| Summary: | 碩士 === 國立宜蘭大學 === 食品科學系碩士班 === 96 === The purpose of this study was to evaluate the antioxidant activity and related compounds in yams and bulbils of three specis, I-Lan, Keelung, and Hualian. Furthermore, the changes of antioxidant activity and its constituents during cooking process were also investigated
The results showed that the yield of different extracts from yams and bulbils were in the order of Water>MeOH> EtAc. The highest yield of extract from Hualian yams and bulbils were observed, The DPPH radical scavenging effect, reducing power, and chelating Fe2+ ability of yams and bulbils increased, while the concentration of extract increased also. However, inhibition of linoleic acid oxidation, in contrary, decreased during increasing concentration. The DPPH radical scavenging activities of extracts were MeOH>Water>EtAc, and the best effect was found in Ilan bulils.
The analysis results of the constituents in yams and bulbils indicated that the total phenolic contents of yams and bulbils were between 235.45-1075.94 mg/100g dw.The content of total flavonoids in yams and bulbils were about 31.21-254.05 mg/100g dw. It was obviously, the contents of bulbils was higher than that in the yams.
The contents of allantoin in water extract were higher than in methanol extract. The allantoin content of yams and bulbils were about 925.30-1382.33mg/100g dw.The content from Ilan’s were higher than other. Two sugars, rhamnose and sucrose, were found in the methanol extracts from yams and bulbils. The sucrose content of yams and bulbils were at the range of 2.88-14.40 mg/100g dw respectively. For the levels of rhamnose were 2.44-6.61 mg/100g for yams and bulbils.
Ferulic acid and p-coumaric acid were identified in methanol extract of yams and bulbils. The contents in methanol extract of yams after alkali hydrolysis were 0.50-0.93 mg/100g dw and 0.39-1.07 mg/100g dw, respectively. However, no free form and acid hydrolysis form existed. For the bulbils, the contents of ferulic acid were 4.92-16.00mg/100g dw for alkali and acid hydrolysis. The contents of p-cumaric acid in bulbils were 2.46-9.62mg/100g dw for alkali and acid hydrolysis. The total ferulic acid and p-cumaric acid in bulbils were much more than that in yams.
Acording to the DPPH addition assay, the ferulic acid and p-coumaric acid could react with DPPH free radical. The quantity of reactivity of both phenolic acids in bulbils were higher than that in yams, which implied that the ester form of phenolic acid might probably play an important role for DPPH radical scavenging effects. There were still many unknowns in methanol extracts of yams and bulbils and need to be elucidated in the future.
The total phenolic contents and DPPH radical scavenging effect of yam and bulbils increased at the first, then decreased during cooking process. The correlation equation between total phenolic contents and DPPH radical scavenging effect was Y=0.4499X+2.3785，r2=0.8630. This indicated that the DPPH radical scavenging activity of bulbils might be affected by the contents of the total phenol in bulbils.
|
|---|
