Watermelon Frost, also known as Watermelon Xiao, is mentioned in the "Complete Collection of Ulcer Doctors". It is a white crystalline powder processed from the mature fruit and nitrate of the watermelon plant, Citrulluis vulgaris Schrad.
[Processing Method] Take fresh watermelon, cut a thick slice along the stem as a cover, dig out some flesh and water, fill the nitrate into the melon, cover with the lid, secure with a bamboo stick, hang it in a cool and ventilated place, brush off the white frost when it appears, until no more white frost appears; or cut fresh watermelon into pieces, put it into an unglazed pot, alternate layers of watermelon and nitrate, seal the mouth tightly, hang it in a cool and ventilated place, and a few days later, white crystalline substances will appear outside the pot, collect them as they appear, until no more crystal is produced. 15kg of nitrate is used for every 100kg of watermelon. It is best prepared in a cool and dry season in autumn, and it is difficult to obtain crystals when the humidity is high in summer.
[Characteristics of the Medicinal Material] It is a white granular crystalline substance, similar in shape to table salt, and melts when heated. It has a slight aroma and a slightly salty taste.
[Processing Functions] Watermelon Frost has a salty and cold nature. It belongs to the spleen and lung meridians. It has the functions of clearing heat and detoxifying, and relieving throat inflammation and swelling. Watermelon can clear heat and relieve toxicity, while nitrate can soften and eliminate stagnation, clear heat and detoxify, and disperse swelling and dissolve masses. The combination of the two medicines can enhance the function of clearing heat and relieving fire. It is used for throat wind, throat obstruction, diphtheria, mouth ulcers, dental caries, chronic cough and sore throat, and red and swollen eyes. For example, Watermelon Frost Moistening Throat Tablets for treating throat obstruction and milk moth (National Catalogue of Chinese Patent Medicines); Yuyao Key for treating throat swelling and pain (Synopsis of Laryngitis Treatment); Gua Frost Powder for treating diphtheria (Synopsis of Diphtheria Treatment); Huanglian Watermelon Frost Formula for treating conjunctivitis and keratitis (Complete Collection of Chinese Traditional Medicine Secrets).
[Processing Research] The processing method of Watermelon Frost was first mentioned in Gu Shi Cheng's "Complete Collection of Ulcer Doctors". The method is as follows: Take one large watermelon, 5kg of nitrate, 1.5-2kg of radish, and obtain 0.4-0.6kg of Watermelon Frost, mix it with borneol, and use it to treat acute pharyngitis, elongated uvula, acute tonsillitis, and other diseases. It is a commonly used medicine in traditional Chinese clinical otolaryngology.
According to analysis, Watermelon Frost contains 18 kinds of cyanogenic acids, including 7 kinds of essential amino acids for the human body. In addition, it also contains aluminum, iron, silicon, magnesium, manganese, calcium, potassium, copper, and sodium. The technological reform of Watermelon Frost: take natural potassium nitrate and natural sodium sulfate, dissolve them in hot water, filter, add 20% radish (washed, sliced, w/w) to the filtrate, boil for 30 minutes, filter again, add 40% watermelon (w/w, washed, crushed, seeds removed) to the filtrate, boil, filter, add 1% activated carbon (w/w), boil, and filter (with a Buchner filter, talcum powder as a filter aid). Filter the filtrate through a melting filter until clear, concentrate under reduced pressure, cool and crystallize, weather the crystals (dry and remove crystalline water), add borneol according to the prescribed amount, mix uniformly, pass through a 100-110 mesh sieve, check and accept, and package. Wash the residue with water, filter, and the solution is used for further processing. This method has stable quality and takes about 6 days to produce, increasing the yield tenfold, suitable for industrial production.
