Source, Etc

Lupulin consists of the glands obtained from the strobiles of HumulusLupulus, Linne (N.O. Urlicaceoe.) The cone-like, collective fruits of the hop (see p. 128) are known as strobiles, and consist of leafy stipules and bracts, the latter enfolding at their base minute fruits. Both the bases of the bracts and the fruits (to a less degree the stipules) are sprinkled over with bright shining glands which when fresh have a pale greenish yellow colour, which darkens as the hops are kept. These glands can be separated more or less completely by shaking and beating the ripe hops, and they are also detached during the manipulations to which hops are subjected in gathering and drying, and collect together with sand, debris, and other extraneous matter, on the floors of the hop-kilns. By sweeping the floors and sifting the sweepings, much, if not all, commercial lupulin is obtained.

Description

Commercial lupulin is a granular, brownish yellow powder with a strong, hop-like odour and bitter, aromatic taste. Examined under the microscope it is seen to be composed of a number of glands, each of which consists of a hemispherical layer of cells, the cuticle of the concave surface of which has been raised, domelike, by the secretion of oil or oleo-resin between it and the cell-wall. When burst by pressure, which is very easily effected, the gland discharges a granular oily liquid.

Fig. 226.   Hop. a, strobile of the Hop, natural size; 6, bract enfolding at its base a small fruit, and showing lupulin glands, natural size; c, fruit magnified. (Tschirch.)

Fig. 226. - Hop. a, strobile of the Hop, natural size; 6, bract enfolding at its base a small fruit, and showing lupulin glands, natural size; c, fruit magnified. (Tschirch).

Lupulin is generally very impure, as indeed it must be if it represents simply the sifted sweepings of the hop-floors, but the glands themselves are easily recognised under the microscope, and as easily distinguished from accidental (sand, debris of the strobiles, etc.) or intentional impurities.

Constituents

Lupulin contains volatile oil, bitter principles, resin, wax, and traces of alkaloids, volatile acids, etc. (compare 'Hops,' p. 127). Pure lupulin yields to ether about 80 per cent. of its weight, and affords about 25 per cent. of ash. Commercial lupulin, however, often gives from 10 to 25 per cent. or even more ash, and yields from 40 to 70 per cent to ether. By keeping, lupulin gradually darkens in colour and acquires an unpleasant odour.

Uses

Lupulin is occasionally employed as a stomachic tonic, and also as an hypnotic to promote sleep.

Uses 332Uses 333Fig. 227.   Lupulin. 1 and 2, side views; 3, seen from below. Magnified 100 diam. (Vogl.)

Fig. 227. - Lupulin. 1 and 2, side views; 3, seen from below. Magnified 100 diam. (Vogl).