| Summary: | 博士 === 國立屏東科技大學 === 食品科學系所 === 98 === The Contents of Abstract in This Thesis:
The studies were composed of two parts. In part Ⅰ, the influence of several operating parameters on yield of supercritical fluid extraction (SFE) for nobiletin and tangeretin from Citrus species peel was investigated. In part Ⅱ, the change of isoflavone (ISF) content and composition in vegetable soybean varieties and their seed tissues was analyzed during two sowing date, five growth period and at two cultural location.
The optimal conditions of supercritical fluid extraction for two polymethoxyflavones, nobiletin and tangeretin, from Citrus depressa Hayata and Citrus mitis Blanco were developed. The effect of modifier type, modifier composition in terms of water content in ethanol, modifier percentage, extraction condition (temperature, pressure and CO2 flow rate) and particle size on the yield of nobiletin and tangeretin were investigated. The conventional extraction method was conducted in parallel for comparison. The contents of nobiletin and tangeretin were determined by HPLC, and their molecular weights and chemical structures were also confirmed by LC-MS/MS. Results showed that: The optimal condition for selective SFE of nobiletin and tangeretin from Citrus depressa Hayata was temperature of 80℃, pressure of 30 MPa, CO2 flow rate of 3.0 mL/min and particle size of 0.375 mm with 9.1% modifier (ethanol: water = 85: 15, v/v). However, the optimal modifier composition, modifier ratio, temperature, pressure, CO2 flow rate and particle size for selective SFE of nobiletin and tangeretin from Citrus mitis Blanco was 85% aqueous ethanol, 9.1%, 80℃, 20 MPa, 3.0 mL/min and 0.188 mm, respectively. Overall, the nobiletin and tangeretin yield of SFE from Citrus depressa Hayata and Citrus mitis Blanco was 108% and 111%, respectively, compared to conventional solvent extraction method (100%). Therefore, SC-(CO2 + aqueous ethanol) extraction is considered as the most environmentally friendly extraction method of nobiletin and tangeretin from Citrus depressa Hayata and Citrus mitis Blanco peel.
For developing vegetable soybean in Taiwan, the influence of sowing date, growth period and cultural location on the isoflavone (ISF) contents and distribution in vegetable soybean varieties and their seed tissues were investigated. For evaluating the change of ISF distribution, twelve ISF´s in whole seeds and seed tissues were quantified by HPLC and sorted into seven ISF groups constituted by TDin, TGlin, TGin, MalGly, Gly, AceGly and AGly. Results showed that: Total isoflavone contents of vegetable soybean varieties and their seed tissues were significantly affected by sowing date, growth period and cultural location. Genetics play a significant role in ISF contents of vegetable soybean varieties. Amount of ISF in whole seeds, hypocotyls and cotyledon was higher at lower temperature and lower at higher temperature during seed filling. Higher isoflavone contents were concentrated in hypocotyles, and glycitein and its three derivates were almost existed in these seed tissue. For the order of proportion of ISF groups, different ISF distribution was observed in the same vegetable soybean variety (whole seed), in different sowing date and growth period. However, the ISF distribution in two seed tissues was independent of sowing date and growth period. Moreover, vegetable soybean varieties grown at the two location were in a same type of ISF distribution as TGin>TDin>TGlin. On the other hand, the order of proportion of MalGly and Gly in vegetable soybean varied at various cultural locations.
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