Effect of Oven Drying on Physicochemical Properties, Antioxidant Activity and 6-Gingerol Content in ‘Bentong’ Ginger (Zingiber Officinale Var.‘Bentong’)

Shooi, Kai En (2024) Effect of Oven Drying on Physicochemical Properties, Antioxidant Activity and 6-Gingerol Content in ‘Bentong’ Ginger (Zingiber Officinale Var.‘Bentong’). Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

The antioxidant activity of ginger spices is well established, but the effect of oven drying temperature on the quality of ‘Bentong’ ginger powder remains unclear. Investigating this gap, the study examined how drying temperature affects the bioactive constituents of ginger powder. A range of temperatures (50 ℃, 60 ℃ and 70 ℃) were used to dry the ‘Bentong’ ginger until it reached a consistent weight. Afterwards, the powders were examined to determine their physicochemical properties (water activity, moisture content, and browning index). The ‘Bentong’ ginger powder extract further evaluates its total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (DPPH and FRAP assays), and 6-gingerol concentration. The results revealed that drying temperatures significantly influenced moisture content, water activity, TPC, TFC, antioxidant activity, and 6-gingerol content. ‘Bentong’ ginger powder dried at 50 ℃ had the highest total phenolic content (TPC) (152.50 mg GAE/100 g) compared to those dried at higher temperatures. Total flavonoid content (TFC) peaked at 70 ℃ (403.00 mg QE/100 g), showing a decline at both 50 ℃ and 60 ℃. Conversely, 60 ℃ emerged as the optimal temperature for antioxidant activity (based on DPPH and FRAP assays). The measured antioxidant activity showed negative correlations with both total flavonoid content and total phenolic content. In contrast, 6-gingerol content, a key bioactive compound ‘Bentong’ ginger, exhibited a decreasing trend with increasing drying temperature, with the highest content found at 50 ℃ (68.90 ppm)