Extraction and characterization of 6-shogaol and 6-gingerol from Zingiber
officinale var.Bentong
Zingiber officinale Roscoe var. Bentong or locally known as Bentong ginger is exclusively planted and harvested in the district of Bentong, Pahang, Malaysia. The demand for this ginger species has dramatically increased due to its high food and medicinal values, owing to the presence of 6-shogaol and 6-gingerol as active compounds. This study aimed to measure the concentrations of those active compounds with respect to their one-year plantation duration (January - December 2018). The proximate analysis, heavy metals and antioxidant activity were simultaneously determined during the plant growth. 6-gingerol was present in both fresh and dried samples whilst 6-shogaol could only be found in dried samples. Fresh ginger recorded the highest 6-gingerol content (2.09 mg/g) in the seventh month of harvesting time. On the other hand, in the sixth month of harvesting time, dried ginger had the highest concentration of 6-gingerol (0.66 mg/g) and 6-shogaol (1.85 mg/g). Notably, the accumulation of heavy metals such as As, Pb, Cd and Hg in Bentong ginger was relatively low and within the permissible limit. Meanwhile, the total polyphenol and phenolic content of Bentong ginger extract solution were observed to decrease as the ginger was maturing. In conclusion, Z. officinale Roscoe var. Bentong yielded different amounts of active compounds with respect to its harvesting time. Nevertheless, it generally exhibits good values in terms of chemical compositions that can be potentially used as nutraceutical food.