How to Ensure Quality in Fried Foods

Editor’s note: This is the first in a series of three articles on frying. Part 2, “Why a Comprehensive Study Is Key to Quality Frying,” was published in the August/September issue of FQ&S, and Part 3, “An Overview of Oil Filtration for Frying Foods,” was published in the October/November issue.

Fried foods are enjoyed the world over. Each country has fried items that may be acknowledged as favorites or comfort foods. There are churros in Mexico, schnitzels in Austria, fish and chips in England, and dumplings in China. Yet according to Dr. Walter Clark, “The popularity of fried food persists in spite of public concern about calories, cholesterol, and saturated fat and that fat intake should be moderated as part of a balanced diet.” This sound like a recent statement? You would be wrong. This is from a 1991 paper in Food Technology.

So, why do frying and fried food persist? There are two reasons. The first has already been alluded to: Fried foods taste good. Properly prepared fried foods have wonderful flavors, textures, smells, and mouthfeel. People simply enjoy good food. The second reason is more practical. Frying is a very efficient means for preparing foods, which not only will fully cook the food but will also help to ensure its overall microbiological safety. To fully cook a piece of chicken in an oven might take 30 to 35 minutes, whereas cooking that same piece of chicken in a deep-fat fryer might take 4 to 6 minutes. For a restaurant or food service operator, time is literally money. The phrase “properly prepared fried food” is used intentionally. The food industry at both the industrial level and for food service and restaurant operators relies on repeat sales, so food quality is an essential element for success. So, quality management in frying is an essential business tool. In fact, the importance of food quality, especially the sensory parameters, was underscored by the first of the eight recommendations that came from the 3rd International Symposium on Deep-Fat Frying in 2000 (see “Recommendations of the 3rd International Symposium on Deep-Fat Frying,” below).

“Principle quality index for deep-fat frying should be sensory parameters of the food being fried.”

At the 10th International Symposium on Deep-Fat Frying, held in Hagen, Germany in March 2020, participants emphasized the importance of food quality by citing the 2000 symposium and making the same statement the symposium’s first recommendation.

Figure 1. Blumenthal’s Frying Oil Quality Curve.

Michael Blumenthal, PhD, was one of the first to look at frying using a systems approach. He described frying as a dehydration process and proposed that the process be defined using a five-phase frying quality curve (see Figure 1). The five phases are break-in, fresh, optimum, degrading, and runaway. To ensure the best quality food, processors and food service/restaurant operators should strive to maintain their oil in the optimum phase for as long as possible.

Elements of Frying Quality Management

So, how do fryer operators best maintain food quality? The key is properly managing the frying oil. There is a very simple equation: Bad oil equals bad food. Oil chemists have tended to focus on the degrading oil, but as Dr. Blumenthal’s work emphasizes, the key is a systems approach. Understand how to manage the different elements making up fryer operations. Canadian scientist Dr. C.J. Robertson (1967, 1968) described six areas to ensure the quality of fried foods. These recommendations, seen below, are more than 50 years old but still apply to frying operations:

• Proper design, construction, and maintenance of equipment;
• Proper operation of equipment;
• Proper cleaning of equipment;
• Minimized exposure to UV light;
• Salt and other metals sources kept away from oil; and
• Regularly filtered oil.

In 1993, Stier and Blumenthal proposed that a seventh principle be added. They suggested that oil be tested regularly. This recommendation was reiterated in the 2000 recommendations shown in “Recommendations of the 3rd International Symposium on Deep-Fat Frying,” below. Of course, fryer operators must select the proper frying oil for their operation and ensure that the oil that is delivered to them meets the established specifications. Selecting the proper oil is a topic unto itself.