جستجوی مقالات مرتبط با کلیدواژه « chitosan » در نشریات گروه « مکانیک »

Using of chitosan biopolymer has been developed in the form of edible film and coating as a packaging material for food products. The physical and mechanical properties of chitosan film are influenced by various factors. To investigate the impact of effective factors on the film-forming solution, the present experiment in a completely randomized design using the 23 factorial method, a total of 8 treatments including the level (2 and 4%), molecular weight (high and low) of chitosan and solvent type (acetic acid and citric acid) used in film preparation was carried out. The physical and mechanical parameters of the films were measured. Also, the microstructure of the films was investigated using scanning electron microscope (SEM) images and infrared spectroscopy (FTIR) spectra. The results showed that 4% high and low molecular weights chitosan films which were dissolved in the acetic acid had the highest tensile strength (0.16 ± 0.01 MPa), Young's modulus (2.45 ± 0.55 MPa) and impermeability (2.17 ± 0.09 ± 0.09 g/msPa), and the highest elongation at break (54.33% ± 0.95%) was observed in 4% high molecular weight chitosan film with citric acid solvent (p<0.05). In addition, high molecular weight chitosan film dissolved in acetic acid was more transparent compared to citric acid (p<0.05). SEM images and IR spectra analysis confirmed the obtained results. Therefore, the physical and mechanical performance of the chitosan film was affected by the level and molecular weight of chitosan, and especially the type of acidic solvent, as well as the interaction effects of these factors. In general, the use of a higher level and molecular weight of chitosan leads to the production of a better film, and acetic acid is a more suitable solvent than citric acid.

The aim of this study was to investigate the effect of polyaniline conductive nano-polymer on the structural, functional and biological properties of chitosan bio-composite. In this study, conductive polyaniline nanoparticles were used to improve the structural properties of chitosan. For this purpose, chitosan-polyaniline nanocomposite in combination of different concentrations of polyaniline and synthesis time (1-60 minutes) with the aim of producing antibacterial and biodegradable packaging was synthesized; also physical, structural, and functional properties of the films were investigated. Structural properties were investigated using infrared spectroscopy and X-ray diffraction and also the size, shape and morphology of the synthesized particles were studied using scanning electron microscopy (SEM). The results showed that the polyaniline nanoparticles synthesized in the chitosan polymer matrix are spherical in dimensions of 45-50 nm. The study of the effect of polyaniline on the physical properties of chitosan films also showed that with increasing the concentration of polyaniline and the synthesis time, the water solubility and water vapor permeability of the films decreased. Also, due to the fading of synthesized nanocomposites at high concentrations of poly-aniline, synthesized nanocomposites can be used in the packaging of light-sensitive foods.

Chitin, chitosan and oligosaccharides derived from them, due to their antimicrobial, non-toxic and biodegradable activity have presented themselves as a versatile, flexible and promising compound for the future uses. Among the various applications of these antimicrobial compounds, packaging is one of the most important systems for improving the quality of food and its protection during the process and storage, which is unique in this regard. Antimicrobial packaging is also effective in increasing the shelf life of food. In addition, the functional properties of chitin, chitosan, and oligosaccharide films are enhanced by combining with other film-forming coatings. In this context, understanding the factors affecting antimicrobial activity and the mechanism of action of chitin and chitosan is an important factor in the optimal use of the elements used in the food industry.

Biodegradable packaging is a good alternative to synthetic film in the packaging industry because of its environmental-friendly. In this study, zinc oxide nanoparticles and thyme oil were used to enhance the structural properties of chitosan, which were produced for the purpose of chitosan - zinc oxide (0.01- 0.03%)  - thyme essential oil (0.25- 0.5%) nanocomposite. The differences between the synthesized samples with control film (blank) are for production of antibacterial and biodegradable packaging, the structural properties were investigated by infrared spectroscopy and X-ray diffraction, also the morphology of the synthesized particles was investigated by scanning electron microscopy. The results of the structural properties showed that the zinc oxide synthesized in the chitosan polymer matrix were nanoparticles. Based on the results, the water solubility and water vapor permeability of films decreased by 70% with increasing zinc oxide concentration and thyme essential oil. The interaction between chitosan, zinc oxide nanoparticles and thyme essential oil was confirmed by infrared spectroscopy and X-ray diffraction pattern. The findings of this study are an important factor for expanding the use of biodegradation films by improving their functional properties by nanoparticles.

The indiscriminate use of plastic packaging films and ecological problems has led to development of biodegradable packaging. These materials are essentially derived from either agricultural raw materials (cellulose, starch and protein) or marine food processing industry wastes (chitin/chitosan). Altghough these materials have problems such as poor mechanical and barrier properties, but applying nanocomposites has overcame these problems to a large extent. Nanocomposites also have other functions such as antimicrobial activity, enzyme immobilization, biosensors, etc. In this paper, some aspects of the potential applications of chitosan, xanthan gum, and lignin in obtaining antimicrobial and antioxidant packaging have been studied. One of the chitosan applications is useing in hydrogels. . Therefore matrices based on covalently cross-linked chitosan hydrogels is produced. Covalent cross-linking leads to the formation of a permanent network allowing drug release by controlled diffusion and enhancing the mechanical properties of the hydrogel. According to the results, release of vanillin from chitosan nanocomposite hydrogels and lignin/ xanthan hydrogels was delayed. I In studies on lignin it was shown that the role of lignin as an antimicrobial and antioxidant agent in the polyolefin composition depends on the type of lignin and its properties.

During the recent past, environmental concerns have been risen on the increasing consumption of petroleum-derived chemicals to produce plastic packaging materials, So it is necessary to use high-strength packaging papers to enhance shelf life of food by inhibiting bacterial growth while providing further health safety for people. For this purpose, resistance of packaging papers and preparation of this target as common of processing methods such as refining and the addition of long fiber-pulp, as well as chemical treatment approaches such as dry- and wet-strength enhancement resins have been in use. However, layer-by-layer sediment way one of the new nanotechnology-based methods is used to enhance paper retaining characteristics and additive adsorption at fiber surface. The method contributes into the establishment of a set of chemical, physical, mechanical, and antibacterial properties for ink structure and layers within the paper. Layer-by-layer precipitation is based on the alternative precipitation of polycations and polyanions via electrostatic interactions. With the aim being to improve antibacterial properties of paper, a large deal of effort has been allocated to the development of organic/mineral hybrids based on metallic salts and biopolymers, so as to combine biopolymer bonding features with the characteristics of metallic ions. Chitosan a high capacity in terms of separating various metallic ions and also separating positively charged chitosan – metal ions, chitosan is expected to make the polymer adsorbed on the negatively charged surface of bacterial cells, so as to reduce growth phase of microorganisms within the paper-made packaging covers, enhancing the product durability and safety. This material have a longer life than organic antimicrobial agents, and cause reduce the use of nanometals in packaging papers. The present research seems to be necessary to come with innovative yet efficient new materials and antibacterial properties.

The production of biodegradable and edible films with appropriate mechanical characteristics and gas barrier properties represents one of the most important challenges in the field of food packaging. Edible films provide foods with physical protection and reduce loss of their moisture, restrict absorption of oxygen, lessen migration of lipids, as well. Natural polymers, like carbohydrates and proteins, offer the greatest opportunities as component of edible films since their biodegradability and environmental compatibility are assured and they can also supplement the nutritional value of specific foods. However, excessive water solubility and poor water vapor barrier properties, and often poor mechanical resistance, have limited their applications. Numerous studies have been carried out to improve their properties by preparing composite and multi-layered films or by physically and chemically crosslinking of their components. In the present review we summarize the application of transglutaminase in preparation of chitosan-based edible films and its effect on mechanical and barrier properties of produced films.

Maturity period and consumption of fresh fruits such as pomegranate are relatively short. In addition, the consumption of pomegranates is not very widespread mainly due to the difficulty of extracting the arils. Hence, minimally processed pomegranate fruit (ready-to-eat arils), presents a more appealing product to consumers than whole fruit and increases the prospect of production and consumption of pomegranate. In recent years, minimally processed “ready-to-eat” pomegranate arils have become popular due to their convenience, high nutritional value, unique sensory characteristics. According to nutritional value of pomegranate, modified atmosphere packaging of minimally processed pomegranate arils offers innovative tool for optimal use of lower grade fruit with superficial peel defects such as cracks, splits, and sun burnt. Minimally processed fruit and vegetables are susceptible to increased deterioration in quality and microbial infestation due to increase in endogenous enzymatic processes and respiration rate. Modified atmosphere packaging (MAP) technology offers the possibility to retard product respiration rate and extend the shelf life of fresh product. Edible coatings also act as a barrier to gas and moisture migration and some of them such as chitosan, have antibacterial and antifungal properties. Incorporation of essential oils into edible coating also helps to improve it’s antimicrobial properties. Coating of pomegranate arils with Aloe vera gel and honey also maintain it’s quality.

In this study, the effect of gelatin-chitosan edible coating on the quality of chicken breast during 9 days of refrigerated storage (4 was investigated. Three concentrations of gelatin (3, 6 and 8% W/V) and two concentrations of chitosan (1 and 2% W/V) were used to prepare the coating materials. Samples was divided in 7 group, no coating (control), gelatin 3% and chitosan 1% (sample 2), gelatin 6% and chitosan 1% (sample 3), gelatin 8% and chitosan 1% (sample 4), gelatin 3% and chitosan 2% (sample 5), gelatin 6% and chitosan 2% (sample 6), gelatin 8% and chitosan 2% (sample 7). The samples were analyzed for microbiological (total microbial count), volatile nitrogen bases and peroxide value during a 9 days with 3 days interval. These parameters was significantly high in the control samples. Microbial growth, volatile nitrogenous bases and peroxide in samples with a higher percentage of chitosan and gelatin was slower. The amount of volatile nitrogen bases was high in control samples because this samples have high total microbial count. Significant difference between gelatin 3% with gelatin 6 and 8% was observed. So it can be said, that the coating maintain quality of the samples during the whole preservative period.