微膠囊(microencapsulation)是一種利用成膜材料,進行包覆、造粒成小粒之技術。海藻酸及鈣鹽之交鏈鍵結、凝膠作用是重要製備材料及關鍵技術之一。本研究探討海藻酸鈉(3%)與不同鈣鹽(氯化鈣、乳酸鈣、醋酸鈣;0.01、0.05、0.1、0.25M)、固化時間(5、30、60min)之微膠囊成型性及評估粒子之各項品質。實驗結果如下:海藻酸鈉、鈣離子濃度及固化時間是影響海藻酸鈣微膠囊化-晶球成型性之重要因子;隨鈣離子濃度提高及固化時間延長,海藻酸與鈣之結合、交鏈作用較多,使其蛋盒立體“egg-box”構造愈完整、緻密,其凝膠晶球粒徑較小、硬度較高、膨潤力及含水率下降,在外觀上三種鈣鹽晶球濕晶球均呈圓球粒,乾晶球在鈣離子0.1M、固化時間30分鐘以下均容易變形;其熱性質起始溫度(To)、尖峰溫度(Tp)及熱焓值(ΔH)以0.25M鈣離子、固化60分鐘者均呈較高值;在晶球粒子表面微細構造觀察,會有較多收縮紋路出現。實驗結果以氯化鈣及醋酸鈣可得到成型性較佳、構造較緻密、硬度較高之海藻酸-鈣晶球粒子。
Microencapsulation is a technique used to form micro beads by granulation and coating with film-forming materials. The cross-linking and hydrogel interaction of alginate and calcium salts play an important role in the preparation of calcium-alginate beads. In this study, we studied the formability and quality index of calciumalginate beads made by sodium alginate (3 %) and different calcium salts (calcium chloride, calcium lactate and calcium acetate with 0.01, 0.05, 0.1, 0.25 M) with different curing time (5, 30 and 60 min). The result showed that the sodium alginate concentration, calcium salts concentration and curing time were important factors of hydrogel bead formability. Increasing the concentration of calcium salts and curing time enhanced the cross-linkage between alginate and calcium. It resulted in enhancing the egg-box structure. It also led to decreasing particle size, raising hardness, and decreasing swelling capacity and moiture content. The appearances of wet hydrogel beads made by different calcium salts were all spherical. However, dry hydrogel beads were easily deformed when the concentration of calcium salts was less than 0.1 M and curing time less than 30 min. The thermo-analysis showed that the onset temperature (To), peak temperature (Tp) and enthalpy (ΔH) were the highest when treated by 0.25 M of calcium salts at 60 min curing time. In the SEM micrographs, there was more shrinking on the surface of samples formed by 0.25 M of calcium salts at 60 min curing time. Finally, the calcium-alginate hydrogel beads which were treated by curing agents, calcium chloride or calcium acetate, have better formability, stronger structure and higher hardness.