The flavonoid contained in the scale leaves of onion mainly constitutes quercetin, which is a kind of glycoside as agricon. In this study, we not only demarcated and identified the flavonoid according to the scale leaves of the Korean onion but also e...
The flavonoid contained in the scale leaves of onion mainly constitutes quercetin, which is a kind of glycoside as agricon. In this study, we not only demarcated and identified the flavonoid according to the scale leaves of the Korean onion but also examined the change of flavonoid contents.
In chapter 1, we analyzed the flavonoid compounds in the first scale leaf of the Korean onion (the Mansang species) using HPLC, LC-MS/MS, FT-ICRMS, and NMR.
1. We can detect distinct 8 peaks in the flavonoid compounds extracted from the first scale leaf of onion as a result of HPLC analysis and also separate completely these into each of peaks within 50 minutes.
2. We could identify seven peaks as quercetin-3,7,4’-triglucoside, quercetin-7,4’-diglucoside, quercetin-3,4’-diglucoside, isorhamnetin-
3,4’-diglucoside,quercetin-3-glucoside, quercetin-4-glucoside and
isorhmnetin-4’-glucoside by LC-MS and LC-MS/MS. In addition, we
was able to find that quercetin-3, 4’-diglucoside and isorhamnetin-
3, 4’-diglucoside are major constituents of the flavonoid in scales
leaves of onion.
3. We could not analyze the peak No.1 using LC-MS because this peak did not ionize. We demarcated and examined this using FT-ICRMS and NMR, therefore, we could identify this as tryptophan.
In chpater 2, we examined the contents of the flavonoid according to scale leaves of onion (from the first to the seventh leaf), species (Caenon boll OP, Red snack, Tubo), size, and processed products (sixteen classes) being sold in USA. In addition, we analyzed the change of flavonoid contents by recipe and exposure on light-irradiation.
1. The more interior side of onion leaves, the lower contents of flavonoid in order of leaves while the contents of tryptophan were in reverse oder of those of flavonoid.
2. The contents of the flavonoid in the OP species were the lowest as 65 mg/kg. According to size in the Tubo species, the contents of the flavonoid in small size of onion were 137 mg/kg, that is 2.1 times of middle size as 65 mg/kg and 2.6 times of large size as 52 mg/kg.
3. The loss of the whole contents of the flavonoid by recipe was as followings; Baking (0.5%), boiling in 1% salt water (1.41%), boiling in 3% salt water (20.4%), Frying (34.7%), Microwaving (8.7%), Sauteing (18.3%), and Steaming (6.3%). The loss of flavonoid was the most high in case of frying and that of flavonoid was slightly increased in roasting recipe.
4. The contents of the flavonoid were increased in the irradiation time-dependent manner. In case of 72 hours-irradiation (percentage; the second and 4th scale of onion leaves), the results were as followings: Q7,4G’: 202, 395; Q3,4G’: 122, 144; IR3,4G’: 132, 229; Q3G: 236, 245; Q4’G: 158, 162; IR4’G: 137, 187; summation: 142, 166.
4. The eight-classes of samples in the sixteen commercialized onion-processed products could not be able to measure the flavonoid. The Q3,4’G was the range of 4.3 to 231.0 in the other eight-classes of samples and the Q4’G was contained in other three samples as a range of 1.9 to 63.0. The seven-classes of flavonoids except Q7,4'G were more enriched in the one of processed products being sold (the spice Hunter Granulated Onion, Organic, O) than any other products.
Key words: Korean onion, onion-processed products, HPLC. LC/MS. FT-ICRMS. NMR. flavonoids. isorhmnetin