生牛乳中游离寡糖的提取工艺优化

为提取生牛乳中游离寡糖，并且排除乳中蛋白质和乳糖的干扰，利用乙腈在不同提取条件（反应时间、相对离心力、反应温度和料液比）下去除蛋白质沉淀并提取总糖，并通过优化Sep-Pak C18固相柱和石墨碳柱条件对游离寡糖进行富集、纯化，减少乳糖的干扰，利用高效液相色谱法测定乳糖去除率。结果显示，生牛乳中寡糖最佳提取条件为反应时间2.5 h，相对离心力4 000×g，反应温度-1 ℃，料液比1∶2（g/mL）。在该提取条件下，蛋白质去除率为93.5%，总糖含量为48.42 mg/mL。利用4%乙腈（含0.1%三氟乙酸）冲洗石墨碳柱可将游离寡糖样品中大部分乳糖去除，乳糖去除率达98.91%。

Optimization of Free Oligosaccharide Extraction from Raw Milk

In order to extract free oligosaccharides from raw milk and eliminate the interference of protein and lactose in milk，acetonitrile was used to remove protein precipitation and extract total sugar under different extraction conditions（reaction time，relative centrifugal force，reaction temperature，and material-liquid ratio），and free oligosaccharides were enriched and purified by optimizing Sep-Pak C18 solid phase column and graphitic carbon column to reduce the interference of lactose. Lactose removal rate was determined by high performance liquid chromatography（HPLC）. The results showed that the optimal extraction conditions for free oligosaccharides from raw milk were reaction time of 2.5 h，relative centrifugal force of 4 000×g，reaction temperature of -1 ℃，and material-liquid ratio of 1∶2（g/mL）. Under these extraction conditions，the protein removal rate was 93.5%，and the total sugar content was 48.42 mg/mL. Flushing the graphitic carbon column with 4% acetonitrile（with 0.1% trifluoroacetic acid）could remove most of the lactose from the free oligosaccharide sample，and the removal rate of lactose was as high as 98.91%.