Application of nanoencapsulated Mofarrah (Nepeta crispa) essential oil as a natural preservative in yogurt drink (doogh)

Abstract

This study aimed to nanoencapsulate the essential oil of the Nepeta crispa and its application in yogurt drink (doogh) to investigate the product's physicochemical, microbial, and sensory properties. N. crispa essential oil was nanoencapsulated with the different ratios of pectin:whey protein concentrate (25:75, 50:50, 75:25 w/w) using spray drying. The highest nanoencapsulation efficiency and the lowest nanoencapsulated phenolic compounds release were obtained in the 75:25 pectin: whey protein concentrate ratio. The nanoparticles had a semi-spherical structure and a size of about 400 nm. FT-IR confirmed the presence of hydroxyl bonds related to phenolic compounds in the essential oil. Different concentrations (0.075, 0.15, and 0.20 mg/mL) of free and encapsulated essential oil were added to the doogh. With the increase in essential oil concentration, acidity had an upward trend. The sample containing 0.20 mg/mL of encapsulated essential oil showed the highest percentage of DPPH radical inhibition and the lowest IC50. The addition of nanoencapsulated essential oil positively affected on the doogh sensory quality. Doogh containing 0.20 mg/mL of nanoencapsulated essential oil had a greater inhibitory effect on Escherichia coli and Staphylococcus aureus. Since this sample had an acceptable sensory quality, it was chosen as the best sample.