壳聚糖对冷却猪肉微生物的抑制效果

就不同脱乙酰度、不同浓度和溶解到不同浓度醋酸的壳聚糖对冷却猪肉中的微生物的抑制效果进行研究,结果表明,壳聚糖对猪肉中的微生物有明显的抑制效果,且壳聚糖浓度为5 mg/mL,壳聚糖脱乙酰度(DAC)≥95%,壳聚糖溶于醋酸浓度为1%时,对肉品中微生物的抑制效果较好.     

高脱乙酰度蛹渣壳聚糖制备工艺优化

制备高脱乙酰度蛹渣壳聚糖。在蛹渣壳聚糖制备工艺单因素试验研究的基础上,应用二次回归正交旋转组合设计方法研究无水乙醇浸泡时间、氢氧化钠溶液质量分数、处理温度、处理时间及料液比对壳聚糖脱乙酰度的影响,建立脱乙酰度对5 个试验因素的正交回归模型,通过频率分析法确定蛹渣壳聚糖较优的制备条件范围并得到蛹渣壳聚糖的最佳制备工艺。最佳工艺为：无水乙醇浸泡1.7h、氢氧化钠溶液质量分数44%、处理温度94℃、处理时间9h、料液比1:28(g/mL)、每2h 换碱1 次。在此工艺条件下,壳聚糖的脱乙酰度95.96%、相对分子质量7.45 × 105、产率56.98%、水分含量3.20%、灰分含量0.35%,产品为原白色,外观色泽好,主要指标均达到相关企业标准。     

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。     

壳聚糖溶液的流变学性质及应用研究

对壳聚糖稀溶液的流变学性质进行了研究,探讨了分子量和脱乙酰度结构参数以及温度、浓度、剪切速率、pH、离子强度等环境因素对壳聚糖稀溶液流变性质的影响。结果表明:壳聚糖溶液的黏度随分子量的增大而增大;随着脱乙酰度的增大和pH的增大,壳聚糖溶液的黏度先减小后增大,分别在脱乙酰度70.8%和pH4.9时黏度达到最小;离子强度的增大导致壳聚糖溶液的黏度降低。壳聚糖溶液是剪切变稀的假塑性流体,其黏度随浓度的增加逐渐增加,随温度的升高而减小,在0~80℃范围内,温度对壳聚糖溶液的黏度的影响符合Arrhenius模型,活化能为32.60kJ/mol。因此当作为食品增稠剂时,应该选用高分子量、高脱乙酰度的壳聚糖,添加到酸性低盐食品体系中。     

Changes in Protein Solubility and Gelation Properties of Chicken Myofibrils during Storage

The effect of storage on protein solubility and heat-induced gelation properties of chicken hen breast and leg myofibrils was investigated. Myofibrils suspended in 0.6M NaCl, pH 6.0, showed increasing protein solubility, viscosity, gel strength and water holding capacity with storage at 4°C. However, the effect of storage was most dramatic only during the initial 10 hr for all of the parameters studied. The relative distribution of the proteins comprising the salt soluble protein (SSP) extract changed during storage. Although storage had little effect on breast SSP, it was detrimental to leg SSP gelation. Breast myofibril suspensions, for all storage times, contained a greater amount of SSP and had better gelation properties than leg myofibril suspensions.     

木瓜蛋白酶降解壳聚糖

通过粘度测定、还原端基测定和凝胶层析分子式量分布测定 ,研究了木瓜蛋白酶非专一性降解壳聚糖过程中温度、pH值、反应时间和酶用量等因素对木瓜蛋白酶降解能力的影响 ,探讨了壳聚糖脱乙酰化度和相对分子质量与木瓜蛋白酶降解反应的关系 .结果表明 :木瓜蛋白酶在温度4 0～ 4 5℃、pH 4 .0～ 5 .0和酶用量 0 .5 %～ 10 %范围内 ,对壳聚糖的降解将随酶用量的增加而加快 ,但随脱乙酰度的升高而减慢 ;木瓜蛋白酶适合作用于数均分子式量在 2 0～ 5万的虾壳聚糖 .     

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。     

响应面法优化丰年虫卵壳脱乙酰度壳聚糖提取工艺

以丰年虫卵壳制备的甲壳素为原料,通过单因素试验和响应面设计法,确定丰年虫卵壳壳聚糖微波辅助提取技术的最佳工艺条件为微波时间33.4min、乙醇浸泡时间86min、碱液质量分数57.27%。按此工艺条件提取可获得脱乙酰度为84.12%的丰年虫壳聚糖。     

超声波预处理醇碱体系进行甲壳素脱乙酰工艺的研究

以自溶法脱蛋白、EDTA·Na2螯合脱钙制备的甲壳素为原料,采用超声波预处理醇碱体系进行甲壳素脱乙酰工艺的研究.以脱乙酰度(D.D.)为考察指标,依据单因素实验结果,采用L9(34)正交试验考察乙醇浓度(A)、氢氧化钠质量浓度(B)、反应时间(C)及超声波处理时间(D)对脱乙酰度(D.D.)的影响.实验结果表明脱乙酰工...     

壳聚糖处理羊毛织物染色工艺探讨

探讨了壳聚糖脱乙酰度、浓度及分子量等对经壳聚糖处理后的羊毛织物染色性能的影响。结果表明 ,提高处理液中壳聚糖的脱乙酰度或浓度都能大大提高B型活性染料对羊毛织物的固色率和K S值 ,而且对染色样的湿处理牢度和摩擦牢度影响不大 ,而壳聚糖的分子量对织物的染色性能无明显影响。     

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。     

Effect of chitin and chitosan on gelling properties of surimi from barred garfish (Hemiramphus far)

The addition of chitin/chitosan significantly increased the breaking force and deformation of gels prepared from barred garfish surimi (P < 0.05). Addition of 7B chitosan with 65.6% degree of deacetylation (% DD) at the level of 15 mg g⁻¹ resulted in the maximum increases in both breaking force and deformation of suwari and kamaboko gels compared to the control and gels containing chitin or chitosan with other % DD (P < 0.05). A chitosan concentration of 10 mg g⁻¹ was found to render the highest breaking force of kamaboko gel compared to other concentrations tested (P < 0.05). Kamaboko gel containing chitosan had an increased breaking force as the calcium chloride concentration increased (P < 0.05), indicating the role of endogenous transglutaminase in cross‐linking of protein–protein and protein–chitosan conjugates. Therefore the incorporation of chitosan and calcium chloride greatly improved the gelling properties of surimi from barred garfish without changes in colour. © 2000 Society of Chemical Industry     

壳聚糖在真丝织物数码喷墨印花中的应用

对壳聚糖作为增稠剂、增深剂应用于丝织物活性染料数码喷墨印花工艺进行了探讨,讨论了壳聚糖脱乙酰度、壳聚糖质量浓度、浆料的pH值对真丝织物数码喷墨印花防渗化性能及印花性能的影响.结果表明,提高浆料中壳聚糖的质量分数或脱乙酰度具有较高的防渗化性,同时能提高织物表面色深值K/S,并且具有较好的色牢度.     

壳聚糖在羊毛织物喷墨印花中的应用

文章对壳聚糖作为增稠剂应用于羊毛织物活性染料数码喷墨印花工艺进行了探讨,讨论了壳聚糖脱乙酰度、壳聚糖浓度对羊毛织物喷墨印花防渗化性能的影响。结果表明,提高处理液中壳聚糖的浓度或脱乙酰度具有较高的防渗化性,能提高活性染料的固色率,提高织物表面色深K/S值,同时具有较好的色牢度和手感。     

非晶化甲壳素脱乙酰制备高脱乙酰度壳聚糖

对甲壳素进行超微粉碎处理,通过控制碾磨时间,得到结晶度为80.91%、58.06%、31.94%和8.09%等4种甲壳素细粉,再对其和普通粉碎甲壳素的非均相脱乙酰制备壳聚糖的反应进行对比研究。结果表明,随着甲壳素样品结晶度的降低,在相同的脱乙酰反应条件下制备的壳聚糖的脱乙酰度更高。采用单次碱处理的方式,使用普通粉碎甲壳素得到的壳聚糖脱乙酰度为84%,使用结晶度为31.94%和8.09%的甲壳素细粉,壳聚糖脱乙酰度可达90%以上。动力学研究分析,普通粉碎甲壳素和超微粉碎处理得到的4种甲壳素细粉非均相脱乙酰反应的活化能分别为58.71、47.23、42.30、35.44和31.73 kJ/mol,即反应的活化能随结晶度的降低而降低,表明非晶化处理能增强甲壳素非均相脱乙酰反应活性。     

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。     

甲壳素传统法与微波法制备壳聚糖的比较

针对甲壳素脱乙酰制备壳聚糖采用的两种方法——微波法与传统法,从反应时间、壳聚糖的得率和品质(脱乙酰度和粘均分子量)等方面进行了比较分析。结果表明,甲壳素传统法一次脱乙酰反应很难制备脱乙酰度大于78%高粘均分子量的壳聚糖;与传统方法相比,甲壳素微波法脱乙酰制备壳聚糖不仅大大减少了反应时间,同时还能避免高温长时间处理导致壳聚糖产品的分子量和粘度下降,从而提高壳聚糖的质量指标。     

Purification and properties of extracellular chitinases from the parasitic fungus Isaria japonica

Two chitinases (P-1 and P-2) induced with colloidal chitin were purified from the culture supernatant of Isaria japonica by chromatography on DEAE Bio-Gel, chromatofocusing and gel filtration with Superdex 75 pg. The enzymes were electrophoretically homogeneous and estimated to have a molecular mass of 43,273 (+/-5) for P-1 and 31,134 (+/-6) for P-2 by MALDI-MS. The optimum pH and temperature was 3.5-4.0 and 50 degrees C for P-1 and 4.0-4.5 and 40 degrees C for P-2. P-1 acted against chitosan 7B (degree of deacetylation, 65-74%) = glycol chitin > colloidal chitin = chitosan 10B (degree of deacetylation, above 99%) and P-2 against chitosan 7B > glycol chitin = chitosan 10B > colloidal chitin in order of activity. The products of hydrolysis of chitin and chitosan hexamer were analyzed by MALDI-MS. The products from the chitin hexamer obtained with P-1 were almost all dimers with only a small amount of trimer whereas those obtained with P-2 were mainly trimers with some dimer and tetramer. No hydrolysis of chitosan hexamer was observed. High homology in the amino-terminal sequence for chitinase P-1 was exhibited by chitinases from Trichoderma harzianum, Candida albicans and Saccharomyces cerevisiae in the range of 48-39%. The highest homology for Chitinase P-2 was shown by an endochitinase from Metarhizium anisopliae of 66%, while 44% homology was exhibited by chitinases of Leguminosae plants.     

Physicochemical and Gelation Properties of Pre- and Postrigor Chicken Salt-soluble Proteins

The physicochemical and gelation properties of salt-soluble proteins (SSP) extracted from chicken muscles were studied at 0.6M NaCl, pH 6.00. Thermally induced protein unfolding and protein-protein interaction were determined by 8-anilino-1-naphthalene sulfonate (ANS) fluorescence and turbidity. Breast and leg SSP showed similar changes in protein unfolding, but differed in protein-protein interactions. Post-rigor breast SSP formed stronger and more elastic gels than prerigor breast and pre and postrigor leg SSP. Leg SSP gelation was less affected by muscle rigor state than breast SSP. Protein conformational changes were concluded to precede SSP association, which was a prerequisite for gel formation.     

壳聚糖生产过程中脱乙酰度的近红外光谱法现场监测

用固态CP/MAS NMR对壳聚糖的脱乙酰度进行测定,建立快速测定壳聚糖的脱乙酰度的近红外方法。该方法对水分、氢氧化钠、乙酸钠、蛋白质对脱乙酰度测定的影响进行了校正,最后建立的最优近红外测定方程的交叉验证标准误差(SECV)为0.6306,交叉验证相关系数(1-VR)为0.9987。用该方程对定标样品组进行验证,其工作标准误差(SEP)为0.4312,检验决定系数(R2)为0.9994,线性斜率(Slope)为0.9999。结果表明该方法准确、可靠、快速,可以用于壳聚糖生产过程中脱乙酰度的现场监测。