[Antioxidant, color and antibacterial properties of edible chitosan film incorporated with Zataria multiflora boiss essential oil against Listeria monocytogenes]

The film containing antimicrobial agents are a type of active packaging which is mainly designed to control microbial and chemical spoilage of food. The aim of this study was to evaluate the antimicrobial, antioxidant and color properties of chitosan film incorporated with essential oil of Zataria multiflora Boiss [ZEO]. In this experimental study which was conducted at Urmia University of Medical Sciences between 2009-2010, the chemical composition of ZEO was analyzed using GC-MS. Chitosan films containing 0, 0.5, 1 and 2% ZEO, were obtained by casting method and subsequently, total phenol [TP], antioxidant, color [accordance with hunter system [L*[luminosity], * [redness, and b* [yelloweness]] and antimicrobial characteristics of films on Listeria monocytogenes were studied. The collected data was analyzed by the SPSS software. The order of TP for all films in the experiment was 2% ZEO>1% ZEO%0.5% ZEO> unsupplemented chitosan film, respectively. It was also conducted that the antioxidant activity of chitosan films was increased by adding various concentrations of ZEO. These increases were significant for film containing 1% [33.98%] and 2% [37.77%] ZEO [p<0.05]. Regarding the color luminosity [L*] of the chitosan film, results indicated no significant changes by incorporating ZEO, whereas the incorporation of ZEO into films had a significant effect on film yellowness, evidenced by lower b* values. Finally, it was shown that the presence of ZEO in chitosan films significantly modified the anti-listerial activity of chitosan, [p<0.05]. The results indicated that an active film from chitosan could be achieved by incorporating ZEO. Addition of ZEO improves functional and antibacterial characteristics of chitosan film

[Chemical composition and antibacterial effects of rosmarinus officinalis L essential oil with lysozyme on listeria monocytogenes]

Rosmarinus officinalis L. as a member of the Lamiaceae family and lysozyme as a natural antibacterial agent is important in food microbiology, because of its characteristics. The aim of the present study was to determine the chemical composition and anti-listerial activity of Rosmarinus officinalis essential oil [REO] alone and in combination with lysozyme for enhancement of anti-listerial activity of both substances. Rosmarinus officinalis L. was purchased from a local grocery store at Shahrekord and was identified by the Institute of Medicinal Plants, ACECR. The air-dried aerial parts were subjected to hydrodistillation using a Clevenger apparatus to obtain essential oil and yielded oil was analyzed by GC/MS. Antibacterial activity [on basis of Minimum Inhibitory Concentration [MIC] of REO was studied separately and in combination with unheated lysozyme [L] and heat-treated lysozyme [HTL] on Listeria monocytogenes at different pH [5, 6 and 7] by a micro-broth dilution assay. The collected data were analyzed by SPSS software. In the current study, 98.05% of constituents of the essential oil were identified. The major components were alpha-pinene [14.06%], 1, 8-cineole [13.62%], verbenone [11.2%], camphor [10.51%], borneol [7.3%], 3-octanone [7.02%], camphene [5.46%] and linalool [5.07%]. The inhibitory action of REO was stronger at lower pH especially 5 [MIC=225 micro g/mL]. Inhibition by L at pH 5 was 640 micro g/mL but no inhibition was seen at pH 7. HTL resulted in more effective inhibition than L, especially at pH 5 and heat-treatment 80°C [MIC: 160 micro g/mL]. Combination of L + REO and particularly HTL + REO was led to enhancement of bacterial inhibition. It was concluded that REQ by the identified chemical composition was effective alone or in combination with L or HTL on Listeria monocytogenes as a food-borne pathogen