Antioxidative effect of amino acids on frying

Authors: Liu, Sean; Hwang, Hong-Sik; Moser, Jill; Doll, Kenneth - Ken

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/3/2019
Publication Date: 10/21/2019
Citation: Liu, S.X., Hwang, H., Moser, J.K., Doll, K.M. 2019. Antioxidative effect of amino acids on frying [abstract]. Euro Fed Lipid Congress and Expo, Seville, Spain, October 20-23, 2019.

Interpretive Summary:

Technical Abstract: Evidence exists that some amino acids have exceptionally strong antioxidant activity in soybean oil at frying temperatures. Further studies were conducted to understand mechanisms and factors affecting their activity. It was found that the synergistic effect of amino acids with tocopherols is one important mechanism for their activity. Amino acids with an extra amine group such as L-arginine, L-lysine, and L-tryptophan had higher activity than other amino acids. It was postulated that the radical scavenging activity of an amine and antioxidant compounds produced by reaction of an amino acid with oxidation products were the main reasons for the stronger activity of these amino acids. In general, the activity increased with increasing lipophilicity of an amino acid although there were some exceptions. Chelation of metals by an amino acid, which was known to be an important factor for its activity, was not confirmed in this study although further studies are needed. Peptides and protein hydrolysates have drawn interest as potential natural antioxidants for frying. We compared their antioxidant activities with those of amino acids. Although protein hydrolysates and dipeptides showed significant antioxidant activity in soybean oil at 180 °C, their activities were not as strong as some single amino acids. Amino acids also showed strong antioxidant activity in six other oils including sunflower oil, peanut oil, corn oil, canola oil, high oleic soybean oil, and olive oil. We found that some amino acids were even more effective than the leading commercial natural antioxidant, rosemary extract, in preventing frying oils from oxidation. Antioxidant activity of mixtures of amino acids with the rosemary extract, the green tea extract, ascorbic acid and the concentration effect will also be discussed.