Stability Enhancement of Ocimum Sanctum Linn. Essential Oils Using Stearic Acid in Aluminum Carboxymethyl Cellulose Film-Coated Gelatin Microcapsules.

Abstract

Holy basil essential oils (HBEO) can be used in many food applications due to antioxidant and antimicrobial attributes, but they are susceptible to degradation upon storage. Therefore, a protective system is required to extend their shelf life. HBEO was microencapsulated by coacervation using gelatin and the microcapsules were subsequently coated with stearic acid (1%, 2%, and 3%) in carboxymethyl cellulose emulsions. The results showed that HBEO contents decreased with increasing stearic acid concentrations from 76% to 59%. Fourier transform infrared spectroscopy analysis suggested that HBEO was stable during microencapsulation. After 3-month storage, changes in appearance were detected in all samples, especially the uncoated and 3% stearic acid-coated microcapsules. Additionally, the surface HBEO content increased significantly, consistent with a distinct increase in darkness and agglomeration. X-ray diffraction analysis revealed the physical change of microcapsules, attributed to the renaturation of gelatin and recrystallization of stearic acid. The antioxidant activity of both non-encapsulated and encapsulated HBEO after storage decreased significantly, except the microcapsule coated with 1% stearic acid (half maximal inhibitory concentration of 0.35 mg/mL), whereas the antimicrobial activity remained constant. The findings suggest that HBEO microcapsules coated with 1% stearic acid could serve as antioxidant and antimicrobial additives in food industries.