Detailed Explanation of Key Points for Harvesting and Processing Gastrodia elata

Gastrodia elata is a perennial parasitic herbaceous plant.

I. Harvesting of Gastrodia elata

For asexually propagated Gastrodia elata planted in winter, it is dug up in the following winter or the spring of the 3rd year. For Gastrodia elata planted in spring, it is dug up in the same winter or the following spring. For sexually propagated Gastrodia elata sown in June of the first year, it is dug up in November of the 2nd year, with 80% being commercial product and 20% being seed tubers. Therefore, the harvesting time for sexually propagated Gastrodia elata can be determined according to production needs.

II. Commercial Processing of Gastrodia elata

After fresh Gastrodia elata is harvested, it begins to rot after being piled for 3-5d. Therefore, it must be processed promptly. Before processing, it should first be sorted and graded: large tubers with a fresh weight of 80-100g or more are Grade 1; 40-79% is Grade 2; those below 40g and those bruised or broken during digging are Grade 3. Sort by grade and wash clean, then process the same day, otherwise the quality and medicinal value of the processed product will be affected.

After washing, the Gastrodia elata is placed in boiling water by grade, with 100g of alum added per 50kg of water, and stirred gently several times to ensure even heating. The boiling time varies with the size of the Gastrodia elata; for Grade 1 large tubers, after being placed in the pot, boil again for 5-8min, and the time decreases successively for the lower grades. The method to check whether they are properly boiled is: after scooping out the Gastrodia elata, the surface moisture can dissipate quickly; when viewed against sunlight or lamplight, there is no black core inside the tuber and it appears translucent; a thin bamboo stick can be inserted smoothly into the tuber. Once these conditions are met, they should be taken out promptly, immersed in clean water and then immediately removed, to prevent overcooking, mutual sticking and shrinking, and tearing of the epidermis. Then they immediately enter the fumigation room and are fumigated with sulfur for 10-12h, making the surface of the Gastrodia elata bright and white, and also preventing insect infestation and mildew.

After fumigation, drying should be carried out promptly, either by sun-drying or oven-drying. When oven-drying, a slow fire should be used; the initial temperature should be kept at around 50°C. After the moisture has been released, the temperature can be raised to 60°C-85°C for slow drying, to prevent the formation of a hard shell due to excessively rapid moisture loss from the epidermis, leaving a hollow center. When dried to 70-80% dryness, take them out, press flat by hand for shaping, pile them up and cover tightly with sacks or similar materials, and let them sweat for 1-2d, then put them back into the drying room until completely dry. Those that produce a crisp sound when tapped against each other, have no scorched spots or blistering on the surface, and have a white, firm cross-section are the best.

Commercial Gastrodia elata must still be graded by size and grade. At the same time, the color and luster should also be considered.