Jacobsen (1991) described the importance of filtration and the removal of particulates that move from the food into the oil. He recommended that operators filter regularly “to remove charred batter and breading materials because these materials can darken oil, contribute bitter flavors to foods, impede heat transfer, and ruin the appearance of fried food.” Particles remaining in the oil continuously leach their components into the oil, chemically degrading the frying medium.
Blumenthal (1987) has observed that “food particles in an oil act as reactive sites for oil degradation.” A simple analogy to particulates in oil may be a starter crystal in a sugar solution in the production of rock candy. Without the starter, the desired crystallization will not occur. The same idea holds true with the chemistry of the frying oil: Remove the particulates, and reaction rates are slowed. Again, this may be seen in Figure 1.
The Pros and Cons of Oil Filtration
In foodservice or restaurant operations, oil life extension is one of the most important elements to ensure profitability. There are other potential benefits, but people also need to understand that oil filtration or treatment is not a panacea. Table 1 lists both potential benefits and concerns.
Let’s take a look at some of these benefits of and concerns with oil filtration and treatment. Some of these issues are closely interrelated. For example, extending oil life, which, as noted, is of paramount importance not only to restaurant and foodservice operators, but also to industrial operators, will also result in reduced oil usage and improved food-to-oil ratios. The food-to-oil ratio is a calculation that shows the amount of food fried to pounds of oil used. This can result in significant savings for the operator and also means that the amount of oil that has to be discarded (waste oil) is reduced. Simply extending fry life from two to three days in a 50-pound fryer will save almost 3,000 pounds of oil per year. Extending the oil life to six days will save 5,800 pounds per year, as may be seen in Table 2. This also means less oil handling, fewer concerns with discard issues, and reduced operating costs.
Food quality is another potential benefit. Food quality is a characteristic that depends upon the operator. It could be improved shelf life, enhanced flavor, or improved overall appearance of the product. One industrial processor adopted an active treatment system, which improved the shelf life, flavor profile, and overall appearance of a fried pepper product. The product fried in oil that was subjected to the oil treatment had improved pepper flavor and aroma when evaluated by an expert sensory panel.
When evaluating any kind of system in a food processing environment, operators must look at both potential benefits and concerns. As an example, Europe discourages the use of powders for oil treatments, whereas they are allowed in the United States. There have also been issues when it comes to handling powders. People should wear the appropriate personal protective equipment (PPE) when handling powders, which should include gloves and masks. This can be more difficult to manage and enforce at the restaurant level than in industrial operations. Lastly, there are products on the market that may seem beneficial but are, in reality, more damaging to the oil. There are treatment products on the market that will reduce free fatty acids in the oil by converting them to alkaline soaps. The soaps are very damaging to frying oil, enhancing the formation of free fatty acids and catalyzing oxidation reactions that will produce off flavors in fried food, in addition to significantly reducing oil life.
Linda says
This is a very good article, thank you for sharing, there are not many such articles in this field.
Karim says
Thanks for the good article.