Development of low-calorie gels from sunflower pectin extracted by the assistance of ultrasound

In this study, the effect of the application of ultrasound for the extraction of sunflower pectin on the elaboration of gels with sucrose, stevia and saccharin was investigated at pH values of 3.0, 4.6 and 6.8. The results pointed out that, in all the conditions tested, gels formed with ultrasound-extracted pectin were stronger than those obtained from pectin extracted with conventional methods. Thus, the optimal conditions to form a gel were Ca²⁺ concentration 25 mg/g, pH 3.0 and 10% sucrose. Under the same conditions it was possible to make gels with similar characteristics to that of sucrose by replacing it with stevia or saccharin, obtaining gels with excellent properties and low glycemic index and caloric content, especially suitable for healthy fruit-derived products such as jams, to be used instead of those made with sucrose. These important differences in gelation could be probably due to differences in galacturonic acid (GalA) content, degree of methyl esterification and molecular weight (Mw) in pectin obtained by ultrasound.