Comparison of physicochemical and gelation properties of pectins extracted from six pericarps

In order to supply useful information to guide the practical production of pectins, the pectins extracted from six pericarps (shaddock peel, passionflower peel, navel orange peel, pomegranate rind, durian shell, sunflower head) were studied for their physicochemical and gelation properties. The recovery, color, viscosity, pectic acid content, methoxy content, the degree of esterification and gelation properties of pectins from the six pericarps were determined. The molecular weights of pectins were exactly analyzed by HPLC. The results showed the pectins of shaddock peel, sunflower head, navel orange peel and passionflower peel were 18.06%, 14.61%, 14.43% and 8.76%, respectively, while those in pomegranate rind and durian shell were low (<3%). The molecular weights of pomegranate rind and navel orange peel pectin were larger than 1000 kDa, and that of the sunflower head was the lowest (483 kDa). Besides, these pectins demonstrated low viscosity (<25 centipoise), which was proved to be the highest at pH value 7.0 and the lowest at pH value 5.0. Pomegranate rind demonstrated the largest molecular weight and the strongest gelatin strength, which was high methoxy pectin, and the recovery was very low. As a comparison, pectins extracted from sunflower head exhibited low molecular weight, high recovery, which was low methoxy pectin, since it could form good gelatin with or without the presence of sugar, which was proved to be a good material for pectin production.