| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 103 === The change in particle morphology has resulted in variations of physicochemical properties and functions. Spray drying is a method to fabricate particles with a controllable size and morphology. During solvent evaporation, colloidal particles were self-assembled inside the droplet toward a close-packed array. With different particle sizes, which is one of the factors aggregating final particle morphology. In our laboratory, spherical cellulose particles have been prepared by utilizing media milling and spray drying. This study was to investigate the effect milling time on morphology and media-milled and spray dried cellulose, its encapsulation efficiency for b-carotene was also evaluated.
5% (w/w) microcrystalline cellulose was media milled for 15, 30, 45 and 90 minutes, and successively was spray dried at 130℃. The data showed that the particle size was decreased as the milling time increased. It appeared that, smaller particles particularly nano/submicron particle were prone to aggregate under the condition of nano/submicron scale particle size. Scanning electron micrograph, the spray dried cellulose powder from 15 min media-milled cellulose exhibited has highly rough surface. When the media milling time increased, the percentages of nano/submicron particles were increased. And the surface spray dried powder became smoother; with a decrease in apparent density and surface area. Data of porosity and density showed that the spray dried cellulose powders were dense particles. Obviously, raw cellulose would not the alike encapsulate b-carotene (encapsulation efficiency of 2.52%). The encapsulation efficiency of media-milled cellulose for 15, 30, 45 and 90 were 19.38, 23.57, 26.36 and 21.19%, respectively. It indicated that size reduction enhanced significantly the encapsulation behavior of cellulose. Among all the milling time tested, 45 min-milling was better choice for encapsulation.
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