Comparisons of Microwave-assisted and Conventional Heating Extraction of Pectin from Seed Watermelon Peel

摘要

The extraction of pectin from seed watermelon peel could reduce environmental problem and offer a way to upgrade byproducts. In this study, variables of microwave-assisted extraction (MAE) and conventional heating extraction (CHE) were tested in order to recovery pectin from seed watermelon peel. After the test of single factor experiments, orthogonal experiments were employed to obtain optimum conditions for pectin extraction from seed watermelon peel. The satisfactory conditions for MAE were as follows: power of 500W, pH of 1.5, time of 7min and SLR of 1:20, and the optimum CHE conditions were temperature of 90°C, pH of 1.0, time of 150min and SLR of 1:20. Proof tests were replicated three times and the products were characterized of their qualitative and quantitative characteristics. The yield of 17.4-17.6%, ash content of 1.6-1.9%, GalA content of 78.3-82.8%, DE of 38.2-41.2% and molecular weight of 110600-128000 of pectin extracted by CHE were obtained. The pectin extracted by MAE achieved a higher yield (19.1-19.6%), and has a higher content of DE (44.3-48.7%), higher molecular weight (143400-154300), lower content of GalA (74.6-76.1%), and almost equal ash content (average value of 1.7% and 1.6%, respectively).