Function-specific volatiles and volatilization characteristics of Dendrobium officinale

The orchid Dendrobium officinale is a medicinal herb that has increasingly been in demand in recent years. It is mainly used for medicinal purposes, and other functional products from it are rarely developed. Here, the volatile organic compound (VOC) composition and functional characteristics of the solid powders and solvent extractives of D. officinale were expounded, and the laws of thermal weight changes of group and surface microstructures were revealed. Many beneficial constituents were detected in the VOCs from powders of the root, stem, and leaf of D. officinale. The roots, stems, and leaves were rich in vitamin E and heptacosane, which can be used as nutritional supplements. The root also contains rich glycerol, can be used as a sweetener and absorbent; the stem is rich in dimethyl phthalate, which can be used to produce mosquito repellent oil; and the leaves contain abundant aldehydes, which can serve as food additives and a component of orange flavoring. However, the root also contains a trace amount of pyrrole (0.09%), which could be used as a negative indicator for the quality evaluation of D. officinale. In addition, many other beneficial VOCs have been detected in extractives of D. officinale, such as phytol, melezitose, hexadecanoic acid, associated esters, and other bioactive components. The total content trend is: ethanol extractive > phenylethanol extractive > petroleum ether extractive, suggesting that the ethanol extractive has the best development prospect. The infrared spectroscopy analysis showed that D. officinale contains aromatic compounds, organic acids, esters, alcohols, aldehydes, and alkanes. It was further confirmed that the alkanes detected in the volatile compounds of D. officinale are natural components of D. officinale, and it was shown that an extraction of organic solvents can cause subtle compound group variation. During the heat loss of D. officinale, there were three distinct stages: 30 °C–130 °C, 130 °C–400 °C, 400 °C–600 °C. The order of quality loss is: second stage > last stage > first stage. The microscopic influence of extraction treatment on D. officinale and the characteristics of microstructural changes showed that the microscopic surface structure characteristics of solid particles of D. officinale, including aggregation degree, shape uniformity, and structure size, are slightly changed. Keywords: Dendrobium officinale, Volatile organic compounds (VOCs), Composition characteristics, Organic solvent extract, Microscopic surface structure