Evaluation of the stability of pistachio green hull microcapsules

Phenolic compounds, especially those of plant origin, constitute an essential part of the human diet, and are of considerable interest due to their antioxidant properties. However, phenolic compounds are susceptible to decomposition during processing and storage due to the presence of oxygen, light and high temperatures. Also, the direct addition of phenolic compounds in the formulation of foodstuffs and pharmaceutiacls could result in unpleasant taste, low solubility and interaction with food components. Encapsulation of Pistachio green hull (PGH) phenolic compounds was done by spray dryer using maltodextrin (MD) as a wall material. Optimization was carried out by changing one-factor-at-a-time. For this purpose, the effective factors including the inlet temperature (140, 150, and 160˚C), wall: core ratio (0.5:1, 1:1, 2:1, and 3:1), and rate of feeding (7, 10, and 13 ml min(-1)) were optimized. MD, PGH extract powder, and encapsulated phenolic compounds produced under optimum conditions (ME) was characterized by FTIR, X-ray and differential scanning calorimetry (DSC). The stability of ME and PGH extract during 40 d storage at 25˚C was studied. Under optimal condition, i.e., extract dilution: 0 v/v, feed flowrates: 7ml min (-1), MD/core ratio: 2:1 w/w and inlet temperature of 150˚C, the amount of phenolic compounds and the encapsulation efficiency were 160.5 mg GAE/gdp and 81%, respectively. DSC results showed that the microencapsulation have improved thermal stability of phenolic compounds. Storage stability results indicate that the amount of phenolic compounds of PGH extract and ME after 40 d storage decreased by more than 20 and 4%, respectively.

کلیدواژه ها:

Pistachio ، Phenolic compounds ، Encapsulation