Optimum parameters for production of chitin and chitosan from squilla (S. empusa)

Chitin and chitosan of high quality were produced from squilla, a by‐catch of Indian Ocean fisheries, by demineralization, deproteination, and deacetylation. Optimum conditions for the production of chitin and chitosan were determined. The quality of chitin was assessed from its ash and protein content. Ash content was below 1% after treatment with 4% HCl for 12 h at 50°C. A protein content of less than 1% could be achieved by treatment with 4% NaOH in 12 h but only at a temperature of 70°C or higher. Production of chitin was also tested by a three‐stage treatment with altering sequence of sodium hydroxide and hydrochloric acid (HCl–NaOH–HCl or NaOH–HCl–NaOH). This three‐step treatment appeared to be successful to achieve a mineral content and protein content below 1% within 30 h and at a temperature not exceeding 50°C. The chitin obtained under optimum conditions was tested for deacetylation using NaOH concentrations of 40 and 50% for 12–44 h at 30, 50 and 70°C. The chitosan obtained had a degree of deacetylation of 77–86%, a viscosity of 8.2–16.2 × 10² cps, solubility of 98%, and molecular weight of ? 1 × 10⁶ dalton. The data show that processing of squilla waste can lead to a high quality chitosan, useful for a broad range of applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 103: 3694–3700, 2007     

Hydrogels Based on 2-Hydroxyethylmethacrylate and Chitosan: Preparation,Swelling Behavior,and Drug Delivery

The authors report preparation of chitosan by deacetylation of chitin extracted from shrimp shells. The quality of chitosan depended on the chemical extraction process, the concentration of chemicals used, soaking time, sequence of deproteination, decalcification, and deacetylation. Hydrogels composed of hydroxyethylmethacrylate and chitosan were subsequently prepared and their swelling and ibuprofen delivery kinetics at various chitosan concentrations were studied. The swelling properties of the network varied with the chitosan concentration. Furthermore, the swelling process followed second-order kinetics, while ibuprofen diffusion into the hydrogel showed Fickian behavior.     

Production of high‐quality chitin and chitosan from preconditioned shrimp shells

Chitin and chitosan with improved characteristics were produced from shrimp shell waste preconditioned by limited decay or by treatment with 0.016 mol L^?1 benzoic acid. Preconditioned shrimp shells were transparent, had a clean surface and were susceptible to demineralization and deproteinization using 0.68 mol L^?1 HCl and 0.62 mol L^?1 NaOH, respectively. The ash and protein residues in the final chitosan were about 0.2% and 0.4%, respectively, the viscosity was up to 7000 cps, and the solubility and transparency nearly 100%. In comparison with treatment at ambient temperature (30 °C) without preconditioning, the chemical consumption, the duration of the treatment, ash and protein residues was reduced to 75–25%, whereas viscosity and absence of insolubles improved by a factor of 2–3. Copyright © 2006 Society of Chemical Industry     

Valorization of chitins extracted from North Morocco shrimps: Comparison of chitin reactivity and characteristics

Huge quantities of waste discharged by the gray and pink shrimp decortication units in the North of Morocco can be valorized by producing about 950 tons of pure chitin, which can be transformed into 700 tons of highly to totally deacetylated chitosan. During the preparation of chitin and chitosan from gray and pink shrimps, differences in reaction behavior were observed even though these are taxonomically close species. The presented results concern several chitinous sources, and they show that the progress in the N-deacetylation reactions of chitin would be linked to the crystallinity index of the starting chitin. Following the kinetic study of the polymer hydrolysis during N-deacetylation, the difference in the molecular weights of the chitosan samples obtained under identical reaction conditions was related to the differences between molecular weights of the native chitin, 478 000 g.mol⁻¹ for pink shrimp and 562 000 for gray shrimp. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47804.     

不同虾壳部位中的甲壳素和壳聚糖

用EDTA的方法分别从虾壳的不同部位:虾头、虾身、虾足和虾头内容物三部分制备甲壳素和壳聚糖,对三组试样的性能参数如脱乙酰度和相对分子量等进行分析研究。得出结论:由虾壳不同部位所制得的甲壳素和壳聚糖结构基本一致,但其脱乙酰度和相对分子量有较大差别,其物化性质也有所不同。在三组试样中,以从虾头壳制备的甲壳素和壳聚糖的相对分子质量为最大;而脱乙酰度则以从虾足和虾头内容物中制得试样较高。     

虾壳制备甲壳素和壳聚糖的研究

用EDTA的方法分别从虾壳的不同部位:虾头、虾身、虾足和虾头内容物三部分制备甲壳素和壳聚糖,对三组试样的性能参数如脱乙酰度和相对分子量等进行分析研究。得出结论:由虾壳不同部位所制得的甲壳素和壳聚糖结构基本一致,但其脱乙酰度和相对分子量有较大差别,所以其物化性质也有所不同。特别值得一提的是,在三组试样中,以从虾头壳制备的甲壳素和壳聚糖的相对分子质量为最大;而脱乙酰度则以从虾足和虾头内容物中制得试样较高。     

Improved chitin production by pretreatment of shrimp shells

Pretreatment of shrimp shells was investigated in order to lower the costs and to improve the sustainability of chitin production. Physical pretreatment comprising drying, grinding and sieving is attractive for the recovery of 50% of shrimp protein as a dry powder. Pretreatment of shells by shearing in acidified water results in the removal of up to 60% of the protein and a reduction of their mineral content without a decrease in the chitin yield. Both pretreatment procedures will lead to cleaner technology for chitin production, to a considerably lower need for chemicals, to useful protein by‐products, and to less‐contaminated industrial effluent. Copyright © 2004 Society of Chemical Industry     

Variation in Properties of Chitosan Prepared at Different Alkali Concentrations from Squid Pen and Shrimp Shell

Chitin from squid pen (Loligo sp.) and kiddi shrimp shell (Parapenaeopsis stylifera) were treated at room temperature (30 ± 2°C) with four different concentrations of sodium hydroxide: 20, 30, 40, and 50% w/w. With 50% sodium hydroxide solution, within 108 h, the chitin from squid pen was deacetylated to give chitosan. But it required 126 h at 40% and 144 h at 30% concentration of sodium hydroxide. In the case of chitin from Parapenaeopsis stylifera, complete deacetylation took place after 120 h and 168 h at 50 and 40% concentrations of sodium hydroxide, respectively. But shrimp shell on treatment with 20 and 30% sodium hydroxide solutions and squid pen kept at 20% sodium hydroxide were not sufficiently deacetylated even after 480 h. Properties like degree of deacetylation, viscosity and molecular weight of the prepared chitosan samples were studied. Minimum alkali concentration required for the formation of chitosan at room temperature was found to be 30% for squid chitin and 40% for shrimp chitin. With the increase in the time of deacetylation, decreases in molecular weight and viscosity were observed in chitosan from both sources. Maximum viscosity was recorded by chitosan prepared from squid pen using 30% sodium hydroxide solution at room temperature.     

The Development of Filter Media Using Plant and Marine Waste for Virus Removal from Drinking Water

Abstract:

Two natural wastes, palm leaves and shrimp shells, were purified and tested for their efficiency in adsorbing enteroviruses from drinking water. The chemical modification of marine waste was evaluated to prepare carboxymethyl chitin, while O-carboxymethyl chitosan was prepared by deacetylation of the carboxymethyl chitin to improve the adsorption of viruses from drinking water. The role of the reaction parameters such as temperature, time, concentration of alkali and etherified agent, and the material-to-liquor ratio were examined. Also, the effect of pH on the adsorption efficiency of enteroviruses in modified waste was evaluated. The results showed that raw palm leaves and O-carboxymethyl chitosan prepared as filter matrix exhibited a better adsorption efficiency in a wide range of pH levels. They can be used to adsorb viruses directly from tap water at ambient pH values without having multivalent-containing salts or adjusting the pH of tap water.     

Comparison of chitins produced by chemical and bioprocessing methods

Lactic acid fermentation was used to extract chitin from prawn shell (Nephrops norvegicus) at two different scales of operation. The fermentation products were characterized and compared with chitin extracted from the same source by a chemical method. Chitosans produced from the obtained chitins were evaluated in terms of their intrinsic viscosity, molecular weight and degree of acetylation (DA). The fermentation removed 690 g kg^?1 and 770 g kg^?1 of inorganic matter, 490 and 440 g kg^?1 of protein and 540 and 770 g kg^?1 of lipids from the shells at laboratory and pilot plant scales, respectively. However, the functional properties such as the DA of the chitin, the molecular weight and the DA of the chitosans were similar to those obtained for the chemically‐obtained chitin and its chitosan. Despite the incomplete extraction of chitin this biological process could be useful to produce chitin and chitosan in a more environment‐friendly approach. Copyright © 2004 Society of Chemical Industry     

相转移催化制备壳聚糖

以虾壳为主要原料制得的天然高分子化合物甲壳素和壳聚糖 ,资源丰富 ,应用范围十分广阔。提出了以 3 5 %(质量分数 )氢氧化钠醇水溶液为反应介质 ,并加入相转移催化剂制备壳聚糖的新方法 ,讨论了一些因素对壳聚糖制备过程的影响。     

Evaluation of molar weight and deacetylation degree of chitosan during chitin deacetylation reaction: Used to produce biofilm

Chitosan is a polysaccharide derived from chitin, mainly of crustacean shells and shrimp wastes. The utilization of chitosan is related to the molar weight and deacetylation degree of the biopolymer. The aim of this work is to study the chitin deacetylation reaction, by the viscosity average molar weight and deacetylation degree of chitosan as a function of reaction time. Deacetylation was carried out in concentrated alkaline solution, 421 g L⁻¹, at 130 °C and the reaction occurred during 4 h. Chitosan paste obtained after 20, 90 and 240 min was used to produce biofilms, which were characterized according water vapor permeability and mechanical properties (tensile strength and percentage tensile elongation at break). During the reaction time deacetylation degree reached 93%, and a 50% reduction in the viscosity average molar weight value in relation to the value of the first 20 min of reaction was found Both reactions presented a kinetic behavior of the pseudo-first order. Biofilm produced from the paste of chitosan with high deacetylation degree showed higher water vapor permeability (WVP), tensile strength (TS) and elongation (E) when compared to films with a low deacetylation.     

Reactivity characteristics of a new form of chitosan

Summary A new form of chitosan prepared by deacetylating squid -chitin was subjected to N-phthaloylation to evaluate the reactivity as compared with that of the conventional chitosan prepared from shrimp -chitin. The reaction proceeded much more efficiently with squid chitosan than shrimp chitosan to give N-phthaloylchitosan, indicating considerable differences in higher-order structures between the two kinds of chitosans. Squid chitosan thus proved to show enhanced reactivity and be superior to shrimp chitosan as a starting material for controlled regioselective chemical modifications of chitin.     

Combined use of waste materials—recovery of chitin from shrimp shells by lactic acid fermentation supplemented with date juice waste or glucose

BACKGROUND: Chitin, a source of chitosan, was extracted from the teguments of white shrimp Parapenaeus longirostris, by means of Lactobacillus helveticus growing on date juice waste or glucose for comparison. A fermentor containing 10% (w/v) of shrimp shells was inoculated with a suspension of L. helveticus strain milano (10% v/v). RESULTS: For an initial pH of 8.5–9.0 and a temperature of 30 °C, maximum deproteinization and demineralization were 76 and 53%, achieved for 80 and 300 g L^?1 glucose, respectively. The level of demineralization increased to 60% for an increase in in temperature from 30 to 35 °C. The use of date juice, as an alternative to the use of a primary carbon source such as glucose, led at best to 44% demineralization, for 208 g L^?1 of total sugar at 35 °C, and 91% deproteinization, for 80 g L^?1 total sugar content at 30 °C. CONCLUSION: Demineralization was not improved by the use of date juice, most likely due to its calcium content, which, during acidification, prevents the diffusion of calcium from the shells to the surrounding medium. Contrarily, the proteolytic activity of LAB appeared to be improved by the mineral content of date juice, leading to almost complete deproteinization of shrimp shells. Copyright © 2008 Society of Chemical Industry     

Chitin characterization by SEM,FTIR, XRD,and 13C cross polarization/mass angle spinning NMR

The full characterization of chitin obtained from squid, shrimp, prawn, lobsters, and king crab is reported. Elemental analysis, including metals such as Ca, Mg, Zn, Cd, Hg, Cr, Mn, Cu, and Pb, was performed, which is quite relevant because the skeleton composition is slightly different for each species. The morphology was studied by means of TEM and their compositions were determined by energy‐dispersive X‐ray analysis. ¹³C cross polarization/magic angle spinning NMR was applied to determine the chemical shift of all the carbons and the difference between them. Chitin was isolated by using chemical methods, alternating hydrochloric acid and sodium hydroxide. The α‐chitin from shrimp, prawn, lobsters, and king crabs showed two signals at 73.7 and 75.6 ppm. Meanwhile, the β‐chitin from squid exhibited one signal at 75.2 ppm. FTIR studies were used to analyze α‐chitin from shrimp and β‐chitin from squid. The α‐chitin exhibited amide I vibration modes at 1660 and 1627 cm^?1, whereas the β‐chitin showed one band at 1656 cm^?1. X‐ray diffraction showed that α‐chitin is orthorhombic (a = 4.74 Å, b = 18.86 Å, and c = 10.32 Å) and β‐chitin had a monoclinic dihydrated form (a = 4.80 Å, b = 10.40 Å, c = 11.10 Å, and β = 97°). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1876–1885, 2004     

Direct chitosan nanoscaffold formation via chitin whiskers

Chitosan nanoscaffold obtained directly from chitin whiskers is proposed. The structural analysis by nuclear magnetic resonance (¹H NMR) confirms that the alkaline treatment changes chitin whisker to chitosan nanoscaffold with as high as 98% degree of deacetylation. The micrographs from scanning electron microscope (SEM) and transmission electron microscope (TEM) confirm that the short fiber of chitin whiskers develop itself to be a network in nano-scale of chitosan or chitosan nanoscaffold. The increase in viscosity of chitosan nanoscaffold as compared to that of the chitin whiskers suggests that the scaffold network performs as a polymer bulk in the solution. The increases in surface area, pore volume, and pore size as studied by the Brunauer–Emmett–Teller (BET) gas adsorption inform the development of porous structure in chitosan. The well dispersion of nanoscaffold in the solution is easily controlled by the solvent polarity and salt concentration.     

几丁聚糖的生产工艺现状

甲壳素是无脊椎动物外骨骼和真菌细胞壁的主要结构成分,在自然界中是仅次于纤维素的第二大类生物材料,几丁聚糖是甲壳素脱乙酰基的产物,是一种天然阳离子聚合物,无毒无害,安全可靠,易生物降解。几丁聚糖的工业化生产方法为化学提取法。分别介绍了以虾蟹壳、真菌、其他动植物为原料的生产工艺。     

Functional and nutritional characteristics of protein recovered during isolation of chitin from shrimp waste

Shrimp shells are a good source of chitin when processed into chitosans. Only about 10% of the raw material dry matter is recovered as chitosan. The objective of this work is to isolate the protein (during de-proteinization of chitin) using nitric acid 30% (this designated as acidic protein) and 1 M sodium hydroxide (this designated as alkaline protein). The functional properties, amino acid contents and nutritional quality of both isolated protein were evaluated. The acidic protein had significantly (p < 0.05) higher emulsification activity (51.58), emulsification stability (48.15) and foam capacity compared to the alkaline protein. The acidic protein also exhibited a broader range of minimum solubility at pH range 4–6 (from 11.21% to 12.54%). Meanwhile, the minimum solubility (22.89%) of the alkaline shrimp waste protein was quite sharp at pH 4. The highest emulsification activities of acidic protein extract were observed at pH 2 (63.82) and pH 10 (68.76) while the lowest were observed at pH 6 (44.32). The same trend was noticed for the emulsification stability. The emulsification activity of the alkaline protein extract ranged from 31.25 (at pH 4) to 52 (at pH 10) and its stability ranged from 44.21 to 51.12 at the same pHs. The alkaline protein is rich in isoleucin and valine compared to the FAO/WHO reference pattern, while leucine and lysine are slightly deficient compared with the same reference. On the other hand, the acidic protein contains higher amounts of lysine, therionin and valine compared to the reference pattern. The alkaline protein had a higher chemical score and calculated protein efficiency ratio (51.46% and 1.94, respectively) compared to 42.10% and 1.75, respectively for acidic protein.     

Chitin sponge,extraction procedure from shrimp wastes using green chemistry

Chitin sponges were obtained from shrimp residues using green chemistry procedures. Partial deproteinization was performed by grinding fresh residues with water during 30 s in a food blender obtaining 39.3% d.b. partial deproteinized cephalothorax (PDC). Protein reduction in this step was 80%, with 49% of mineral salts (measured as ashes), 97% fat, and 41% being chitin product. To separate chitin from PDC, a mixture of 8.75 mL MeOH, 16.25 mL water, and 25 g of CaCl₂ was used (solvent MAC) per gram of PDC. Chitin dissolved in MAC under mechanical agitation to form a sponge, which had an overall composition of 42% chitin, 46% ashes, and 11% proteins. Chitin sponge weathering and biodegradation tests showed that during 30 days, the sponge is stable at ambient conditions in southern Mexico City environment, and when placed in compost‐soil mixtures is degraded in about two weeks. These results open new possibilities to the recycling of crustacean residues. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3909–3916, 2007     

Application of Saponin for Cholesterol Removal from Pacific White Shrimp (Litopenaeus vannamei) Lipid

The removal of cholesterol from lipid obtained from Pacific white shrimp (Litopenaeus vannamei) cephalothorax using saponin in conjunction with celite under various conditions is investigated. Various lipid:saponin ratios (1:2, 1:4, and 1:6, W/W) with different lipid:solvent ratios (1:20, 1:40, and 1:80, W/V) are employed with a treatment time of 4 h. The highest cholesterol removal (88.77 ± 0.18%) is obtained with a lipid:saponin ratio of 1:6 and 20 volumes of 50% ethanol. As the treatment time is increased from 1 to 4 h, higher cholesterol removal is achieved. Lipid peroxides and conjugated dienes are higher in the lipid after cholesterol removal compared to untreated lipid, while thiobarbituric acid reactive substances, the ρ‐anisidine value and free fatty acids are reduced. However, the polyunsaturated fatty acid (PUFA) content in the saponin‐treated lipid (18.06 ± 0.37 g/100 g^?1) is higher than that of untreated lipid (15.80 ± 0.17 g/100 g^?1). FTIR spectra confirmed the formation of hydroperoxides, with lower aldehyde, phospholipid and free fatty acid contents in the cholesterol‐removed lipid. The process developed employing saponin is able to produce crude shrimp lipid with a pronounced decrease in cholesterol, but augmented PUFAs, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Practical Applications: Shrimp lipid is a vital byproduct capable of extraction from cephalothorax. Due to the presence of astaxanthin, EPA and DHA, shrimp lipid is considered to be a highly useful nutraceutical product. However, the cholesterol content of shrimp lipid is a major constraint on its human consumption. The negative impact of cholesterol content can be overcome by lowering the cholesterol content. Saponin treatment of shrimp lipid is able to reduce the cholesterol level and increase the PUFA, thus solving the high cholesterol problem and also gaining augmented health benefits.