Food Microbiology

Biography

Biography: Maarit Maki

Abstract

Antioxidative and antimicrobial properties were tested from the samples of berries and juice press cake of blackcurrant (Ribes nigrum), chokeberries (Aronia melanocarpa/mitchurinii) and rose hips (Rosa rugosa), leaves of sea buckthorn (Hippophae rhamnoides), lingonberry (Vaccinium vitis-idaea), and bilberry (Vaccinium myrtillus) and stems and shrubs of bilberry. All samples were extracted with two different solvents: water and 50 % ethanol (aq) with solid/liquid ratio approximately 1:10. The most interesting samples, sea buckthorn leaf, bilberry shrub and blackcurrant juice press cake, were selected for further extraction studies with pressurized hot water extraction (PHWE). Antioxidant capacities were measured from all above extracts. The radical scavenging ability of the plant extracts was measured with the ABTS method and a lecithin liposome model was utilized to investigate the ability of the extracts to inhibit lipid oxidation. As a result, the highest antioxidant capacities were observed with the extracts from the leaves of sea buckthorn, lingonberry and bilberry, and bilberry shrubs. The 50 % ethanol extraction yielded to higher antioxidant capacities than the water extraction. The PHWE treatment yielded to slightly higher radical scavenging activity and slightly lower lipid oxidation inhibition activity than the 50 % ethanol extraction. Antimicrobial properties of the most interesting PHWE extracts were tested by agar diffusion tests. The extracts were tested on Pseudomonas fluorescens, Staphylococcus aureus, Yersinia enterocolitica, Yersinia pseudotuberculosis and Listeria monocytogenes. Except for blackcurrant juice press cake, PHWE extracts showed good antimicrobial effect on S. aureus, P. fluorescens, Y. enterocolitica and Y. pseudotuberculosis. No inhibition was detected on L. monocytogenes.