 75% Omega-9, while canola oil is only 62%. This form of fatty acid is also the only type to be produced naturally by the human body, which is why it is so essential.
Meanwhile, oils rich in polyunsaturated fatty acids, Omega-3 and Omega-6 do not have good thermal stability and tend to form peroxides that shorten the lifespan of oils when heated. For example, corn oil contains 57% Omega-3 and Omega-6, while soya oil is only 54%.
Oils containing Omega-3 and Omega-6 also cause gumming in fryers. This gumming is due to the formation of polymer, which increases the oil’s viscosity, causing it to stick to equipment. Polymerization occurs when the oil is exposed to heat and oxygen over a long period of time. Polyunsaturated fatty acids have several double bonds that are broken during the frying process. As the unsaturated fatty acids begin to reform as solids, the surfaces of equipment that come into contact with the oil and its mist are covered with a sticky gum-like substance.
Buildup of this polymerized oil creates significant and costly cleaning challenges. The strong alkaline cleaners that are traditionally used are not optimal, and more suitable chemicals are often needed to remove these polymers from equipment. Cleaning this buildup also requires more manual labour.
Sani Marc has developed TFF Gel, a powerful degreaser in a ready-to-use formula. TFF Gel penetrates the stubborn buildup of polymerized fat, degreasing quickly and efficiently to increase productivity.