Title: Medium-chain alkyl esters of tyrosol and hydroxytyrosol antioxidants by cuphea oil transesterification Authors
Submitted to: European Journal of Lipid Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 30, 2012
Publication Date: March 15, 2013
Citation: Laszlo, J.A., Cermak, S.C., Evans, K.O., Compton, D.L., Evangelista, R.L., Berhow, M.A. 2013. Medium-chain alkyl esters of tyrosol and hydroxytyrosol antioxidants by cuphea oil transesterification. European Journal of Lipid Science and Technology. 115(3):363-371. Interpretive Summary: A new biobased antioxidant was created for the food industry. Foods can contain fats and oils that are susceptible to deterioration during storage, which can limit product quality and shelf-life. Synthetic antioxidants can slow the spoilage process, although there are limitations to how much can be added to foods. The food industry is interested in using natural ingredients to solve storage stability problems. We found that the oil from the plant Cuphea, cultivated in the upper Midwest region of the U.S., is very useful for modifying olive oil waste molecules to create antioxidants for use in foods. The developed process would be suitable for commercial production. This research creates a new commercial use for a specialty oil seed crop, expands the market for cuphea oil, and has developed two novel antioxidants to help the food industry improve food quality.
Technical Abstract: Effective lipophilic antioxidants were readily prepared by non-aqueous enzymatic transesterification of plant phenols with cuphea oil. Tyrosol (2-(4-hydroxyphenyl)ethanol) and hydroxytyrosol (2-(3,4-dihydroxyphenyl)ethanol), abundantly available phenols from olive oil processing byproduct, were found to be predominately acylated with capric acid (C10:0) derived from the triglyceride fraction of the Cuphea germplasm line PSR 23 (Cuphea Viscosissima × C. lanceolata). Under optimal conditions (60 degree C, 1:3 mole ratio of phenol to triglyceride) the reaction was complete within 2 h, with a >97% yield (based on phenol consumption) using immobilized Candida antarctica lipase B. The reaction products were good solvents for tyrosol or hydroxytyrosol, suggesting a facile manufacturing route not dependent on use of organic solvents or high vacuum. Phenolic derivatives were assessed for their ability to serve as antioxidants for preventing the oxidation of polyunsaturated fatty acyl groups in model membrane phospholipid vesicles. Phenolic derivatives were incorporated into single-lamellar liposomes comprised of 1,2-dioleoyl-sn-glycero-3-phosphocholine and an oxidation-sensitive fluorophoric fatty acid, and then subjected to 2,2'-azobis(2-amidinopropane) dihydrochloride-initiated oxidation. The antioxidant capacities of the cuphea-derived fatty acyl derivatives of tyrosol or hydroxytyrosol were the same as their respective derivatives prepared from decanoic acid, presumably due to the absence of natural antioxidants in cuphea oil. These biobased antioxidants may improve the oxidative stability of sensitive fatty acids in food applications.