超滤浓缩制备南瓜果胶的工艺研究

Research on the preparation of pumpkin pectin by ultrafiltration concentration

采用超滤浓缩后乙醇沉淀的方法制备南瓜果胶。通过单因素试验,确定优化超滤条件为:超滤膜截留分子量50kD,压力0.08MPa,温度25℃,溶液pH7.0;在该条件下,将南瓜果胶提取液浓缩至原体积1/5,再加入80%乙醇溶液沉淀果胶并洗涤果胶1次,所得的南瓜果胶纯度为80.08%,得率为8.50%,凝胶度为120.25,酯化度为31.82,干燥失重为4.26%,总灰分为3.22%,半乳糖醛酸为88.10%,pH为2.7,铅及砷含量分别为1.2mg/kg和0.036mg/kg,各项指标均达到国家质量标准QB2484——2000。

The pumpkin pectin was obtained by alcohol precipitation after ultrafiltration. Through the single-factor design experiments, the optimal conditions of ultrafiltration were obtained, which as follows： ultrafiltration membrane MWCO was 50 KD, pressure was 0.08 MPa, temperature was 25 ℃ and pH was 7.0. On the basis of optimal condition of ultrafiltration, Pumpkin pectin extract was concentrated five times, then 80% ethanol solution was used to precipitate pectin and washed pectin one time.As a result, the purity of pectin was 80.08%, pectin yield was 8.50%, gelation degree was 120.25, esterification degree was 31.82, loss on drying was 4.26%, total ash was 3.22%, galacturonic acid was 88.10%, pH was 2.7, Pb was1.2 mg/kg and As was 0.036 mg/kg, the indicators reached the national quality standard QB 2484——2000.