R-300.03.901 [2022-03] Conductometer Value and Content of Total Resins, Soft and Hard Resins in Whole Hops and Hop Products

Application/Purpose

This analysis provides hop processing plants with information regarding their yield during operational testing and enables inferences to be made regarding how processing affects the quality of the final product. This method provides the industry not only with a value for the amount of bitter substances in the product but also with important information regarding hop variety, provenance and age of raw and processed hops, as well as the concentration in the product. However, measuring hop additions based solely on the conductometer value can in some cases lead to substantial differences in the bitterness of beer produced using them.

Scope of Application

Hops and hop products intended for use in beer brewing or elsewhere in the food industry

Principle

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.

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