Quality of dry ginger (Zingiber officinale) by different drying methods

Area of Science:

• Agricultural Engineering
• Food Science
• Postharvest Technology

Background:

• Ginger (Zingiber officinale) is a globally important spice crop valued for its essential oils and oleoresins.
• Optimizing drying methods is crucial for preserving ginger's quality and bioactive compounds.

Purpose of the Study:

• To investigate the impact of ginger rhizome slicing and various drying methods on drying time and the retention of essential oil and oleoresin content.
• To determine optimal drying conditions for maximizing the quality of dried ginger.

Main Methods:

• Ginger rhizomes were sliced to lengths of 5-50 mm or used whole and dried using sun, solar tunnel, and cabinet tray methods at 50-65°C.
• Essential oil and oleoresin content were analyzed using gas chromatography and reverse-phase high-performance liquid chromatography, respectively.
• Moisture content was reduced from 81.3% to below 10%.

Main Results:

• Slicing ginger significantly reduced drying time across all methods.
• Whole rhizomes dried under sun or solar tunnel methods retained the highest essential oil (13.9 mg/g) and oleoresin (45.2 mg/g) content.
• Decreasing slice length and increasing drying temperature led to significant reductions in essential oil and oleoresin content.

Conclusions:

• For maximum retention of essential oils and oleoresins, drying whole ginger rhizomes using sun or solar tunnel methods is recommended.
• While slicing reduces drying time, it compromises the quality of dried ginger in terms of bioactive compound content.
• Cabinet tray drying at 60°C is an optimum mechanical drying temperature, though it results in approximately 12.2% essential oil loss.