Deproteinization Process Research Articles

Optimization of the Deproteinization Process via Response Surface Methodology, Preliminary Characterization, and the Determination of the Antioxidant Activities of Polysaccharides from Vitis vinifera L. SuoSuo.

In this study, the response surface method (RSM) was used to optimize the deproteinization process of polysaccharides from Vitis vinifera L. SuoSuo (VTP). The antioxidant capacities of polysaccharides before and after deproteinization were evaluated. The structure of deproteinized VTP (DVTP), which has relatively strong antioxidant activity, was characterized, and the protective effect of DVTP on H2O2-induced HT22 cell damage was evaluated. The results of the RSM experiment revealed that the ideal parameters for deproteinization included a chloroform/n-butanol ratio (v/v) of 4.6:1, a polysaccharide/Sevage reagent (v/v) ratio of 2:1, a shaking time of 25 min, and five rounds of deproteinization. Preliminary characterization revealed that the DVTP was an acidic heteropolysaccharide composed of seven monosaccharides, among which the molar ratio of galacturonic acid was 40.65. FT-IR and the determination of uronic acid content revealed that DVTP contained abundant uronic acid and that the content was greater than that of VTP. In vitro, the antioxidant activity assay revealed that the hydroxyl radical scavenging capacity and total antioxidant capacity of DVTP were greater than those of VTP. In the range of 0.6~0.8 mg/mL, the DPPH scavenging capacities of VTP and DVTP were greater than that of vitamin C. In addition, cell viability was measured via a CCK-8 assay, which revealed that DVTP had a strong defense effect on H2O2-induced damage to HT22 cells. These findings suggest that DVTP has high antioxidant activity and could be used as a natural antioxidant in functional foods and medicines.

Sodium dodecyl sulfate assisted electric field treatment for deproteinization of chitosan

Chitosan with a low protein residue is required as it is widely used in the field of biomedicine. Herein, we proposed a novel method for deproteinizing industrial grade chitosan via electric field treatment in a medium containing sodium dodecyl sulfate (SDS). The effects of electric field intensity, SDS concentration, and electrophoresis time on the protein removal efficiency were optimized by orthogonal experimental design and model building. Chitosan with an ultra-low protein residue (0.151 wt%) can be obtained at the voltage of 300 V, the SDS concentration of 1 wt%, and the electrophoresis time of 2 h. The strong binding between SDS and residue protein renders the conjugate with negative charges, which can migrate under the electric field. In addition, the electric field deproteinization process reduces the heavy metal content of chitosan slightly, while keeping the chemical structure of chitosan unchanged. The methodology provided in this work suggests the great potential of electric field treatment in removing residue protein in chitosan.

Pretreatment of shrimp shells with an acidic deep eutectic solvent system for chitin extraction and its enhanced performance as a carrier for immobilized lipase

Existing methods for chitin extraction usually produce substantial waste, which poses ecological hazards. Natural deep eutectic solvent (NADES) offers a promising one-step pretreatment alternative, replacing the resource-intensive demineralization (DM) and deproteinization (DP) process. Hence, in this study, the influence of various acidic NADES, on achieving a simplified one-step DM and DP in the chitin extraction process was investigated. The study yielded chitin with 87.73 % purity, and microstructural analysis showed that NADES pretreatment minimally affected chitin quality without deacetylation. In addition, chitin extracted using choline chloride-oxalic acid as a carrier displayed excellent performance in the immobilization of Geobacillus thermocatenulatus lipase 2 (GTL2) because of obvious Ca2+ activation effect. This process contributed to enhancement of immobilized enzyme activity. The immobilized GTL2 showed excellent hydrolytic capabilities, with its highest activity reaching 547.80 ± 20.62 U/mg, significantly better than the five commercial lipases that exhibited <40 % of the enzyme activity. Furthermore, the hydrolytic capacity of immobilized GTL2 was notably high for 4-nitrophenyl butyrate, measuring 935.47 ± 51.60 U/mg. This study provided a constructive approach for the one-step pretreatment of shrimp shells with organic acid-based NADES to isolate and purify chitin and its potential application as an immobilized carrier to enhance enzyme activity.

Optimizing Chitin Extraction and Chitosan Production from House Cricket Flour

Chitin and its derivative, chitosan, have diverse applications in fields such as agriculture, medicine, and biosensors, amongst others. Extraction is primarily conducted from marine sources, such as crustaceans, which have been the focus of process optimization studies. However, there are other sources that are more readily available, such as insects, where insufficient research has been conducted. The house cricket (Acheta domesticus) is a promising source for chitin extraction because of its high chitin content, availability, and short lifespan. Modern chemical chitin extraction methods have not been standardized due to the use of different reagents, molar concentrations, temperatures, and reaction times across publications. Therefore, in this study, the composition of Acheta domesticus cricket flour was determined: 2.62% humidity, 4.3% ash content, 56.29% protein, 13.35% fat, 23.44% carbohydrates, and 15.71% crude fiber content. After a drying, defatting, demineralization, deproteinization, and bleaching process, chitin extraction was performed, and chitosan was obtained via a deacetylation reaction. The demineralization process was standardized at 30 °C for 3 h using HCl 2 M, resulting in 95.85 ± 0.012%. The deproteinization process was optimized at 80 °C for 45 min using NaOH 2.56 M, yielding 43.23 ± 1.25%. Finally, the identity and physicochemical characteristics of the compounds were confirmed and determined through characterization with Fourier-Transform Infrared Spectroscopy, X-ray Diffraction, Scanning Electron Microscopy, and Differential Scanning Calorimetry.

Study of physico-chemical properties of biopolymers chitin-chitosan synthesized from poddle bees Apis Mellifera

The article presents the optimal method for the synthesis of chitin polymers - chitosan from dry dead bees. In the experiment, the first deproteinization process was carried out, which was carried out in two stages by treating crushed dead bees with 0.5 N sodium hydroxide solution for 1 hour at 100 0C using the chitinase enzyme. At the second stage, by treating dead bees with a 2 M hydrochloric acid solution for 5 hours at room temperature according to the Hackman method, a demineralization reaction was carried out and a chitin polymer was obtained. demineralization was carried out on the basis of 2-normal hydrochloric acid from dead bees. When chitin was deacetylated with a 35% NaOH aqueous solution for 1.5 hours at a temperature of 85 0C and dried at 50-55 0C, chitosan was obtained. Study of the physicochemical properties of chitosan. Methods for determining the molecular weight, viscosity, moisture content, degree of deacetylation, and nitrogen content in polymers are presented. When determining the constants, the optimal media were chosen.

CrabCare: Innovative Chitosan Biopolymer-Based Ointment from Crab Shell Waste by Utiling

Wounds are a common problem that requires effective care to prevent infection and accelerate the healing process. The use of conventional antiseptics is often unsatisfactory due to the long time required. Therefore, the innovation of using chitosan from crab shell waste as a base material for ointment becomes the focus of this research. This study aims to develop a chitosan-based ointment that can accelerate the wound healing process more efficiently. The research results show that the ointment developed from crab shells through the deproteinization process can significantly accelerate wound healing. Chitosan extracted from crab shells has unique properties such as bioactivity, biodegradability, and biocompatibility, which are effective in inhibiting bacterial and pathogen growth, as well as stimulating granulation tissue formation. Thus, the CrabCare ointment made from crab shell chitosan offers a promising alternative as a therapeutic agent for more effective and environmentally friendly wound care. In conclusion, the development of CrabCare provides new opportunities in wound therapy through innovative and sustainable means.

Pengaruh Variasi Konsentrasi Nabh4 dan Suhu Operasi Terhadap Nilai Derajat Deasetilasi Kitosan Dari Limbah Cangkang Rajungan

Researchers aim to make chitosan with variations in operating temperature and the addition of NaBH4 at the deacetylation stage. Chitosan is produced through three stages namely demineralization, deproteination and deacetylation. The deproteination process with 3.5% NaOH ratio 1:10 (w/v) was reacted at 80°C for 2 hours, then continued with the demineralization process with HCl 1 N, 1:10 (w/v) ratio reacted at 38°C for 1 hour. For the final stage of making chitosan, a deacetylation process with 60% NaOH is carried out, a ratio of 1:20 (b / v) with the addition of NaBH4 (0.5 and 1) g and variations in operating temperature (100,110,120) °C at the deacetylation stage for 2 hours. In calculating the value of the degree of deacetylation, researchers use the ratio of absorption band A1655 / A3450 to calculate the value of the degree of deacetylation and the baseline method to assist in the calculation, from this calculation, the value of the degree of deacetylation of chitosan is obtained as much. (46.8%, 49.4%, 56.6%, 62.1%, 72.1%, and 74.8%). The best treatment in this study is the deacetylation process temperature of 120 ° C and the addition of NaBH4 concentration as much as 1 g with a deacetylation degree value of 74.8%.

Analisis Kitin dari Cangkang Kepiting Rajungan (Portunus pelagicus)

Crab skin is a processing waste that reaches 50-60% by weight intact, with a chitin content of 20-30%. If this waste can be utilized, then in addition to overcoming the problem of water pollution, it will also provide added value to the fisheries processing business. Until now, the use of these wastes is still very limited. Its use includes making petis, shrimp paste, flavor, and as a feed ingredient. This research is about the isolation of chitin from crab shell shells through the stages of demineralization and deproteination. The research method used in this study has 2 stages, namely deproteination with variations in NaOH reagent concentrations of 3.5%, 45.0%, 5 and 6.5%, and demineralization with HCl reagent concentrations of 1 M. Test characteristics of chitin and chitosan isolated results carried out with IR. The results of data analysis showed that the isolation of chitin from crab shells went through several stages, namely two stages of deproteination and demineralization stages. The optimum concentration of NaOH reagents used in the deproteination process is 4.50% with the concentration of protein that can be released in the first test of 18.0467 gr and in the second test of 17.8445 gr. The optimum concentration of HCl reagent used in the demineralization stage is 0.1 N. The optimum incubation time for the chemical deproteinas stage i is 2 hours with chitin levels produced of 32.8320 gr

The impact of non-deproteinization on physicochemical and biological properties of natural rubber latex for biomedical applications

Latex is a colloidal suspension derived from the Hevea brasiliensis tree, derived from natural rubber, poly(isoprene), and assorted constituents including proteins and phospholipids. These constituents are inherent to both natural rubber and latex serum. This investigation was undertaken to examine the impact of the deproteinization process on chemical and biological dynamics of natural rubber latex. Natural Rubber (NR) extracted from the pure latex (LNCP) was obtained through centrifugation, followed by six rounds of solvent purification (LP6). The structure was characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), swelling test, surface zeta potential (ζ), scanning electron microscopy (SEM) and in vitro assay. The results revealed that the LP6 group presented decreased swelling kinetics, reduced cell adhesion and proliferation, and a smoother surface with decreased negative surface charge. Conversely, the LNCP group shown accelerated swelling, heightened adhesion and cellular growth, and a more negatively charged and rougher surface. As such, the attributes of latex serum and proteins have potential usage across numerous biomedical applications.

Microextraction of Tigecycline Using Deep Eutectic Solvents and Its Determination in Milk by LC-MS/MS Method.

The occurrence of tigecycline (TGC), a new first glycylcycline antibiotic residues in food products harmfully influences potential human consumers health. Therefore, analysts are forced to develop new microextraction methods connected with modern extractants for effective isolation of this compound. For this purpose, deep eutectic solvents (DES) as the extraction media were used. Liquid-liquid microextraction (LLME) of tigecycline from milk samples with application of the hydrophobic deep eutectic solvents: decanoic acid:thymol (1:1), thymol:camphor (2:1), dodecanoic acid:menthol (2:1), and dodecanoic acid:dodecanol (1:1) was developed. The studied samples were subjected to a deproteinization process using trichloroacetic acid solution and acetonitrile. The optimal microextraction parameters, molar ratio of DES components, amount of extraction solvents, pH of milk sample, shaking, and centrifugation time, were chosen. Tigecycline in the obtained microextracts of deep eutectic solvents was analyzed using a liquid chromatographic technique connected with a tandem mass spectrometry (LC-MS/MS) system. The limits of detection and quantification values for TGC determination followed by DES-LLME-LC-MS/MS method were in the 1.8 × 10-11 mol L-1 (0.01 μg kg-1) to 4.0 × 10-9 mol L-1 (2.28 μg kg-1) and 5.5 × 10-11 mol L-1 (0.03 μg kg-1) to 1.2 × 10-8 mol L-1 (6.84 μg kg-1) ranges, respectively. The RSD values of precision were in the range 1.4-7.8% (intraday) and 5.4-11.7% (interday). The developed procedures were used for the determination of tigecycline in different bovine milk samples.

Physicochemical Properties of Golden Apple Snail (Pomacea canaliculata) Shell Chitosan

The golden snail (Pomacea canaliculata) is an animal that lives in rice fields and is one of the agricultural pests that often suffers and can interfere with the growth of rice plants because of its very fast development. unused and become waste for the environment. The golden snail shell contains a chitin polysaccharide which can be reduced to chitosan (β1-4 N-acetyl D-glucosamine) through the deacetylation stage, namely the process of taking the acetamide group in chitin (CH3CONH) so that it becomes an amine group (NH2) in chitosan. The manufacture of chitosan is carried out through 3 stages, namely the process of deproteination, demineralization, and deacetylation. The purpose of this study was to determine the characteristics and quality of chitosan produced from golden snail shells. Based on the analysis conducted, chitosan has a yield of 53.91%; water content 1.68%; ash content 12.31%; molecular weight 640.83 kDa; solubility 95.53; and deacetylation degree 82.33%.

Evaluation of the Effect of Enamel Deproteinization Combined with a Self-etching Primer on the Adhesion of Orthodontic Brackets: An In Vitro Study

Aim:The study aimed to evaluate enamel deproteinization with sodium hypochlorite in the enamel conditioning using a self-etching primer for adhesion in orthodontic brackets.Background:The bonding in orthodontics plays a major role in the success of the treatment. The self-etching primers reduce the chair time and diminish the risk of saliva contamination.Methods:The sample comprised 80 bovines' incisors, divided into 4 groups according to the deproteinization process and adhesive system used: G1: enamel deproteinization + Transbond Plus self-etching primer + Transbond XT adhesive; G2: enamel deproteinization + 37% phosphoric acid + conventional primer + and Transbond XT adhesive; G3: Transbond Plus self-etching primer + Transbond XT adhesive; and G4: 37% phosphoric acid + conventional primer + Transbond XT adhesive. EMIC®DL 500 Universal Testing Machine was used for testing the shear bond strength of the samples.Results:Brackets bonded with self-etching primer showed greater adhesion force. The enamel deproteinization did not improve the bonding strength, regardless of the primer used.Conclusion:The deproteinization process does not improve the result of the adhesive bonding when using a self-etching primerin vitro.

Assessment of nutritional quality of non‐conventional millet malt enriched bar

AbstractMillet malt is a nutrient‐dense diet for children and elders. There is a lack of research studies dealing with malt‐based protein substitutes in snack bars. This research presents a novel concept for using millet malt for the production of the snack bar. Given health credentials, millet malt can be a healthier alternative to conventional snack bars. The study found the effect of millet malt addition ranges from 10, 12, 14, and 16% on the quality of snack bars. The most acceptable snack bar was millet malt level at 12% (M12), which contributes to 21.82% of protein and 450 kcal of energy. Millet malt–enriched bars (MMEB) have good antioxidant activity (95.89%), in vitro protein digestibility (79.08%), and total phenolic content (105.7%), which provide several health benefits and increase the oxidative stability of food. This research depicted effectively the use of millet malt for snack bars as a nutritional supplement in a low‐protein bar. The developed MMEB can recommend for nutritionally risk groups like malnutrition and protein deficiency.Novelty impact statementThe novelty of the present invention millet malt bar comprises the following: The underused millet malt was used as a plant protein source and plant protein was made from millet malt by liquefaction and deproteinization process, which contributes to greater protein digestibility. Natural color and flavor obtained from millet malt syrup by saccharification process were used as the substitute for artificial additives. It has a good balance of protein and energy, besides regular enhanced nutrition, and possesses greater antioxidant activity with the contribution of phenolic compounds. Nutribar provides all the essential nutrients, packed with fiber and phytochemicals.

The prebiotic properties of polysaccharides obtained by differentiated deproteinization methods from Flos Sophorae Immaturus on Lactobacillus fermentum.

The polysaccharides derived from various deproteinization methods were prepared from Flos Sophorae Immaturus (FSI) to investigate the prebiotic efficacy of Lactobacillus fermentum (L.f ). The implications of polysaccharides from FSI (PFSI) gained after purification performed by non-deproteinization and different deproteinization processes (Savage method, papain method, and TCA method) via one-factor optimization were firstly investigated for the influences on the growth of L.f. The utilization of carbohydrate sources and the synthesis of protein and lactate during its growth were analyzed, as well as the variations of LDH, SOD, and GSH- Px enzyme dynamics. The results showed that the one-factor optimization of the deproteinization process with the protein removal rate and polysaccharide retention rate as the indexes led to the optimal methods of the Sevage method with 5 elution times, papain method with 80 U/mL concentration, and TCA method with 2.5 ratio, respectively. In addition, the PFSI obtained with or without deproteinization purification had a certain effect on promoting L.f proliferation. Moreover, the PFSI gained by the third deproteinization purification, at a concentration of 10 g/L, significantly elevated L.f biomass and growth rate compared with the blank control, and the utilization of reducing sugars and the synthesis of protein and lactic acid were higher than the control (P < 0.05); improved LDH, SOD, and GSH-Px activity in L.f (P < 0.05), and the TCA method could be effectively applied to eliminate the proteins affecting FSI in probiotics, and PFSI may be a potentially beneficial prebiotic and intestinal reinforcer.

Evaluation of enamel deproteinization in bond strength of orthodontic accessories: A split-mouth randomized clinical trial

This split-mouth randomized clinical trial aimed to evaluate the influence of dental enamel deproteinization with sodium hypochlorite on orthodontic accessories breakages using 2 orthodontic adhesives. Forty patients with indications for orthodontic treatment with fixed appliances were randomly divided into 2 groups according to the orthodontic adhesive used: Transbond XT (3M Unitek, Monrovia, Calif) (n= 20) and Orthocem (FGM Dental Products, Joinville, Santa Catarina, Brazil) (n= 20). A split-mouth trial was conducted in the maxillary teeth; the deproteinization process with 5% sodium hypochlorite was performed on the experimental side. The opposite side served as a control without deproteinization. The primary outcome was the number of orthodontic accessories breakages. The randomization was performed using the BioStat software (AnalystSoft Inc, Walnut, Calif). Single-blind was applied for patients. Orthodontic accessories were bonded according to the manufacturer's instructions. The accessories breakages were followed during the first 6 months of treatment. Intergroup comparisons were performed with t tests and 1 and 2-way analysis of variance. Thirty-nine patients concluded the trial. The Transbond XT group comprised 20 patients (9 male, 11 female), with a mean age of 20.77 ± 6.44 years. The Orthocem group included 19 patients (9 male, 10 female), with a mean age of 23.14 ± 7.98 years. The application of sodium hypochlorite before bonding did not influence the number of orthodontic accessories breakages (P= 0.867). The type of adhesive used, associated or not with the deproteinization, did not affect the number of orthodontic accessories breakages (P= 0.929). Enamel deproteinization with 5% sodium hypochlorite did not impact the number of orthodontic accessories breakages. In addition, the 2 bonding adhesives used showed similar clinical results, with or without the enamel deproteinization. The trial was registered at ensaiosclinicos.gov.br, ReBEC (no. RBR-39ntmjk). The protocol was not published before trial commencement. This research did not receive any grant from funding agencies.

The Feasibility of Using Agarophyte Processing Waste

When agarophytes are processed, 16-89% algal waste (AW) is formed. Due to the high content of minerals in this waste and the presence of proteins that are resistant to the action of proteolytic enzymes, such AW is mainly used in the production of feed for farm animals. The significant content of polysaccharides in dry AW indicates that it could be used as a raw material for the production of dietary fiber (DF). Due to the difference in the chemical composition of AW depending on the type of red algae, different approaches for its deproteinization have been used. Thus, a 3% alkali solution should be used for the deproteinization of algal waste from the red algae Gracilaria, a 0.5% alkali solution for GelidiumAW, and a 1% sodium carbonate solution for A. plicataAW.The duration of the deproteinization process is 30 min at a temperature of 97±2 ∘C for all types of AW. In this study, functional and technological solutions of DF from AW were developed. The results showed that their water binding capacity was 6-22 g of water per 1 g of the preparation, the fat binding capacity was 1.6-3.3 g of fat per 1 g of the preparation, and the swelling capacity was 46-312% depending on the type of red algae.The obtained DF was used in the production of minced fish food products of the ‘fish sticks’ type, based on minced fish and consisting of cod and pink salmon. The study of the chemical composition and calorie content of the developed food product showed the possibility of its use in dietary nutrition.&#x0D; Keywords: red algae, algal waste, deproteinization, dietary fiber

Isolasi dan Karakterisasi Kitin dari Limbah Cangkang Kerang Asia (Corbicula fluminea)

Chitin compounds are compounds that can be found from various animals of the Crustaceae group, for example such as crabs, shrimp, and shellfish. The purpose of this study was to find out the chitin content and chitin characteristics of asian shell waste (Corbicula fluminea). The stage of chitin insulation includes the process of deproteination using Sodium Hydroxide 3.5%, and the next process is the process of demineralization using Hydrochloric Acid 1 N. From the results of the isolation obtained chitin characterization in the form of chitin yield is 82.75%, with a grayish-white powder texture, and odorless, it perfectly soubled in Hydrochloric Acid 1 N, has a water content of 0.1764% and ash content of 58.0753%.

Extraction and deproteinization process of polysaccharide from purple sweet potato.

Extraction and deproteinization process of polysaccharide from purple sweet potato (PPSP) were optimized via the response surface methodology (RSM). The results indicated that the optimal conditions of extraction in hot water of PPSP were as follows: The extraction temperature was 120℃, the extraction time was 2.5hr, and the solid-liquid ratio was 1∶10 (g/ml). The optimal conditions of Sevage deproteinization were as under the oscillation time was 20min, the deproteinization times was twice, and polysaccharide solution-Sevage reagent ratio was 1:1 (ml/ml). The extraction yield of PPSP was 3.32%, and the protein removal rate was 93.14% insuchacondition.

Proteases Production and Chitin Preparation from the Liquid Fermentation of Chitinous Fishery By-Products by Paenibacillus elgii.

Chitinous fishery by-products have great application in the production of various bioactive compounds. In this study, Paenibacillus elgii TKU051, a protease-producing bacterial strain, was isolated using a medium containing 1% squid pens powder (SPP) as the sole carbon/nitrogen (C/N) source. P. elgii TKU051 was found to produce at least four proteases with molecular weights of 100 kDa, 57 kDa, 43 kDa, and 34 kDa (determined by the gelatin zymography method). A P. elgii TkU051 crude enzyme cocktail was optimally active at pH 6–7 and 60 °C. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and α-glucosidase inhibitory activity of the hydrolysates obtained from the hydrolysis of shrimp shell powder, shrimp head powder, shrimp meat powder, fish head powder and soya bean powder catalyzed by the P. elgii TkU051 crude enzyme cocktail were also evaluated. P. elgii TKU051 exhibited a high deproteinization capacity (over 94%) on different kinds of shrimp waste (shrimp heads and shells; fresh and cooked shrimp waste; shrimp waste dried by oven and lyophilizer), and the Fourier-transform infrared spectroscopy profile of the chitin obtained from the deproteinization process displayed the characteristic of chitin. Finally, the obtained chitin exhibited an effect comparable to commercial chitin in terms of adsorption against Congo Red (90.48% and 90.91%, respectively). Thus, P. elgii TKU051 showed potential in the reclamation of chitinous fishery by-products for proteases production and chitin extraction.

Characterization of Chitosan Extracted from Fish Scales of the Colombian Endemic Species Prochilodus magdalenae as a Novel Source for Antibacterial Starch-Based Films.

Scales of Prochilodus magdalenae, a Colombian endemic fish species, were used to obtain chitosan for application as an antibacterial agent integrated into starch-based films. Analysis of its composition during the demineralization and deproteinization process indicated that minerals and protein were both removed successfully. At this point, mild conditions for the deacetylation process were employed, namely, 2, 4, and 6 wt.% NaOH at room temperature for 16 h. Chitosan processed under 2 wt.% NaOH had low molecular weight, with the lowest value of 107.18 ± 24.99 kDa, which was closely related to its antibacterial activity. Finally, this chitosan was integrated into a banana starch-based film, and its antibacterial activity was assayed in Escherichia coli and Staphylococcus aureus cultures, with positive results in the former culture, especially due to the low-molecular-weight characteristic of chitosan.