Polyphenolic Composition and Antioxidant Capacity of Extruded Cranberry Pomace

Cranberry pomace was mixed with corn starch in various ratios (30:70, 40:60, 50:50 pomace/corn starch DW) and extruded using a twin-screw extruder at three temperatures (150, 170, 190 degrees C) and two screw speeds (150, 200 rpm). Changes in the anthocyanin, flavonol, and procyanidin contents due to extrusion were determined by HPLC. Antioxidant capacity of the extrudates was determined using oxygen radical absorbance capacity (ORAC). Anthocyanin retention was dependent upon barrel temperature and percent pomace. The highest retention was observed at 150 degrees C and 30% pomace. Flavonols increased by 30-34% upon extrusion compared to an unextruded control. ORAC values increased upon extrusion at 170 and 190 degrees C. An increase in DP1 and DP2 procyanidins was also observed; however, a decrease was observed in DP4-DP9 oligomers. These data suggest that extrusion alters the polyphenolic distribution of cranberry pomace and has application in the nutraceutical industry as a means of improving the functionality of this coproduct.