Supervisor : Prof. Ir. Hari Purnomo, M.AppSc, Ph.D,
Co-Supervisor: Prof. Ir. Simon Bambang Widjanarko, M.App.Sc., Ph.D
The thermal processing of ginger could changed the antioxidant activity either quantitatively and qualitatively. Boiling and roasting times of 2, 4, 6, 8 and 10 minutes respectively had been used to study the activity and the alteration of antioxidant compounds of ginger rhizome without organic solvent. Honey was also used as material antioxidant source in producing a functional drink. It was used in the concentration of 15%, 30% and 45% (v/v) respectively.
The study results showed that boiling time of 6 minutes gave the best effect on the activity and contain of antioxidant compounds of ginger rhizome. The antioxidant activity of this product was free radical scavenger activity of 84.21±0.18%; phenolic total of 30.87±0.26 mg/g; and gingerol content of 20.78±0.14 mg/g. The analysis with GC-MS identified methyl ester (0.17%), 9-octadecenoic (0.32%), (-)-nortrachelogenin (0.30%) compounds as antioxidant agent. Moreover, the zingerone compound total area increased from 5.68% to 6.32%. The FTIR analysis showed that C-O-C antisym stretch vibration at 1270,04 cm-1 wave was found for the methyl ester compund and OH stretch H-bonded at 2870,84 and 2982,71 cm-1 wave were found for the 9-otadecenoic compund.
Whilst the best functional drink was obtained from the combination of 15% (v/v) honey in 25 ml of ginger water extracts. It had the following properties: free radical scavenger activity of 35.51±0.02%; phenolic total of 1.31±0.018 mg/g; and gingerol content of 0.74±0.010 mg/g; taste score of 4.95 (slightly like); colour score of 7.65 (very like); and aroma score of 7.4 (very like). The analysis with GC-MS identified 1-hexadecene (47.81%); hexadecanoic acid (14.25%); and 9-octadecenoic (15.33%) compounds as antioxidant agent. The FTIR analysis showed that CH2 kel. bid. def. vibration at 816,80 cm-1 wave was found for the hexadecene compund, and OH stretch H-bonded at 2944,13 cm-1 wave was found for the hexadecanoic acid and 9-otadecenoic compunds.
It could be concluded that the best treatment combination was the 6 minutes boiled ginger extract with and honey concentration of 15% (v/v) and it was proven that the functional drink produced had an acceptable organoleptic properties.
Keywords: ginger rhizome, antioxidant, thermal processing, honey concentration
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