| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 91 === Short-chain amylose or amylodextrin was obtained from 2.2N HCl hydrolyzed corn starch at 35℃. The average DPw of short-chain amylose is 19, and polydispersity is 1.22. Following debranching with isoamylase, the average DPw and polydispersity of short-chain amylose is 15.4 and 1.25 respectively.
The solubulized short-chain amylase could recrystallize and form spherical precipitate from aqueous solution in a concentration of 5% at 4℃. The precipitates, termed spherulites, formed in different ethanol concentration had different X-ray diffraction patterns. Between 0~20% ethanol concentration had B-type x-ray diffraction patterns. Between 21~25% and 30~40% had C-type and A-type, respectively. The results indicated that the A-type and B-type crystallines can exist at the same time. The short-cnain amylose spherulites prepared in 30% ethanol and aqueous solution were designated spherulite A and B, respectively and their properties were compared. The spherulites had tendency to aggregate during the drying process. The particle size of solvent dehydrated-spherulite was larger than the particle size of the intacted and spray-dried spherulites. Spherulite A and B were unstable in solution, most of spherulites had dissolved in 55℃ and water soluble index was over 70%. The modification increased the phase transition temperature To, Tp, Tc of spherulite A were from 49.89℃, 88.17℃, 108.23℃to 54.31℃, 89.51℃, 118.77℃, respectively. And the modification increased the phase transition temperature To, Tp, Tc of spherulite B were from 50.83℃, 71.57℃, 86.44℃ to 54.19℃, 71.33℃(85.9℃), 113.08℃, respectively. The phase transition range of spherulite A was broader than spherulite B. The results indicated that crosslinking modification increased the heat stability of the spherulites.
A applicattion of used as emulsion stabilized was evalutated. To compared the properties of emulsion that spherulites as emulsion stabilizer. Rheological properties reveal for two types of spherulites had good emulsion stability, in which the B-type higher than A-type. Use Herschel-Bulkley model to describe the flow properties of emulsions, which contain 40% soybean oil, 10% egg yolk and 50% spherulites. The emulsions were shear-thinning fluid, and its Herschel-Bulkley flow parameters τ0 ,k ,n were 5.97, 23.85, 0.32 (A-type) and 23.80, 82.70, 0.23 (B-type), respectively.
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