Microencapsulation of total saponins from stem and leaf of <i>Panax notoginseng</i> by freeze and spray drying: Process optimization, physicochemical properties, structure, antioxidant activity, and stability

Ginsenosides are the primary active substance in ginseng plants and have a variety of benefits. However, its light and heat stability are weak and easy to decompose. This study used gum arabic (GA) and maltodextrin (MD) as wall materials, and 1% Tween 80 was used as emulsifier. Response surface methodology was used to optimize the preparation process of total saponins in the stems-leaves of Panax notoginseng (SLPNs) (SSLP) microcapsules by spray drying and freeze drying techniques. Under optimal process conditions, the two microcapsules have better solubility and lower moisture content (MC). The color of spray-dried SSLP microcapsules was greener and bluer, and the color was brighter. In morphology, the spray-dried SSLP microcapsules were spherical with a slightly shrunk surface, whereas the freeze-dried ones were lamellar and porous. The two microcapsules have strong stability under different storage conditions and in vitro gastrointestinal digestion simulation. In addition, both microcapsules and free SSLP contained multiple ginsenosides. At the same time, both microcapsules had good free radical scavenging ability. These results indicate that the microencapsulation technology could improve the stability and bioavailability of SSLP, which is expected to provide a reference for the intensive processing of the SLPN. PRACTICAL APPLICATION: After microencapsulation, the stem and leaf extract of Panax notoginseng improved its stability and taste, which laid a foundation for making more nutritious and better tasting food of the stem and leaf of P. notoginseng.