离子交换层析色谱法分离壳聚糖

用CMsepharoseCL 6B离子交换剂,使用不同的柱尺寸,采用离子强度线性梯度洗脱,对脱乙酰度80%,90%的壳聚糖样品进行分离。从脱乙酰度80%的壳聚糖样品分离得到3个组分实验结果表明,采用线性梯度洗脱时,直径相同的柱子,长的离子交换柱有利于壳聚糖的分离;对同一根离子交换柱,线性梯度洗脱体积的增加有利于壳聚糖的分离.分离不同脱乙酰度壳聚糖时,高脱乙酰度壳聚糖较低脱乙酰度壳聚糖在起始缓冲液洗脱时,洗脱出的壳聚糖含量较低,在高离子强度处洗脱出的壳聚糖含量较高.     

不同粒度甲壳素对所制备壳聚糖脱乙酰度和相对分子质量影响的研究

研究不同粒度甲壳素制备壳聚糖时,在不同反应时间对壳聚糖脱乙酰度和壳聚糖相对分子质量的影响,并求得不同粒度甲壳素脱乙酰反应的动力学公式.又采用凝胶过滤色谱测定不同脱乙酰度壳聚糖的相对分子量分布,结果表明：脱乙酰反应10 h所得壳聚糖的相对分子质量较反应8 h所得壳聚糖的小,脱乙酰反应14 h时,多糖主链的糖苷键已经发生断裂.     

响应面法优化制备高脱乙酰度小龙虾壳聚糖工艺及产物表征

以小龙虾虾壳为原料，脱乙酰度（DD）为评价指标，响应面法优化制备高脱乙酰度壳聚糖工艺。结果表明，最佳制备工艺为：氢氧化钠浓度50%、球磨处理时间12 h、料液比1:15(g/mL)，在此条件下进行验证试验，可得到脱乙酰度为88.1%的小龙虾壳聚糖。制备得到的高脱乙酰度小龙虾壳聚糖颗粒均匀有序，适合作为壳聚糖解聚原料，具有广泛应用前景。为小龙虾副产物开发利用提供理论参考。     

双突跃电位滴定法测定壳聚糖脱乙酰度的影响因素

研究了双突跃电位滴定法测定壳聚糖脱乙酰度的准确性以及壳聚糖溶液质量浓度、粘度、不同脱乙酰度等因素对滴定终点测定结果的影响.结果表明:壳聚糖样品质量浓度控制在2～6g/L,利用双突跃电位滴定法可以测定壳聚糖的脱乙酰度,不同样品脱乙酰度测定结果RSD(相对标准偏差)小于0.61%(n=3),该方法具有较高地准确性,可以用于壳聚糖生产和加工过程中的质量控制与检测.     

不同脱乙酰度蚕蛹壳聚糖抑菌性能的比较

研究了3种不同脱乙酰度蚕蛹壳聚糖对9种供试菌的抑菌效果。结果表明:3种壳聚糖对蜡状芽孢杆菌、鼠伤寒杆菌、枯草芽孢杆菌、白色念珠球菌、绿脓假单胞菌、大肠杆菌和金黄色葡萄球菌有明显的抑制作用,对巨大芽孢杆菌和嗜热脂肪芽孢杆菌的抑制作用不明显。随着壳聚糖溶液浓度的增大,其抑菌能力也增强。3种壳聚糖的抑菌活性为:脱乙酰度为95.96%的壳聚糖>脱乙酰度为86.45%的壳聚糖>脱乙酰度为78.12%的壳聚糖。壳聚糖的抑菌活性呈现随pH降低而增加的趋势,当pH值在pH 4.0～5.0,壳聚糖对所有供试菌均能完全抑制。高脱乙酰度蚕蛹壳聚糖作为热加工食品的防腐剂,可稳定保持其抑菌防腐性能。     

壳聚糖对亚硝酸盐清除作用的研究

研究了体外模拟胃液条件下壳聚糖对亚硝酸盐的清除作用；用分光光度法测定了壳聚糖对亚硝酸盐的清除率，考察了反应时间、壳聚糖用最、壳聚糖的脱乙酰度和分了量对清除亚硝酸盐效果的影响；结果表明：随反应时间的延长、壳聚糖用晕的增加，壳聚糖脱乙酰度的增高和分了量的降低，壳聚糖对亚硝酸盐的清除能力升高；分了量0．98万的壳聚糖37．5mg能完全清除亚硝酸盐。     

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。     

甲壳素微波法脱乙酰制备壳聚糖的研究

本文采用微波技术由甲壳素脱乙酰制备壳聚糖，首次对在微波反应前采用乙醇浸泡对甲壳素进行预处理的条件进行了较为系统的研究，并通过单因素试验和正交试验分析了微波反应时间、碱液浓度、乙醇浸泡时间、乙醇浓度、微波功率对壳聚糖脱乙酰度和粘均分了量的影响，提出了制备高脱乙酰度、高粘均分予量壳聚糖的最优条件为（微波功率462W）：微波反应时间20min，NaOH浓度50％，乙醇浸泡时间2、5h，乙醇浓度80％。在该条件下制得的壳聚糖脱乙酰度为77.07％，粘均分子量为43．13万，得率为68．98％。     

壳聚糖的乳化性能、絮凝能力和Ca2+螯合能力

壳聚糖的乳化性能、絮凝能力和金属离子螯合能力对其应用,特别是对其在食品工业中的应用有重大影响.本文研究了特性粘度和脱乙酰度对壳聚糖乳化性能、絮凝能力和Ca2 螯合能力的影响,结果表明,脱乙酰度相同的壳聚糖,特性粘度越高,乳化能力和乳化稳定性越好,絮凝能力和Ca2 螯合能力越强;而对于特性粘度相近的壳聚糖,脱乙酰度越高,乳化能力和乳化稳定性反而越差,但絮凝能力和Ca2 螯合能力,随壳聚糖脱乙酰度升高而增强.     

壳聚糖整理真丝绸的活性染料染色工艺探讨

经壳聚糖处理与未处理的真丝织物用KE型活性染料染色，研究了pH值、温度、壳聚糖脱乙酰度、浓度等的影响因素，结果表明pH值4.6、温度85~C~，染料上染真丝的固色率较高。提高处理液中壳聚糖的浓度或脱乙酰度能增加活性染料对织物的固色率，壳聚糖处理对皂洗牢度及摩擦牢度影响较小。     

Gel Filtration Fractionation of the Whole Water-Extractable Soybean Proteins

SUMMARY— The water-extractable soybean proteins (WESP) were fractionated into five fractions by gel filtration with Sephadex G-200 column. Four of the five fractions were protein fractions, while the fifth fraction was nonprotein fraction. The first two fractions were heterogeneous by sedimentation analysis, while the third and fourth fractions give homogeneous fractions with 7s and 2s respectively. The trypsin inhibitor activity was found only in the fourth fraction.     

小麦麸皮中戊聚糖的纯化分级及组成分析

用乙醇逐步沉淀和离子交换柱层析方法对麸皮中制备的水溶戊聚糖(WSP)和水不溶戊聚糖 (AEP)进行分级纯化 ,并对各组分的组成进行了分析 .结果表明 ,用乙醇逐步沉淀时 ,随着乙醇体积分数的增加 ,所得分级组分具有较高的分支 ;用离子交换柱层析时 ,WSP可分级为 2个组分 ,AEP可分级为 3个组分 ,并且用NaCl较H2 O洗脱的组分具有较高的分支和较高的相对分子质量     

Characteristics of fractionated flours from whole buckwheat grain using a gradual milling system and their application for noodle making

BACKGROUND: Recently, the quality of buckwheat (Fagopyrum esculentum, Moench) flour was improved by using a gradual milling method in which whole buckwheat grains were milled into various fractions. In this study, 16 fractions milled from whole buckwheat grains from the outer to inner parts are characterised and used for noodle making. RESULTS: Protein and ash contents of flours increased in the order from the inner to the outer fractions. Each fraction contained nine main fatty acids in which the concentration of palmitic, stearic, linoleic and linolenic acids tended to decrease from the inner to outer parts of the grain, whereas the concentration of oleic acid in the middle parts of grain was higher than in the other parts. The peak viscosity was different among the fractions and the middle fractions had significantly higher peak viscosity than the other fractions. The optimum cooking time and whiteness of uncooked and cooked noodles substituted with 40% of the fractions decreased from the inner to outer fractions, whereas noodles made from the inner fractions were harder and less elastic than those from the outer fractions. CONCLUSION: The different buckwheat fractions contributed to different quality of soba noodles. However, the appropriate fractions could be used for noodle making to improve the quality of noodles depending on nutritional demands. Copyright © 2007 Society of Chemical Industry     

米胚蛋白组分的提取及功能性质研究

采用Osborne的方法,从米胚中提取清蛋白、球蛋白、醇溶蛋白和谷蛋白,4种蛋白中谷蛋白的含量最高,占72.69%,其余3种蛋白的含量相差不大;考察4种蛋白的溶解性得出,在pH5下4种蛋白的溶解性最低,随着pH的增大或减小,溶解性逐渐增加,且清蛋白和球蛋白的溶解性较醇溶蛋白和谷蛋白高;在pH11、0.1mol/L NaCl浓度、1mg/mL蛋白浓度下,加入3mL大豆油,4种蛋白的乳化活性及乳化稳定性均达到最大值。     

Pilot scale preparation of wheat gluten protein fractions: II. Technological properties of the fractions

Fractions differing in prolamin compositions were obtained on a pilot scale when wheat gluten proteins were separated by differential extraction in dilute acetic acid. The soluble fractions were enriched in gliadins and the insoluble ones were richer in glutenins. The effects of the gluten fractions on the technological properties of wheat flours were investigated using an alveographic test and a comparison was made with gluten-added flours. Gliadin-rich fractions increased the extensibility of the dough and reduced its resistance to deformation. On the other hand, glutenin-rich fractions had an opposite effect and increased the dough resistance more than that of equally-concentrated whole gluten. The magnitude of the effects was strongly related to the gliadin and glutenin contents of the fractions. Prediction of technological effects is thus possible using composition analyses based on protein extractibility or size-exclusion chromatography. Finally, the improving effects of the gliadin-rich and of the glutenin-rich fractions were observed at different stages of the breadmaking process.     

Antioxidant and cytotoxic activities of various fractions of ethanol extract of Dianthus superbus

This study examined the antioxidant and cytotoxic activities of various fractions (prepared by using solvents of varying polarity) of ethanol extract of Dianthus superbus (DS). The antioxidant activities of various fractions were evaluated in terms of their free radical-scavenging activity. The total phenolics and reducing powers of the fractions were measured. The cytotoxic activities of the fractions on three human malignant cell lines were also investigated. Among all fractions, the ethyl acetate fraction (EE-DS), which had the highest phenolic content and the strongest reducing power, exhibited the strongest antioxidant and cytotoxic activities.     

Performance of selected milk fat fractions in cold-spreadable butter.

Based on solid fat content profiles, milk fat fractions produced by fractional crystallization procedures employing melted milk fat and milk fat dissolved in acetone were selected for incorporation into soft butter samples. Butter samples made from low melting liquid fractions or a combination of primarily low melting liquid fractions and a small amount of high melting solid fractions exhibited good spreadability at refrigerator temperature (4 degrees C) but were almost melted at room temperature (21 degrees C). Butters made with a high proportion of low melting liquid fraction, a small proportion of high melting solid, and a small proportion of very high melting solid fractions were still spreadable at refrigerator temperature and maintained their physical form at room temperature. Very high melting fractions, which provided key structural functionality in spreadable butter, were obtained from acetone fractionation. Because the use of acetone in processing may hinder or prevent commercialization of these fractions, other means to obtain very high melting fractions from milk fat should be pursued.     

Physicochemical Characteristics of Dry-Roasted Navy Bean Flour Fractions

Navy beans (Phaseolus vulgaris) were dry roasted in a particle-to-particle heat exchanger, dehulled by air aspiration, pin-milled and air-classified to yield whole, hull, high protein, and high starch flour fractions. Proximate analysis, color, ENDF, starch, nitrogen solubility indices, and oligosaccharide contents of these flour fractions were determined. Compositional differences were demonstrated among all flour fractions. Stachyose was the major oligosaccharide in all fractions and was highest in the protein fraction. Substituting 10% bean flours for wheat changed water absorption and dough stability for all fractions. Dry roasted navy bean flour fractions appeared to be suitable ingredients for use in appropriate food systems.     

Versuche zur Wirksamkeit von Ligninabbauprodukten und löslichen Laubholz-Bestandteilen gegen Hausbockbefall von Bauholz

The study deals with larvae development of the house longhorn beetle (Hylotrupes bajulus L.) in pinewood treated with different beech-wood extracts and their fractions. One of the hot water extracts and several fractions were characterized by high-performance liquid chromatography, ultimate and sugar analysis and determination of ash and lignin contents. It was found that hot water extracts and some fractions deriving from organosolv-pulping inhibit larvae development. The fractions with the greatest inhibitive properties mainly contain hardwood xylane. Lignin contents of these fractions were found to be relatively low.     

Classified processing of different rice bran fractions according to their component distributions

Rice grains were obtained from two Chinese provinces (Hubei and Guangxi) and then their rice bran was abraded into four equal fractions by weight from outside to inside. The component distributions in these four fractions were then investigated. The contents of total lipid-soluble antioxidant showed no significant difference between rice bran from the Hubei province and the Guangxi province. But the content of total water-soluble antioxidant was 1690.20 ± 86.40 mg kg⁻¹ for rice bran from the Hubei province, significantly higher than those from the Guangxi province (1014.67 ± 71.09 mg kg⁻¹). Obvious differences between four rice bran fractions or two provinces were proved by principal component analysis (PCA). Lipase activities decreased significantly from outer fractions to inner fractions, and lipids mainly distributed in three outer fractions. The essential element contents decreased significantly, but a main heavy metal element (Pb) in cereal increased significantly to 0.36 mg kg⁻¹ from outer fractions to inner fractions, which was just slightly below the upper limit of Chinese Standard (0.40 mg kg⁻¹). Although protein contents had no significant difference in four fractions, the amino acid compositions were quite different. In summary, different fractions of rice bran had different compositions, which could provide guidance for the classified processing of rice bran.