Toasty oat aroma influenced by presence of health-linked polyphenols

Washington, D.C. --- Penn State food scientists have shown that the amount of health-linked polyphenols present during roasting or baking influences the toasty aroma developed by oats and might be used to limit the generation of off-flavors in oat products.

Polyphenols are a large family of naturally occurring plant components that have been associated with a wide variety of health benefits. Flavonoids and some anti-oxidants belong to the polyphenol family and have been shown to have heart-healthy and anti-cancer effects, for example.

The polyphenols the Penn State team studied were hydroxycinnamic acids, which have been associated with reduced risk of chronic diseases or for optimal health.

Dr. Devin Peterson, assistant professor of food science and director of the study, says, "Our research has shown that polyphenols are key to aroma and flavor formation in oats during the Maillard reaction which is the browning process that occurs when foods are roasted or baked. Polyphenols have not been identified as major flavor producers before or associated with the Maillard reaction."

Peterson presented his results today at the national meeting of the American Chemical Society in Washington, D. C. His paper is, "Effects of Phenolic Content on the Generation of Maillard-type Aroma Compounds in Toasted Oat Groats". His co-authors are Stacy L. Schwambach, master's student, and Vandana A. Totlani, doctoral student.

In their experiments, Peterson and his research group took a batch of rolled oats and divided it into two samples. They boosted the level of polyphenols in one of the samples by an amount that can be found in nature and then roasted both samples. The sample that had the added polyphenols developed a lower level of Maillard-type aroma compounds as measured by gas chromatography and a panel of trained human sniffers.

The Penn State group's analyses show that the polyphenols inhibit the Maillard reaction by tying up or quenching some of the sugars and other transient reaction products the process needs to proceed.

Peterson explains that the Maillard reaction not only produces desirable changes, such as a golden brown color and toasty aroma, but also can sometimes cause off-flavors or stale odors. The reaction not only proceeds during roasting or baking but also during storing. The new Penn State results suggest that controlling the levels of polyphenols, which are found naturally in all food plants, might prevent undesirable results of the Maillard reaction.

In addition, the Penn State scientist points out that the Maillard reaction also occurs in the human body as part of the aging process, in tanning, hardening of the arteries, and diabetes as well as other diseases.

"The polyphenols' ability to quench sugars and inhibit the Maillard reaction may have positive implications for health besides improving the quality of food products," he says.

The study was supported by a grant from the U.S. Department of Agriculture Cooperative State Research, Education and Extension Service (CSREES).