Encapsulation of basil (Ocimum basilicum) essential oil

Abstract

Basil (Ocimum basilicum) is an aromatic plant widely used as a culinary herb, commonly added as fresh. There are many scientific studies that have confirmed health benefits of the basil oil. Bioactive compounds of the essential oils found in basil have antioxidant and antimicrobial properties. However, effectiveness of these compounds depends on preserving their stability, which can be increased by encapsulation. The aim of this study was to encapsulate the basil essential oil (EO) in alginate microbeads in order to protect and stabilize bioactive compounds in it. Calcium alginate microbeads entrapping the EO were produced by electrostatic extrusion technique. The obtained microbeads were characterized from the aspect of total phenol content, encapsulation efficiency and antioxidant capacity. Total polyphenol content (TPC) of microbeads was analyzed by the Folin-Ciocalteu reagent. Encapsulation efficiency was calculated as the ratio between the TPC in the citrate solution of dissolved microbeads and the TPC of the initial EO. The radical scavenging activity was determined as Trolox equivalent antioxidant capacity (TEAC) and by using stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). The rehydration properties of air dried calcium alginate gel microbeads were investigated in water and phosphate buffer solution. Also, samples were analyzed by optical microscopy (OM). Encapsulation efficiency was obtained to be approximately 60 %. The results of TEAC and DPPH tests indicate that antioxidant activity was preserved at a satisfactory level. The average diameters of fresh and dried microbeads were 860.8±44.9 and 416.0±37.2 μm, respectively. The particles, with and without EO, rehydrated in buffer were highly swollen, from 5000 to 10000 %w/w. The results suggest that alginate microbeads encapsulating EO appeared to be suitable dosage forms. Thus, possible applications of these microbeads could be in the production of functional foods.