[Mechanism of "herb soaking with exact amount of water" during moistening process of ginseng based on needle pressure sensor].

In this study, the texture analyzer acupuncture pressure sensor was used to objectively characterize the "herb soaking with exact amount of water" for moistening process of ginseng. The single factor rotation experiment was used to investigate the effects of puncture speed, puncture depth and puncture site on puncture force and work. According to ginseng processing method in Chinese Pharmacopoeia, ginseng medicinal materials with diameters of about 1 cm and 2 cm were selected, and puncture experiments were carried out at the set measurement time to determine the hardness, work and water absorption of the ginseng moistening process. The endpoint threshold for the ginseng softening process was determined and verified. To reflect the actual internal conditions of the ginseng softening process, the puncture depth was preferably 70%, and the puncture speed was 30 mm·min~(-1). In the ginseng moistening process, the softening hardness and the puncture work were in accordance with the first-order kinetic equation y=a×exp(-k×x). The 0 h initial hardness a of 1 cm and 2 cm ginseng herbs were 289.8 N and 1 227 N, and the rate constants K were 0.149 4 N·h~(-1) and 0.100 7 N·h~(-1), respectively. After the ginseng was completely softened, the force required for puncture was 10 N, which can be used as the standard for "drug penetration". At this time, the water absorption rate of ginseng was 70%-100%. The softening time of ginseng with a diameter of 1 cm was about 20-22 h, and the softening time of ginseng with a diameter of 2 cm was about 40-46 h. A needle-type pressure sensor was used to accurately determine the end point of the softening process of ginseng and reduce the loss of active ingredients. The study results provide reference for the softening process kinetics and the process intelligent monitoring of other dried roots and rhizomes.