The constituents of hops / Frederick B. Power, Frank Tutin and Harold Rogerson.
- Frederick Belding Power
- Date:
- [1913?]
Licence: Public Domain Mark
Credit: The constituents of hops / Frederick B. Power, Frank Tutin and Harold Rogerson. Source: Wellcome Collection.
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![CXXXV.— 77le Constituents of Hops. By Frederick Belding Power, Frank Tutin, and Harold Rogers on. On account of the extended use of hops in the brewing industry, and also, but in a very much less degree, for medicinal purposes, they have been the subject of numerous investigations. The chief object of these investigations appears to have been to ascertain the nature of the bitter principles, or to determine the proportion in which they are present. Although a considerable number of products have thus from time to time been obtained, to which various names and formulae have been assigned, the character of most of them clearly indicates that they do not represent definite chemical compounds. Apart from the essential oil yielded by the distillation of hops with steam, which has been the subject of several independent investigations by Chapman and others (T., 1903, 83, 505; J. pr. Chem., 1911, [ii], 83, 483), the determination of the presence of tannin and sugar, and the isolation of a very small amount of choline, the information respecting the other constituents, which are mostly contained in the resinous material, has been exceedingly deficient and by no means satisfactory. The confusion which pervades the subject will be apparent from the following brief survey of the literature. Vlaanderen (Jahresb. Chem., 1858, p. 448) obtained from lupulin (the glandular powder from hops) a resin to which he assigned the formula C54H70On, and from which copper compounds of varying composition were prepared. Wagner (Dingier's polyt. J., 1859, 154, 65), in determining the tannin of hops, states that he found a yellow colouring matter which behaved towards reagents like quercitrin, and could be split into quercetin and dextrose, but no evidence of the identity of these substances was recorded. The tannin (“ humulotannic acid ”) has been especially studied by Etti (Annalen, 1876, 180, 223), and more recently by Chapman (J. Inst. Brewing, 1907, 13, 646), with reference to its quantitative determination. Lermer (J. pr. Chem., 1863, 90, 254) states to have isolated from hops a crystalline substance, insoluble in water, but the alcoholic solution of which possessed a bitter taste. This substance, which was very unstable, becoming in a few hours soft and yellow, was called the bitter acid of hops (“ hopfenbittersaure ”), and from the analysis of a copper compound it was considered to possess the formula CaoH^O?. Lermer also indicated that the hop gland contains a wax consisting of myricyl palmitate.](https://iiif.wellcomecollection.org/image/b30620387_0003.jp2/full/800%2C/0/default.jpg)
