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Total Phenolics and Antioxidant Activity of Water and Ethanolic Extracts from Distillers Dried Grains with Solubles With or Without Microwave Irradiation

¹Cereal Products & Food Science Research Unit, National Center for Agricultural Utilization Research, USDA, ARS, 1815 N. University Street, Peoria, IL 61604. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Phone: 309-681-6363. Fax: 309-681-6685. E-mail address: George.Inglett@ars.usda.gov ³Present address: National Starch, 10 Finderne Ave, Mail Stop 2130, Bridgewater, NJ 08807. ⁴Plant Polymers Research Unit, National Center for Agricultural Utilization Research, USDA, ARS, 1815 N. University Street, Peoria, IL 61604.

The purpose of this study was to determine the efficacy of extracting phenolic compounds with antioxidant activity from distillers' dried grains with solubles (DDGS) with water, 50% aqueous ethanol, and absolute ethanol, using microwave irradiation or a water bath at various temperatures. DDGS was extracted for 15 min with each solvent while heating at 23, 50, 100, and 150°C by microwave irradiation or in a water bath at 23, 50, and 100°C. Phenolic content of extracts increased with increasing temperature to a maximum of 12.02 mg/g in DDGS extracts that were microwave irradiated in water or with 50% aqueous ethanol at 150°C. Antioxidant activity range was 1.49–6.53 μmol of Trolox equivalents/g of DDGS. Highest antioxidant activities were obtained from 50% aqueous ethanol extracts at all temperatures, and water extracts that were heated at 100 and 150°C. These data indicate that DDGS extracts with high phenolic content and antioxidant activity can be obtained from DDGS, particularly with the use of water or 50% ethanol and high temperature (100 or 150°C). This may be valuable to ethanol manufacturers, livestock producers, and food and nutraceutical companies.