EXTRACTION OF PECTIN FROM FRUIT MATERIALS PRETREATED IN AN ELECTROMAGNETIC-FIELD OF SUPER HIGH-FREQUENCY

Laboratory studies on the extraction of pectin from orange, lemon and apple wastes pretreated in an electromagnetic field of super-high frequency were carried out. A 10-min preliminary microwave heating (2450 MHz, 0.5 kW) of crushed fruit materials was found to provide a higher pectin yield. The extracted pectin exhibited higher values for degree of esterification and gel strength compared with the control sample. The effect depends on the kind of raw material. The favourable effect of microwave heating on the yield and quality of pectin is assumed to be due first to the partial disintegration of the plant tissue and hydrolysis of protopectin, and second, to the rapid inactivation of the pectolytic enzymes in the raw material. The second hypothesis has been partly confirmed by model experiments. The results presented can serve as a basis for improving pectin manufacturing. It is expedient that fresh pectinous raw materials should be subjected to microwave heating before drying.