Shan Zha, also known as Crataegi Fructus or Chinese hawthorn fruit, is a commonly used herb for dispersing food stagnation. In addition to its traditional actions and indications, Shan Zha is also well-known for its applications in cardiovascular disease. Traditionally, different processed forms of Shan Zha were used for different applications, and a significant amount of modern research has gone into the effects of processing (pao zhi) on its chemistry and pharmacology.
According to TCM, Shan Zha is especially suitable for dispersing and transforming accumulations and stagnation from rich, fatty foods and meat. It is often used with Shen Qu (Massa Medicata Fermentata) and Mai Ya (Hordei Fructus Germinatus) to treat food stagnation, and it is used with qi-moving medicinals such as Qing Pi (Citri Reticulatae Pericarpium Viride) and Zhi Shi (Aurantii Fructus Immaturus) for severe cases of food accumulation. Shan Zha is also used to quicken the blood, and it is indicated for painful menstruation as well as a variety of postpartum disorders. Finally, Shan Zha is an important medicinal for moving qi in the treatment of shan qi (mounting qi), as well as dysentery cases manifesting in abdominal pain.
Traditionally, raw (unprocessed) Shan Zha was thought to be stronger for moving the blood, while scorch-fried or stir-fried Shan Zha (Jiao Shan Zha or Chao Shan Zha) were thought to be best for dispersing food accumulation. Shan Zha is frequently used in its raw form for the treatment of hypertension, hypercholesterolemia, and coronary heart disease. For dysentery, it is usually used in its char-fried form (Shan Zha Tan).
The use of dry stir-frying as a processing technique for Shan Zha was historically useful for its shelf life, though baking has been used in recent years as a method of drying the fruit and replicating its various processed forms. Some sources indicate that heat of 180 degrees Celsius replicates a form similar to the traditional stir-fried (Chao Shan Zha) form, while temperatures of 220 degrees Celsius produce a product similar to scorch-fried Shan Zha (Jiao Shan Zha).
Organic acids and flavones are key chemical constituents of Shan Zha, and the processing method used influences these components quantitatively. The organic acids within Shan Zha are pharmacologically active, but they also have the potential to irritate the digestive system. After stir-frying (stir-frying until the color changes slightly), some reports indicate that the total organic acids are reduced by about 17%. After scorch-frying (stir-frying until the edges are burned), the organic acids are reduced by nearly 54%. The char-fried form (stir-frying until charred) contains only about 3% of the original total organic acids. Interestingly, research conducted at the Academy of Chinese Medical Sciences in Beijing has shown that much of the reduction of organic acids in simple stir-frying is related to reduction in citric acid content, while the ursolic acid content remains less affected.
Basic stir-frying reduces the flavone content by about 20%, while scorch-frying reduces flavone content by about 58%. The flavone content in char-fried Shan Zha is reduced by about 74%. Additionally, the ratio of trace minerals varies in the various processed forms.
In terms of pharmacology, unprocessed Shan Zha has the strongest effect on promoting peristalsis. However, the promotion of peristalsis is still seen in processed forms, as long as the processing temperature remains below 240 degrees Celsius.
In China, Shan Zha is commonly consumed as a juice or concentrated tea, and it can be found in Chinese supermarkets as a relatively thick, nectar-like juice along with other fruit juices. Unfortunately, such drinks are usually intensely sweet from the addition of too much sugar. Shan Zha is also a key ingredient in Suan Mei Tang, which is a sour and sweet beverage that is commonly served with spicy food in China (Wu Mei is in the drink as well). Shan Zha is naturally very sour and can be mixed with sugar, water, and lemon juice to make a delicious lemonade.