antioxidant effect of the aerial parts of basil (ocimum basilicum) and clary sage (salvia sclarea) essential oils in iranian white cheese

introduction: there have been great efforts to find safe and potent natural antioxidants from various plant sources. there is, at present, increasing interest both in the industry and scientific research for spices and aromatic herbs because of their strong antioxidant and antimicrobial properties, which exceed many currently used natural and synthetic antioxidants. medicinal plants are complex natural mixtures which contain compounds at quite different concentrations, have antioxidant activities these properties are due to many substances, including some vitamins, flavonoids, terpenoids, carotenoids, phytoestrogens, minerals, etc. and render spices and some herbs or their antioxidant components as preservative agents in food and they were proposed as potential substitutes of synthetic antioxidants in food stuff. the number of contributions to isolation methods, techniques and activity testing of plant-origin antioxidants has significantly increased in recent years. antioxidants are also widely used as additives in fats and oils and in food processing to prevent or delay spoilage of foods regarding to the harmful effects of synthetic preservatives on consumers’ health, there is an increasing attention, both in food industry and authorities, to medicinal and aromatic plants as natural preservatives in food products. oxidation is one of the major causes of chemical spoilage, resulting in rancidity and deterioration of the nutritional quality, colour, flavour, texture and safety of foods .oxidation occurrence in cheese especially full-fat types causes rancid odor and taste and loss of nutritional quality. the objectives of the present study were evaluation of aerial parts of basil (ocimum basilicum) and clary sage (salvia sclarea) essential oils (eos), study their antioxidant effect on the lipid oxidation and sensorial acceptability when applied to iranian white cheese. materials and methods: investigations were carried out to assess the efficiency of two plant essential oils; clary sage and basil as natural food preservatives. in this study, the antioxidant effect of clary sage (salvia sclarea) and basil (ocimum basilicum) essential oils in iranian white cheese shelf-life, at 26 ° c for 39 and 4 ° c for 90 days, were examined. samples at three levels 0.5%, 0.75%, 1% (w/v) were treated, negative control cheese without antioxidant and positive control sample with synthetic antioxidant (bht) 0.05% were selected. the essential oils chemical composition were determined by gas chromatography equipped with mass spectroscopy (gc/ms). gc-ms analysis of the essential oil was performed using agilent-technologies 6890n network gas chromatographic (gc) system, equipped with agilent technologies 5975 inert xl mass selective detector and agilent-technologies 7683b series auto injector (agilent- technologies, little falls, ca, usa). the antioxidant capacity of the essential oils were assessed by measuring their scavenging abilities to 2,2 diphenyl-1-picrylhydrazyl stable radicals using dpph method and anti-oxidative stability with peroxide value (pv) and thiobarbituric acid (tbars) test were evaluated. results & discussion: main components of clary sage eo included linalyl acetate, linalool, α-terpineol and α-pinene and the major aroma constituents of basil eo consisted of linalool and α-cadinol, eugenol ,α –bergamotene and 1,8- cineole. linalyl acetate and linalool (oxygenated monoterpenes) showed stronger antioxidant activities than did the other components tested in the assays. maximum free radical scavenging activity for clary sage and basil eos at 1% concentration was 84.66% and 72.72% respectively that was weaker than (bht) free radical scavenging activity (95%) by dpph test. at 1% concentration, clary sage and basil eos were most effective treatment at 4 and 26 c°, in free radical scavenging activity comparing to other concentrations. at 4 c° there is no any difference between all treatments up to 30th days in pv and tbars number. the most effective treatment against lipid oxidation was at 0.75, 1% concentration basil and 1% saliva eos at 90th days observed. finally it seems that basil eo was more effective than clary sage eo at both 0.75 and 1% concentration. at 1% concentration of basil eo according at 90th day storage time not observed significant difference in peroxide value and tio barbituric acid number comparing to first day. at 26 c° highest antioxidant activity was obtained at 1% concentration of basil eo. final peroxide value (meq o2/kg oil) and tio barbituric acid (m mol/gr oil md) number using basil and saliva eos was 1.379, 0.0680 and 1.817, 0.096 respectively. that significant deference was observed comparing to control sample (p<0.05). finally it seems that basil eo was more effective than clary sage eo to protection against lipid oxidation and anti-oxidative activity was increased significantly by increasing the concentration of essential oils. in sensorial evaluation test best quality was obtained for 0.75% basil eo at 90 days storage time and obtained the highest score of overall organoleptic acceptance. regarding to this study basil and clary sage eos as natural antioxidant substances can be used to replace the synthetic antioxidants and fortification with natural eos increased shelf-life and anti-oxidative stability of cheese and enhance the quality of white cheese. it also does not have much impact on the organoleptic properties but increasing food product shelf life resulting from their preservative inherent features.