antioxidant effect of olive leaf on stability of butter

in this study extract of olive leaf was added to butter samples at three concentrations, 0.05, 0.1 and 0.5% and after vaccum packaging, were kept in refrigerator for 90 days. acid and peroxide value, microbial culture , polyphenol content of samples ,hardness, oxidative stability, sensory characteristics of samples including flavor, textural and apparent characteristics of samples and dpph radical scavening assay of olive leaf extract were evaluated. results showed that samples which contained olive leaf extract had lower microorganisms content, acid and peroxide value, hardness and also higher oxidative stability and polyphenol content than samples without extract. acid value was increased during storage and extract enriched samples showed lower increase. peroxide value and polyphenol content of samples were decreased during storage too hardness of olive leaf extract enriched samples was lower than control. the growth of microorganisms in sample which contained 0.1% olive leaf extract was lower than other samples. dpph. radical scavening assay proved that antioxidant activity of olive leaf extract is lower than quercetin. sensory characteristics evaluation also showed that acceptability of samples decreased significantly with an increase in concentration of extract.