摘要
The by-products of Mediterranean agriculture that remain after the production of fruit wines,juices and extracts represent a large source of raw materials rich in phenolic compounds.As a contribution to the current state of knowledge,this study investigated the biological activity and phenolic composition of extracts obtained from blackberry,chokeberry and juniper by-products,as well as the interactions of the extracts in mixtures.The total phenolic content of the samples ranged from 44.42 to 250.28 mg gallic acid equivalents(GAE)/g dry extract,with the extracts from blackberry leaves and juniper needles being the highest.The highest concentration of phenolics detected by high performance liquid chromatography(HPLC)was also found in blackberry leaves(41.30 mg/g dry extract),with rutin dominating.The antioxidant activity of the samples,as measured by ferric reducing antioxidant power(FRAP),oxygen radical absorbance capacity(ORAC)and 2,2-diphenyl-1-picrylhy-drazyl(DPPH)scavenging activity,ranged from 3.4 to 26.8 mM Trolox equivalents(TE),15.8-58.4 mM TE and 80.1%-91.8%,respectively.Among the extract mixtures,the highest synergistic interaction was observed between blackberry leaves and juniper by-products extracts at 1:2 and 2:1 ratios.The antimicrobial activity of the extracts was tested against Gram-positive and Gram-negative foodborne pathogens and spoilage bacteria,with the lowest minimal inhibitory concentration(MIC)and minimal bactericidal concentration(MBC)values against Staphylococcus aureus,Listeria innocua,Bacillus cereus,Campylobacter jejuni,Pseudomonas spp.and She-wanella spp.On the other hand,the antimicrobial activity of blackberry leaf extract in combination with selected phenolic compounds(vanillic acid,catechin,rutin and apigenin)showed no synergy against the tested micro-organisms.Overall,the results suggest that the tested by-products extracts could be utilized for the production of natural antioxidants and antimicrobials for further use in the food industry.
基金
supported by the PRIMA Program under the Bio-ProMedFood(Project ID 1467)project
supported by the European Union.The authors are also thankful for the scientific-research equipment financed by the EU grant“Functional integration of the University of Split,PMFST,PFST and KTFST through the development of the scientific and research infrastructure”(KK.01.1.February 1,0018).
