This article was prepared by Jorge Luis Alonso G.
The National Autonomous University of Mexico conducted research to analyze the physicochemical and quality differences between two frying methods: (1) traditional immersion in canola oil and (2) forced air convection frying.
The study aimed to provide knowledge to improve and diversify the application of this emerging frying technology. This is a summary of the study.
The Rise of the French Fry: A Culinary Staple
In recent decades, the production and consumption of French fries has increased significantly. In order to achieve the crispy, golden-brown fries that consumers crave, raw potatoes undergo an elaborate process. While potatoes are rich in nutrients and have the potential to address nutritional deficiencies, the process of frying can cause chemical changes. These changes, in turn, affect both their sensory appeal and nutritional quality.
The Science of Starch: A Key Ingredient
The moisture and oil content of potatoes is critical because the chemical reactions during frying depend on these elements. The primary component of potatoes is starch, which makes up 60–80% of the tuber’s dry matter. This starch plays a key role in determining the texture and color of the final fried product.
Health Concerns: The Dark Side of Fries
Despite their popularity, French fries have been linked to health problems such as cardiometabolic disease, diabetes, and hypertension. As a result, there’s a growing demand for alternative processing techniques that can maintain the nutritional integrity of French fries while preserving their flavor.
The Acrylamide Factor: A Hidden Risk
One concern is acrylamide, a potent carcinogen produced by Maillard reactions at temperatures above 120°C. Because of their specific composition, including L-asparagine and sugar, and the frying process itself, French fries are particularly susceptible to acrylamide formation. It’s important to note that acrylamide is not present in raw foods; it’s the overheating during cooking that leads to its formation.
Traditional Frying: The Old Guard
Historically, frying has meant immersing food in oils at temperatures between 120°C and 200°C. This approach causes both physical and chemical changes, including the gelatinization of starch and the formation of a surface crust. The high-fat content of such foods has earned them a link to cardiovascular disease and even cancer.
Air Frying: The New Frontier
Enter air frying, a newer technique that offers the tantalizing promise of frying food with minimal oil. In this process, food is exposed to circulating hot air, resulting in the formation of crusts reminiscent of conventional frying. The benefits of air frying include more even heat distribution, resulting in superior product quality. Significantly, air frying reduces oil consumption by approximately 50–70%, which not only affects the characteristics of the food, but may also reduce acrylamide formation.
Preliminary Findings: The Promise of Air Frying
Preliminary studies suggest that air frying could reduce acrylamide levels by about 90% compared to traditional frying. However, there is a need for more in-depth research on air frying to clarify its effects and potential benefits. The aim of the present study is to compare conventional frying and air frying and to investigate how each affects the quality of French fries.
The Nitty-Gritty: Key Observations
- Moisture Matters: Moisture content plays a key role in the frying process due to its influence on heat and mass transfer.
- Color Considerations: Color changes in French fries after frying are primarily attributed to the Maillard reaction.
- Texture Talk: Texturally, IF fries are more tender due to the higher oil content, giving them a softer feel.
- Microscopic Insights: Examination of fries under SEM micrographs reveals differences in surface structure.
- Thermal Transitions: MDSC analysis reveals three primary transitions in thermal behavior.
- Chemical Clues: FTIR spectroscopy provides insight into the vibrations of functional groups and atoms.
The Future of Frying
When comparing conventional immersion frying to air frying, a key difference is the use of oil. On a chemical, thermal, and structural level, air frying introduces significant changes to the surface of the food, affecting both texture and color. Delving into the science of air frying reveals groundbreaking methods for producing reduced-fat products.
These methods not only offer a wider range of choices in the marketplace but also either maintain or improve the essential physicochemical attributes of French fries. These attributes play a key role in influencing consumer purchasing decisions.
Coria-Hernández, J., Arjona-Román, J. L., & Meléndez-Pérez, R. (2023). Comparative study of conventional frying and air frying on the quality of potatoes (Solanum tuberosum L.). Food Science & Nutrition, 00, 1–10. DOI
Author: This article was prepared by Jorge Luis Alonso G.