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In this paper, influence of increasing concentrations of beeswax on the antimicrobial activity of chitosan-caraway essential oil biofilm was investigated. Selected microorganisms for the test were Salmonella Typhimurium and Listeria monocytogenes. Reduction of S. Typhimurium and L. monocythogenes viable counts in bacterial suspension in the presence of chitosan films with or without added beeswax amounted over 80 % after 24 h contact time, and over 95 % after 3 h of contact time, respectively and influence of added beeswax on growth reduction was not detected. However, when number of S. Typhimurium viable cells was analyzed (log CFU/ml), it was shown that addition of beeswax led to increased activity of films, especially for the films with 36 kg/m3 and 54 kg/m3of beeswax. When films were transferred, after 24 h in bacterial suspension, onto Petri dishes with nutrient agar and incubated for 24 h on 37°C, results also showed beeswax contribution to growth inhibition of S. Typhimurium.

Growing consumer demand for the food without chemical preservatives focused significant extent of research in the direction of finding natural compounds that can be used in food preservation. In this context, natural substances with strong antimicrobial and antioxidant properties, like essential oils, as well as natural biopolymers, particularly draw attention. Natural biopolymers can serve as carriers of the active components, such as essential oils in order of their sustained release to the food during storage, and may themselves exhibit activity in protecting foods from oxidation and/or microbial spoilage. Chitosan has been extensively studied as semi-natural polymer with expressed bioactive properties. While antimicrobial activity of chitosan solution in different acids has been confirmed towards different bacteria, yeasts and moulds, reports concerning intensity, underlying machanism and different factors afecting antioxidant activity of chitosan vary through the available literature. This paper presents a review in the field of antioxidative activity of chitosan with different properties, as well as chitosan based biopolymer films in order to clarify this aspect of chitosan bioactivity and confront different reports found in the literature.

The aim of this study was to evaluate bioactivity of chitosan film with incorporated caraway essential oil by measuring antioxidant and antimicrobial activity. A Fourier transform infrared spectroscopy was used to determine the potential interaction of functional groups of chitosan film and incorporated caraway essential oil. New detected peaks and main shifts in the peaks of chitosan spectra are attributed mainly to presence of s-(+)-carvone and limonene, the main components of caraway essential oil. The antioxidant activity of chitosan film was analyzed by DPPH method. Chitosan film without incorporated caraway essential oil showed the lowest scavenging ability (29.95%, after 24 h). The addition of different concentrations of caraway essential oil into chitosan film significantly enhanced antioxidant activity of pure chitosan film, reaching the maximum of 95%. ASTM E 2149 - 01 method was performed to evaluate the antimicrobial activity of chitosan films. The reduction of bacteria cell number in contact with examined films was tested on Gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes and Gram-negative bacteria Escherichia coli and Salmonella Typhimurium. The most sensitive bacteria was Staphylococcus aureus and the most resistant bacteria was Salmonella Typhimurium for all tested films. These results suggested that incorporation of caraway essential oil into chitosan film significantly improved its antioxidant and antimicrobial activity. The film showed a great potential to be used as an active packaging material.

In this paper, active edible packaging material was prepared and designed for potential application in sausage preservation. Material was prepared from chitosan with the addition of four oleoresins: garlic, black pepper, caraway and cinnamon. Antioxidative and antimicrobial activities of prepared films were tested and the film with optimal activity was further analysed as a food-packaging material. Chitosan film with added four oleoresins at a volume concentration of 2% (0.5% garlic, 0.5% black pepper, 0.5% caraway and 0.5% cinnamon) was found to be an effective antioxidant and antimicrobial material. Tensile strength and elongation at break showed weakening of the chitosan film with the addition of oleoresins. Water sensitivity of the chitosan film was lowered with oleoresins addition, considering film water content and swelling ability. Similar to pure chitosan film, chitosan film with oleoresins had very good barrier properties to oxygen and air, which could be compared to commercial barrier and high barrier films. The high water vapour permeability of the chitosan film was not decreased with the addition of oleoresins. Physical-mechanical properties and water vapour-barrier properties stay main possible drawbacks in application of chitosan film with oleoresins as self-standing packaging material, but its application would be possible as active coating and in combination with compatible materials. [ABSTRACT FROM AUTHOR]