微波协同提取柚子皮中果胶的工艺研究

以柚子皮为原料,微波协同提取柚皮中果胶。采用单因素试验和正交试验,对微波协同提取柚皮中果胶的提取工艺进行优化研究。探讨了液料比、pH值、辐射时间、微波强度等因素对柚皮中果胶提取率的影响。试验结果表明,微波协同提取lOg粒径为0．25mm的柚皮粉末中果胶的最佳工艺条件为：总液料质量比30：1,提取液pH2．0,微波功率450W,提取时间60s。提取液经硫酸铝盐析,析出沉淀用酸化醇处理脱盐,过滤,滤渣用乙醇反复洗涤干燥即得果胶,产率14．7％。与加热提取法比较,微波协同提取能大大缩短提取时间,并提高了果胶的产率。     

从西瓜皮中提取果胶的工艺研究

果胶以其良好的稳定、增稠、乳化和胶凝效用,在食品、冶金、纺织、医药等领域有着广泛的应用。近年来一些关于瓜果皮类中果胶提取的研究较多,主要以橘类果皮为主。利用西瓜皮提取果胶,将果皮中含有的有益物质,进行收集再利用,将带来巨大的经济效益。以新鲜西瓜皮为原料,利用无机酸与有机酸混合作为酸提剂,乙醇作为沉淀剂,从西瓜皮中提取果胶,混合酸为冰乙酸与10%盐酸。试验考察了混合酸pH值、固液比、酸解温度、酸解时间、沉淀剂用量等因素对果胶提取的影响。以单因素实验为基础,通过正交试验优化果胶提取的实验条件,进而得到最佳的反应工艺,并对果胶样品进行检测。当提取温度保持80℃附近,pH值为2.0,提取时间持续70 min,瓜皮中果胶的浸提率接近10%。     

Modulation of extraction variables of pectin from Manilkarazapota fruit peel,its bio characterization,and comparative study using dynamic light scattering studies

Influence of variables has a great impact upon yield of pectin. The present study was organized to harmonize these variables and examine the extracted pectin. In view of this, bio-characterizion and structure analysis of pectin through FTIR was performed. Additionally, a polydispersity and particle size study was also conducted using dynamic light scattering (DLS) of the Manilkarazapota fruit peel. The best extraction variables according to the response optimization predicted model were noted as pH of 5 at 61.11°C for 90 min of heating time, which lead to a 3.7% yield. Bio-characterization revealed that pectin extracted at pH 5 has characteristics similar to HM pectin influence of methoxyl content, degree of esterification, and Galacturonic acid content at 5.11%, 73. 63%, and 77.7%, respectively. The FTIR spectrum depicted a similar surface structure to food-grade pectin. DLS studies revealed that extracted pectin at pH 5 has a particle size in the range of 390.21–421.17 nm and polydispersity (?) of 28.2%-29.3%. These findings indicate that sapodilla is a potential source of pectin for food and pharmaceutical preparation.     

Column chromatographic extraction for quickly separating the volatiles,flavonoids, and pectin from tangerine peel

Tangerine peel, a very abundant natural resource, only part of which has been used in traditional Chinese medicine and health foods but most were discarded as the waste, which should be fully utilized. Previous studies showed its functional components include volatiles, ?avonoids, phenolic acids, and pectin, all of which cannot be effectively extracted through traditional methods. A column chromatographic extraction with gradient elution was developed for one-step extraction of all bioactive substances from tangerine peel. Dried material was loaded into a column eluted with 2-fold of petroleum ether: ethanol (7:3, PE) for the volatiles fraction. Sequentially eluted with 4-fold of ethanol: water (5:5, EW) then separated into ?avonoids and polysaccharides by 80% ethanol precipitation of polysaccharides. The third eluted with 5-fold of water and then 60% ethanol precipitation of pectin. Through these procedures, volatiles, ?avonoids, and pectin in tangerine peel were simultaneously extracted at 98% extraction rates and simply separated at higher than 95% recovery rates. To further reduce solvent consumption and the volume of the final extract, cyclic column chromatographic extraction should be used. The method provides a simple and high ef?cient extraction and separation of a wide range bioactive substances.     

Characterization of enzymatically synthesized amylopectin analogs via asymmetrical flow field flow fractionation

Asymmetrical flow field flow fractionation (AF4), when coupled with multi-angle laser light scattering (MALLS), is a very powerful technique for determination of the macromolecular structure of high molar mass (branched) polysaccharides. AF4 is a size fractionation technique just as size exclusion chromatography (SEC), nevertheless can overcome some crucial problems found in SEC analysis especially in starch like structures. This paper describes a detailed investigation of the macromolecular structure of two groups of well-defined synthetic amylopectin analogs – synthesized via an in vitro enzyme-catalyzed reaction using the enzymes phosphorylase b from rabbit muscle and Deinococcus geothermalis glycogen branching enzyme (Dg GBE). Size, molar mass distributions and structural data were studied by AF4 coupled with online quasi-elastic light scattering (QELS) and multi-angle light scattering (MALLS).     

超声波辅助酶解法提取桔皮中果胶的工艺研究

文章采用超声波辅助酶解法提取桔皮中的果胶,研究了pH、提取温度及提取时间对果胶提取率的影响,确定了提取的最佳工艺条件：pH 4.6,提取温度41℃,提取时间50 min。在最佳提取工艺条件下,桔皮中果胶的提取率约为2.08%。     

A COMPARISON OF DIFFERENT TECHNIQUES FOR WATER-BASED EXTRACTION OF PECTIN FROM ORANGE PEELS

The extraction of pectin from orange peels has been studied using microwave and conventional extraction, with operating conditions including different extraction periods, different solvent pHs, and different types of solvent systems. The extracted pectin from orange peels was initially precipitated with concentrated ethanol and was quantified by the carbazole assay. For microwave extraction, the greatest total amount of pectin yield was found to be 5.27% on a dry basis for 15 minutes of extraction, although the greatest amount of material per unit time (%/min) was obtained after 5 minutes. This amount was the same as that extracted using Soxhlet extraction for three hours. The 15-minute microwave extraction period was further investigated at pH values of 1.5, 2.0, 5.5, and 10.0. The greatest amount of pectin was extracted from orange peels at the most strongly acidic condition of pH 1.5. The effect of a solvent system containing ethanol and EDTA (ethylenediamine tetraacetic acid) with a 15-minute extraction period and a pH of 1.5 was studied, giving approximately double the amount of pectin extracted using distilled water.     

A COMPARISON OF DIFFERENT TECHNIQUES FOR WATER-BASED EXTRACTION OF PECTIN FROM ORANGE PEELS

The extraction of pectin from orange peels has been studied using microwave and conventional extraction, with operating conditions including different extraction periods, different solvent pHs, and different types of solvent systems. The extracted pectin from orange peels was initially precipitated with concentrated ethanol and was quantified by the carbazole assay. For microwave extraction, the greatest total amount of pectin yield was found to be 5.27% on a dry basis for 15 minutes of extraction, although the greatest amount of material per unit time (%/min) was obtained after 5 minutes. This amount was the same as that extracted using Soxhlet extraction for three hours. The 15-minute microwave extraction period was further investigated at pH values of 1.5, 2.0, 5.5, and 10.0. The greatest amount of pectin was extracted from orange peels at the most strongly acidic condition of pH 1.5. The effect of a solvent system containing ethanol and EDTA (ethylenediamine tetraacetic acid) with a 15-minute extraction period and a pH of 1.5 was studied, giving approximately double the amount of pectin extracted using distilled water.     

Water-based extraction of pectin from flavedo and albedo of orange peels

The extraction of pectin from orange peels has been studied at different sample to solvent ratios, different pHs and with different extraction techniques using water. The highest pectin and total nitrogen was produced by a sample to solvent ratio of 1:12.5. The amount of pectin extracted reduces as the pH increased, while the extractability of crude protein is not affected so significantly. Previous workers have found similar results. Considerably more pectin was obtained by the Soxhlet method than by microwave extraction by a factor of two, with a longer extraction duration than the microwave extraction by a factor of 240, so microwave extraction showed a much higher extraction rate (per unit time) by a factor of 120. Pectin existed mainly in the albedo, but the flavedo still contained 27% of the amount of pectin in the total extract. The total pectin yield from the dried peel was 2.2%. The combination of hand-pressure and microwave on pectin yield from flavedo was 12% better than hand-pressure alone, which was also better than microwave extraction alone.     

超声波辅助提取橘子皮中果胶的研究

采用超声波辅助酸法从橘子皮中提取果胶。实验中对固液比、pH值、提取温度和超声波提取时间等四个影响果胶提取率的因素分别进行考查,依据单因素实验结果进行正交试验。通过R和K值的比较,确定pH值、固液比对果胶提取率的影响较大,并确定最佳实验条件:pH值1.5、提取温度70℃、提取时间45 min、固液比20∶1,在该条件下果胶提取率可达到20.8%。采用红外光谱法对产品进行定性分析。     

微波辅助提取南瓜皮中果胶的研究

讨论了利用微波辐射萃取法从南瓜皮中提取果胶的不同因素的影响,通过实验确立了微波条件下提取果胶的最佳工艺条件为:用盐酸调pH值为1.8,用水作为溶剂,料液比为1∶20,微波辐射功率为600W,辐射时间为4min,乙醇(体积分数)为60%,提取率可达到16.9%。     

微波辅助提取西瓜皮中果胶的研究

讨论了利用微波辐射萃取法从西瓜皮中提取果胶的不同因素的影响,通过实验确立了微波条件下提取果胶的最佳工艺条件：用盐酸调pH值为1.8,用水作为溶剂,料液比为1∶20,微波辐射功率为600 W,辐射时间为4 min,乙醇浓度为60%,提取率可达到17.8%。     

从橙子皮中提取果胶的工艺研究

采用乙醇沉淀法从橙子皮中提取果胶;并对萃取时间、萃取液pH值、萃取温度、果胶酶和水质及其它因素等对果胶的影响进行了研究。     

Optimization of pectin extraction from dried peel of citrus grandis

Summary The influence of acid concentration, temperature, and extraction time on pectin extracted from dried peel of Citrus grandis have been investigated. The dependence of pectin yield and of the relative viscosity of pectin solution on experimental conditions has been described by mathematical models.To obtain suitable pectin for immobilizing biocatalysts, the extraction should be carried out at low acid concentration, low temperature, and for long periods of time.     

pH‐responsive polyzwitterions: A comparative study of acrylamide‐based polyampholyte terpolymers and polybetaine copolymers

A comparative study of pH‐responsive polyzwitterions (PZs) with polyampholyte or polybetaine architectures was conducted with well‐defined model polymer systems. Low‐charge‐density PZs, including ampholytic terpolymers composed of acrylamide (AM), sodium 3‐acrylamido‐3‐methylbutanoate, and (3‐acrylamidopropyl)trimethylammonium chloride and carboxybetaine copolymers composed of AM and 3‐(3‐acrylamidopropyldimethylammonio)propionate, were prepared via free‐radical polymerization in 0.5M NaCl to yield ter‐ and copolymers with random termonomer and comonomer distributions. Sodium formate was used as a chain‐transfer agent during the polymerizations to eliminate the effects of the monomer feed composition on the degree of polymerization (DP) and to suppress gel effects and broadening of the molecular weight distributions. The polymer compositions were determined via ¹³C‐NMR spectroscopy, and the residual counterion content was determined via elemental analysis for Na⁺ and Cl^?. The molecular weights (MWs) and polydispersity indices (PDIs) were determined via size exclusion chromatography/multi‐angle laser light scattering (SEC–MALLS); the polymer MWs ranged from 1.4 to 1.5 × 10⁶ g/mol, corresponding to DPs of 1.6–1.9 × 10⁴ repeat units, with all the polymers exhibiting PDIs less than or equal to 2.1. The intrinsic viscosities determined from SEC–MALLS data and the Flory–Fox relationship agreed with the intrinsic viscosities determined via low‐shear dilute‐solution viscometry. Data from the SEC–MALLS analysis were used to analyze the radius of gyration/molecular weight (R_g–M) relationships and the Mark–Houwink–Sakurada intrinsic viscosity/molecular weight ([η]–M) relationships for the PZs. The R_g–M and [η]–M relationships and viscometric data revealed that under size exclusion chromatography conditions, the poly[acrylamide‐co‐3‐(3‐acrylamidopropyldimethylammonio)propionate] betaine copolymers had more open, random‐coil conformations and greater polymer–solvent interactions than the ampholytic poly[acrylamide‐co‐sodium 3‐acrylamido‐3‐methylbutanoate‐co‐(3‐acrylamidopropyl)trimethylammonium chloride] terpolymers. The pH‐ and salt‐responsive dilute‐solution viscosity behavior of the PZs was examined to assess the effects of the polymer structure and composition on the solution properties. The polyampholyte terpolymers had greater solution viscosities and more pronounced stimuli‐responsiveness than the polybetaine copolymers because of their stronger intramolecular interactions and increased chain stiffness. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 24–39, 2004     

超声波辅助提取南瓜皮中果胶的研究

利用超声波辐射萃取法从南瓜皮中提取果胶,讨论了不同因素的影响。通过实验确定了超声波条件下提取果胶的最佳工艺条件:用盐酸调节pH=1.8,以水作溶剂,料液体积比1∶20,超声功率600 W,作用时间40 m in,乙醇体积分数60%。提取率可达到17.8%。     

柚皮提取果胶水解条件的研究

研究了以柚皮为原料提取果胶时的酸水解条件 ,通过正交实验确定最佳水解条件为 :温度 95℃ ,液固比 1 5 ml g,p H值 1 5 ,水解时间 1 h,此时果胶得率在 2 6 %以上。实验还发现从白果皮层提取果胶得率高、色泽好 ,柚皮的不同干燥方法对果胶提取率没有影响 ,用水浸泡原料不能提高提取率 ,而原料的粉碎度越高 ,越有利于果胶提取。     

Methacryloylpropyl–βcyclodextrin and vinylpyrrolidone copolymers: Synthesis and characterization as potential chiral selector

The free radical copolymerization of vinylpyrrolidone (VP) with 2‐hydroxy‐3‐methacryloyloxypropyl β‐cyclodextrin (βW7 MAHP), a derivative of hydroxypropyl β‐cyclodextrin (CD) substituted by polymerizable methacryloyl groups, is carried out in water by varying the molar ratio of the comonomers. It is found that the higher the molar ratio of βW7 MAHP to VP, the larger the molar mass of the water‐soluble copolymer. A size exclusion chromatography analysis coupled with multiangle laser light scattering detection (SEC–MALLS) suggests that VP‐rich copolymers with a mass‐average molar mass (MM) of about 2.5 × 10⁴ g mol^?1 may consist of βW7 MAHP dimers, trimers, and oligomers containing few CD units whereas βW7 MAHP rich copolymers with an MM of about 5.5 × 10⁶ g mol^?1 are likely to be dominated by crosslinked polymer materials. βW7 MAHP‐co‐VP copolymers coated on porous silica are used as high‐performance liquid chromatography chiral selectors. The effects of the structural features of the guest molecule and the characteristics of the chiral stationary phases on the retention and resolution are evaluated. SEC–MALLS detection shows that, by varying the comonomer feed, copolymers with different molar masses and macromolecular structures are formed. The chiral separation ability of Copo VP is evaluated toward enantiomers having one or more aromatic rings as a function of the amount of copolymer adsorbed onto the silica surface, the βW7 MAHP content, and the concentration of solute. It is clear that the column combining the greater amounts of adsorbed copolymer and βW7 MAHP exhibits better resolving power. Moreover, the size, geometry, and functionality of the guest molecule are important factors that strongly affect the enantioselectivity. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2364–2374, 2005     

Improved methods for evaluating the molar mass distributions of cellulose in kraft pulp

Multi‐angle laser light scattering (MALLS) was used to characterize birch kraft pulps with respect to their absolute molecular mass distributions (MMDs). The pulps were dissolved in lithium chloride/N,N‐dimethylacetamide and separated by size exclusion chromatography (SEC). The weight‐average and number‐average molecular masses of the cellulose fractions of the pulps obtained from the absolute MALLS measurements were compared with the molar masses obtained by direct‐standard‐calibration relative pullulan standards. Discrepancies between the two detection methods were found, and two ways of correlating the relative pullulan molar masses to the absolute molar masses were examined. In the first method, the correlation was made over a large range of molecular masses. The second method correlated the molecular masses of the standards to the molecular masses of samples by the calculation of fictitious, cellulose‐equivalent molar masses of the standards. With the preferred second method, a more correct MMD of kraft pulp samples could, therefore, be obtained from an SEC system calibrated with narrow standards. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1170–1179, 2003     

Effect of extraction conditions on yield and degree of esterification of durian rind pectin: An experimental design

The effect of time (1 and 4 h), pH (2.0 and 2.5) and temperature (80 and 90 °C) on yield and degree of esterification (DE) of durian rind pectin was investigated. The yield and DE of the extracted pectin ranged from 2.1 to 10.3% (w/w, based on dry weight of durian rind) and 45.6–64.8% respectively. Yield was significantly affected by time, temperature and pH, and interactions between temperature and pH, and heating time and pH. DE was significantly affected by heating time and pH, and interactive effects of temperature and pH, and heating time and pH. The extraction yield was not related to DE. By considering pectin yield and DE, the acid extraction of durian rind pectin at 80 °C, for 4 h and at pH 2.5 could be suitable.