介質研磨纖維素經不同條件噴霧乾燥的形貌及包覆效用

Abstract

粒子的形態是粉末技術的重點，因為改變粒子型態，會改變產品的理化性質。噴霧乾燥技術是能夠有效控制顆粒型態的方法之一，可以透過調控參數，如入料濃度、進料口溫度、氣體流量 (gas flow rate) 等，影響粒子的形貌。本實驗探討濕式研磨纖維素入料濃度 (1% (w/w) 、3% (w/w) 及5% (w/w) )，與不同的入料口溫度 (100℃、115℃、130℃及200℃)進行噴霧乾燥，分析噴霧乾燥粉末的物理性質及觀察表面形態，並進行β-胡蘿蔔素的包覆實驗，評估介質研磨纖維素做為載體的潛力。結果顯示，隨著入料濃度提高，纖維素粉末粒徑提高，當濃度為5% (w/w)時，粉末的粒徑約是1% (w/w) 粉末的兩倍。在SEM下， 1% (w/w)的纖維素粉末較不規則，5% (w/w) 則近似球形；隨著溫度提高，5%的纖維素顆粒也越接近球形，此結果可能與蒸發速率相關。蒸發速率影響了粒子的型態，而入料口溫度提高與入料濃度越高，蒸發速率也越快，造成粒子型態的差異。當入料濃度為5% (w/w) 時，孔隙率最低，為55% - 56%，可能與粉末的開孔體積較少有關。包覆率方面，1% (w/w) 的研磨後噴乾纖維素，包覆率介於12-19%；5% (w/w)研磨噴乾纖維素包覆率則約在36 – 45%之間。而5% (w/w) 研磨纖維素在進料口溫度為100℃、115℃、130℃及200℃的包覆率分別為35.56、40.05、45.13及38.97%，因此研磨後纖維素在130℃的入料口溫度及5% (w/w) 入料濃度條件下進行噴霧乾燥，有較佳的β-胡蘿蔔素包覆效果。

In powder technology, control of particle morphology has received a lot of attention. The change of shapes has caused unprecedented chemical and physical properties that differ markedly from those of raw material. Spray dried technique is suggested to be a prospective way to produce various morphologies. Changing parameters of spray dryer is one of the strategy to control the morphology, including inlet temperature, solid concentration, gas flow rate, and so on. In this experiment, 3 different concentration (1% (w/w), 3% (w/w) and 5% (w/w)) of media milled cellulose and 4 different temperature (100℃, 115℃, 130℃ and 200℃) are chosen to spray dry. Physical properties and morphology of the cellulose spray dried powder would be analyzed. It shows that higher feed concentration produces larger spray dried particles. The particle size of 5% (w/w) feed concentration is two times as big as 1%(w/w). According to scanning electron micrograph, the spray dried cellulose powder at high concentration and high inlet temperature seems to form more spherical particle. It may relate to the evaporation rate, which affects the powder morphology, during drying. Higher inlet temperature and higher feed concentration result in faster evaporation, which leads to morphology variance. Also, the porosity of 5% feed concentration is the lowest, which infers to less open pore volume of the powder. Then, to assess the potential of media cellulose as a carrier, β-carotene is added into, according to the spray dried conditions mentioned above. It indicates that at 1% (w/w) feed concentration, the loading capacity is around 12-19%, while 5% (w/w) feed concentration is around 36-45%. The result implies that the particles at 130℃ inlet temperature and 5% (w/w) feed concentration show the highest loading capacity.