Changes in phenolic acid content during dry-grind processing of corn into ethanol and DDGS.
BACKGROUND
Nine fractions (1, ground corn; 2, cooked slurry; 3, liquefied slurry; 4, fermented mash; 5, whole stillage; 6, thin stillage; 7, condensed distillers soluble (CDS); 8, distillers wet grains (DWG); and 9, distillers dried grains with solubles (DDGS)) were collected at different steps from three commercial dry-grind bioethanol processing plants. Samples were analyzed for individual and total phenolic acid content by HPLC and the antioxidant capacity by ferric reducing antioxidant power (FRAP) assay.


RESULTS
There were significant differences in phenolic acid (individual and total) content and the antioxidant capacity in the nine fractions collected from the three processing plants, but the changing trends in all three plants were very similar. The four phenolic acids identified in all fractions were caffeic, p-coumaric, ferulic and sinapic acids. Vanillic acid was present in all fractions except fractions 2 and 3. All fractions collected following fermentation, except fractions 6 and 7, had higher concentrations of phenolic acids than fractions before fermentation, with DWG having the highest phenolic acids content.


CONCLUSIONS
The increased concentration of phenolic acid content after fermentation in four fractions (4, 5, 8 and 9) was primarily due to depletion of starch during dry-grind processing. Further research is needed to investigate the influence of enriched phenolic acid concentration in DDGS on diet palatability (sensory property) and animal health.
Food Composition and Methods Development laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, US Department of Agriculture, Beltsville, MD, 20705-3000, USA.
Devanand L
DL
Luthria
Ayaz A
AA
Memon
Keshun
K
Liu
D000821:Animal Feed; D000818:Animals; D000975:Antioxidants / Q000032:analysis / Q000494:pharmacology*; D002109:Caffeic Acids / Q000032:analysis; D002264:Carboxylic Acids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000032:analysis; D004032:Diet; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005511:Food Handling / Q000379:methods*; D062385:Hydroxybenzoates / Q000032:analysis; D010636:Phenols / Q000032:analysis*; D011422:Propionates; D012639:Seeds / Q000737:chemistry; D013213:Starch / Q000032:analysis; D014641:Vanillic Acid / Q000032:analysis; D003313:Zea mays / Q000737:chemistry*
D000975:Antioxidants; D002109:Caffeic Acids; D002264:Carboxylic Acids; D003373:Coumaric Acids; D062385:Hydroxybenzoates; D010636:Phenols; D011422:Propionates; D000431:Ethanol; C073734:sinapinic acid; D013213:Starch; C004999:ferulic acid; D014641:Vanillic Acid; C017616:phenolic acid; C495469:p-coumaric acid; C040048:caffeic acid
HPLC-DAD-MS analysis; antioxidant capacity; dry-grind processing of corn to ethanol and DDGS; ferric reducing antioxidant power (FRAP) assay; phenolic acids