After harvesting, the processing of fresh and dried dendrobium requires different techniques to achieve quality transformation. The core steps revolve around removing impurities, preserving active ingredients, and improving shelf life, with slight adjustments made depending on the variety. Fresh processing prioritizes rapid handling and minimizing loss. Immediately after harvesting, impurities such as fibrous roots, leaves, and dirt must be removed to prevent accelerated decay. In some regions, damp sand storage or bamboo baskets covered with thin mats are used to store fresh dendrobium in a cool, well-ventilated place for short-term preservation to maintain its moisture and active ingredients. For long-term storage, fresh dendrobium can be washed and refrigerated directly, or simply washed and used for fresh consumption or juicing, maximizing the retention of polysaccharides, alkaloids, and other active substances.
Dried processing focuses on achieving long-term preservation through dehydration while retaining its medicinal value. The process includes washing, softening, shaping, and drying. Taking traditional dendrobium processing as an example, after harvesting, the fibrous roots and leaves of dendrobium need to be removed. After sorting, they are categorized by stem thickness and age to provide uniform raw materials for subsequent roasting. Roasting is a crucial step in softening the stems. The dendrobium stems are placed in a pot at 110-120℃ and stir-fried until the leaf sheaths open and the stems soften. This process requires constant stirring to prevent scorching, demanding extremely high levels of skill in controlling the heat and technique. After roasting, the leaf sheaths are removed by rubbing, and any remaining impurities are further purified by rinsing with clean water.
Shaping is a distinctive step in dried product processing, especially evident in the spiral shape of dendrobium. The softened stems are twisted and wound around a 2-2.5 mm diameter stainless steel wire, forming a tight spring shape. Both ends are secured with sedge to prevent loosening. The flexibility and high-temperature resistance of sedge make it the preferred material for securing the product. After shaping, dendrobium requires multi-stage baking and drying: first, surface moisture is quickly removed over medium heat (70-80℃), then the interior is slowly dried over low heat (30-50℃). During baking, it must be turned evenly to ensure uniform drying. To improve appearance and quality, some processes include a second baking step, which makes the stems firmer and the color more uniform through secondary heating.
Controlling the degree of dryness directly affects the quality of the medicinal material. After baking, dendrobium should have a moisture content ≤8%. At this point, the stems are golden yellow with a slightly bluish tinge, and the texture is brittle but not easily broken. Cooling and removing the binding are the final steps in shaping. The baked dendrobium is placed in a cool, dry place to cool naturally, avoiding high temperatures that could cause moisture regain. Then, the root hairs and stainless steel wire are removed, and excessively long roots are trimmed with scissors, retaining 2-3 rootlets about 2-4 mm in length, which meets medicinal standards and improves aesthetics. After shaping, the remaining leaf sheaths need to be checked again to ensure the surface is smooth and free of impurities.
Different varieties and origins of dendrobium require different processing details. For example, in Sichuan, fresh dendrobium is soaked for several days or piled up and covered with straw mats, with regular water spraying to promote leaf sheath decay, followed by scrubbing with a brush or rice husks. In Guizhou, methods such as scalding with boiling water, rubbing with burlap, or stir-frying with river sand are used to remove the leaf sheaths. Although these methods differ, they all aim for "efficient sheath removal and reduced loss," adapting to local climates and variety characteristics.
The processing differences between fresh and dried dendrobium stem from intended use and preservation requirements. Fresh dendrobium emphasizes the integrity of active ingredients, with simple processing steps, primarily for quick use or short-term preservation. Dried dendrobium, on the other hand, extends shelf life through dehydration and shaping, while roasting and baking enhance the density and stability of the herb, facilitating transportation and long-term storage. Regardless of whether it is fresh or dried, the entire processing must avoid high temperatures that could damage heat-sensitive components such as dendrobium alkaloids, ensuring that its medicinal value is not compromised.
The transformation from fresh to dried dendrobium is a crucial leap from the field to the pharmacy. Fresh processing focuses on "freshness," preserving its original flavor and nutrients; dried processing, on the other hand, pursues "refinement," using complex processes to endow it with higher commercial value and medicinal stability. Although the two methods differ, both embody the wisdom of traditional Chinese medicine processing—"tailoring techniques to the material and striving for excellence"—laying the foundation for the widespread application of dendrobium.
