| Summary: | 碩士 === 國立宜蘭大學 === 食品科學系碩士班 === 101 === In this study, the phenolic composition of hot water extract from immature kumquat (Fortunella Magarita) was investigated using LC/MS . The amount of phenolic compounds found in immature kumquat was in the following order: DGPP > Margaritene > Isomargaritene > Fortunellin > Narirutin 4’-O-glucoside > Naringenin 6-C-rhamnoside 8-C-glucoside > Apigenin 8-C-neohesperidoside > Poncirin > Rhoifolin.
The antioxidant activity and phnolic compounds of hot water extract from immature kumquat was evaluated after different drying processing, included 110℃, 130℃ for 0.5-2.0 hr and 150℃for 1.5 hr. The results showed that total phenolic contents increased significantly after drying processing, while the highest quantity was observed at 130℃ for 2.0 hrs with the level of 4,827 GAE mg/100 g dry extract. All of the phenolic compounds increased during drying processing until 110℃ for 2.0 hrs or 130℃ for 1.0 hr except DGPP and Rhoifolin. When drying at 130℃ more than 1.5 hrs, the four major phenolic compounds, DGPP, Margaritene, Isomargaritene and Fortunellin, decreased significantly, in contrast, the contents of Narirutin 4’-O-glucoside, Naringenin 6-C-rhamnoside 8-C-glucoside, and Rhoifolin increased. The antioxidant activity meanwhile also increased significantly.
In order to elucidate the free and bound phenolic compositions and antioxidant activities of immature kumquat, a successive extraction procedure was carried out. The extraction was in following order: hexane, ethyl acetate, hot water, alkaline hydrolysis and acid hydrolysis. The results indicated that total phenolic composition of immature kumquat were 6,810 GAE mg/100 g dry extract, which was composed of 50% free form and 50% bound form.
Flavonoids existed mainly in free form, while phenolic acids were in bound form with the major two ester linkage compounds p-Coumaric acid and Ferulic acid. More Ferulic acid was observed than p-Coumaric acid. The highest content of phenolic compounds was obtained in hot water extract, The free form phenolic compounds of hot water extract had the best scavenging activity on DPPH radical and ORAC.
The free form and bound form total phenolic compounds and antioxidant
activities increased significantly after drying at 130℃ and 150℃, while the highest level was observed at 150℃, with the values of 7,824 GAE mg/100 g
dry extract for free form and 7,333 for bound form, respectively. Interestingly, the contents of each phenolic compound increased significantly. The Naringenin 6-C-rhamnoside 8-C-glucoside and Narirutin 4’-O-glucoside increased obviously at 130℃. However, the phenolic compound decreased significantly, when temperature increased up to 150℃. For the antioxidant activity, the scavenging effect on DPPH radical and ORAC of free form and bound form phenolic compounds could be enhanced by drying at 130℃.
Ten fractions (I-X) of hot water extract from immature kumquat were separated and collected by semi-preparative HPLC and the antioxidant activities were also investigated. The DGPP and Apigenin 8-C-neohesperidoside showed the best ORAC and DPPH scavenging ability. However, the antioxidant activities of immature kumquat increased after drying, while the levels of Narirutin 4’-O-glucoside and Naringenin 6-C-rhamnoside 8-C-glucoside also increased. These suggested that the phenolic compounds, DGPP and Apigenin 8-C-neohesperidoside, might contribute the DPPH scavenging activity in
immature kumquat, while Narirutin 4’-O-glucoside and Naringenin 6-C-rhamnoside 8-C-glucoside might probably play an important role to DPPH scavenging activity after drying.
|
|---|
