How to Ensure Quality in Fried Foods

Equipment design and maintenance will contribute to the potential for exposure to metals. As an example, on an industrial frying line producing potato chips, the seasoning reel will be located far enough from the fryer so that seasoning will not get into the oil. In a restaurant, one should never season or salt fried foods while they are draining after being removed from the fryer.

All fryers, including those that are used industrially and in food service and restaurants, should be constructed from stainless steel. This must include all plumbing. If valves or fittings have to be replaced, replacements must be stainless. A sure way to destroy frying oil and the product being fried is to use a brass or bronze fitting instead of stainless steel.

It has already been mentioned that metals in cleaning compounds will react with oils in the presence of water to form alkaline soaps, which are significant prooxidants.

Filter Regularly

Today, most fryers include a built-in system to filter oil. Filtration will remove charred materials, breading, and other materials that come from the food being fried. These materials will darken oil and may re-deposit on finished, fried foods, compromising their appearance. Removing particulate from frying oil will help extend oil life. Food particles often act as the focus for degradation reactions, which will damage oil and compromise food quality.

There are two kinds of filtration systems used in frying operations:

• Passive Filtration—These systems simply remove particulate from the oil through sieving. Some also call passive filtration simply filtration.
• Active Filtration—Active systems are much more complex. These systems not only remove particulates but will also remove oil soluble components. Active systems are also referred to as treatments.

A well-designed filtration or treatment system can significantly enhance oil quality and extend oil life. The frying oil quality curve in Figure 1 also shows how the use of an oil treatment product called Supersorb by Filtercorp extends the optimum frying period, thereby extending oil life and helping maintain food quality for a longer period.

Test Oil Regularly

As noted, testing oil regularly was suggested by Stier and Blumenthal as a tool for quality management. This is where the “rubber hits the road,” so to speak. Dr. Robertson’s six principles of quality will help maintain oil quality and, therefore, allow the fryer operator to produce high quality food, but the question is, “At what point does oil quality change to the point where food is now unacceptable?” Unfortunately, there is no such thing as one size fits all, since each and every fryer operator’s perception of quality differs. It is up to each operator to conduct frying studies to establish the relationship between oil and food quality.

There are many chemical markers of frying oil degradation (see “Chemical Markers of Oil Degradation,” below). There are also a number of rapid tests available that can be used in lieu of conducting a chemical test. It is up to the fryer operator to determine which chemical marker or markers correlate with optimum food quality and the point at which the oil degrades to the point that food quality is unacceptable. Chemical testing of the progressively degrading oil must be accompanied by sensory testing of the food. The processor or restaurant operator must be involved with the sensory work as they know what is acceptable better than anyone else.

There are challenges when it comes to oil testing. One is determining the end point, the second is determining which test or tests to use, and the final is actually doing the test. It is much easier to test degrading frying oil in an industrial operation than it is in a restaurant. Restaurant operators must use a simple, quick test, as the people working in restaurant operations are generally not very sophisticated. Most foodservice and restaurant operators do no testing at all, but instead discard oil based on schedules.