Extraction and deglycosylation of flavonoids from sumac fruits using steam explosion

The effects of steam explosion on the extraction and conversion of flavonoids from sumac fruits were studied. Steam explosion caused the reduction of particle size and led to the formation of large fissures and micropores on the sumac fruit coat. However, there was little change in total flavonoid content. A study of the process kinetics showed that the flavonoid yield of sumac fruits steam-exploded at 200 degrees C for 5 min reached the maximum of 19.65 mg/g dry weight at 20 min, which was about 8-fold higher than that of the raw sample. In addition, quercitrin (quercetin-3-O-rhamnoside), the dominant flavonoid in sumac fruits, was deglycosylated and converted into quercetin by steam explosion. The conversion ratio was 84.51% under the steam explosion condition of 200 degrees C for 5 min. It can be concluded that steam explosion is a promising process for application in flavonoid extraction and conversion in the food industry. (c) 2010 Elsevier Ltd. All rights reserved.