Nowadays, deep frying foods is one of the most widespread culinary and industrial cooking techniques in the world. But with an emphasis on healthy eating on the rise, information about food sources has become more important to consumers. So, even though the appeal of fried foods remains strong, it is prudent to offer the consumer some assurance of care and attention to detail regarding the health and quality of your menu items and fried products. Monitoring the composition of fryer oil for its polar content is a key step in producing a desirable, quality fried product. In this paper, we will explain how polar compounds are created and then how they can be easily monitored.
How are polar compounds created?
Oil Alteration
The technique of deep frying involves a series of complex processes that affect the composition of both the oil and the product being fried. Each type of product has several variables that affect the optimum deep frying conditions:
The moisture contained in foods, atmospheric oxygen, and high temperatures (320° – 400° F) produce reactions such as hydrolysis, oxidation and polymerization. These reactions change and modify the chemical composition of the used frying oils, releasing free fatty acids and free radicals that in turn combine to make monoglycerides, diglycerides and polymeric trigylicerides. All of these products of alteration are considered polar compounds and grouped under the term Total Polar Compounds, which is a reliable benchmark for measuring the degradation of the oil.
Since these polar compounds are not digestible, consumption can impact consumer health, posing a greater risk of heart disease in the long term and gastrointestinal disorders in the short term. Expired oil renders the fried foods greasier and negatively impacts flavor and color, detracting from the appeal of the product.
Monitoring fryer oil for polar content will ensure that the product is of consistent quality, and won’t have a negative impact on consumer health.
Hydrolysis and the Release of Free Fatty Acids
The water content of food is necessary in the deep frying process, creating a protective layer that simultaneously prevents oil from penetrating the product and allows the product to cook thoroughly. As the water evaporates, fatty acids, monoglycerides, and diglycerides are released. During hydrolysis, water alters the bond between glycerol and fatty acid, and is then itself split into two parts. One part attaches itself to the free radicals, while the other remains attached to the fatty acid radical. The hydrolysis derivatives increase the oxidation and reactivity higher than the original triacylglycerides, which in turn accelerate degradation. The intensity of this process depends on different factors: