Characteristics of Dioxane Lignins Isolated at Different Ages of Nalita Wood (Trema orientalis)

Abstract

Nalita (Trema orientalis) is one of the fastest growing trees in the tropical countries. The structural characteristics of lignin isolated at different ages of Nalita wood (Trema orientalis) by acidolytic dioxane method were examined by UV, FTIR, ¹H‐NMR and ¹³C‐NMR spectroscopy, alkaline nitrobenzene oxidation, molecular weight determination, elemental and methoxyl analysis. The data were compared with aspen lignin. The structural analysis revealed that Nalita wood lignin is syringyl‐guaiacyl type. The methoxyl content in Nalita wood lignin was lower than aspen lignin. The C₉ formulas for 30‐months‐old Nalita was C₉H_9.31O_3.13(OCH₃)_1.27, whereas that of aspen was C₉H_8.94O_3.15(OCH₃)_1.47. The weight average molecular weight of Nalita wood lignin was decreased from 36,500 to 25,500 with increasing tree age from 12 to 30 months, whereas weight average molecular weight of aspen was 20,000. Both alcoholic and phenolic hydroxyl group in Nalita wood lignin is lower than aspen lignin.     

Defining the stability interfaces of apple juice: Implications on the optimisation and design of High Hydrostatic Pressure treatment

In this article an experimental approach is applied to determine the impact of High Hydrostatic Pressure (HHP) processing (350 to 550 MPa at 20 °C and for 1 to 25 min of holding time) on the survival of Issatchenkia orientalis and the spoilage of apple juice (with 300 ppm added ascorbic acid) during different storage conditions, i.e., 4 to 12 °C and 0 to 36 days of storage. Probabilistic modelling approaches based on logistic regression models were developed in order to describe quantitatively the spoilage/no spoilage and survival/death interfaces. For a microbially stable processed apple juice treated at 400 MPa, 10 °C and a holding time of 15 min the degradation kinetics of vitamin C were described quantitatively during subsequent storage at 4, 8, 12 °C. The rate of vitamin losses were highly reduced after the first 13 days of storage. The stability of the apple juice with respect to browning and cloudiness was evaluated by studying qualitatively the activity of polyphenol oxidase (PPO), and pectin methyl esterase (PME) enzymes at combined treatments of HHP and temperature (10 to 50 °C, HHP at 750 MPa and holding time from 1 to 25 min). The highest achieved reduction of PPO and PME was 51.47% and PME 81.44%, respectively.

Industrial relevance

This paper demonstrates an approach based on quantitative probabilistic and qualitative studies for defining the stability interfaces of apple juice. Its applicability contributes on the design and optimisation of High Hydrostatic Pressure treatments.     

两株高效代谢木质纤维素稀酸水解物产乙醇的酵母特性及耐毒研究

对实验室筛选出的两株高效代谢木质纤维素稀酸水解液产乙醇的酵母菌Y1(Candida tropicalis)和Y4(Issatchenkiaorientalis)的乙醇发酵特性及耐毒能力进行了的研究。以未经任何脱毒处理的木质纤维素稀酸水解液为发酵底物进行乙醇发酵(原位脱毒乙醇发酵)。结果表明,Y1和Y4均能在24h内将水解液中所有的葡萄糖消耗完,乙醇产率分别为0.49g/g和0.45g/g,分别达到了理论值的96.1%和86.0%。在含有不同浓度梯度的糠醛及5-羟甲基糠醛的模拟水解液中,Y1和Y4能耐受的最高糠醛浓度均为5.0g/L,最高的5-羟甲基糠醛浓度均大于7.0g/L,当两种抑制剂等量混合时,两株菌能耐受的最高浓度为4.0g/L。两株菌均有较好的乙醇发酵及耐毒能力。该研究结果为木质纤维素水解液的原位脱毒发酵生产然料乙醇奠定了基础。     

不同树龄侧柏木精油差异的研究

本文采用超临界流体法提取三种不同树龄的侧柏木精油,并研究了三种侧柏精油在提取率、感官性状、精油组成和抑菌功效等方面的差异。研究结果表明,树龄越老的侧柏木的精油提取率越高,最高可达到9.98%,精油的芳香气味也更浓郁醇正;采用GC-MS法分析精油成分,发现树龄越老的侧柏木的精油其主要成分罗汉柏烯、雪松醇、花侧柏烯等含量也越高;采用最低抑菌浓度(MIC)法比较了三种精油的抑菌功能,发现树龄越老的侧柏木精油其MIC也越低,对四种细菌(金黄色葡萄球菌、乳酸菌、大肠杆菌和沙门氏菌)的MIC均可低至0.05 mg/m L,说明其具有高效的抑菌效果。本文研究结果表明,侧柏木的陈化时间对其精油的风味、含量、组成和功能等方面均具有重要影响,树龄越老的侧柏木精油利用价值越高。     

陆生伊萨酵母降解L-苹果酸和柠檬酸的研究

利用陆生伊萨酵母对L-苹果酸和柠檬酸进行降解,考察菌株的耐受性,陆生伊萨酵母可耐受SO2的最大质量浓度为450mg/L、体积分数5%的酒精、最低pH值为2的酸度。对培养基进行优化,最佳氮源胰蛋白胨质量浓度为0.5g/100mL时,降酸率最高,达90%以上。对降酸条件进行优化,接种量在1.25×106～7.5×106CFU/mL范围内,培养时间为60h时,菌株对质量浓度为8～20g/L的L-苹果酸和质量浓度为8～12g/L柠檬酸降解率均达90%以上。     

用ICP—MS法测定四个不同地区泽泻中微量元素的含量

本文采用电热板—HNO_3—H_2O_2消解体系,电感耦合等离子体质谱(ICP—MS)法对分别产于福建建瓯、福建龙海、江西彭山、四川罐县等四个不同地区的泽泻进行微量元素的定量分析,通过数据处理统计,对泽泻中微量元素含量测定的结果、方法的准确性及其应用进行初步探讨。     

Selective Biosorption of Zirconium and Hafnium from Acidic Aqueous Solutions by Rice Bran,Wheat Bran and Platanus Orientalis Tree Leaves

Abstract

The Zr(IV) and Hf(IV) biosorption characteristics of rice bran, wheat bran and Platanus orientalis tree leaves were examined as a function of initial pH, contact time, temperature, and initial metal ions concentration. Adsorption equilibriums were achieved in about 1, 5 and 40 min for rice bran, wheat bran, and leaves respectively. The biosorption behavior of leaves was significantly affected by solution pH whereas rice bran and wheat bran adsorption efficiencies were slightly affected by solution pH. The Freundlich and Langmuir adsorption equations, which are commonly used to describe sorption equilibrium for metals removal by biomasses, were use to represent the experimental and equilibrium data fitted well to the Langmuir isotherm model. The negative Gibbs free energy values obtained in this study with rice bran wheat bran and Platanus orientalis tree leaves confirmed the feasibility of the process and the spontaneous nature of sorption. In the optimum conditions, the adsorption efficiencies of other metal ions such as Fe³⁺, Cu²⁺, Pb²⁺, Hg²⁺, La³⁺, Ce³⁺ were significantly lower than Zr(IV) and Hf(IV) ions and these biomasses are excellent sorbents for the selective uptake of proposed ions from acidic aqueous solutions.     

泽泻提取物中萜类单体V-54对小RNA病毒增殖的抑制效应

目的探讨泽泻提取物中提取的萜类衍生物单体V-54对小RNA病毒感染增殖的抑制效应及其生物学机理。方法采用KMB17细胞,分别感染HAV-H、PV-Ⅰ和Cox-B2病毒,经V-54处理后检测病毒滴度,分析PV-Ⅰ和Cox-B2病毒增殖抑制的动力学及V-54对KMB17细胞凋亡的影响。结果V-54可抑制3种病毒在KMB17细胞上增殖,PV-Ⅰ和Cox-B2病毒感染滴度比未处理组明显降低,V-54对两种病毒的抑制作用呈剂量依赖性。作用24h内,V-54可使KMB17细胞凋亡率明显增加,随后逐渐恢复正常。结论V-54可抑制特定的小RNA病毒的感染增殖,其机制可能为V-54分子结合到细胞表面的相关受体,导致病毒感染效率降低。     

Reliable identification of closely related Issatchenkia and Pichia species using artificial neural network analysis of Fourier‐transform infrared spectra

A reliable identification system for closely related species of the genera Issatchenkia and Pichia was established, using artificial neural network‐based Fourier‐transform infrared (FTIR) spectroscopy; 16 common Pichia species and all five known Issatchenkia species were included. A total of 238 strains isolated from a large variety of habitats were used as reference strains to generate an artificial neural network (ANN) identification system. This system consists of 10 single subnets connected to an ANN with four consecutive levels. An internal validation of the system, using unknown spectra of each reference strain, yielded an identification rate of 99.2%. To evaluate the performance of the ANN in routine diagnostics, 1608 spectra of 179 strains unknown to the ANN were used as a test dataset in an external validation. An overall identification rate of 98.6%, including a success rate of 100% for two common species, P. anomala and P. membranifaciens, demonstrates considerable potential of this FTIR‐based artificial neural network for the identification of closely related yeast species. Copyright © 2008 John Wiley & Sons, Ltd.