Quality and functional properties of red ginseng prepared with different steaming time and drying methods

The quality and functional properties of red ginseng in relation to steaming and drying conditions were evaluated. Fresh ginseng (5-year roots), cultivated in the Punggi region, were steamed for 2.5, 3.5, or 4.5 hr, and then dried by hot-air (60-65°C/24 hr and 40°C/3-4 d), freezing (-80°C/56 hr), and infrared (900 W/62°C/68 hr). Hunter's yellowness (b-value) and browning indexes (420 nm) of the samples were higher in the rootlets than in the main roots. Furthermore, these same index values were found to be high in the order of 3.5, 4.5, and 2.5 hr and infrared, hot-air, and freezing for steaming and subsequent drying, respectively. Analysis of soluble solids, total phenolics, total flavonoids, acidic polysaccharides, and electron donating abilities of the steamed and dried samples showed that 3.5 hr of steaming with infrared drying was optimal. However, crude saponin contents were not influenced by steaming and drying conditions. The contents of ginsenoside-Rg₁ -Re, -Rf, and -Rb₂, which were the major components in the samples, were reduced with steaming time, while the amounts of -Rg₃ and -Rh₂ increased, reaching the highest levels at 3.5 and 4.5 hr in the main roots and rootlets, respectively. The contents of -Rg₃ and -Rh₂ were similar in both the freeze-dried and hot-air dried samples.