Investigating the extraction of pectin from the melon skin of winter and Mashhad (Qasri) cultivars using microwave pretreatment

This research was carried out in order to extract valuable and widely used materials in food and pharmaceutical industries from the waste of agricultural products. In this research, with the aim of extracting pectin from the melon skin of winter and Mashhad (Qasri) cultivars, it was carried out by acidic method using microwave pretreatment. Pectin was extracted under microwave conditions (fixed power of 900 W), irradiation time (1 and 3 minutes) and the ratio of extraction solvent to raw material 15:1 weight / volume and at a constant pH of 1.5. The results showed that the highest extraction efficiency of Mashhad melon in the extraction conditions (power 900 watts and duration 3 minutes) was equal to 13.5% and with the increase of duration from 1 to 3 minutes, the extraction efficiency of pectin in both Melon variety increased. Also, the pectin obtained from all the treatments had a favorable degree of purity (with galacturonic acid content above 65%). Checking the degree of esterification revealed that the pectins obtained from all treatments of winter and Mashhad melons are among pectins with low esterification.The highest equivalent weight was related to the pectin obtained from Mashhad melon in the extraction conditions (power 900 watts and duration 3 minutes), which was equal to 890 mg. The emulsifying activity of pectins obtained from both melon varieties was also low. Also, the amount of water retention capacity of pectins obtained from all treatments of winter and Mashhad melons was at the optimal level and showed that the pectins obtained from this research can be used to preserve water in some food systems. From all of the above, it can be concluded that the melon skin of winter and Mashhad varieties, which is considered as agricultural waste, can be used as a promising source for pectin production.