碩士 / 輔仁大學 / 食品科學系碩士班 / 102 / The climate of Taiwan is suitable to breed the soft-shell turtle. The quality of soft-shell turtle eggs is high and they are mostly exported to China at high price. Since un-fertilized soft-shell turtle egg can’t hatch, it is worthless in the market and often used as animal feed. However, soft-shell turtle egg is rich in nutrients. And it also possesses the antioxidant activity and has the ability to lower the blood cholesterol. The researches on the physicochemical properties of soft-shell turtle egg are scarce, thus, the application of soft-shell turtle egg in food processing is not definite. The objectives of this research were to investigate the physicochemical and functional properties of soft-shell turtle egg and to observe the effects of pH, heat and concentration on functional properties. Egg yolk and egg white in the soft-shell turtle eggs were separated first. The egg yolk was then separated into granule and plasma fractions. The egg yolk, egg white, granule and plasma were freeze-dried into dried sample for further analysis. The compositions, protein components, sulfhydryl group content and surface hydrophobicity of soft-shell turtle egg were assessed. Effects of pH, concentration and temperature on the solubility, emulsifying properties, foaming properties, water-holding capacity, fat-absorption capacity and gelling proerties of soft-shell turtle eggs were evaluated. The results showed that soft-shell turtle eggs were spherical with diameter about 20 mm. Its shell was flimsier than hen egg shell and the weight of each egg was about 5 g. The ratio of egg yolk to egg white was 3:2. The granules fraction contained most of the egg yolk protein, while the plasma fraction contained most of the egg yolk lipid. The egg white contained lot of minerals. The main protein components of granules, plasma and egg white were HDL and phosvitin, LDL and liventin and lysozyme, respectively. The solubility of egg yolk and granules was the lowest at pH 4-5, while the solubility of egg white was not affected by pH. The solubility of plasma was poor at acidity condition. The emulsifying and foaming properties increased with increasing the concentration of all samples. Both emulsifying activity and stability of 2.5% granules were superior to others due to the attributes of HDL and phosvitin in the granules. The egg white had the highest value in foaming properties because of the interaction among ovalbumin, ovomucin and lysozyme. Besides, the water-holding capacity, fat-absorption capacity and gelling properties of egg white were also high. This might be related to the lower denaturation temperature of ovotransferrin and lysozyme. This research provides useful information of the physicochemical properties of soft-shell turtle eggs for food applications.
Keywords: soft-shell turtle egg, egg yolk fractionation, physicochemical properties, functionl properties
| Identifer | oai:union.ndltd.org:TW/102FJU00254022 |
| Date | January 2014 |
| Creators | Szu-Yu Chen, 陳思宇 |
| Contributors | Meng-I Kuo, 郭孟怡 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 115 |
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