甘薯果胶的乳化特性研究

Emulsion Properties of Pectin Extracted from Sweetpotato Starch Residues

【目的】探讨甘薯果胶构成及乳化特性,为开发和利用薯渣中的果胶资源提供理论依据。【方法】采用酸法从薯渣中制备果胶,咔唑硫酸法测定果胶半乳糖醛酸含量,滴定法测定酯化度,高效液相色谱法测定果胶分子量。在不同果胶浓度(0.5%-4.0%,w/v)和不同油相体积分数(5%-40%,v/v)条件下进行乳化液特性研究。【结果】甘薯果胶半乳糖醛酸含量为73.28%,酯化度31.71%,分子量约为292kD。随着果胶浓度升高,乳化液粒径(d4,3)减小,乳化颗粒吸附果胶比例显著升高,乳化液表观黏度增大,乳化活性(EA)和乳化稳定性(ES)升高(P<0.05)。此外,随着油相体积分数的增加,d4,3增大,EA及乳化液表观黏度升高(P<0.05),被乳化颗粒吸附果胶比例下降及ES呈现出先升高后降低的趋势。【结论】薯渣是制备果胶的良好材料,酸法制备甘薯果胶属低甲氧基果胶,具有良好的乳化能力和乳化稳定性。

【Objective】 In order to provide a theoretical basis for development and utilization of the pectin resources in sweetpotato residues,the characteristics of pectin and its emulsion properties were investigated. 【Method】 The pectin was extracted by using hydrochloric acid solution,in which,the galacturonic acid content,degree of esterification （DE） and molecular weight were determined by carbazole and sulphuric acid spectrophotometric determination method,titration method and HPLC,respectively. The effects of different pectin concentrations （0.5%-4.0%,w/v） and oil-phase volume fraction （5%-40%,v/v） on emulsion properties of sweetpotato pectin were studied. 【Result】 The galacturonic content,DE and molecular weight of sweetpotato pectin were 73.28%,31.71% and 292 kD,respectively. With increasing the pectin concentration,the particle size （d4,3） of emulsion decreased,while adsorbed fraction of pectin onto emulsion droplets,apparent viscosity of emulsion,the emulsion activity （EA） and emulsion stability （ES） of emulsion increased （P0.05）. Furthermore,with increasing the oil-phase volume fraction,d43,EA and the apparent viscosity of emulsion increased （P0.05）,whereas the value of adsorbed fraction of pectin onto emulsion droplets and ES presented a trend of increasing firstly and then decreasing. 【Conclusion】 Sweetpotato starch residues is a kind of potential resource for pectin extraction,the pectin extracted by using acid solution belongs to low methoxy pectin,which has excellent emulsion ability and emulsion stability.