The Diastatic Activity of Hops, Together With a Note on Maltase in Hops

Although it is forty-six years since Brown and Morris demonstrated the presence of diastase in hops, additions to our knowledge of hop diastase do not appear to have been reported. In the present communication details are given of experiments concerned with this subject. The object of these experiments was to ascertain the relative degrees of diastatic activiy possessed by hops of different variety, origin and age and, generally, to gain information which would help to throw light on the processes which occur in cask as a result of dry-hopping, this being part of a scheme of investigation concerned with flavour and aroma. Examination of thirty-three samples of different seeded hops showed that they did not vary widely in saccharifying activity towards soluble starch at PH 4–8, irrespective of their variety, country of origin, age (up to 3½ years) and conditions of storage (cold-store or warehouse). Seedless hops showed less saccharifying activity than seeded hops. The saccharifying activity did not vary appreciably over the range of PH values from 4-1 to 4–8. The experimental work has indicated a laboratory procedure for the comparison of the saccharifying activity of hops. This involves the use of peptone, which has been found to be much superior to hide-powder (used by Brown and Morris) as a binding agent for tannin. The conclusion of Brown and Morris that dry-hopping in cask produces an appreciable quantity of sugar in a dextrinous beer, and so promotes “after fermentation,” has been confirmed. In addition, the opinion has been formed that one or more additional factors, at present unknown, operate in stimulating “after fermentation” during dry-hopping. The enzyme maltase has been shown to be present in dry hops.