TEMPO氧化魔芋葡甘露聚糖微球的制备及其在运载食品活性因子中的应用

以2,2,6,6-四甲基哌啶-1-氧自由基（2,2,6,6-tetramethyl-piperidine-1-oxyl，TEMPO）为催化剂，次氯酸钠为氧化剂，对魔芋甘露聚糖（konjac glucomannan，KGM）进行氧化，制备出氧化度为80%的TEMPO氧化魔芋多糖（TEMPOoxidizedkonjac glucomannan，OKGM）。用OKGM为原料、Fe3＋为交联剂借助双重乳液法制备微球。内油相中包覆β-胡萝卜素，多糖水相吸附花色苷，实现亲疏水活性因子的共装载。红外光谱显示出KGM上羟基成功氧化为羧基；MTT法验证了OKGM没有细胞毒性；采用单因素试验，确定制备微球的最佳工艺条件是OKGM质量分数10%、FeSO4·7H2O与OKGM质量比1∶5、交联时间30 min、交联温度35 ℃；通过动态光散射法发现微球粒径分布在20～40 μm之间，平均粒径为26.8 μm；通过扫描电子显微镜和原子力显微镜观察了微球的表面形貌；荧光共聚焦显微镜显示微球中能够同时分布着花色苷和β-胡萝卜素。结果表明OKGM微球在多种活性因子的共装载方面有良好的应用前景。

Preparation and Application of TEMPO-Oxidized Konjac Glucomannan Micropsheres in Delivery of Food Bioactives

2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) was applied to catalyze the oxidation of konjac glucomannan
(KGM), which was selectively oxidized by sodium hypochloryte to 80% degree of oxidization (DO) yielding TEMPOoxidized
konjac glucomannan (OKGM). A microsphere delivery system that allowed the co-delivery of hydrophobic and
hydrophilic ingredients was prepared by cross-linking the carboxyl groups of TEMPO-OKGM polymers with ferric ions
through double emulsion cross-linking reaction which enabled the dissolution of β-carotene in the inner oil phase and
the absorption of anthocyanins to the polymer phase. Fourier transform infrared spectroscopic (FT-IR) results proved
the oxidation of the hydroxyl groups into carboxyl groups. The cell viability experiment showed that the OKGM polymer had
negligible cytotoxicity. The optimum conditions for OKGM microspheres preparation were as follows: OKGM concentration,
10%; mass ratio of cross-linker FeSO4 ·7H2O to polymer, 1:5; cross-linking time, 30 minutes; and reaction temperature, 35 ℃. The
size distribution of OKGM microspheres measured by dynamic light scattering was 20 to 40 μm, and the average diameter was
26.8 μm. The surface morphology of microspheres was observed by scanning electron microscopy and atomic force microscopy.
By confocal laser scanning microscopy, the distribution of hydrophobic and hydrophilic ingredients was observed simultaneously.
OKGM microspheres showed a great potential for delivering multiple nutrients.