Physicochemical and Thermal Properties of Ceiba pentandra Bark Fiber

Owing to their low weight-to-high strength ratio and recyclable features, the natural fibers are the most potential choice in place of synthetic fibers and been used as reinforcement materials in polymer matrix composites. Characterization of Ceiba pentandra bark fibers (CPFs) such chemical analysis, Fourier Transform-Infrared Analysis (FTIR), X-ray diffraction, thermogravimetric analysis, and Differential thermogravimetric analysis (DTG) analysis has analyzed. CPFs contain 60.9% (w/w) of cellulose, 17.5% (w/w) of hemicellulose, and 23.5% (w/w) of lignin. Besides, its density and crystallinity index are 682 kg m^?3 and 57.94%, respectively. TG and DTG analysis discovered that CPFs are thermally stable up to 342.1°C. Further, all the resources of CPFs ensured that it can be an excellent alternative for synthetic fibers in polymer matrix composites.     

Physicochemical,tensile, and thermal characterization of new natural cellulosic fibers from the stems of Sida cordifolia

Natural fibers are the one worthy substitute for replacing synthetic fibers and used as a polymer reinforcement due to their eco-friendly nature. This investigation deals with the newly identified Sida cordifolia fibers (SCFs) characterized by chemical analysis, single fiber tensile test, thermogravimetric analysis (TGA/DTG), Fourier transform-infrared spectroscopy (FT-IR) analysis, X-ray diffraction (XRD), and atomic force microscopy (AFM). The chemical constituents of SCFs contains cellulose (69.52%), hemicellulose (17.63%), and lignin (18.02. %). The SCFs are thermally stable up to a temperature of 338.2°C evidenced by TGA analysis. The X-ray diffraction confirmed that SCFs were rich in cellulose fraction with a crystallinity index of 56.92%.     

Characterization of natural cellulosic fiber from Epipremnum aureum stem

The natural fiber Epipremnum aureum was extracted from its plant. E. aureum fibers (EAFs) were investigated by chemical analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and single fiber tensile test. Chemical analysis, FTIR, and X-ray analysis evidenced that these fibers has 66.34% cellulose content with crystallinity index of 49.33%. The thermogravimetric analysis reveals that EAFs can thermally withstand temperatures until 328.9°C. The morphology of the EAFs was observed by scanning electron microscope. It was established that the fiber can be utilized as reinforcement in polymer composites.     

番木瓜中皂苷类成分的研究

目的：研究番木瓜果肉的化学成分,寻找活性物质。方法：用85% 乙醇提取,大孔吸附树脂、ODS、MCI 柱层析进行分离,NMR 波谱法鉴定化合物的结构。结果：从番木瓜果肉乙醇提取物中分离到3 种化合物,分别为2β,3β - 二羟基- 乌苏酸(Ⅰ)、3-O- 葡萄糖- 甾苷(Ⅱ)、薯蓣皂苷元-3-O- β -D- 吡喃葡萄糖基(1 → 3)- β -D- 吡喃葡萄糖基(1 → 4)-[α -L- 吡喃鼠李糖基(1 → 2)]- β -D- 吡喃葡萄糖苷(Ⅲ)。     

番木瓜籽蛋白质的提取工艺及其功能性质

以番木瓜籽为原料,经脱脂以酸沉碱溶法提取其中的蛋白质,并研究其乳化、起泡等功能性质。结果表明,最佳的提取工艺条件:料液比1∶40,p H为9.3,温度50℃,碱提时间120 min时最高提取率达到48.53%。番木瓜籽蛋白质的乳化性及稳定性随着蛋白质的浓度升高而升高,在p H3时最小,其乳化性在Na Cl浓度为0.2%时最大,而稳定性呈下降趋势;起泡性及稳定性随蛋白浓度升高而升高,在p H3.0,其起泡性和泡沫稳定性最小,在离子浓度(Na Cl)为0.2 mol/L时,其起泡性和泡沫稳定性最高。可见,此提取工艺效果较好,能将部分番木瓜籽蛋白质提取出来;番木瓜籽分离蛋白质乳化性和起泡性良好,这为番木瓜籽蛋白质的开发利用提供参考依据。      

Characterisation of odour‐active compounds in papaya (Carica papaya L.) wine

The volatile compounds of papaya wine were isolated by continuous solvent extraction and analysed by gas chromatography‐flame ionization detector and gas chromatography‐mass spectrometry. A total of 118 volatile constituents were detected, and ninety‐seven were positively identified. The composition of papaya wine included fifty‐three esters, twenty‐two alcohols, nine acids, seven phenols and derivatives, seven sulphur compounds, five lactones, five terpenes, three ketones, two aldehydes and five miscellaneous compounds. The aroma‐active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis and by odour activity values. Six odorants were considered as odour‐active volatiles: ethyl octanoate, (E)‐β‐damascenone, 3‐methylbutyl acetate, benzyl isohtiocyanate; ethyl hexanoate and ethyl butanoate.     

Characterization and antioxidant evaluation of phenolic compounds extracted from the protein concentrate and protein isolate produced from pawpaw (Carica papaya Linn.) seeds

In this study, the qualitative and quantitative analysis of the absolute (100%) and aqueous (80%) methanolic extract of Carica papaya Linn processed seed flour samples in terms of their antioxidant properties and their phenolic compounds was investigated. The antioxidant properties were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power, and metal chelating assay methods. The protein isolate exhibited higher radical scavenging activity power as compared to other samples. Ferulic acid, caffeic acid, p-coumaric acid, kaempferol-3-glucoside, p-hydroxybenzoic acid, and quercetin-3-galactoside were phenolic compounds isolated with ferulic acid as high as 0.62 mg/DWg. Carica papaya seed isolates and concentrate demonstrated potent antioxidant activity and could be of nutraceutical importance in the pharmaceutical and food industry.     

黄麻纤维中黄酮类化合物提取工艺优化及表征

为充分开发黄麻纤维的应用价值,探究其中是否含有黄酮类化合物,采用水醇提取法制备了黄麻纤维提取液,利用紫外分光光度法测试提取液中黄酮含量,按照二次通用旋转组合设计方法对提取工艺进行优化,研究了乙醇体积分数、浴比、提取时间3个工艺因子与黄酮类化合物提取率之间的关系.对经过旋转蒸发和真空冷冻干燥后黄麻纤维提取物的化学结构、热...     

Characterization of cellulosic fibers from Morus alba L. stem

The chemical microstructural, physical, and thermal properties of the Morus alba L. stem fibers (MAFs) are described for the first time in this work. By analyzing the results of chemical composition, it was observed that the cellulose content of the stem of MAFs is an acceptable value when compared with other fibers and showed better results. Due to their lightweight (1316 kg/m³) and the presence of high cellulose content (58.65%) with very little amount of wax (0.56%), they provide good bonding properties. In addition, analyzing the results of X-ray diffraction and Fourier transform infrared spectroscopy, we observe a degree of crystallinity of 62.06%, which is closely associated with the presence of crystalline cellulose, while the other components are amorphous. The diameter of the extracted cellulosic fibers was in the range 6–20 µm. Moreover, it was possible to identify the degradation step of each primary component of lignocellulosic fiber and to observe that it is thermally stable up to 216°C. The characterization results show that the MAF is a better replacement material for synthetic fibers because of its significant physical, chemical, and thermal properties.     

Physicochemical properties of konjac glucomannan extracted from konjac flour by a simple centrifugation process

Konjac flour (KF) contains main polysaccharide, konjac glucomannan (KGM) that is applied in various applications; however, extraction of KGM is complicated. A simple centrifugation process was used to extract KGM from KF and the influence of extraction temperatures on its physicochemical properties was determined. The centrifugation process was effective for the extraction of KGM and the results revealed two effective temperatures (35 °C and 75 °C). The extracted KGM was easy to grind. Ash and protein contents of the extracted KGM were clearly reduced, however the ash and protein contents of the KGM extracted at the high temperature (75 °C) were significantly lower than that extracted at the low temperature (35 °C), and thus proofs the extraction at the high temperature to be more effective. Furthermore, improved purities in both extracted glucomannan samples were attained in comparison to commercial KGM. While the yield percentages of the samples differed, no significant disparity in morphology and particle size was determined. Particles of both extracted KGM were comparable in shape and size. Moreover, the transparency of both extracted KGM solutions was higher than commercial KGM solution. These results suggested that the extraction temperature at 75 °C is effective in extraction KGM from KF.     

原生态椰子油不同提取方法下理化特性比较研究

采用湿磨加工、干法加工、热处理和酶解法从椰子中提取原生态椰子油(VCO),利用气相色谱仪、油脂氧化稳定性测定仪、差示扫描量热仪对VCO进行了理化特性的研究,并与商业椰子油进行对比。同时利用酶解法提取的VCO与商业棕榈油的抗氧化性进行比较。结果表明:VCO的脂肪酸组成以饱和脂肪酸为主,约为90%左右,酶解法提取的VCO的饱和脂肪酸含量高达95.1%,干法加工提取的VCO具有较高的不饱和脂肪酸,其中油酸含量较高;酶解法提取的VCO的氧化诱导时间差异显著,在140℃下的氧化诱导时间最长,达7.5 h,且显著长于棕榈油的,酶解法提取的VCO氧化稳定性最好;VCO熔点范围和结晶温度范围分别为25~26℃和-10~10℃。     

Physicochemical and emulsifying properties of protein extracted from soybean meal assisted by steam flash-explosion

The conventional alkaline aqueous extraction is not effective in promoting maximum protein yield from soybean meal (SBM). In this study, the steam flash-explosion (SFE) treatment was firstly employed to significantly improve the protein yield, while the protein content of soy protein isolate (SPI) decreased, concomitant with increase in carbon content of SPI. The SFE treatment led to the dissociation of insoluble protein aggregates in SBM, with subsequent increase of soluble protein aggregates formed via on-disulfide covalent bonds. The covalent coupling of the carbohydrate to the protein during SFE treatment can contribute to the dissolubility of protein and the formation of protein aggregates. After SFE treatment, surface hydrophobicity of SPI was decreased, however the emulsifying properties were improved. The emulsifying activity index and emulsifying stability index were improved to 41.94 m²/g and 35.27 min under 1.3 MPa, 180 s treatment condition. It indicated that compared to surface hydrophobicity, changes of other aspects of protein structure including the covalent coupling of carbohydrate to protein were the predominant factors that ruled the emulsifying property of protein.Industrial relevanceThe steam flash-explosion treatment (SFE) is an eco-friendly, low-energy and non-traditional technology, which could be performed on a large scale for the industry. The SFE treatment can effectively change the physicochemical properties of protein resulting in significant increase of protein yield and improvement in emulsifying properties of protein. After SFE treatment, the protein from heat-denatured soybean meal can be refunctionalized for application in food industry.     

Isolation and characterization of a 'quinone-trapping' substance from a crude Carica papaya protein preparation

The oxidation of different phenols [4-methylcatechol, chlorogenic acid, (−)-epicatechin and (+)-catechin] by endive polyphenoloxidase (PPO) was investigated in the presence of an extract from Carica papaya . The occurrence of cysteine and another 'quinone-trapping' substance in the extract was demonstrated. The unknown substance was purified, as a 4-methylcatechol conjugate form, by a combination of Bio-gel Pz chromatography and semipreparative high-performance liquid chromatography (HPLC). Use of liquid chromatography/tandem mass spectroscopy (LC–MS/MS) equipment and an amino acid analyser allowed us to identify this agent as a dipeptide cysteine-glutamic acid, commercially available as γ-Glu-Cys. γ-Glu-Cys formed one adduct compound with 4-methylcatechol and chlorogenic acid, and two with the flavan-3-ols. The thiol adducts were not substrates for endive PPO but, in the case of the 4-methylcatechol conjugate, they acted as competitive PPO inhibitors.     

Physicochemical properties of the starchy flour extracted from sweet potato tubers through lactic acid fermentation

The efficiency of starch extraction from sweet potato tubers was improved by lactic acid fermentation using a mixed culture inoculum. Study of the properties of the starchy flour showed that there was a significant reduction in the starch content and consequently the soluble and apparent amylose contents of fermented samples from all six varieties used. A fall in peak viscosity and viscosity breakdown was observed for fermented samples, while the pasting temperature was enhanced significantly. The fermented flour showed greater solubility and reduced swelling. Differential scanning calorimetry studies indicated a delay in gelatinisation and a fall in enthalpy of gelatinisation of the starch on fermentation. Unlike cassava, all the properties of the starch from sweet potato tubers, ie viscosity, swelling, solubility, gelatinisation temperature, amylose content and starch content, were affected by fermentation, and variation was also observed among cultivars. Copyright © 2005 Society of Chemical Industry     

白木通籽分离蛋白的理化与功能性质研究

以白木通籽为原料,采用碱提酸沉法,制备白木通籽分离蛋白（API）,并对其理化性质与功能性质进行了分析。结果表明:白木通籽分离蛋白含17种氨基酸,其中谷氨酸和天门冬氨酸的含量相对较高,有贮藏蛋白的共性。苏氨酸为白木通籽分离蛋白的第一限制性氨基酸。通过SDS-PAGE分析,白木通籽分离蛋白的亚基分子量范围为25～35ku。圆二色性光谱分析表明,白木通籽分离蛋白的二级结构主要由β-折叠和无规则卷曲组成,含量分别为31.2%和36.6%。白木通籽分离蛋白的等电点在pH4～5之间,在此pH范围内,蛋白的溶解性和起泡能力均最低。      

Micro-heterogeneity of cellulosic fiber biopolymer prepared from corn hulls

Z-trim is a zero calorie cellulosic fiber biopolymer produced from corn hulls. The micro-structural heterogeneities of Z-trim biopolymer were investigated by monitoring the thermally driven displacements of well-dispersed micro-spheres via video fluorescence microscopy named multiple-particle tracking (MPT). By comparing the distribution of the time-dependent mean-square displacement (MSD) of polystyrene micro-spheres embedded in three concentrations of Z-trim, we found that the degree of heterogeneity of the suspensions increased dramatically within a narrow range of concentrations. The ensemble-averaged MSD of 0.5 g/100 g Z-trim biopolymer exhibited a power-law behavior that scaled log-linearly with time lag. This behavior was similar to that of homogeneous aqueous glycerol solution. But the MSD distribution for Z-trim was wider and more asymmetric than for glycerol. Increasing Z-trim concentration caused more deviation of micro-spheres colloidal dispersion from homogeneity as detected by the MPT.     

响应面试验优化番木瓜籽中硫代葡萄糖苷酶解工艺

通过单因素试验和Box-Behnken试验设计响应面分析对番木瓜籽中硫代葡萄糖苷（硫苷）的酶解条件进行优化。通过气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用仪鉴定酶解产物中的异硫氰酸酯种类。结果表明：酶解缓冲液pH值、酶解时间对异硫氰酸酯得率有显著影响,酶解温度影响不显著;得到的最优酶解条件为酶解缓冲液pH 4.8、酶解时间40 min、酶解温度27 ℃,在此条件下异硫氰酸酯得率为13.5‰;GC-MS结果表明,番木瓜籽硫苷酶酶解产物中只含有异硫氰酸苄酯一种异硫氰酸酯。