Increasing the functional properties of fish oil microcapsules with olive leaf extracts

The impact of two different concentrations (1500 and 2000 ppm) of olive leaf extract (OLE) on functional properties of anchovy oil (Engraulis encrasicolus) emulsified with sodium caseinate and maltodextrin and microencapsulated by spray drying method were investigated. OLE groups were compared with the control group that did not contain any antioxidant additives and the group containing BHT. Scanning electron microscopy (SEM) image showed that microcapsules varied in size but no more 27 mu m and had wrinkled irregular cylindrical shape without cracks. Total phenol content of OLE was 98.55 mg GAE/g, whilst total antioxidant activity and DPPH radical scavenging capacity of OLE were found as 286.14 mg AA/g and 60.56%, respectively. Gas chromatography/mass spectrometry (GC/MS) identified a total of 40 compounds, the main ones being tyrosol (21.64%) and ethyl alpha.-d-glucopyranoside (11.77%) in OLE. Gram-positive Staphylococcus aureus and Enterococcus faecalis were the most resistant strains against microcapsules, although of the fish spoilage bacteria tested, Pseudomonas luteola was the most susceptible bacteria. The highest inhibition zone of microencapsulated fish oil was observed against P. luteola (18.38 mm). The BHT groups appeared generally inactive, whereas the OLE groups showed obvious bacteriostatic and bactericidal effect, with varying value of 6.25-25 mg/ml and 25-50 mg/ml, respectively. The study results revealed that the application of OLE notably increases the bioactivity of anchovy oil in microencapsulation, so combinations of fish oil and OLE microcapsules may be fairly strong antimicrobial agents in food, in addition to their nutraceutical properties.