Influence of Material Collection Time on Pectin Precipitation from Apple Pomace

Galacturonic acid content,pectin yield and other indexes of apple pomace(AP) at different stages were studied.The influence of oven drying and air drying was compared,and the gels variation of pectin which was conserved for different periods was measured.The result showed that the galacturonic acid content of AP kept a high level from August to November,then decreased continuously,reached the highest level in September.The pectin yield of AP was consistent with the galacturonic acid content,and it was higher under oven drying than air drying.The gels of pectin which was conserved for a period decreased to some extent.