Specification & Spread
Galls are called pathological growths on leaves, the stems and other plant organs caused by various pests - viruses, fungi, bacteria, insects.
In medicine, galls are used, caused by insects that pass inside the affected organ during part of their development cycle. Due to the distortion of metabolism under the influence of insect development. Galls are enriched with tannins and can be used for the industrial production of tannin.
Turkish galls: Turkish galls are formed on the leaves of black oak (Quercus infectoria Oliv.) of beech family (Fagaceae). Black oak is a small tree or shrub with alternate, dense and pinnatilobate leaves. It grows in the Balkans, in Asia Minor and Iran. The formation of galls is initiated by an insect - a nut-crop of the genus Cynus (hymenoptera detachment - Hymenoptera). In the spring, the female pierces the young leaves of an oak with an egg-laying and lays eggs, from which later the larvae form, then pupae, which turn into an adult insect. The whole development cycle takes place simultaneously with galling. The adult nut gnaws a hole in the wall of the gall and flies away. Galls can form with undeveloped or dead insects.
Chinese galls: it is formed in Chinese sumac (half-winged sumac) - Rhus chinensis Mill. (Rh. Semialata Murr.) of sumac family - Anacardiaceae. Chinese sumac is a shrub with large, single-pinpest leaves that grows in Korea, Vietnam, China and India, where, in addition, it is also widely cultivated. The insect pathogen is an aphid (Schlechtendalia chinensis, posteroptera order - Homoptera). The females stick to young twigs and leaf stalks, laying numerous eggs in the punctured parts. The development cycle of insects is accompanied by the formation of galls and begins with the formation of bubbles, which gradually increase in size.
Pistachio galls: it is formed on the pistachio tree - Pistacia vera L. of sumac family - Anacardiaceae. Pistachio (pistachio tree) is a dioecious small tree or shrub 3-5 (10) m tall with unpaired pinwisy and dense leaves. This is a relict species, dominant savanna-like communities of Central Asia. It grows on the mountain slopes, prefers waterless low mountains with loess and loess-gravelly soils. It is cultivated in the Crimea, in the Caucasus. The main thickets of pistachios are in Central Asia.
Turkish galls contain 50-60 (up to 70%) gallotannin, which is hexa- and heptagalloylglucose (Turkish tannin), as well as free gallic acid, starch, and gums. Chinese galls contain 50-80% gallotannin, which is octa- and nonagloylglucose. The related substances include free gallic acid, starch (up to 8%), sugar and tar. Pistachio galls contain up to 50% gallotannin, which is identical to tannin derived from Turkish galls.
Harvesting and storage of raw materials
Turkish galls are harvested in autumn and dried to full hardening. The freshly picked Turkish galls are green, soft, juicy, have a spherical-pineal shape. After drying, it becomes grey and very hard. It is drown in water. The diameter is about 1.5 cm. The raw materials are imported.
Chinese galls are harvested in the autumn from the branches and leaf stalks, then it is treated with water vapor and dried. Chinese galls are light, irregular, thin-walled, with a wide cavity formation. The length can reach 6 cm, the width is 20-25 mm, the wall thickness is 1-2 mm. Outside it is grey or brown in colour and inside it is light brown with glitter. It is received on import.
Storage. No more than 3 years in a dry place.
The raw of pear-shaped pistachios are light, 0.5–3 cm long, with a matt wrinkled surface.
Properties and application
Galls are the main industrial raw material for obtaining medical tannin and its preparations.