A novel active bionanocomposite film incorporating rosemary essential oil and nanoclay into chitosan
Highlights
► Preparing a functional bionanocomposite containing nanoclay and rosemary from chitosan. ► Studying combined effect of nanoparticle and essential oil on film properties. ► Decreasing water sensitivity of chitosan-based films with incorporating nanoclay and rosemary essential oil. ► Improving the mechanical properties of the films using nanoclay and the essential oil. ► Improving antibacterial and total phenol content of the nanocomposite using the essential oil.
Introduction
Biopolymers have been widely investigated over the last two decades because they can be a viable solution to the waste disposal of foods’ plastic packaging materials. Furthermore, biopolymer films are excellent vehicles for incorporating a wide variety of additives, such as antioxidants, antifungal agents, antimicrobials, colours, and other nutrients (Rhim and Ng, 2007, Wong et al., 1994), and so these biodegradable materials can also improve food quality and extend shelf life by minimizing microbial growth in the product.
Chitosan, a deacetylated derivative of chitin, is the second most abundant polysaccharide found in the nature after cellulose. It has been found to be non-toxic, biodegradable, biofunctional, and biocompatible (Rinaudo, 2006, Shahidi et al., 1999, Srinivasa and Tharanathan, 2007). Chitosan brings some advantages over other biomolecule-based active polymers used as packaging materials because of its antibacterial behavior and bivalent minerals chelating ability (Aider, 2010). However, poor mechanical and gas barrier properties, and weak water resistance limit its application particularly in the presence of water and humidity (Wang et al., 2005, Xu et al., 2006).
As for other biopolymers, many strategies have been explored to improve the barrier and mechanical properties of chitosan-based biodegradable films. These include the addition of plasticizers and salt, chemical modification of hydroxyl groups, cross-linking of polysaccharides, the use of suitable solvent, the change of pH, the addition of different polysaccharides, and blending with other polymers (Bourtoom and Chinnan, 2008, Ghosh et al., 2010, Hoagland and Parris, 1996, Park and Zhao, 2004, Srinivasa et al., 2007, Li et al., 2010, Gómez-Estaca et al., 2011).
Recently, polymer–clay nanocomposites have received significant attention as an alternative to conventional filled polymers, because of their ability for nano-scale dispersion, which brings significant improvement in mechanical and physical properties compared to micro-scale polymer composites. Several studies have reported amelioration of mechanical properties (Lavorgna et al., 2010, Xu et al., 2006), thermal stability (Darder et al., 2003, Wang et al., 2005), functional properties (Rhim et al., 2006), barrier properties (Casariego et al., 2009, Rhim et al., 2006), and water solubility (Casariego et al., 2009) of chitosan films via incorporation of nanoclay into chitosan in the range of 1–5 wt.%. Montmorillonite is the most widely studied type of clay which is a hydrated alumina-silicate layered clay consisting of an edge-shared octahedral sheet of aluminum hydroxide between two silica tetrahedral layers. The imbalance of the surface negative charges is compensated by exchangeable cations (typically Na+ and Ca2+) (Azeredo, 2009).
On the other hand, antibacterial and antioxidant activities of essential oils (EOs) have long been acknowledged, but the food industry has recently been paying more attention to their application as natural antimicrobials and antioxidants (Du Plooy et al., 2009, Sánchez-González et al., 2010a). The main advantage of EOs’ application is their greater activity as compared with the effects of the individual active compounds, probably due to the synergistic effects (Bakkali et al., 2008, Sánchez-González et al., 2010b, Burt, 2004). Among essential oils the largest number of reports on the effective antioxidant properties pertains to extracts from plants belonging to family Labiatae, particularly rosemary (Rosmarinus officinalis L.) (Waszkowiak, 2008). Phenolic compounds such as carnosol, carnosoic acid, rosmanol, rosmadial, epirosmanol, rosmadiphenol, rosmarinic acid, etc. are considered to have antioxidant ability (Bozin et al., 2007). Major components of REO which have showed antimicrobial properties are α-pinene (2–25% of composition), bornyl acetate (0–17%), camphor (2–14%), and 1,8-cineole (3–89%) (Burt, 2004).
Although several reports on chitosan/clay nanocomposites have appeared in the literature, to the best of our knowledge there are no reported data on the combined effect of nanoclay and antioxidant/antimicrobial compounds like EOs. It seems that the combination of nanoclay and an antimicrobial/antioxidant compound in chitosan films can be suitable due to its acceptable structural integrity and barrier properties imparted by the nanocomposite matrix, and the antimicrobial/antioxidant properties contributed by the natural antimicrobial/antioxidant agents impregnated within. In addition, such nanocomposite films prepared based upon natural biopolymers are environmentally friendly with all the benefits one may expect from biopolymer and nanocomposite packaging materials (Rhim and Ng, 2007). In the present study, the combined effects of montmorillonite nanoclay and rosemary essential oil on the physico-chemical and antimicrobial properties of chitosan composite films have been investigated.
Section snippets
Materials
Crab shell chitosan (medium molecular weight, 190–310 kDa, 75–85% deacetylated, Sigma–Aldrich Chemical Co., USA) and Na+-montmorillonite (MMT) from Southern Clay Products, USA were used as received. Glacial acetic acid and Tween 80 were purchased from Merck, Germany. Rosemary essential oil was obtained from Barij Essence Pharmaceutical Co., Kashan, Iran, and stored in dark container at 4 °C until used.
Preparation of chitosan/clay-rosemary solutions
Aqueous solution of chitosan was prepared by dissolving 20 g of chitosan powder in 1000 mL of
XRD analysis of chitosan nanocomposites
Wide-angle X-ray diffraction is a classical method for determining the gallery height (d-spacing distance) in clay particles. During intercalation, the insertion of polymer into the organoclay galleries forces the platelets apart and increases the d-spacing, resulting in a shift of the diffraction peak to lower angles (Xu et al., 2006). Results of XRD characterization of chitosan and chitosan/MMT nanocomposite are shown in Fig. 1. in the text. The crystalline structure of chitosan is strongly
Conclusions
It was shown that incorporation of very low amounts of nanoclay into chitosan significantly improves its physical and mechanical properties. XRD pattern showed MMT exfoliation and FTIR spectra demonstrated good interaction between chitosan and MMT. The compatibility of REO with chitosan/MMT nanocomposite was confirmed in order to produce an active bionanocomposite for food packaging. Good interaction between chitosan and MMT could improve WVP, water sensitiveness, and mechanical properties of
Acknowledgments
We are grateful to Dr. Badiei for preparing some experimental facilities for this research. We also thank to Dr. Zarei for graciously providing some raw materials.
References (49)
Chitosan application for active bio-based films production and potential in the food industry: Review
LWT - Food Science and Technology
(2010)Nanocomposites for food packaging applications
Food Research International
(2009)- et al.
Biological effects of essential oils - A review
Food and Chemical Toxicology
(2008) - et al.
Preparation and properties of rice starch-chitosan blend biodegradable film
LWT - Food Science and Technology
(2008) Essential oils: their antibacterial properties and potential applications in foods-a review
International Journal of Food Microbiology
(2004)- et al.
Chitosan/clay films’ properties as affected by biopolymer and clay micro/nanoparticles’ concentrations
Food Hydrocolloids
(2009) - et al.
Barrier membranes
Journal of Membrane Science
(1988) - et al.
Essential oil amended coatings as alternatives to synthetic fungicides in citrus postharvest management
Postharvest Biology and Technology
(2009) - et al.
Modification of microstructural morphology and physical performance of chitosan films
International Journal of Biological Macromolecules
(2010) - et al.
Antioxidant properties of tuna-skin and bovine-hide gelatin films induced by the addition of oregano and rosemary extracts
Food Chemistry
(2009)
Effects of gelatin origin, bovine-hide and tuna-skin, on the properties of compound gelatin–chitosan films
Food Hydrocolloids
Biodegradable gelatin-chitosan films incorporated with essential oils as antimicrobial agents for fish preservation
Food Microbiology
Changes in free-radical scavenging ability of kombucha tea during fermentation
Food Chemistry
Study of the combined effect of both clay and glycerol plasticizer on the properties of chitosan films
Carbohydrate Polymers
Preparation and functional properties of blend films of gliadins and chitosan
Carbohydrate Polymers
Comparative studies on the characterization and antioxidant properties of biodegradable alginate films containing ginseng extract
Journal of Food Engineering
Development and evaluation of a novel biodegradable film made from chitosan and cinnamon essential oil with low affinity toward water
Food Chemistry
Chitin and chitosan: properties and applications
Progress in Polymer Science
Physical properties of edible chitosan films containing bergamot essential oil and their inhibitory action on Penicillium italicum
Carbohydrate Polymers
Physical and antimicrobial properties of chitosan-tea tree essential oil composite films
Journal of Food Engineering
Food applications of chitin and chitosans
Trends in Food Science & Technology
Physical properties and antioxidant activity of an active film from chitosan incorporated with green tea extract
Food Hydrocolloids
Effect of plasticizers and fatty acids on mechanical and permeability characteristics of chitosan films
Food Hydrocolloids
Preparation and properties of chitosan nanocomposites with nanofillers of different dimensions
Polymer Degradation and Stability
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