Stability of Phytochemicals and Antioxidant Properties in Ginger (Zingiber officinaleRoscoe) Rhizome with Different Drying Methods

Abstract

Effects of drying methods on the stability of phytochemicals and antioxidant properties of ginger (Zingiber officinale) were assessed. The rhizomes were collected at 9 and 12 months after planting and sun-dried, freeze-dried, or oven-dried at 40 • , 50 • , 60 • , or 70 • C. Oven drying at 60 • C resulted in significant gains of phenolics (441.85 mg.100g -1 d.w), antioxidant activities (78.45 ± 2.04% and 650.45 ± 50.04 μmol Fe (II).g -1 dry extract) of ginger rhizomes at 9 months after planting. Oven drying at 70 • C resulted in significant gains of phenolics (450.02 mg.100g -1 dry weight), antioxidant activities (79.34 ± 1.20% and 662.31 ± 17.01 μmol Fe (II).g -1 dry extract) of ginger rhizomes at 12 months after planting.

Effects of Pretreatments and Drying Temperatures on Drying Characteristics, Antioxidant Properties and Color of Ginger Slice

“…A shorter drying time is required at higher drying temperatures, resulting in the similar values of TPC in samples dried at diff erent temperatures. This result is inconsistent with that of Chumroenphat et al (2011), who reported that the TPC in ginger rhizome increased with increasing drying temperature.…”

“…This is probably due to a lower value of TPC in the blanched sample. Chumroenphat et al (2011) found a positive correlation between TPC and DPPH assay of ginger extracts; the samples with higher TPC showed higher antioxidant activity. This indicated that phenolic compounds in ginger contributed to their antioxidant activity.…”

“…The maturity of the plant also aff ects the TPC in ginger rhizome. Chumroenphat et al (2011) reported that the ginger rhizome at 12 months a er planting had higher TPC than that at 9 months a er planting.…”

“…It was found that drying at higher temperatures resulted in lower 6-gingerol content. Chumroenphat et al (2011) reported that the TPC and the antioxidant activity of ginger rhizome were higher when drying was performed at higher drying temperatures. However, the browning of ginger was greater at higher drying temperatures (Phoungchandang et al, 2009).…”

Is air-drying of plant-based food at low temperature really favorable? A meta-analytical approach to ascorbic acid, total phenolic, and total flavonoid contents

“…While decrease in TPC with the increase in temperature from 40°C to 70°C was published for cocoa bean (10), sweet corn (11), tomatoes (12), carrots (13), gac fruit (14), leaves of Stevia (15) or jaboticaba fruit (16), the increase in TPC with the increase of drying temperature was observed for apple (17), ginger rizome (18), cucumber (19) or quinoa seed (20).…”