Is There a Way to Safely Reuse Frying Oil?

Deep fat frying is a processing procedure used world-wide for the preparation and production of foods. During the deep frying process, oil is subjected to high temperatures, air, and moisture. These conditions cause a variety of degradation reactions to occur such as thermal polymerization, auto-oxidation isomer cyclization, and hydrolysis.

The overuse of frying oil will noticeably affect the flavor stability, color, and texture of fried food. The oil itself undergoes chemical and physical changes resulting in increased smoking, foaming, and changes in viscosity and color. Filtering systems such as the Allen Fry Life System can significantly extend the life of frying oil by using adsorbent material to reduce the level of free fatty acids and colored compounds as well as the polar compounds, the peroxides, and saturated carbonyls.

The Allen Fry Life System consists of a solids filter vessel with two 5-micron filter elements and an activated carbon filter vessel with two cartridges of treated activated carbon, which adsorbs the contaminants from the used frying oil. A reversible oil pump pumps the hot oil via the inlet hose through the filters into the insulated tank for temporary storage while the fryer is being cleaned. The hot oil is then returned to the clean fryer via the reversible pump and the outlet hose. For the best results, the solids and carbon filter elements should be changed between filtration jobs to prevent cross-contamination.

Experimental data concluded the following decrease in contaminants of the filtered frying oil:

These values were reached after nine treatments. More details can be obtained from the following references:

McNeill, J. et al. “Improving the Quality of Used Frying Oils by Treatment with Activated Carbon and Silica.” JAOS vol. 63, no. 12, December 1986.

Orthoefer, F.T. “Care of Food Service Frying Oils.” JAOCS vol. 65, no. 9, September 1988.