Effect of encapsulation of polyphenolic compounds of unripe (sour) grape waste on its quality and stability

In the present study, to prepare the polyphenolic extract of sour grape waste, the simultaneous effect of enzyme (pectinase, Yieldmash) and ultrasound (for 10, 25 and 40 minutes at sound intensity of 30, 60 and 90%) treatments was used and the best sample was encapsulated with maltodextrin and basil seed gum (BSG). To optimize the preparation of microcapsules, Design-Expert 13.0 and response surface methodology (RSM) were used. This design included 3 independent variables of maltodextrin level, BSG level and spray dryer inlet temperature. Finally, the best sample in encapsulation was examined by scanning electron microscope (SEM) and differential scanning calorimetry (DSC). The results showed that by increasing sound intensity, extraction efficiency, total phenol and antioxidant activity increased significantly (p ≤ 0.01). The highest factors were observed in the sample extracted by enzyme and ultrasound at 90% sound intensity for 40 minutes (p ≤ 0.01). In second phase, increasing the inlet temperature of the dryer and the level of maltodextrin as a carrier reduced the encapsulation efficiency and the DPPH radical scavenging activity of the capsules non-linearly. The optimum conditions included 12.129% maltodextrin, 0.5% BSG and the inlet temperature of the dryer of 177.22 °C. The results of DSC showed that the formation of complexes between the compounds led to the formation of heat-stable capsules. The average size of the particles was 1.04 micrometers. According to the results of SEM, the microcapsules had an irregular and quasi-spherical shape. At all the pH and temperatures, the microencapsulated sample had higher stability (p ≤ 0.05). Over time, the bioavailability and release of phenolic compounds increased significantly (p ≤ 0.05).