Encapsulation of Pistachio Green Hull Phenolic Compounds by Spray Drying

Application of antioxidants is a common way for retarding oxidation. Due to adverse effects of synthetic antioxidants on health, the use of natural and safe antioxidants is considered essential. Pistachio green hull is a waste product and low-cost source of phenolic compounds. The use of phenolic compounds in food formulations has some limitations. In this study, the encapsulation of Pistachio Green Hull (PGH) phenolic compounds was carried out by spray-dryer using Maltodextrin (MD) as a wall material. For this purpose, the effective factors including the inlet temperature, dilution factor, wall:core ratio, and rate of feeding were optimized. MD, PGH extract powder, and encapsulated phenolic compounds produced under optimum conditions (ME) were characterized by Scanning Electron Microscopy (SEM), FTIR, X-ray Diffractometry (XRD), and Differential Scanning Calorimetry (DSC).Under optimum conditions, the amount of phenolic compounds and the encapsulation efficiency were 32.1 mg GAE g-1 dp and 81%, respectively. DSC results showed that the microencapsulation had improved thermal stability of phenolic compounds. The DPPH test results indicated that the antioxidant activity of the free PGH extract was 10% higher than encapsulated one (ME). Storage stability results indicated that the amount of phenolic compounds of PGH extracts and ME after 60 days storage decreased by more than 29 and 4%, respectively. The microcapsules obtained can be used in the production of functional foods and pharmaceutical products, due to their antioxidant content and presence of phenolic compounds.