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Characterization of the Unfertilized and Fertilized Hop Varieties Progress and Hallertauer Tradition Analysis of Free and Glycosidic-Bound Flavor Compounds and β-Glucosidase Activity
K. Haslbeck, S. Jerebic, and M. Zarnkow

Fertilized or unfertilized, hops have an impact on the characteristics of beer that determine quality. Unique, comparable samples of unfertilized and fertilized plants of the Progress (Goudhurst, United Kingdom) and Hallertauer Tradition (Hll, Germany) varieties were cultivated. Different cultivation methods were applied depending on the growing region. The success of the methods was verified by high seed contents of fertilized plants and only minimal formation of semen by plants that were prevented from pollinating. The comparability of the samples was targeted by similar growth and harvest conditions, managed at the same location. No significant differences occurred in the composition of the essential oils of fertilized or unfertilized samples. The disadvantages of fertilized hops as a result of decreased α-acid content or a lower essential oil quantity as described in the literature could not be confirmed. The glycosidically bound flavorings of fertilized or unfertilized hop samples were released by preparation of the Rapidase F64 enzyme. Approximately 2g of glycosidically bound linalool could be released from one gram of hops (dry matter). In the hops, β-glucosidase enzyme activity could be verified at approximately 0.11U/g (dry matter hops) on average in all examined samples.

Descriptors: humulus lupus L., unfertilized and fertilized hops, glycosides, essential oil, gas chromatography, β-glucosidase activity

BrewingScience, 70 (November/December 2017), pp. 148-158