离子液体在多糖溶解中的应用进展

由于分子内或分子间的氢键作用,部分多糖难溶解于水或常规有机溶剂,因此限制了多糖在诸多领域的应用。而离子液体的出现则为难溶多糖的应用提供了可能。针对国内外关于离子液体溶解纤维素、甲壳素、壳聚糖等几种多糖的研究成果进行了综述,并对其溶解特性、溶解机理以及离子液体结构对多糖溶解特性的影响进行了探讨和总结,对今后利用离子液体溶解多糖的研究方向进行了展望。     

离子液体溶解天然高分子材料及绿色纺丝技术研究综述

针对离子液体溶解纤维素、甲壳素/壳聚糖、角蛋白及其他天然高分子化合物的构效关系、溶解机理及纺丝过程的研究现状进行了综述,认为,离子液体在溶解天然高分子材料及干喷湿纺纺丝方面显示出独特的优势,为发展新一代绿色纺丝技术提供了新途径.然而离子液体溶解纺丝要实现大规模工业化应用,尚需解决一些关键问题,如溶解机理的深入研究、功能化离子液体的设计、溶液流变性及可纺性的研究、离子液体的再生纯化等.     

天然蛋白质材料在离子液体中的溶解与再生

蛋白质材料作为可再生的资源,在纺织业中发挥着重要的作用,然而大量不能直接利用的蛋白质需要通过再生的方法进行加工,传统加工技术带来了环境保护的压力.作为-种新开发的"绿色溶剂"--离子液体,有望作为天然高分子材料如纤维素、蛋白质、甲壳素的直接溶剂实现其清洁化生产.文章综述了离子液体在天然蛋白质中应用研究的最新成果,包括蛋白在离子液体中的溶解、溶解前后蛋白结构的变化、蛋白质的再生方法及再生产物的结构和性能,以期为深入研究蛋白质的绿色加工技术提供借鉴.     

离子液体在制浆造纸及纤维素工业的应用

从离子液体结构、溶解反应条件对纤维素溶解的影响以及纤维素溶解前后的差异等方面总结了离子液体对纤维素的溶解能力,阐述了可能的溶解机理。从选取离子液体,确定反应条件的角度提出了提高纤维素溶解率的方法。介绍了以离子液体为溶剂制备磁性材料、吸附剂、生物膜等纤维衍生材料及其应用于相关领域的优势,展望了离子液体在制浆造纸废水处理、脱墨、制浆领域中的应用前景。提出了离子液体工业化存在的问题及离子液体的研究方向。     

含脱乙酰甲壳素纤维伤口敷料

丹麦Coloplast公司申请一项关于含脱乙酰甲壳素纤维伤口敷料的专利，它采用不溶解甲壳素纤维的酸溶液处理脱乙酰甲壳素纤维并且经热处理使甲壳索纤维改性。经处理的甲壳素纤维能吸收液体而形成一种膨胀的有粘附性凝胶。它解决了甲壳素纤维吸收性较差并且缺少粘附力的问题，以前敷料用甲壳素纤维难以从伤口整体揭下。新型含甲壳素纤维的敷料以凝胶形态吸收大量液体，     

离子液体在天然高分子材料中的应用进展

近几年离子液体在聚合反应和聚合物加工方面的应用研究引起了广泛的关注。详述了纤维素、蛋白质等天然高分子材料在离子液体中的溶解和再生,包括溶解现象、溶解机制以及溶解和再生前后天然高分子的结构和性能变化等,为开发以离子液体为溶剂的天然高分子材料的加工技术奠定基础。     

蛋白质在离子液体中的溶解研究进展

介绍了离子液体的概念及其在溶解丝素蛋白、角蛋白、胶原蛋白等方面的研究进展,并对离子液体在溶解蛋白质方面的应用前景进行了展望。     

废纸在离子液体[Emim]Br中的溶解特性

为了回收及充分利用废纸原料,用溴代1-乙基,3-甲基咪唑([Emim]Br)离子液体对废纸进行溶解实验。结果表明:适宜的溶解温度130℃,溶解时间10min,废纸与离子液体质量比为1:6,在此条件下,溶解百分率可以达到12.5%。废纸溶解再生产物的红外谱图与微晶纤维素基本吻合,说明废纸在离子液体中的溶解产物主要是纤维素,且纤维素在离子液体中的溶解属于直接溶解。     

咪唑啉类离子液体制备及对分散染料溶解性研究

首先通过无溶剂参与的亲核加成反应,制备了两种咪唑啉类离子液体,并采用FTIR、~1HNMR、UV等方法对制备的离子液体产物进行了表征,然后用其对分散染料进行溶解,探究分析了离子液体种类、温度、时间等因素对分散染料在离子液体中溶解度的影响。结果表明:经红外光谱和核磁共振谱的综合分析,所制备的两种离子液体确实是预期合成的目标产物。不同结构、不同分子质量的分散染料在同种离子液体中的溶解度不同,分散蓝395较分散红60的溶解度大些。分散蓝395和分散红60在咪唑啉离子液体中的溶解温度为90℃,溶解时间为40 min。     

离子液体在溶解纤维素和蛋白质方面的研究进展

介绍了离子液体及其目前在溶解纤维和胶原蛋白等方面的研究进展,并对离子液体溶解皮革蛋白的特性及应用前景进行了分析与展望。     

虾、蟹壳利用的研究进展

虾、蟹壳是虾、蟹加工过程中产生的主要废弃物,含有较大量的蛋白质、灰分和甲壳素,以及少量的脂肪、游离氨基酸和虾青素等。近年来,随着我国养殖、捕捞技术的进步以及伏季休渔制度的实施,虾、蟹产量逐年上升。因此,有效利用虾、蟹壳副产物,开发基于虾、蟹壳废弃物的利用途径和产品类型,以提高产品附加值,减少环境污染,对于虾、蟹产业的健康发展具有重要意义。目前,采用酸碱法制备甲壳素是虾、蟹壳利用的主要方法,该方法易于操作,但能耗高且污染严重,近年来研究人员对传统的酸碱法制备甲壳素的工艺进行了优化,并积极探索酶法和发酵法等新型提取工艺。此外,虾、蟹壳中其他可利用成分(蛋白质、脂肪、钙质和虾青素)的提取和利用也获得了许多研究成果。本文主要综述了虾、蟹壳的组成成分,虾、蟹壳整体利用途径以及虾、蟹壳中甲壳素、蛋白质、脂肪、钙质、虾青素等成分的提取和利用途径的研究进展,以期为虾、蟹壳的高效、低成本、无污染和高附加值利用提供借鉴。     

虾壳在1-乙基-3-甲基咪唑醋酸盐离子液体中的溶解特性

为探索从对虾加工废弃物中回收甲壳素的绿色工艺,本文以离子液体1-乙基-3-甲基咪唑醋酸盐([C₂mim]Ac)为溶剂,系统考察了溶解时间、溶解温度、固-液比3个因素对虾壳的溶解度、回收率以及再生后的组分、表观形貌和晶体结构的影响规律。结果表明,固-液比为1:20 w/w、100℃下加热1 h后,虾壳溶解度最高,为15.30%。与未处理的虾壳相比,经过[C₂mim]Ac溶解再生后的样品表面多孔、粗糙或扭曲变形,而且结晶结构被破坏,蛋白质和矿物质脱除率可分别达到67.13%和42.84%。当温度超过120℃,溶解时间超过2 h时,不利于[C₂mim]Ac对虾壳的溶解。     

柠檬酸用于虾头、虾壳的脱钙处理

以南美白对虾虾头、虾壳为原料,利用柠檬酸对其脱钙处理制备甲壳素,通过单因素和响应面试验优化提取条件。结果表明：当柠檬酸质量浓度12.00g/L、料液比1:2.00(g/mL)、时间3.88h时,所得甲壳素灰分含量为1.0g/100g,即已经达到食品级甲壳素的要求。利用柠檬酸脱除虾头、虾壳中的钙盐制备甲壳素,不仅获得食品级的甲壳素,而且反应条件温和、污染小,生成的副产物柠檬酸钙可以作为钙强化剂,提高虾头、虾壳的资源利用率。     

对虾加工下脚料的综合提取技术研究进展

随着我国对虾加工行业的迅速发展,产生的加工下脚料也急剧增多,主要包括虾头、虾壳和虾尾,这些下脚料中有很大一部分未被利用导致了资源浪费。工厂一般采用化学法等较简易的方法提取甲壳素、蛋白质、虾青素和虾油,得率低、纯度不高、综合利用率较差,且由于使用大量化学试剂也易造成环境污染。近期的研究发现了超临界CO₂萃取、离子液体等新的提取工艺对虾加工下脚料中营养物质的方法,不仅更环保,还能提高得率和纯度以及避免活性物质的破坏和损失。本文针对对虾加工下脚料中营养成分的提取方法进行了综述,比较并分析了化学法、酶法等传统提取技术与微生物发酵法、离子液体法、超临界及亚临界等新的工艺技术的特点,并对其综合提取技术进行了初步探讨,以期为进一步高效开发利用对虾的加工下脚料资源提供一定借鉴。     

New route of chitosan extraction from blue crabs and shrimp shells as flocculants on soybean solutes

The chitosan extracted from blue crabs and shrimp shells using calcium oxide (deproteinization) followed by deacetylation which eliminated the demineralization step to reduce the chemical usage and environmental protection. The extracted chitosan examined the flocculation to soybean solutes. The optical density (OD), solid%, and purity% (carbohydrates/soluble solids) after flocculation were measured. The OD was significantly decreased from 0.76 to 0.16 with blue crabs and 0.06 with shrimp shells chitosan-acetate dosing (0.5 g/L). The removal of about 68 and 66% solids was achieved by the addition of 0.5 g/L chitosan-acetate. The purity% was reached about 80% with blue crabs, and 78% with shrimp shells chitosan-acetate. The results of this study verified that the calcium oxide treatment should remove protein and increase the chitin extraction yield on blue crab and shrimp shells. This new route of chitosan extraction should be a useful method for making flocculants in the soybean solutes.     

Conversion of chitinous wastes to hydrogen gas by Clostridium paraputrificum M-21

The chitinolytic bacterium Clostridium paraputrificum strain M-21 produced 2.2 and 1.5 mol hydrogen gas from 1 mol N-acetyl-D-glucosamine (GlcNAc) and ball-milled chitin equivalent to 1 mol of GlcNAc, respectively, at pH 6.0. In addition, strain M-21 efficiently degraded and fermented ball-milled raw shrimp and lobster shells to produce hydrogen gas: 11.4 mmol H2 from 2.6 g of the former and 7.8 mmol H2 from 1.5 g of the latter. Hydrogen evolution from these shell wastes were enhanced two fold by employing acid and alkali pretreatment. Waste from the starch industry was also converted to hydrogen. When C. paraputrificum M-21 was cultivated on ball-milled chitin and ball-milled shrimp shells for 14 and 12 h, respectively, chitinases ChiA and/or ChiB were detected as the major chitinase species in the supernatant of the cultures, suggesting that the play a critical role in the degradation of chitinous materials.     

Production,properties, and some new applications of chitin and its derivatives

Chitin is a polysaccharide composed from N-acetyl-D-glucosamine units. It is the second most abundant biopolymer on Earth and found mainly in invertebrates, insects, marine diatoms, algae, fungi, and yeasts. Recent investigations confirm the suitability of chitin and its derivatives in chemistry, biotechnology, medicine, veterinary, dentistry, agriculture, food processing, environmental protection, and textile production. The development of technologies based on the utilization of chitin derivatives is caused by their polyelectrolite properties, the presence of reactive functional groups, gel-forming ability, high adsorption capacity, biodegradability and bacteriostatic, and fungistatic and antitumour influence. Resources of chitin for industrial processing are crustacean shells and fungal mycelia. Fungi contain also chitosan, the product of N-deacetylation of chitin. Traditionally, chitin is isolated from crustacean shells by demineralization with diluted acid and deproteinization in a hot base solution. Furthermore, chitin is converted to chitosan by deacetylation in concentrated NaOH solution. It causes changes in molecular weight and a degree of deacetylation of the product and degradation of nutritionally valuable proteins. Thus, enzymatic procedures for deproteinization of the shells or mold mycelia and for chitin deacetylation were investigated. These studies show that chitin is resistant to enzymatic deacetylation. However, chitin deacetylated partially by chemical treatment can be processed further by deacetylase. Efficiency of enzymatic deproteinization depends on the source of crustacean offal and the process conditions. Mild enzymatic treatment removes about 90% of the protein and carotenoids from shrimp-processing waste, and the carotenoprotein produced is useful for feed supplementation. In contrast, deproteinization of shrimp shells by Alcalase led to the isolation of chitin containing about 4.5% of protein impurities and recovery of protein hydrolysate.     

EXTRACTION OF CAROTENOPROTEIN FROM BLACK TIGER SHRIMP SHELLS WITH THE AID OF BLUEFISH TRYPSIN

The effect of bluefish (Pomatomus saltatrix) trypsin on the recovery and characteristics of carotenoprotein from black tiger shrimp (Penaeus monodon) shells was investigated. Trypsin concentration and reaction time both affected the hydrolysis and the recovery of carotenoproteins ( P <  0.05). The recovery of carotenoproteins from shrimp shells was maximized by the hydrolysis of shrimp shells using 1.2 trypsin units/g shrimp shells for 1 h at 25C. Freeze-dried carotenoprotein recovered contained 70.20% protein, 19.76% lipid, 6.57% ash, 1.50% chitin, and 87.91 µg total astaxanthin/g sample, indicating a substantial reduction in the levels of antinutrients associated with shrimp waste, while enriching the product in carotenoid pigments and valuable essential nutrients (proteins and lipids). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the recovered carotenoprotein revealed that protein with molecular weight of 45 kDa was the major constituent. When hydrolytic activities of bluefish and bovine trypsins toward carotenoproteins in black tiger shrimp shells were compared, the recovery efficacy of protein and pigment by bluefish trypsin was similar to that achieved by trypsin from bovine pancreas. Therefore, bluefish trypsin could be used as an alternative cheap proteinase for extraction of carotenoproteins from black tiger shrimp shells.

PRACTICAL APPLICATIONS

Carotenoproteins from black tiger shells, the byproduct of shrimp processing, can be recovered with the aid of fish trypsin. This product can be used for both food and feed applications. Additionally, the fish trypsin can be used instead of bovine trypsin. As a whole, the utilization of fish and shellfish processing wastes can be maximized.     

桔橙小单孢菌产几丁质脱乙酰酶的酶学性质研究

从海边红树林虾场土壤中筛选的一株产几丁质脱乙酰酶（CDA）的放线菌桔橙小单孢菌（Micromonospora aurantiaca）,研究其产CDA的酶学性质。结果表明,CDA的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)电泳结果显示为单一条带,分子质量为81.8 ku。最适pH值为7.0;最适温度为40 ℃;Ca2+对此CDA酶活有促进作用,而Cu2+、Zn2+、Mg2+表现出了抑制作用。CDA对虾壳来源的几丁质有明显的脱乙酰效果,红外光谱测得样品脱乙酰度由39.03%提高至78.40%。扫描电镜发现CDA酶解过的几丁质样品表面疏松多孔、出现凹槽、晶体消失,进一步印证了该酶的良好脱乙酰效果,也力证了该酶拥有较好的特性。     

One-step bio-extraction of chitin from shrimp shells by successive co-fermentation using Bacillus subtilis and Lactobacillus plantarum

Chitin was bio-extracted in one-step from shrimp shells by successive co-fermentation using Bacillus subtilis and Lactobacillus plantarum in this study. To construct this co-fermentation system, B. subtilis was first cultured for 3 days for deproteinization (DP), and then L. plantarum was inoculated for demineralization (DM). After 6 days of co-fermentation, the final DP and DM efficiency reached 94.1% and 96.3%, respectively. The molecular weight, degree of acetylation, and crystalline index of chitin were reduced by 9.8, 5.6 and 1.4% with the DP time of 2 days extending to 3 days. Meanwhile, L. plantarum instead of B. subtilis became the dominant bacterium on day 5 of co-fermentation, with L. plantarum count of 6.19 log CFU/mL and lactic acid concentration of 28.22 g/L, respectively. The chitin prepared in this study exhibited similar structural characterization as commercial chitin. One step successive co-fermentation was a simple and feasible approach for high-quality chitin preparation.Industrial relevance: This study establishes one-step bio-extraction of chitin from shrimp shells by successive co-fermentation using B. subtilis followed by L. plantarum. One-step successive co-fermentation simplifies the intermediate processes of conventional two-step fermentation for extracting chitin. DP and DM happen during the entire co-fermentation period, which helps to achieve satisfactory DP and DM efficiency. This innovative yet simple method provides more possibilities for the biotechnological production of chitin on an industrial scale.