**1. Introduction**

*Panax quinquefolius* L. (American and Canadian ginsengs) is the main ginseng cultivar in the United States and Canada [1]. *P. quinquefolius* administration is known to be e ffective in recovering fatigue, improving immunity, and controlling blood pressure and cholesterol level [2–4]. These e ffects are mediated by ginsenosides, ginseng-specific saponin components [5]. Ginsenosides have a glycoside structure, and their biological e ffectiveness varies depending on their structure. In addition to ginsenosides, ginseng is known to contain other active ingredients such as acidic polysaccharides and phenolic compounds [6].

The ginsenosides of ginseng include Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, Rg2, Rg3, Rh, Compound K, F1, and F2 [7,8]. Ginsenosides are divided into protopanaxadiols (PPD) and protopanaxatriols (PPT) depending on the presence of a hydroxyl group at C3 or C6 and the presence or absence of sugar [9]. Among them, ginsenosides Rb1, Re, Rg1, Rc, and Rd account for more than 70% of the total amount of *P. quinquefolius* ginsenosides [10]. The genus *Panax* includes two main species, *Panax ginseng* (Korean ginseng) and *P. quinquefolius* [11]. There are distinctive di fferences in ginsenoside content between *P. ginseng* and *P. quinquefolius*. Ginsenoside Rg1, Rb1, and Rf contents are high in *P. ginseng*, while

*P. quinquefolius* contains low levels of them [12]. In general, *P. quinquefolius* is known to have higher amounts of ginsenoside Rb1 and Re [13]. It was reported that ginsenosides Rg2, Rg3, Rh1, and Rh2, specific components produced by thermal stimulation, showed preventive e ffects against cancer and inhibited cancer cell growth [14].

In Asia, there are two types of ginseng: white ginseng is produced by drying raw ginseng, and red ginseng is produced by steaming raw ginseng at 98–100◦C for 2–3 h [15]. Red ginseng shows a larger number of pharmacological e ffects than white and raw ginseng [16]; in particular, antioxidant activity, antioxidant enzyme activity, and cell viability are high [15]. It was reported that the minor ginsenosides content of red ginseng is high [17], while these compounds are not found in white ginseng [18]. In 2015, ginseng was registered as an international food standard by CODEX (Codex Alimentarius International Food Standards). Changes in the content of ginsenosides and bioactive ingredients in ginsengs usually take a long time; therefore, red ginseng production and pu ffing may be useful to enhance the pharmacological properties of ginseng products. In the near future, processed ginseng products will be major items in the international functional food market.

To execute pu ffing, a unique food-processing method, pressure is suddenly lowered to atmospheric level from a high pressure in a high temperature regime. Pu ffing induces the gelatinization of starch and increases the volume of the material resulting from the evaporation of water [18]. Pu ffing occurs in two steps. After rapid heating at atmospheric pressure, the sudden evaporation of water causes a rapid decrease in pressure by transfer of superheated steam [19]. Pu ffing causes chemical and physical changes including starch gelatinization in cereal grains [20], ginsenoside profile changes in red ginseng [18], increase in antioxidant activity of white ginseng [21], denaturation and reorganization of proteins in ginseng [22], removal of water and formation of a porous structure in barley [23], and inactivation of enzymes that cause deterioration by lipid oxidation during storage of red ginseng [24]. *P. ginseng* has been mainly used in studies on the changes in ginsenoside content caused by pu ffing [18,25]. Pu ffing of herbal resources has been reported to the greatly increase antioxidant activities [18,21,24,25]. However, limited information is available on the e ffect of pu ffing on the ginsenosides and the bioactive components of *P. quinquefolius*. In this study, we thoroughly investigated the changes in ginsenosides content and antioxidant activity of American and Canadian ginsengs caused by pu ffing at di fferent pressures.

#### **2. Materials and Methods**
