脱乙酰化甲壳素制备药用胶囊的实验研究

研究利用一定脱乙酰度的甲索具具有溶解怀好而粘度大于明胶的特点，进行了甲壳素脱乙酰化反应及脱乙酰化甲壳素制备药用胶囊的实验，取得了满意的效果。     

脱乙酰化反应条件对壳聚糖性能的影响

本文研究了甲壳素在脱乙酰化反应时不同反应条件,如碱浓度、反应时间、反应温度和处理方法对壳聚糖性能,如分子量、脱乙酰化度的影响,探讨了分子主链降解反应与脱乙酰化反应之间的关系。结果表明:随着碱浓度和反应时间的增加,壳聚糖脱乙酰化度提高,而分子量降低;脱乙酰化越高,主链降解程度增加;反应温度升高,脱乙酰化反应速度加快;而采用短时重复多次反应的处理方法,则可增加壳聚糖的脱乙酰化度,并减少主链降解程度。     

棉织物微波染色研究

研究了棉织物的微波活性染色与固色,并与常规染色工艺进行了比较.试验结果表明:经微波染色或固色的织物,其上染率和色牢度普遍达到或高于常规水浴加热法染色;微波加热可以大大缩短染色时间,节能效果明显.     

脱乙酰化甲壳素制备药用胶囊的实验研究

研究利用一定脱乙酰度的甲壳素具有溶解性好而粘度大于明胶的特点,进行了甲壳素脱乙酰化反应及脱乙酰化甲壳素制备药用胶囊的实验,取得了满意的效果。     

甲壳素脱乙酰化研究

针对甲壳素脱乙酰化的反应特点,对脱乙酰化工艺进行研究,研究不同反应温度和不同NaOH浓度下甲壳素脱乙酰化反应的动力学行为,从脱乙酰化反应的整体反应模型理论出发,探讨脱乙酰化反应的双分子亲核取代反应机制,并成功运用双分子亲核取代反应机制和整体反应模型理论,得到黏度为647 cPa.s、脱乙酰度为68%的壳聚糖产品。     

不同物理法改性醇洗大豆浓缩蛋白功能性及微观结构比较研究

采用超声波技术、水浴加热法和微波处理3种物理方法对醇洗大豆浓缩蛋白（ALSPC）改性,并对不同方法的改性产品的功能特性和微观结构作了比较。水浴加热法改性产品的溶解性、乳化性、起泡性和凝胶性比其他两种方法好,而持水性、吸油性及乳化稳定性差别不大。扫描电镜结果表明,水浴加热改性产品蛋白质表面微观结构呈絮状聚集体,而超声波和微波改性产品蛋白质颗粒粒径较小,呈碎状小颗粒。     

甲壳素——壳聚糖在纺织工业中的应用

本文论述了甲壳素脱乙酰化产物--壳聚糖在纺织工业中的多种应用。甲壳素是自然界中数量仅次于纤维素的有机物,其脱乙酰化产物壳聚糖由于具有特殊结构而具有独特的性质和功能。     

螺旋藻脱腥工艺的筛选

比较几种螺旋藻的脱腥方法,包括遮蔽法,加热法,发酵法以及遮蔽法与加热法的混合脱腥法的脱腥效果.研究表明:各种方法均具有一定脱腥效果,以添加β-环糊精在加热的情况下脱腥效果最佳.其最佳的脱腥条件为:β-环糊精添加量4g/L,水浴温度为30℃,水浴时间40 min.在该条件下进行脱腥,不仅脱腥和护色效果较佳且不会导致螺旋藻蛋白质的变性.     

离子色谱乙酸定量法测定壳聚糖脱乙酰度

建立离子色谱-电导法测定甲壳素发酵液中乙酸根含量,以确定甲壳素脱乙酰化过程中脱乙酰度。样品前处理为取发酵液放入无菌离心管中,以10 000 r/min离心15 min,取上清液过0.45 μm醋酸纤维滤膜后进样分析,将检测的乙酸值换算成脱乙酰度。结果表明,该方法达到很好的分离效果,在0.5～25.0 mg/L范围内呈现良好的线性关系,回收率为95.04%～102.25%,相对标准偏差不大于2.99%,与目前常用的酸碱滴定法和电位滴定法相比,具有简单、快捷、数据准确等特点,适用于生产企业对甲壳素脱乙酰化过程的实时监控及甲壳素脱乙酶的优化,可为工业化壳聚糖脱乙酰度的监测以及评价降解酶活性提供一定依据。     

壳聚糖的成膜性及其工业应用进展

综述了壳聚糖的结构及成膜材料的组成与膜性质的关系，简要讨论了壳聚糖的脱乙酰化度、交联度与相对分子量的大小等内在结构因素，以及成膜时的pH、增塑剂的类型和浓度、其它高分子材料与膜的存放时间等外界成膜条件对壳聚糖膜的通透性、柔顺性、抗拉强度等性质的影响。介绍了天然壳聚糖资源及壳聚糖膜在食品保鲜、医疗及膜分离等方面的应用进展，从而展示其研究开发的广阔前景。     

壳聚糖纺丝原液性能及其湿法纺丝工艺

壳聚糖由于其优异的生物性能备受人们关注,但目前壳聚糖纤维的强度低,严重制约了其应用的领域。研究了乙酸的体积分数、温度以及壳聚糖的质量分数对壳聚糖纺丝原液稳定性的影响,并进行湿法纺丝工艺制备纯壳聚糖纤维。研究表明:纺丝原液壳聚糖的质量分数为3%～4%,乙酸的体积分数为2%,纺丝温度为30～50℃时,可得到力学性能良好的初生纤维;以5%NaOH加入适量乙醇和Na2SO4作凝固浴较好;适当增大凝固时间,提高卷绕速度,可得到高取向、高强度的壳聚糖初生纤维。     

南极磷虾壳聚糖、壳寡糖的制备与品质鉴定

本研究以南极磷虾壳为原料,制备较高品质的壳聚糖与壳寡糖,并对二者的品质进行鉴定。南极磷虾壳经脱钙、脱蛋白处理,探索脱乙酰反应条件（碱溶液浓度、反应温度与反应时间）,制备具有较高脱乙酰度的南极磷虾壳聚糖,并对壳聚糖的理化指标进行鉴定;探索酶法降解条件（壳聚糖酶添加量、酶解时间）,制备较高纯度的南极磷虾壳寡糖,并对壳寡糖的结构特征进行鉴定。结果表明,使用60%的氢氧化钠于110 ℃脱乙酰处理4 h制备的南极磷虾壳聚糖脱乙酰度为85.74%,粘均分子量为 305.65 kDa,水分含量4.66%,灰分含量0.98%,酸不溶物含量0.40%,各项理化指标均符合食品级壳聚糖的要求;使用壳聚糖酶水解南极磷虾壳聚糖制备壳寡糖,在壳聚糖酶添加量为0.2% （m/V）,酶解16 h条件下,南极磷虾壳寡糖产品得率为46.0%,红外光谱与NMR谱图显示了表征壳寡糖结构的全部特征峰,质谱结果显示南极磷虾壳寡糖主要由二糖(GlcN)₂、三糖(GlcN)₂-GlcNAc与四糖(GlcN)₃-GlcNAc构成。本研究通过制备较高品质的壳聚糖与壳寡糖,为南极磷虾壳的高值综合利用与南极磷虾新产品开发提供了技术支持。     

Physicochemical and functional properties of chitosans affected by storage periods of crab leg shell

Effects of storage period (0, 1, 2, 3 and 4 months) of crab leg shell at room temperature on selected physicochemical and functional properties of E‐ and G‐chitosans, respectively, prepared from entire (E) and ground (G) shells were evaluated. Increased storage period of crab shell generally increased degree of deacetylation (DD) and viscosity, but decreased DPPH radical scavenging activity of both chitosans. Water‐binding (WBC) and fat‐binding (FBC) capacities of E‐chitosan were not affected by storage period of crab shell; however, those of G‐chitosan significantly increased when crab shell was stored for more than 1 month. Dye‐binding capacity (DBC) of both chitosans decreased when crab shell was stored for 1 month, but further decrease was not observed with increased storage period to 4 months. Prepared with 4‐month stored crab shell, E‐chitosan exhibited comparable viscosity, colour whiteness index, DPPH radical scavenging activity and DBC, but lower DD, WBC and FBC than G‐chitosan.     

The preparation of chitosan nanoparticles by wet media milling

Three different molecular weights of chitosan were pulverised to nanoparticles by wet media milling. The effects of the milling on properties of chitosan, such as viscosity average molecular weight (Mv), ash content, the degree of deacetylation (DD), particle size, chemical structure, colour, swelling power and apparent viscosity, were investigated. Our results showed that high (578.3 kDa), medium (181.6 kDa) and low (66.3 kDa) molecular weight chitosan with particle size of 342.7, 358.1 and 346.2 μm were milled to nanometre range after 1, 1.5 and 2.5 h of milling, respectively. After 5 h of milling, the particle sizes of the three samples were decreased to 543.8, 366.6 and 308.4 nm, respectively. Chitosan did not show significant increase in ash contents after milling. The milling decreased the Mv of chitosan, but did not change DD and the chemical structure. The suspension of chitosan nanoparticles was of cream‐white colour. The swelling powder and apparent viscosity of chitosan increased after the milling treatment.     

Enzymatic preparation of chitooligosaccharides by commercial lipase

The effect of a commercial lipase on chitosan degradation was investigated. When four chitosans with various degrees of deacetylation were used as substrates, the lipase showed higher optimal pH toward chitosan with higher DD (degree of deacetylation). The optimal temperature of the lipase was 55 °C for all chitosans. The enzyme exhibited higher activity to chitosans which were 82.8% and 73.2% deacetylated. Kinetics experiments show that chitosans with DD of 82.8% and 73.2% which resulted in lower K_m values had stronger affinity for the lipase. The chitosan hydrolysis carried out at 37 °C produced larger quantity of COS (chitooligosaccharides) than that at 55 °C when the reaction time was longer than 6 h, and COS yield of 24 h hydrolysis at 37 °C was 93.8%. Products analysis results demonstrate that the enzyme produced glucosamine and chitooligosaccharides with DP (degree of polymerization) of 2–6 and above, and it acted on chitosan in both exo- and endo-hydrolytic manner.     

壳聚糖制备方法比较及其性能研究

目的 研究壳聚糖的制备方法.方法 以甲壳素为原料,分别采用微波法和间歇碱液法制备壳聚糖,分析不同方法制备壳聚糖的粘均分子量、黏度、抗氧化性、吸湿保湿性能及表面形态的差异.结果 微波法制备壳聚糖的最佳工艺条件为:氢氧化钠浓度为55％,料液比为1:15(g/mL),微波功率为400 W,时间20 min;间歇碱液法制备壳聚...     

Extraction of chitin from prawn shells and conversion to low molecular mass chitosan

Extraction and depolymerisation of chitin and chitosan from prawn shells was carried out using various chemical procedures. Sodium hydroxide and hydrochloric acid solutions were used for deproteination and demineralisation, respectively, while acetone was used for decolourisation. The amount of chitin and subsequently chitosan obtained was ∼35% and 25% respectively of the dry weight of the shells. The chitin was deacetylated using sodium hydroxide at 100 °C and the influence of the concentration of the reagent and duration of the reaction was investigated. The degree of deacetylation (DD) of the chitosan was evaluated by FTIR and NMR spectroscopy and the molecular mass distribution was determined by Gel Permeation Chromatography. It was found that the final DD was significantly higher using 50% sodium hydroxide solution (73% ± 9%) compared to 25% sodium hydroxide solution (40% ± 5%). It was noted also that the deacetylation reaction was more than 80% completed after 2 h but the chitosan produced had higher molecular mass while chitosan produced after 10 h had lower molecular mass and higher degree of deacetylation. The molecular mass distribution was bimodal for all the samples and consisted of a broad high molecular mass peak (peak 1) and a sharp low molecular mass peak (peak 2). The Mw of peak 1 decreased from ∼1.3 × 10⁶ after 2 h reaction with sodium hydroxide to 3.1 × 10⁵ after 10 h reaction indicating that depolymerisation and deacetylation occurred simultaneously. Peak 2 had a Mw of ∼2.4–9.9 × 10³.     

Preparation and characterisation of selected physicochemical and functional properties of β‐chitosans from squid pen

Squid pen β‐chitosans prepared under various deacetylation conditions (30%, 35%, 40% and/or 45% NaOH for 15, 30 and/or 60 min) were characterised. β‐Chitosans (deacetylated with 35–45% NaOH for 15–60 min) had 87.1–96.2% degree of deacetylation (DD), 93.5–96.7% solubility and 120.5–654.9 mPa s viscosity. Treatment with 30% NaOH for 15–60 min yielded inadequately deacetylated β‐chitosans (DD = 51.9–80.2%). Two chitosans prepared under 35% NaOH for 15 min and 45% NaOH for 30 min (designated as 35%–15 and 45%–30, respectively) were further compared. Drying (sun‐drying vs. oven‐drying) methods did not affect DD. 35%–15 chitosan exhibited lower nitrogen, DD and bulk density, but higher viscosity compared with 45%–30 chitosan. Higher water‐ and fat‐binding capacity but lower DPPH radical scavenging activity were observed for 35%–15 chitosan compared with 45%–30 chitosan. Compared with 45%–30 chitosan, 35%–15 chitosan exhibited higher antibacterial activity against Salmonella Enteritidis and Listeria monocytogenes, but lower antibacterial activity against Escherichia coli.     

壳聚糖纺丝原液性能及其成纤性能的研究

研究壳聚糖纺丝原液的流变性能及其成纤工艺影响因素。试验结果表明,在20℃条件下,壳聚糖纺丝原液的稳定性较好,长时间放置其黏度值波动较小;温度升高,壳聚糖纺丝原液的黏度下降,但在20～30℃范围内黏度变化幅度小,超过30℃后,黏度降低较快。壳聚糖成纤的正交试验表明,壳聚糖成纤的最佳工艺组合为:壳聚糖质量浓度0.05 g/mL,凝固浴中NaOH质量浓度0.15 g/mL,纺丝温度20～25℃,凝固浴温度25℃。本研究获得了形态结构相对较好的壳聚糖纤维,为壳聚糖纤维的开发利用提供理论依据和技术路径。