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R-310.06.999 [2016-03] α-Acid Content for the Manual Inspection of Whole Hops

In the past, the only method available for evaluating hop quality was manual examination and evaluation. With the development of more discriminating analysis methods, manual evaluation has become less essential.

Today, it is used for the general differentiation of hop varieties as well as in the determination of physical quality defects. Manual examination methods are still commonly employed by hop growers and hop brokers for the evaluation of hop quality, for example, at trade exhibitions. In the standard method for manual hop evaluation developed by the Wissenschaftliche Kommission des Europäischen Hopfenbaubüros (see form below), up to 100 points may be awarded for positive quality attributes, while up to 30 points may be subtracted for negative ones [1].

Literatur

H. Kohlmann, A. Kastner, Der Hopfen 183, Hopfen-Verlag, Wolnzach, 1975

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Application/Purpose

For the overall evaluation of whole hops according to R-310.10.999 Overall Evaluation of Whole Hops, the α-acid content is evaluated in addition to the sensory characteristics. This is determined analytically using conductometric titration according to R-300.03.901 Conductometer Value and Content of Total Resins, Soft and Hard Resins in Whole Hops and Hop Products.

Points to be awarded: 1–30

Scope of Application

Whole hops intended for use in beer brewing or elsewhere in the food industry

Principle

from R-300.03.901 Conductometer Value and Content of Total Resins, Soft and Hard Resins in Whole Hops and Hop Products

Hop constituents are distributed between an aqueous acidic methanolic phase and diethyl ether. Hop bitter substances extracted with ether are subsequently separated according to their different solubility properties in cold methanol and hexane into fractions: total resins, soft resins and hard resins. The soft resins are further separated according to their capacity to form complexes with lead salts into α-acids (conductometer value) and a β-fraction.