Antioxidant Characteristics of Hops and Hop Products

Abstract

The method based on the reaction of stable DPPH radical proved to be the best for the determination of antioxidant characteristics of hops and hop products. Antioxidant activity is expressed as the rate of decline in absorbance of the reaction environment and assessed in relative percents. Differences in the values of antioxidant activity were determined in Czech and foreign hop varieties. The highest antioxidant activities in the scope of 70 to 80% rel. were measured in Saaz and Spalter Select. Antioxidant activity in most of the varieties moved in the scope of 40 to 60% rel. A part of antioxidant activity of hops is irreversibly lost in the course of drying. The loss does not usually exceed 5% of the original RA DPPH value. Drying also resulted in a decrease of polyphenol compound contents. Drying in belt and chamber kilns is comparable from the point of view of preserving hop antioxidant properties. Results of determination of antioxidant activity in hot water extracts of raw hops and ground hops were comparable and statistically non-significant. The same held true for pelletizing of ground hops. The antioxidant activity of raw hops declined in the course of long-term storage in dependence on storage temperature. Storage temperature had no effect on the antioxidant activity of the hop pellets packed in a multi-layer foil without air access.

VITAL - The Czech hop hybrid variety - Part II.

“…4). Obsah polyfenolových látek a stejně tak antioxidační aktivita rámcově klesá od aromatických odrůd po odrůdy vysokoobsažné (Krofta et al, 2008). Biochemické cesty vedoucí k tvorbě flavonoidních polyfenolů a hoř-kých kyselin jsou provázané (Stevens et al, 1998), šlechtění na vysoký obsah hořkých látek vede k určitému potlačení tvorby polyfenolů.…”

Effect of the Addition of Propolis Extract on Bioactive Compounds and Antioxidant Activity of Craft Beer

“…Beer is a product rich in polyphenols and bioactive compounds due to the raw materials used in brewing such as barley malt and hops [24][25][26]. However, during the mashing and boiling stages some phenolic compounds could be removed via fining, filtration, or oxidation [27].…”

Impact of hop raw material type on antioxidant behaviour of beer.

“…Obsah celkových polyfenolů ve chmelu je přibližně 2 až 6 % hm. a zá-visí na odrůdě chmele [1][2][3]. Polyfenolové látky chmele ovlivňují antioxidační aktivitu piva a tím potenciálně i senzorickou stabilitu piva [4][5][6].…”

“…The main antioxidants in hops are polyphenolic and phenolic substances, the weak reducing ability was demonstrated even in bitter acids [1]. Content of total polyphenols in hops is approximately 2-6 % w. and depends on the variety of hops [1][2][3]. Polyphenolic substances in hops affect the antioxidant activity of beer, and thus potentially sensory stability of beer [4][5][6].…”