What is propolis?

　　Propolis is a kind of soft and sticky gelatinous substance with fragrant smell, which is made from the resin (GUM) collected by bees from plant spores or tree trunks, mixed with the secretion of glands in bee mouthparts, and processed with pollen and beeswax.

　　Propolis is an effective substance used by bees to maintain the health of the whole population. A colony of 50000-60000 bees can only produce 70-110g propolis a year, which is known as "purple gold". The propolis production period is mostly summer and autumn. The gum source plants in China mainly include most species of birch, willow, pine, cypress and lacqueraceae, as well as peach, plum, apricot, chestnut, rubber, eucalyptus and sunflower. Propolis is an opaque solid with smooth or rough surface. The broken surface is in the shape of sand grains, and the cut surface is similar to the shape of marble. It is yellowish brown, Tan, grayish brown, grayish green and dark green, and a few are dark black. It has a special and pleasant fragrance. The taste is slightly bitter and slightly spicy. It is sticky when chewed. It can be softened by kneading with hands. When the temperature is lower than 15 ℃, it becomes hard, brittle and easy to crush; It is soft, sticky and plastic at 36 ℃; When the temperature reaches 60-70 ℃, it melts into a viscous fluid and separates beeswax. The specific gravity varies with different plant species, generally between 1.112-1.136. Insoluble in water, slightly soluble in turpentine, partially soluble in ethanol, very soluble in ether and chloroform. Dissolved in 95% ethanol, it is transparent chestnut with granular precipitation. Pure propolis shall be free of other impurities.