| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 100 === The aim of the present research was to study the composition and physicochemical properties of various fiber-rich fraction prepared from the Dimocarpus longan Lour. hull (DLL hull) and Litchi chinensis Sonn. hull (LCS hull) via different preparation methods by using distilled water, alcohol, and enzymatic hydrolysis. The physicochemical properties of fiber types including water holding capacity, oil-holding capacity, swelling property, glucose adsorption capacity, glucose adsorption capacity. Furthermore, the effects of these insoluble fibers on bile acid binding capacity, lipase activity, and cholesterol-micelle disintegration were investigated. These results demonstrated that DLL hull and LCS hull were rich in insoluble fiber (71.286.1 and 70.181.1 g/100 g, respectively). DLL hull and LCS hull fibers were predominantly composed of uronic acid and cellulosic glucose, suggesting the presence of high amount pectin substances and cellulose. In view of the physicochemical properties, water insoluble solid (WIS) prepared from DLL hull and LCS hull showed significantly (P < 0.05) higher bulk density, water-holding and oil-holding capacity than those of cellulose. The WIS derived from both hulls markedly postponed the adsorption of glucose as compared with that of cellulose. Compared to cellulose, the WIS of DLL hull and LCS hull significantly (P < 0.05) increased bile acid binding capacity and decrease lipase activity. Alcohol insoluble solids (AIS) and WIS of DLL hull siginificantly （P < 0.05） decrease the solubility of cholesterol micelles. Insolule dietary fiber (IDF) and WIS of DLL hull siginificantly （P < 0.05） decrease the solubility of cholesterol micelles. The extractable polyphenols and nonextractable polyphenols content of insoluble fibers from DLL hull and LCS hull reached 6.3712.56 and 3.6615.5 g/100 g, respectively. Flavonoids contents in insoluble fibers from DLL hull and LCS hull reached 0.370.76 and 0.260.80 g/100 g, respectively. In the determination of antioxidant model systems including trolox equivalenr antioxidant capacity, DPPH (2,2’-diphenyl-1-picrylhydrazyl) scavenging activities, and reducing powers, AIS among these insoluble fibers was the best , followed by IDF and WIS. In conclusion, WIS parepared from both hull possessed desired physicochemical properties, they can be applied as low-calorie bulk ingredients requiring oil and water retention.
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