Changes in antioxidative properties of hops in the course of drying, milling, pelletization and storage.

Abstract

Post harvest drying of green hops causes loss of some antioxidative activity. This loss does not generally exceed 5 % of the original RADPPH value. Drying also affected decrease in polyphenol substances content. Drying in chamber and belt dryers did not show any significant difference in terms of maintaining antioxidative characteristics of hops. Results of determined antioxidative activity in hot water extract of whole and ground hops are comparable and differences are not statistically significant. Pelletizing of ground hops does not significantly change their antioxidative activity either. During a long-term storage of hops, antioxidative activity declines in dependence on the storage temperature and form of hops.Storage temperature has not detectable effect on antioxidative activity of hop pellets packed in multi-layer foils without air access.Post harvest drying of green hops causes loss of some antioxidative activity. This loss does not generally exceed 5 % of the original RADPPH value. Drying also affected decrease in polyphenol substances content. Drying in chamber and belt dryers did not show any significant difference in terms of maintaining antioxidative characteristics of hops. Results of determined antioxidative activity in hot water extract of whole and ground hops are comparable and differences are not statistically significant. Pelletizing of ground hops does not significantly change their antioxidative activity either. During a long-term storage of hops, antioxidative activity declines in dependence on the storage temperature and form of hops.Storage temperature has not detectable effect on antioxidative activity of hop pellets packed in multi-layer foils without air access.

Keywords

• hops
• polyphenols
• antioxidants
• drying
• milling and pelletizing
• hop storage
• DPPH