西兰花茎果胶的提取及理化性质研究

Extraction and Physicochemical Characterization of Pectin from Broccoli Stalks

以西兰花废弃茎为原料,探究其果胶提取工艺和理化性质。通过单因素试验和正交试验优化果胶提取工艺,以商品橘子皮果胶(commercial orange pectin,COR)为对照,通过西兰花果胶(Brassica oleracea L.pectin,BOP)酯化度、溶解度、半乳糖醛酸含量等指标来评价其理化性质,采用扫描电镜和傅里叶红外光谱表征其结构。结果表明,BOP提取最佳条件为pH值1.5,料液比1∶25(g/mL),提取温度90℃,提取时间80 min,该条件下验证试验的平均得率为9.42%;与COR相比,BOP中半乳糖醛酸含量为70.34%,酯化度为46.7%,西兰花果胶属于低酯果胶、溶解度为74%,果胶灰分含量为7.56%,果胶酸不溶物含量为3.85%,果胶pH值为3.05。BOP和COR的表观颗粒形态存在较大差异,BOP颗粒直径较COR的大,呈清晰片状,排列不紧密,有较多的孔隙。

The broccoli pectin(Brassica oleracea L.pectin,BOP)was extracted from raw broccoli stalk waste and subsequently characterized based on its physicochemical properties.The pectin extraction process was optimized through single factor and orthogonal experiments;commercial orange peel pectin(COR)served as a control.The degree of esterification,solubility,galacturonic acid content,and other physicochemical properties were evaluated.The structure of pectin was characterized through scanning electron microscopy(SEM)and Fourier infrared spectroscopy(FTIR).The following optimal conditions were observed for pectin extraction:pH,1.5;material-to-liquid ratio,1∶25(g/mL);extraction temperature,90°C;and extraction time,80 min.Under these conditions,the average pectin yield was 9.42%.The physicochemical properties of BOP were as follows:galacturonic acid content,70.34%;degree of esterification,46.7%(low-ester pectin);solubility,74%;pectin ash content,7.56%;insoluble acid content,3.85%;and pH,3.05(acidic).The particle morphology of BOP was comparatively different from that of COR;BOP particles were clear and loosely arranged flakes,larger than those of COR.In addition,BOP particles contained more pores than COR particles.