The researchers at Penn State university studied the impact of the polyphenols hydroxycinnamic acids on flavour formation.
They report that the polyphenols were "key to aroma and flavour formation in oats during the Maillard reaction."
The Maillard reaction, called after the chemist Louis-Camille Maillard, is a chemical reaction between an amino acid and a reducing sugar, usually requiring the addition of heat. Like caramelisation, it is a form of non-enzymatic browning.
Each type of food has a very distinctive set of flavour compounds that are formed during the Maillard reaction.
This is, according to the food scientists, the first time that polyphenols have been identified as major flavour producers, or associated with the Maillard reaction.
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.
Dr. Devin Peterson and his team at Penn State 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, report the scientists, and then roasted both samples.
They report that 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.
According to Peterson, the Maillard reaction not only produces desirable changes, such as a golden brown colour and toasty aroma, but also can sometimes cause off-flavours or stale odours.
The reaction not only proceeds during roasting or baking but also during storing.
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.
Polyphenols, antioxidant phytonutrients such as resveratrol, anthocyanins, catechins, and quercetin that are believed to help the body's cells resist damage by free radicals, are enjoying a growing popularity among food makers keen to tap into the burgeoning health and wellness market.
Peterson presented his paper, Effects of Phenolic Content on the Generation of Maillard-type Aroma Compounds in Toasted Oat Groats this week at the national meeting of the American Chemical Society in Washington, D. C.