大孔吸附树脂法柚皮果胶脱色工艺研究

比较了AB-8、S-8、X-5、聚酰胺、NKA-Ⅱ、NPD-600等6种大孔吸附树脂对柚皮果胶的脱色效果.在静态吸附试验研究的基础上,筛选出效果较好的树脂进行动态试验研究.实验表明:AB-8型大孔吸附树脂对柚皮果胶提取液具有较好的吸附脱色效果和较低的果胶损失率,该树脂对柚皮果胶脱色的适宜工艺参数为:室温(约20℃),流速3BV/h,溶液处理量为5BV,上柱液pH值为4～6.此工艺对果胶提取液中色素的吸附率约80%.树脂吸附后可用70%乙醇进行洗涤再生,果胶提取液脱色后经喷雾干燥所得的果胶成品质量符合QB2484-2000标准.     

离子色谱法测定大豆种皮提取液中(FeⅡ)和(FeⅢ)

采用国产YSC-1阳离子分离柱,用pH 4的草酸、柠檬酸、醋酸钠和亚硫酸钠溶液为淋洗液,用邻菲啰啉、盐酸羟胺为显色剂,测定了大豆种皮提取液中的Fe(Ⅱ)和Fe(Ⅲ)。     

烟草果胶的提取分析研究进展

果胶是自然界广泛存在的一种物质,其含量对烟草的评吸质量有重要的影响。文章主要介绍了果胶的各种提取和分析方法,并对果胶提取分析的发展方向进行了展望。     

从芒果皮中提取果胶的工艺研究

果胶是一种大分子多糖类物质 ,具有良好的胶凝作用 ,用途广泛 ,在国内外市场上的销量很好。 1 990年世界上果胶总产量约 2 5 0 0 0吨 ,而我国 1 990年仅在食品工业上消耗的果胶就达 1 0 0 0吨 ,但国内市场上销售的果胶大部分为进口货[1] 。果胶在我国的生产仍处于开发阶段 ,所以发掘新的提取资源、提高果胶质量、降低果胶生产成本的意义十分重大。目前 ,已有以柑桔皮、向日葵盘、苹果皮、香蕉皮、马铃薯渣为原料提取果胶的研究报道 ,如何从芒果皮中提取果胶却未见报道。芒果在制造罐头和饮料中副产大量下脚料———芒果皮 ,未能得到充分利用…     

脐橙皮中黄酮类化合物与果胶的分离和提取研究

黄酮类化合物是具备主要生物活性的天然产物,果胶是人体7大营养素中膳食纤维的主要成分.实验就黄酮和果胶提取分别作L9(34)和L16(44)正交化实验.工艺条件表明,提取黄酮的较佳工艺条件是:固液比1∶30,超声处理时间55 min,处理温度50℃,浸提液浓缩得到粗黄酮.提取黄酮后的脐橙皮渣中提取果胶的较佳工艺条件是:70℃的温度,提取时间为55 min,pH=2.0,固液提取比为1∶25.     

大孔吸附树脂提取麦拓莱霉素的工艺研究

研究了用大孔吸附树脂从发酵液中分离提取新型大环内酯类抗生素-麦拓莱霉素的吸附工艺过程，对吸附条件进行了优化，得到了适宜的操作条件．结果表明：NKA树脂为最佳吸附剂：吸附最佳pH值为10．32；吸附流速选择为1ml／min；NaCl的加入对吸附不利，选择NaCl浓度为0．6％左右，本实验条件下，发酵液中的麦拓莱霉素浓度为0．18mg／ml；NKA的吸附量可达33．7mg／g树脂。     

大叶金花草中碱溶性多糖提取工艺的研究

蕨类多糖复合物具有多种生理活性和药理活性,如抗肿瘤、免疫促进、抗凝血、抗补体、抗溃疡、抗炎、抗病毒和降血糖等[1]。目前对蕨类植物多糖的研究较少,主要有紫萁多糖[2,3]、芒萁多糖[4]、半边旗多糖[5]、毛叶蕨多糖[6]、海金沙多糖[7]等。大叶金花草是鳞始蕨科植物乌蕨(Sten     

花生油提取工艺研究

以花生为原料,研究回流法,索式提取法和超声波辅助提取花生粗油脂的工艺条件,结果显示超声波提取在低温短时间内提取率有优势。通过单因素试验和正交试验优化了超声波辅助提取花生粗油脂的工艺条件。结果表明：超声波辅助提取花生粗油脂工艺的最佳条件是：石油醚作为溶剂,料液比1：12（g/mL）,提取温度35℃,提取时间25min,超...     

沙田柚皮水溶性多糖的提取工艺研究

沙田柚皮细颗粒经石油醚回流脱脂、热水提取,以葡萄糖为参照品,利用分光光度法测定柚皮中水溶性多糖的含量。葡萄糖浓度在15.0~100.0μg/mL范围内与吸光度有良好的线性关系,回归方程为:A=0.00755x+0.07475(R=0.9992)。测出柚皮中水溶性多糖的含量为7.28%,精密度为0.82%(n=3);对照实验的回收率为(99.00±1.15%),精密度为0.59%(n=5)。此法操作简便,结果稳定可靠,是柚皮及其果肉中水溶性多糖含量测定的有效方法。     

指甲花色素提取工艺研究

以指甲花色素提取量为评价指标,采用可见分光光度法测定指甲花色素的含量,选取甲醇水溶液的浓度、pH、提取时间和温度四个因素对指甲花提取率的影响,并设计了正交实验进行提取工艺优化研究.结果显示指甲花色素最佳提取工艺条件为:甲醇水溶液的浓度为75%;pH为2;提取时间50min;提取温度70℃.该提取方法简单、方便,为指甲花色素的进一步研究提供依据.     

Synthesis of hexasaccharide fragments of pectin

Short syntheses of partially methyl-esterified hexagalacturonates 1-5 are described as part of the development of strategies for the preparation of larger pectic oligosaccharides. The methodology is based on the repeated coupling of galactose mono- and disaccharide donors onto a galactose acceptor until a hexagalactan is obtained. All glycosylations are carried out with n-pentenyl glycosides to provide good yields of the desired alpha anomers. Pentenyl disaccharide donors are prepared by the coupling of two pentenyl galactosides controlled by either the armed-disarmed effect or by converting one pentenyl galactoside into the corresponding galactosyl bromide or fluoride. Two orthogonal protecting groups are employed at C6, which makes it possible to oxidize these positions to either the carboxylic acid or to the methyl ester. Each hexagalactan is therefore able to bifurcate into two different hexagalacturonates with a reverse methyl-esterification pattern. The methyl ester distribution in the hexagalacturonates is confirmed by tandem mass spectrometry.     

Effect of annealing on calcium pectin gel formation by thermomechanical analysis

Pectin solutions were annealed at various temperatures and time intervals. Calcium pectin gels were prepared by mixing aqueous solutions of pectin and calcium chloride (CaCl₂). The degree of Na to Ca substitution (DS) was calculated based on the data obtained by atomic absorption spectrometry. DS increased with increasing Ca content and levelled off at the characteristic Ca content which corresponds to the saturated value assuming all -COOH was converted into -COO₂Ca. The characteristic saturated values depended annealing temperature and time at sol state. DS was calculated and it was found that DS decreased with increasing annealing temperature. Viscoelastic properties of gels in water were investigated using a thermomechanical analyzer (TMA). Dynamic modulus increased and tanδ decreased with increasing DS. Swelling ratio of gels decreased with increasing annealing temperature and time at sol state showing a similar tendency to the results of DS. It can be concluded that a large network structure was formed when the samples were annealed at high temperature for a long time at sol state. This revised version was published online in July 2006 with corrections to the Cover Date.     

改良的橘皮果胶抑制半乳糖凝集素-3与肿瘤相关功能的研究进展

半乳糖凝集素-3(Gal-3)是半乳糖凝集素家族中唯一一种嵌合体结构蛋白,含有一个特定的糖基识别结构域(CRD),能够特异性识别并结合半乳糖,此结构域可介导细胞与细胞之间的黏附和识别,并且能够促进部分肿瘤细胞的增殖和转移等。改良的橘皮果胶(MCP)可通过特异性结合肿瘤相关蛋白Gal-3糖基识别结构域,抑制Gal-3与其相关肿瘤受体的结合,阻断肿瘤细胞之间相关信号的传导,从而表现出较强的抗肿瘤活性。本文综述了MCP在Gal-3介导肿瘤发生发展过程中相关作用的研究进展。     

Effects of ascorbic acid on the physiochemical,rheological, and antioxidant properties of citrus essential oil-based emulsion stabilized by pectin

The present study was conducted to enhance the peel of Citrus sinensis (sweet orange) by using their essential oils (EOs) as a potential source of natural bioactive molecules. EOs were obtained by hydrodistillation and their chemical profile was determined through GC-MS analysis. O/W EO emulsions were prepared using pectin as biopolymer emulsifier at different proportions, including different amounts of ascorbic acid (0, 0.5, and 1% w/w). The effect of pectin and ascorbic acid concentrations on the stability and rheological behavior of emulsions was investigated. It was found that adding ascorbic acid to the appropriate concentration of pectin enhances the interfacial membranes surrounding the oil droplets and decreases the droplet sizes. As a result both the viscoelastic modules and the resulting viscosity of emulsions increase leading to an improvement of their stability. Antioxidant activity of orange EO emulsion in combination with ascorbic acid was found significantly higher than that without ascorbic acid, and higher than that of individual components. Overall, this study would be helpful in developing more effectives systems with promising physical and antioxidant characteristics for the preservation of foods.     

向日葵盘果胶对碳钢的缓蚀性能研究

以向日葵盘为原料,利用纤维素酶制备果胶(SFP)。采用静态失重、极化曲线和交流阻抗技术研究SFP在1mol/L HCl及0.5mol/L H_2SO_4溶液中对碳钢的缓蚀性能,并探讨其在碳钢表面的吸附机理。结果表明,缓蚀效率随SFP浓度增大而增大,随温度升高而降低。在HCl和H_2SO_4溶液中,SFP的吸附方式分别服从Langmuir和Temkin等温式,属于物理吸附;极化曲线测试显示SFP是一种混合型缓蚀剂。本文的研究表明,向日葵盘果胶是碳钢的绿色高效缓蚀剂,且在HCl溶液中的缓蚀性能优于在H_2SO_4溶液中。     

Influence of calcium lactate and pH on emulsification of low-methoxylated citrus pectin in a Pickering emulsion

An emulsion was prepared by homogenizing 30% rapeseed oil with 70% (w/w) aqueous solution. The emulsion viscosity increased when the concentrations of calcium lactate and low-methoxylated citrus pectin (LMP) in the emulsion were increased. A stable emulsion was obtained when the concentrations of LMP and calcium lactate were 1% and 9?mM at pH 3, respectively. Optical microscopy and laser scanning confocal microscopy revealed that the stable emulsion was a Pickering emulsion. In the Pickering emulsion, LMP with calcium formed micro gels that can be absorbed on the oil surface. The emulsifying property of LMP could widen the applications of pectin.     

Effects of pectin and xanthan gum on induced-flocculation phenomenon in an acidic model emulsion system

Mayonnaise is one of the most well-known dressings in the world and has properly found its impossibility to apply thermal processing, the high level of cholesterol and some consumers’ allergy to egg. In this study, the production of egg- free mayonnaise in model system has been investigated with the emphasis on flocculation enhancement in the system. Flocculation of emulsion droplets can have beneficial or harmful effect on food quality depending on product nature. In this study, influence of flocculation inducing on the stability, microscopic structure, zeta potential, droplet size and rheological properties of egg-free mayonnaise system were evaluated. Xanthan (XG), pectin (PE) and modified starch (MS) biopolymers mixed at different concentrations were used as flocculation inducer in emulsion system. XG-MS and PE-MS mixed polymers created depletion flocculation and reduced the speed of the oil droplets movement in the product and thus increased emulsion stability. In addition, an increase of all gum concentration caused an increment in the stability, consistency coefficient and heat stability values. Depending on the desirable level of xanthan gum and pectin gum for creating depletion flocculation, production of egg-free mayonnaise with properties closely matching those of commercial ones with egg is possible.     

Solid‐phase microextraction Arrow for the volatile organic compounds in soy sauce

A novel solid‐phase microextraction Arrow was used to separate volatile organic compounds from soy sauce, and the results were verified by using gas chromatography with mass spectrometry. Solid‐phase microextraction Arrow was optimized in terms of three extraction conditions: type of fiber used (polydimethylsiloxane, polyacrylate, carbon wide range/polydimethylsiloxane, and divinylbenzene/polydimethylsiloxane), extraction temperature (40, 50, and 60°C), and extraction time (10, 30, and 60 min). The optimal solid‐phase microextraction Arrow conditions were as follows: type of fiber = polyacrylate, extraction time = 60 min, and extraction temperature = 50°C. Under the optimized conditions, the solid‐phase microextraction Arrow was compared with conventional solid‐phase microextraction to determine extraction yields. The solid‐phase microextraction Arrow yielded 6–42‐fold higher levels than in solid‐phase microextraction for all 21 volatile organic compounds detected in soy sauce due to the larger sorption phase volume. The findings of this study can provide practical guidelines for solid‐phase microextraction Arrow applications in food matrixes by providing analytical methods for volatile organic compounds.     

分散固相萃取结合气相色谱-高分辨质谱快速筛查酱油中多种氯丙醇

建立了酱油中1，3-二氯-2-丙醇、2，3-二氯-1-丙醇、3-氯-1，2-丙二醇和2-氯-1，3-丙二醇的分散固相萃取-气相色谱-高分辨质谱快速筛查检测方法。样品采用乙酸乙酯提取，提取液浓缩后经N-丙基乙二胺净化，气相色谱-高分辨质谱测定，内标法定量。结果表明，该方法对于酱油中4种氯丙醇的定量限为0.5~10 μg/kg。在3个浓度水平下的加标回收率为78%~103%；相对标准偏差均不大于8.8%。该方法快速、简便、准确、灵敏，可作为酱油中4种氯丙醇的有效检测方法。