High Molecular Weight Chitosan Research Articles

Chitosan mitigates the adverse effects and improves photosynthetic activity in rice (Oryza sativa L.) seedlings under drought condition

ABSTRACT The ability of chitosan to promote rice growth, physiological traits, and photosynthetic performance in rice seedlings under drought stress was investigated. Rice seedlings (Oryza sativa L. cv. KDML105) were treated with 100 mg l−1 low and high molecular weight (MW) chitosan via a combination of seed priming and foliar spray. The seedlings were subjected to drought stress by withholding water for 4 days, which resulted in the U-shaped (scale 5) leaf rolling. The results showed that drought significantly decreased shoot and root growth. Chitosan application, particularly with high MW chitosan, improved shoot and root growth under drought stress. Chitosan treatment also alleviated the effects of drought stress by elevating relative water content, as well as reducing electrolyte leakage and malondialdehyde content. Antioxidant enzyme activities, including guaiacol peroxidase (GPX) and ascorbate peroxidase (APX), were increased in response to chitosan. Additionally, treating the plant with chitosan improved photosynthetic efficiency as evidenced by increased CO2 response, the maximum rate of Rubisco carboxylase activity (Vcmax), and photosynthetic rate. We conclude that the exogenous application of chitosan aids the plant in coping with the severity of drought stress. While both low and high MW chitosans were effective at alleviating the effect of drought on rice seedlings, high MW chitosan might have a slight advantage with respect to increased effective duration.

Preparation, characterization and antimicrobial activities of cyclic substituted chitosan derivatives

Six cyclic substituted chitosan derivatives were synthesized, and their structures were characterized by FTIR, 13C NMR and elemental analyses. Additionally, their antimicrobial properties were studied. The synthesized derivatives showed significantly greater zones of inhibition compared with chitosan. The zone of inhibition values produced by C2-2-naphthylamine formamide-C6-2-naphthylamine formyl ester-polymer chitosan against Sarcina sp., Staphylococcus aureus and Escherichia coli were 24 mm, 21 mm and 21 mm, respectively, whereas those of C2-cyclohexylamine formamide-C6-cyclohexylamine formyl ester-low chitosan against Fusarium equiseti and Verticillium dahliae were 14 mm and 15 mm, respectively. The antibacterial abilities of chitosan and its derivatives against the Gram-positive bacteria Sarcina sp. and Staphylococcus aureus were stronger than those against the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa. In addition, all of the high and low molecular weight chitosan derivatives showed greater bacteriostatic activities than antifungal activities. The results provided a useful reference for the development of chitosan and its derivatives used as new pesticides.

Oligochitosan Hydrochloride: Preparation and Characterization

The methods commonly used for depolymerization of chitosan and preparation of oligochitosan are discussed. A synthetic approach to oligochitosan hydrochloride with a molecular weight below 16 kDa based on the treatment of parent industrial high molecular weight chitosan with a mixture of hydrochloric acid and hydrogen peroxide is described. A series of analytical protocols are used to determine the physicochemical properties and quality of resulting oligochitosan hydrochloride according to the European Pharmacopoeia 4.0.

Design of Experiments to Achieve an Efficient Chitosan-Based DNA Vaccine Delivery System.

In current times, DNA vaccines are seen as a promising approach to treat and prevent diseases, such as virus infections and cancer. Aiming at the production of a functional and effective plasmid DNA (pDNA) delivery system, four chitosan polymers, differing in the molecular weight, were studied using the design of experiments (DoE) tool. These gene delivery systems were formulated by ionotropic gelation and exploring the chitosan and TPP concentrations as DoE inputs to maximize the nanoparticle positive charge and minimize their size and polydispersity index (PDI) as DoE outputs. The obtained linear and quadratic models were statistically significant (p-value < 0.05) and non-significant lack of fit, with suitable coefficient of determination and the respective optimal points successfully validated. Furthermore, morphology, stability and cytotoxicity assays were performed to evaluate the endurance of these systems over time and their further potential for future in vitro studies. The subsequent optimization process was successful achieved for the delivery systems based on the four chitosan polymers, in which the smallest particle size was obtained for the carrier containing the 5 kDa chitosan (~82 nm), while the nanosystem prepared with the high molecular weight (HMW) chitosan displayed the highest zeta potential (~+26.8 mV). Delivery systems were stable in the formulation buffer after a month and did not exhibit toxicity for the cells. In this sense, DoE revealed to be a powerful tool to explore and tailor the characteristics of chitosan/pDNA nanosystems significantly contributing to unraveling an optimum carrier for advancing the DNA vaccines delivery field.

Characterization and Optimization of Chitosan-Coated Polybutylcyanoacrylate Nanoparticles for the Transfection-Guided Neural Differentiation of Mouse Induced Pluripotent Stem Cells.

Gene transfection is a valuable tool for analyzing gene regulation and function, and providing an avenue for the genetic engineering of cells for therapeutic purposes. Though efficient, the potential concerns over viral vectors for gene transfection has led to research in non-viral alternatives. Cationic polyplexes such as those synthesized from chitosan offer distinct advantages such as enhanced polyplex stability, cellular uptake, endo-lysosomal escape, and release, but are limited by the poor solubility and viscosity of chitosan. In this study, the easily synthesized biocompatible and biodegradable polymeric polysorbate 80 polybutylcyanoacrylate nanoparticles (PS80 PBCA NP) are utilized as the backbone for surface modification with chitosan, in order to address the synthetic issues faced when using chitosan alone as a carrier. Plasmid DNA (pDNA) containing the brain-derived neurotrophic factor (BDNF) gene coupled to a hypoxia-responsive element and the cytomegalovirus promotor gene was selected as the genetic cargo for the in vitro transfection-guided neural-lineage specification of mouse induced pluripotent stem cells (iPSCs), which were assessed by immunofluorescence staining. The chitosan-coated PS80 PBCA NP/BDNF pDNA polyplex measured 163.8 ± 1.8 nm and zeta potential measured −34.8 ± 1.8 mV with 0.01% (w/v) high molecular weight chitosan (HMWC); the pDNA loading efficiency reached 90% at a nanoparticle to pDNA weight ratio of 15, which also corresponded to enhanced polyplex stability on the DNA stability assay. The HMWC-PS80 PBCA NP/BDNF pDNA polyplex was non-toxic to mouse iPSCs for up to 80 μg/mL (weight ratio = 40) and enhanced the expression of BDNF when compared with PS80 PBCA NP/BDNF pDNA polyplex. Evidence for neural-lineage specification of mouse iPSCs was observed by an increased expression of nestin, neurofilament heavy polypeptide, and beta III tubulin, and the effects appeared superior when transfection was performed with the chitosan-coated formulation. This study illustrates the versatility of the PS80 PBCA NP and that surface decoration with chitosan enabled this delivery platform to be used for the transfection-guided differentiation of mouse iPSCs.

Clinical and Radiographic Evaluation of Chitosan Particles in Treatment of Intrabony Periodontal Defects: A Clinical Trial.

Objectives: Intrabony defects are among the most important signs of progression of periodontal disease. Complete tissue regeneration is the ideal goal of periodontal treatment, and regenerative methods aim to achieve this goal. New studies have reported the positive efficacy of chitosan to enhance the recovery of bony defects. This study aimed to clinically and radiographically assess the efficacy of chitosan particles for treatment of intrabony periodontal defects. Materials and Methods: In this clinical trial, 18 intrabony three-wall periodontal defects were randomly divided into three groups (n=6). The control group only received conventional flap surgery with a sulcular incision. In the second group, low molecular weight (100,000-300,000g/mol) chitosan was used in the three-wall intrabony defects during surgery while high molecular weight chitosan particles (600,000-800,000 g/mol) were used in the third group. The probing pocket depth (PPD), clinical attachment level (CAL) and radiographic defect depth (RDD) were measured at baseline and at 6 and 12 months later. Repeated measures ANOVA, and McNemar’s test were used for statistical analysis. Results: In both the control (P<0.001) and coarse chitosan (P=0.035) groups, a significant difference was noted in PPD before and after surgery. CAL was not significantly different among the three groups (P>0.05). No significant difference was noted on radiographs between the groups regarding the regenerated bone density. Conclusion: Chitosan showed no positive efficacy for treatment of three-wall periodontal bone defects.

Dry powder formulation for pulmonary infections: Ciprofloxacin loaded in chitosan sub-micron particles generated by electrospray

Electrospray was used as a one-step technique to generate inhalable ciprofloxacin-loaded chitosan sub-micron particles with potential use in the treatment of pulmonary infections. The effect of operating parameters was studied and the preparation method optimized. The final sizes of ciprofloxacin-loaded particles were 386.1 ± 248.5 nm and 501.1 ± 276.3 nm for high and low molecular weight chitosan, respectively. The high surface charge of the particles formed, around +45 mV, enhances their mucoadhesive properties. The particles were biocompatible with alveolar cell line (A549), and showed a high antimicrobial activity against two of the most common respiratory pathogens Staphylococcus aureus and Pseudomonas aeruginosa.

Swallowing Gel for Patients with Dysphagia: A Novel Application of Chitosan.

Dysphagia refers to difficulty swallowing certain foods, liquids, or pills. It is common among the elderly with chronic diseases who need to take drugs for long periods. Therefore, dysphagia might reduce compliance with oral drug administration in the aging population. Many pharmaceutical companies search for new products to serve as swallowing aids. Existing products are expensive and do not suit all geriatric patients. Therefore, this study aimed to develop and investigate pill swallowing aid gels prepared from carboxymethyl cellulose and chitosan. We formulated gels by dissolving different concentrations of carboxymethyl cellulose and low or high molecular weight chitosan in solvents to find appropriate gel rheology properties. We then added several portions of glycerin as the glidant of the formulation. We found that the optimized gel formulation was 6.25% (w/w) chitosan with a molecular weight of 80–120 kDa dissolved in 1.2% acetic acid and 4% (w/w) glycerin. The developed pill swallowing gel’s rheology was pseudoplastic with a viscosity of 73.74 ± 3.20 Pa⸱s. The developed chitosan gel had enhanced flow ability; it allowed the pill to cross a 300 mm tube within 6 s, while the reference product took 3 s. Even though the reference product could carry the pill in the tube faster, the chitosan gel better covered the pill, making it more convenient to use. Finally, using a theophylline tablet as a model tablet dosage form, we assessed the gel’s effect on drug disintegration and dissolution. The chitosan gel delayed the tablet disintegration time by about 3–7 min and slightly affected the theophylline dissolution rate. Lastly, all gels were physically stable after a month of storage in the stress condition. These results show the feasibility of manufacturing a chitosan gel usable as a pill swallowing gel for patients with dysphagia.

Preparation of low molecular chitosan by microwave-induced plasma desorption/ionization technology

Compared with high molecular weight chitosan (HMWC), low molecular weight chitosan (LMWC) has better solubility and biological activity. However, there is no quick and environmentally friendly to prepare low molecular chitosan. In this study, microwave induced plasma desorption/ionization (MIPDI) was used for the first time to prepare LMWC through the degradation processes of HMWC. The results showed that MIPDI has the most abundant ∙OH content at the gas-liquid interface, and the active particles represented by ∙OH can degrade chitosan with a molecular weight of 540 KDa into soluble chitosan (≤ 10 KDa), and the yield of soluble chitosan can reach 61% in 60 min. Moreover, a series of characterization results showed that the chain structure and crystal structure gradually degraded as the treatment time increased while the chemical structure of chitosan did not change significantly. Antibacterial experiments also indicated that the antimicrobial property of LMWC obtained by MIPDI degradation was improved. In short, this method has proven to be a new, fast and green processing method for the preparation of low molecular chitosan.

Inhibitory effects of high molecular weight chitosan coating on ‘Hom Thong’ banana fruit softening

This study was undertaken to examine the effects of different molecular weights of 1% (w/v) chitosan coating on physicochemical characteristics and softening of ‘Hom Thong’ banana. The results indicated that high and medium molecular weights of chitosan coating (HMW-CTS; 540 kDa and MMW-CTS; 265 kDa) maintained banana fruit qualities during 25 °C storage compared to a low molecular weight of chitosan coating (LMW-CTS; 65 kDa) and control treatments. HMW-CTS expressed the highest ability to reduce respiration rate and ethylene production of the fruit and preserved fruit firmness by inhibiting cell wall degrading enzymes including polygalacturonase and pectate lyase activities which play an important role in pectin degradation. Additionally, HMW-CTS influenced a decrease in disease severity and cell membrane injury in relation to low malondialdehyde content and high antioxidant activities of coated fruit. The overall results suggest that HMW-CTS is a promising postharvest chitosan coating in maintaining fruit firmness and extending the shelf life of ‘Hom Thong’ banana fruit after harvest.

Time dependent synthesis of gold nanoparticles using chitosan as reducing agent: A spectroscopic approach

The present study attempted synthesis of gold nanoparticle using chitosan from shrimp waste and evaluated the kinetics of gold nanoparticle (AuNPs) formation. Two different forms of chitosan (high molecular weight and medium molecular weight forms) were used for the preparation of AuNPs. The formation of nanoparticles was studied using UV-VIS spectra obtained at different time intervals during synthesis. The typical UV-VIS spectrum of non-aggregated spherical AuNPs at 520 nm was obtained for both chitosan forms and the maximum absorbance was higher for the sample prepared with medium molecular weight chitosan. The results clearly indicated that the characteristic surface plasmonic resonance (SPR) peak became recognisable at 5 min of heating for the sample with high molecular weight chitosan and 3 min of heating for medium molecular weight chitosan. This indicated that, the lower the molecular weight, the faster the formation of nanoparticles. The wavelength (λ) of absorption maxima was selected and normalised with respect to the absorption maxima at 15 min. The sigmoidal shape of kinetic curve implied the autocatalytic character of AuNP formation. The data from the samples were fitted with two step Finke-Watzky kinetics model and the kinetics constants were derived. The rate constant of the nucleation reaction was found higher for the medium molecular weight chitosan. Keywords: AuNPs, Chitosan, Gold nanoparticles, Molecular weight, Rate constant

Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry Analysis for Molecular Characterization of Chitosan

Chitosan oligosaccharides designated to COS were derived from the hydrolysis of high molecular weight chitosan (HMWC). The range of molecular weight of COS was estimated to be approximately 0.5 to 2.5 kDa after the fractionation performed through gel-filtration, followed by MALDI-TOF mass spectrometry analysis. It was confirmed through the results that significant separation or fractionation was not observed well. Also, both dialyzed COS using a 12~14 kDa molecular weight cut-off (MWCO) membrane and salting-out COS were also showed no significant difference in the molecular weight of COS by MALDI-TOF mass spectrometry analysis. These results suggested that it is difficult to separate the chitosan hydrolysates bigger than 1 kDa according to the size (6-glucosamine) due to their high affinity between molecules which may tightly be associated together by hydrophobic or van der Waals force. Therefore, further examination on chitosan hydrolysis and fractionation for the production of COS with various sizes i.e., 7 or 8 units of glucosamine in large-scale, should be carefully considered for various applications.

APPROACHES TO THE SELECTION OF EXCIPIENTS FOR DENTAL GEL WITH CETYLPYRIDINIUM CHLORIDE

The aim of the study was to determine the excipients influence on the characteristics of gels with cetylpyridinium chloride and to select the dental gel formulation gelation agents promising for the development of dental gel compositions. Hereby, the properties of the active pharmaceutical ingredient, characteristics of the specific gelation agents, as well as their influence on stability, biopharmaceutical and application properties of gels, were taken into account. Materials and methods. In this study, polymers with various gelation mechanisms were considered. Their compatibility with cetylpyridinium chloride as well as storing kinetic and colloid kinds of stability, pH of aqueous solutions, spreadability and textural properties, a penetration ability by the agar diffusion method, an osmotic activity and rheological properties of the gels, were examined. For a complex evaluation of gel compositions study results, a desirability function was used.Results. Stable homogenous dental gels with cetylpyridinium chloride can be obtained by using 25% poloxamer 407 and 5.0% high molecular weight chitosan as the basis.The addition of poloxamer 188 to high molecular weight chitosan gels can produce stable systems with improved textural characteristics as well as increase their osmotic activity. Agar and low molecular weight chitosan addition significantly decrease, whereas poloxamer188 and various molecular weight polyethyleneglycol increase the osmotic activity of 25 % poloxamer 407 gels which are also characterized by a high penetration ability.Conclusion. A complex evaluation of biopharmaceutical, physicochemical and application properties of the gels made it possible to establish that combinations of poloxamer 407 with polyvinylpyrrolidone, agar, and low molecular weight chitosan, can be recommended as a base for a dental gel with cetylpyridinium chloride.

Spray Drying of Chitosan Acid Salts: Process Development, Scaling Up and Physicochemical Material Characterization.

We investigated a spray drying process for preparing water-soluble salts of high molecular weight chitosan (CH) intended for pharmaceutical excipient applications. CH was derived from chitin of marine lobster origin (Panulirus argus). The effects of organic acid (acetic or lactic acid) and the ratio (difference) of inlet/outlet air temperature (140/90 °C or 160/100 °C) on spray drying were studied. The yield of spray-dried CH salt powders ranged from 50% to 99% in laboratory and industrial-scale processes. The spray-dried dry powder of CH salts consisted of spherical agglomerated particles with an average diameter of 36.2 ± 7.0 µm (CH acetate) and 108.6 ± 11.5 µm (CH lactate). After dispersing the spray-dried CH salt powder samples in purified water, the mean particle sizes obtained for the CH acetate salts were 31.4 nm (batch A001), 33.0 nm (A002) and 44.2 nm (A003), and for the CH lactate salts 100.8 nm (batch L001), 103.2 nm (L002) and 121.8 nm (L003). The optimum process conditions for spray drying were found: an inlet air temperature of 160 ± 5 °C, an outlet temperature of 100 ± 5 °C and an atomizer disk rotational speed of 18,200 min−1. The X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC) results confirmed the amorphous state of the CH salts. The 1H nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectra of CH acetate and lactate salts verified that the spray drying process does not affect the polymer backbone. In conclusion, both laboratory and industrial-scale spray drying methods for preparing water-soluble acid salts of CH are reproducible, and the physicochemical properties of the corresponding CH acid salts are uniform.

Antibacterial Effect on Enterococcus Faecalis and Physical Properties of Chitosan Added Calcium Hydroxide Canal Filling Material

The aim of this study was to evaluate the antibacterial effect on Enterococcus Faecalis and physical properties of chitosan added calcium hydroxide canal filling material.&lt;br/&gt;Low, medium, high molecular weights of chitosan powder were mixed with calcium hydroxide canal filling material. Also, for each molecular weight group, 1.0, 2.0, 5.0 wt% of chitosan powder were added. An overnight culture of &lt;i&gt;E. faecalis&lt;/i&gt; was adjusted to 1 × 10&lt;sup&gt;6&lt;/sup&gt; CFU/ml. For test of antibacterial effect, three different molecular weights of 2.0 wt% chitosan and three different concentrations of high molecular weight chitosan were mixed with calcium hydroxide canal filling material. The absorbance of plates was analyzed using spectrophotometer at 570 nm with a reference wavelength of 600 nm. Physical properties such as flow, film thickness and radiopacity were examined according to ISO 6876 : 2012.&lt;br/&gt;All molecular weight type of chitosan containing material showed inhibitory effect against E. faecalis growth compared to non-chitosan added calcium hydroxide canal filling material group (&lt;i&gt;p&lt;/i&gt; &lt; 0.05). High molecular weight chitosan containing material showed the most antibacterial effect. Also, the antibacterial effect decreased as the incorporated amount of chitosan decreased (&lt;i&gt;p&lt;/i&gt; &lt; 0.05). Every molecular weight group of material containing chitosan had a tendency for reduced flow and radiopacity, increased film thickness according to amount of chitosan. Low molecular weight of 1.0 wt% chitosan addition did not show any significant difference of physical properties compared to conventional calcium hydroxide canal filling material.&lt;br/&gt;In conclusion, for reinforcement of antibacterial effect against &lt;i&gt;E. faecalis&lt;/i&gt; and for favorable physical properties, 2.0 wt% of chitosan adding is recommended. Considering its antibacterial effect of chitosan, further studies are required for clinical application of chitosan in endodontics and pediatric dentistry.

The effect of tarragon (Artemisia dracunculus) essential oil and high molecular weight Chitosan on sensory properties and shelf life of yogurt

This study aimed to investigate the effects of high molecular weight CH and TEO on increasing the shelf life of yogurt as well as improve the consistency and reduce hydration. First, different concentrations of CH (2%, 4%, and 6%) were made and added to yogurt. Then, tarragon essential oil (TEO) was inoculated into yogurt in different concentrations (20, 40, and 60 ppm). The samples were kept at two temperatures, refrigerator and room temperature, for three weeks. Afterward, the effects of different concentrations of CH and TEO on yogurt properties such as pH, acidity, dry matter, fat, protein, syneresis, and the survival of microorganisms such as bacteria, mold, and yeast were investigated. The results showed that CH concentration, temperature, and storage time had a statistically significant effect (ρ < 0.05) on pH, acidity, syneresis, and the bacterial count and yeast. The best results were related to yogurts containing 6% CH with 60% TEO. Nevertheless, samples containing 2% CH had the highest score in sensory evaluation. It is concluded that the addition of high molecular weight CH at a concentration of 6% with 20% TEO leads to the production of high-quality yogurt and greater durability.

Electrophoretically deposited high molecular weight chitosan/bioactive glass composite coatings on WE43 magnesium alloy

Abstract Mg-based materials are good candidates for biodegradable bone regeneration implants due to their favorable mechanical properties and an excellent compatibility with human bone. However, too high corrosion/degradation rate in body fluids still limits their applicability. Coatings based on chitosan (CS) and bioactive glass (BG) particles fabricated by electrophoretic deposition (EPD) on Dulbecco's Modified Eagle Medium (DMEM) pre-treated magnesium alloys have promising potential to suppress the substrate corrosion and additionally to incorporate bioactivity. However, the impact of processing parameters or type of coating components on the long-term substrate corrosion behavior and cell response have not been investigated previously. In this study, two types of composite coatings based on a high molecular weight CS (Mw 340–360 kDa, DDA ≥ 95%) and embedded particles: solid BG (2 μm) and a mixture of BG and mesoporous bioactive glass nanoparticles (MBGN, 100–300 nm with mesopores 2.3–5.6 nm) were fabricated by EPD on DMEM pre-treated WE43 magnesium alloy. It was found that partial replacement of BG particles with MBGN (ratio 3:1) in the composite coating increases the water contact angle, surface roughness and induces a positive cell response. Although the acidic CS-based solutions and applied EPD conditions may decrease the stability of the temporary barrier formed during the DMEM pre-treatment on WE43 substrate therewith slightly increasing its corrosion sensitivity, the composite coating with a mixture of different sizes of particles (BG, MBGN) is a promising candidate for bone regeneration applications.

Synthesis and properties of oligochitosan ascorbate from Bombyx mori

Oligochitosan samples were obtained by acid hydrolysis of high molecular weight chitosan isolated from Bombyx mori (B.M.). Carrying out acid hydrolysis for 6 hours, it was found that after 4 hours and further with increasing duration, the molecular weight of chitosan decreases to a value corresponding to the ranges of mo-lecular weights of oligochitosan 2–16 kDa. It has been seen that the optimal duration of hydrolysis, leading to the production of oligochitosan with a molecular weight of less than 16 kDa, should be considered 4–5 hours. Depolymerization of chitosan with a molecular weight of 177 kDa was carried out using sodium nitrite in so-lution to obtain oligochitosan with a molecular weight of 6 kDa. On the basis of oligochitosan samples ob-tained by two methods, their ascorbates were received. Under constant conditions with varying the ratio of the components (ChS:AA) and the pH of the solution, the reaction of chitosan ascorbate formation was car-ried out on the basis of the suspension method. The composition, structure, and molecular weight characteris-tics of oligochitosan ascorbate and oligochitosan Bombyx morisamples were confirmed by physicochemical methods. It has been seen that the obtained samples have antimicrobial properties against Fuzarium oxysporum.

Chitosan Films Obtained from Brachystola magna (Girard) and Its Evaluation on Quality Attributes in Sausages during Storage.

High molecular weight chitosan (≈322 kDa) was obtained from chitin isolated from Brachystola magna (Girard) to produced biodegradable films. Their physicochemical, mechanical and water vapor permeability (WVP) properties were compared against commercial chitosan films with different molecular weights. Brachystola magna chitosan films (CFBM) exhibited similar physicochemical and mechanical characteristics to those of commercial chitosans. The CFBM films presented lower WVP values (10.01 × 10−11 g/m s Pa) than commercial chitosans films (from 16.06 × 10−11 to 64.30 × 10−11 g/m s Pa). Frankfurt-type sausages were covered with chitosan films and stored in refrigerated conditions (4 °C). Their quality attributes (color, weight loss, pH, moisture, texture and lipid oxidation) were evaluated at 0, 5, 10, 15 and 20 days. Sausages covered with CFMB films presented the lowest weight loss (from 1.24% to 2.38%). A higher increase in hardness (from 22.32 N to 30.63 N) was observed in sausages covered with CFMB films. Compared with other films and the control (uncovered sausages), CFMB films delay pH reduction. Moreover, this film presents the lower lipid oxidation level (0.10 malonaldehyde mg/sample kg). Thus, chitosan of B. magna could be a good alternative as packaging material for meat products with high-fat content.

PREPARATION AND CHARACTERIZATION OF LOW MOLECULAR WEIGHT CHITOSAN WITH DIFFERENT DEGREES OF DEACETYLATION BY THE ACID HYDROLYSIS METHOD

Objective: The objective of this research is to prepare Low Molecular Weight Chitosan (LMWC) by the acid hydrolysis method, using dilute hydrochloric acid (2M). LMWC has superior properties compared to the High Molecular Weight Chitosan (HMWC), especially in terms of water solubility, antibacterial and antifungal properties. These could open new potential applications for LMWC in sectors such as the cosmetics, food, and pharmaceutical industries.&#x0D; Methods: In this work, the acid hydrolysis method was used to produce LMWC with different molecular weights starting from 500 kDa and 93% degree of deacetylations (DDA). The molecular weights of the produced grades were determined by applying Mark-Houwink equation while the %DDA was determined and verified by the use of the 1st derivative UV method and 1HNMR method, respectively. The depolymerization reactions were carried out with different time intervals to produce totally deacetylated LMWC of 30 kDa, 15 kDa, and 7.5 kDa. The LMWC was characterized by FTIR, XRD, and DSC to evaluate the functionality, microstructure and thermal properties.&#x0D; Results: The FTIR spectra revealed that there is no significant difference in the main skeletal structure of the LMWC and HMWC. On the other hand, the XRD and DSC results showed that the LMWC of different molecular weights and degrees of deacetylation are of semi-crystalline structure, similar to the HMWC.&#x0D; Conclusion: The obtained results showed that the used acid hydrolysis procedure can produce LMWC grades of desired specifications, yields, and quality which are suitable for use in different applications.