Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 17, 2009
Publication Date: November 6, 2009
Citation: Inglett, G.E., Rose, D.J., Stevenson, D., Chen, D., Biswas, A. 2009. Total Phenolics and Antioxidant Activity of Extracts from Distillers' Dried Grains. Cereal Chemistry. 86(6):661-664. Interpretive Summary: Corn is an abundant source of phenolic acids. Phenolic acids are antioxidants that have been shown to have health benefits in humans, and prolong shelf-life of foods. Distillers’ dried grains (DDG), the residues remaining after fermenting corn to ethanol, may be an important source of phenolic acids, because the fermentation process does not utilize these compounds. In the present study, we extracted phenolic compounds from DDG under various conditions, and determined their antioxidant activity. We found that, although high temperatures were the most effective at extracting phenolic compounds, extracts with high antioxidant activity could be obtained after extraction for all temperatures tested. Water and a 1:1 mixture of water and ethanol were the most efficient extraction solvents. These data suggest that DDG may be a good source of valuable antioxidants. Commercialization of phenolic extracts from DDG would benefit farmers by increasing the value of corn, manufacturers by increasing the value of a traditionally low-value byproduct, and consumers by decreasing the costs associated with corn products.
Technical Abstract: Corn is an abundant source of phenolic acids; therefore, distillers’ dried grains (DDG), may exhibit important market value for its phenolic content and antioxidant activity. The purpose of this study was to determine the efficacy of extracting phenolic compounds with antioxidant activity from DDG with water, 50% aqueous ethanol, and absolute ethanol, using microwave irradiation or a water bath at various temperatures. The phenolic content of extracts increased with increasing temperature. The highest phenolic contents were found in the DDG extracts that had been microwave irradiated in water or 50% aqueous ethanol at 150 deg C. Antioxidant activity was less dependent on extraction temperature. The 50% aqueous ethanol extracts showed the highest antioxidant activities with both heating methods at 23 and 50 deg C. At 100 deg C with both heating methods and at 150 deg C with microwave irradiation, the water and 50% aqueous ethanol extracts had the highest antioxidant activities. These data indicate that the highest phenolic contents of extracts are obtained when using water or 50% aqueous ethanol at high temperatures, while the highest antioxidant activities are obtained from 50% aqueous ethanol extracts at any temperature, and water or 50% aqueous ethanol at high temperature.