Effect of different wall material combinations on antioxidant and antimicrobial effect of microcapsulated clove essential oil

The purpose of present study was to determine whether improvement in antioxidant and antimicrobial activity of clove essential oil (CEO) microencapsulated by different wall material combinations could be achieved. For this purpose, maltodekstrin (M), sodium caseinate (S), gam arabic (G) and gelatine (G) were used to prepare three different wall formulations (M:S, M:S:G, M:S:G). Emulsions prepared with a wall material:CEO ratio of 3:1 were freeze-dried, powdered and used in the experiments. The characterization, antioxidant activity and antimicrobial activity properties in food system of the obtained microencapsules were investigated. Eugenol (71.86%) was determined as the major compound of clove essential oil. The highest microencapsulation efficiency was determined in M/S (86.22%) microencapsules. The M/S microencapsules exhibited a spherical structure, while the others exhibited a notched and broken glass-like structure. In the release test, it was observed that the solubility of the wall materials affected the release properties of the microencapsules and M/S/G microencapsules have the lowest release rate. In antioxidant activity tests, it was determined that the antioxidant activity of CEO was positively affected by the microencapsulation process. Clove essential oil in free form showed the highest antimicrobial activity on Streptococcus mutans (7 μg/mL), while it showed a lower effect on Gram-negative bacteria and yeasts. While M/S and M/S/G microencapsules have a minimum inhibition concentration value close to each other, M/S/G microencapsules were determined as the microencapsule with the lowest antimicrobial effect. Antimicrobial activities in real foods (cherry juice, apricot juice and whole milk) were monitored for 24 hours. It was determined that the free CEO provides complete microbial inhibition in all three food environments, while microencapsulated counterpart was successful in sour cherry and apricot juice environments, however, it had a low antimicrobial effect in whole milk at every test time of 24 h storage. As a result, it was determined that the microencapsules prepared with formulations M/S and M/S/G were better antioxidant and antimicrobial activity compared to wall material formulation of M/S/G. Keywords: Clove essential oil, Microencapsulation, Antioxidant, Antimicrobial