The effects of autohydrolysis pretreatment on the structural characteristics, adsorptive and catalytic properties of the activated carbon prepared from Eucommia ulmoides Oliver based on a biorefinery process.

Eucommia ulmoides Oliver (EU) wood was consecutively treated by autohydrolysis pretreatment and chemical carbonization post-treatment based on a biorefinery process. Results showed that the optimal condition of the autohydrolysis pretreatment and carbonization process yielded 10.37kg xylooligosaccharides (XOS), 1.39kg degraded hemicellulosic products, 17.29kg other degraded products from hemicelluloses and 40.72kg activated carbon (SBET of 1534.06m2/g) from the 100kg raw materials. Simultaneously, 29.14kg gas products generated from the optimum integrated process was significantly lower than that from the direct carbonization process (68.84kg). Besides, the optimal activated carbon (AC170-1.0) also showed a moderate catalytic activity and high stability for hydrogen production by catalytic methane decomposition. Overall, the data presented indicated that the integrated process is an eco-friendly and efficient process to produce XOS and activated carbon, which is beneficial for value-added and industrial application of EU wood.

Effect of structural changes of lignin during the autohydrolysis and organosolv pretreatment on Eucommia ulmoides Oliver for an effective enzymatic hydrolysis.

Eucommia ulmoides Oliver (EU) wood was successively treated by autohydrolysis and organosolv pretreatment integrated process. Autohydrolysis pretreatment facilitated xylooligosaccharides production, subsequent organosolv pretreatment to obtain high-purity lignin and digestible cellulose-rich residue. Results showed that the lignin fractions obtained exhibited smaller molecular weights, narrow polydispersity, more phenolic OH groups and higher syringyl/guaiacyl ratios (S/G) than the milled wood lignin. NMR characterization of the lignin revealed that the ß-O-4 linkages significantly cleaved and the structure of stilbene formed, but its resinol (ß-ß) was resistant to be degraded by organosolv delignification. Moreover, the glucose yield of the integrated residue achieved a maximum value of 89.3% after enzyme hydrolysis, separately about 1.0, 1.3, 3.8 times as compared to that of the ethanol organosolv residue, the hydrothermally treated residue and the EU wood, respectively, which indicated that the integrated process was a promising approach to value-added utilization of the EU wood.

Reduced polyphenol oxidase gene expression and enzymatic browning in potato (Solanum tuberosum L.) with artificial microRNAs.

BACKGROUND: Polyphenol oxidase (PPO), often encoded by a multi-gene family, causes oxidative browning, a significant problem in many food products. Low-browning potatoes were produced previously through suppression of PPO gene expression, but the contribution of individual PPO gene isoform to the oxidative browning process was unknown. Here we investigated the contributions of different PPO genes to total PPO protein activity, and the correlations between PPO protein level, PPO activity and tuber tissue browning potential by suppression of all previously characterized potato PPO genes, both individually and in combination using artificial microRNAs (amiRNAs) technology. RESULTS: Survey of the potato genome database revealed 9 PPO-like gene models, named StuPPO1 to StuPPO9 in this report. StuPPO1, StuPPO2, StuPPO3 and StuPPO4 are allelic to the characterized POTP1/P2, POT32, POT33 and POT72, respectively. Fewer ESTs were found to support the transcriptions of StuPPO5 to StuPPO8. StuPPO9 related ESTs were expressed at significant higher levels in pathogen-infected potato tissues. A series of browning phenotypes were obtained by suppressing StuPPO1 to StuPPO4 genes alone and in combination. Down-regulation of one or several of the PPO genes did not usually cause up-regulation of the other PPO genes in the transgenic potato tubers, but resulted in reduced PPO protein levels. The different PPO genes did not contribute equally to the total PPO protein content in the tuber tissues, with StuPPO2 accounting for ~ 55% as the major contributor, followed by StuPPO1, ~ 25-30% and StuPPO3 and StuPPO4 together with less than 15%. Strongly positive correlations between PPO protein level, PPO activity and browning potential were demonstrated in our analysis. Low PPO activity and low-browning potatoes were produced by simultaneous down-regulation of StuPPO2 to StuPPO4, but the greatest reduction occurred when StuPPO1 to StuPPO4 were all suppressed. CONCLUSION: StuPPO1 to StuPPO4 genes contributed to browning reactions in tuber tissues but their effect was not equal. Different PPO genes may be regulated independently reflecting their diversified functions. Our results show that amiRNAs can be used to suppress closely related members of highly conserved multi-gene family. This approach also suggests a new strategy for breeding low-browning crops using small DNA inserts.

Improved on-line high performance liquid chromatography method for detection of antioxidants in Eucommia ulmoides Oliver flower.

Eucommia ulmoides Oliver is a traditional Chinese medicine and material for functional food with a strong antioxidant activity. To investigate antioxidants in E. ulmoides Oliver flower, an improved on-line high performance liquid chromatography method with the radical cation 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS(+)) as a stable model free radical for the detection of radical scavenging ability was developed. The radical concentration, flow rate, and length of reaction coil were optimized with rutin as a model antioxidant. Under the optimized instrumental set-up, a radical solution of 0.32 mM ABTS(+) is delivered by a pump equipped with a superloop at 0.5 mL/min through a reaction coil of 10 m × 0.25 mm. This method showed a high sensitivity since the system noise was reduced by the superloop. The minimum detecting concentration of the method was in the range of 0.03-0.10 µM for the negative peaks of rutin, quercetin, ascorbic acid, and α-tocopherol. Importantly, the method could be not only used for detection of antioxidants in plant extracts but also combined with mass spectrometry to obtain the structural messages of peaks in high performance liquid chromatography profiles. After analysis by the method, nineteen antioxidants were found in E. ulmoides Oliver flower extract, and the main active compound was identified as chlorogenic acid.

Seasonal difference in antioxidant capacity and active compounds contents of Eucommia ulmoides oliver leaf.

Leaf of Eucommia ulmoides Oliver (EU) is a Traditional Chinese Medicine and a functional food in China. Antioxidant contents of EU leaves, which were collected monthly during the period of May-October in three years, were determined. Samples' antioxidant capacity was characterized by DPPH radical scavenging activity, hydroxyl radical scavenging activity, ferrous chelating ability, and antioxidant capacity in linoleic acid emulsion and in rapeseed oil assays. The results showed that contents of some active compounds and antioxidant activity were related to a certain time of the year. Samples collected in August showed high content of phenolics, and the samples collected in May contained higher amount of flavonoids than other samples. Leaves collected in May or June exhibited high contents of rutin, quercetin, geniposidic acid and aucubin. The August leaves showed stable and high DPPH radical scavenging activity, and ferrous chelating ability. May samples showed strong inhibitory effects on oxidation of rapeseed oil and linoleic acid. The DPPH radical scavenging activity was related to the total phenolics content. Flavonoids played an important role in the inhibitory effects on rapeseed oil and linoleic acid oxidation. Therefore, August and May were indicated as the best months to harvest EU leaves for industry.

[Carbon sequestration of young Robinia pseudoacacia plantation in Loess Plateau].

In order to understand the carbon sequestration of ecological forests in Loess Plateau, a comparative study was made on the organic carbon density (OCD) of soil, litter, and plant organs in an 8-year-old Robinia pseudoacacia plantation and nearby barren land. Comparing with the barren land, the young R. pseudoacacia plantation had a decrease (0.26 kg x m(-2)) of soil OCD, but the OCD in its litter, root system, and aboveground organs increased by 121.1%, 202.0%, and 656. 7%, respectively, with a total carbon sequestration increased by 3.3% annually, which illustrated that R. pseudoacacia afforestation on Loess Plateau had an obvious positive effect on carbon sequestration.

Studies on the preparation of biodiesel from Zanthoxylum bungeanum Maxim seed oil.

To reduce the cost of biodiesel production, the feasibility of Zanthoxylum bungeanum Maxim seed oil (ZBMSO) was studied to produce biodiesel. A methyl ester biodiesel was produced from ZBMSO using methanol, sulfuric acid, and potassium hydroxide in a two-stage process. The main variables that affect the process were investigated. The high level of free fatty acids in ZBMSO was reduced to < 1% by an acid-catalyzed (2% H2SO4) esterification with methanol to oil molar ratios of 20-25:1 for 1 h. A maximum yield of 96% of methyl esters in ZBMSO biodiesel was achieved using a 6.5:1 molar ratio of methanol to oil, 0.9% KOH (percent oil), and reaction time of 0.5 h at 55 degrees C. Further investigation has also been devoted to the assessment of some important fuel properties of ZBMSO biodiesel produced under the optimized conditions according to specifications for biodiesel as fuel in diesel engines. The fuel properties of the ZBMSO biodiesel obtained are similar to those of no. 0 petroleum diesel fuel, and most of the parameters comply with the limits established by specifications for biodiesel.

Periploca sepium Bunge as a model plant for rubber biosynthesis study.

Periploca sepium Bunge (Chinese silk vine) is a woody climbing vine belonging to the family Asclepiadaceae. It originally comes from Northwest China. Periploca resembles the Para-rubber tree, Hevea brasiliensis, regarding a similar body plan to produce a milky exudate containing rubber latex. The Periploca plant was assessed as a rubber-producing plant by rubber structure elucidation and its molecular weight distribution. A rubber fraction purified from the milky exudate was subjected to 1H NMR analysis, and a characteristic signal derived from cis-polyisoprene was observed. In addition, when the molecular weight distribution of rubber components in the exudate was measured (using size-exclusion chromatography), the number-average molecular weight (Mn), weight-average molecular weight (Mw), and polydispersity (Mw/Mn) were estimated to be Mn = 1.3 x 10(5), Mw = 4.1 x 10(5), and Mw/Mn = 3.1, respectively. Furthermore, the presence of polyisoprene, with Mn = 4.0 x 10(4), Mw = 7.6 x 10(4), and Mw/Mn = 2.5, was also confirmed in plantlets obtained from shoots as a result of tissue culture.

Comparative study of crude and purified cellulose from wheat straw.

A sequential totally chlorine-free procedure for isolation of cellulose from wheat straw was proposed in this study. The dewaxed straw was pretreated with 0.5 M NaOH in 60% methanol at 60 degrees C for 2.5 h under ultrasonic irradiation for 0-35 min and sequentially posttreated with 2% H(2)O(2)-0.2% TAED at pH 11.8 for 12 h at 48 degrees C, which together solubilized 85.3-86.1% of the original hemicelluloses and 91.7-93.2% of the original lignin, respectively. The yield of crude cellulose ranged between 46.2 and 49.2% on a dry weight basis related to wheat straw, which contained 11.2-12.2% residual hemicelluloses and 2.5-2.9% remaining lignin. Further treatment of the corresponding crude cellulosic preparations with 80% acetic acid-70% nitric acid under the condition given yielded 36.8-37.7% of the purified cellulose, which contained minor amounts of bound hemicelluloses (2.5-2.8%) and was relatively free of associated lignin (0.1-0.2%). The isolated crude and purified cellulose samples were comparatively studied by FT-IR and CP/MAS (13)C NMR spectroscopy, and the relative crystallinity was also estimated. The final stage treatment with 80% acetic acid-70% nitric acid decreased the hemicelluloses and lignin associated in the crude cellulose but led to 3.1-5.4% degradation of the original cellulose; in addition, the purity of the obtained cellulose was high. However, it was found that the final stage treatment is not severe enough to cause decrystallization of cellulose. The thermal stability of the purified cellulose is higher than that of the corresponding crude cellulose.

Fractional and physico-chemical characterization of hemicelluloses from ultrasonic irradiated sugarcane bagasse.

The present study was undertaken to investigate the extractability of the hemicelluloses from bagasse obtained by ultrasound-assisted extraction methods. The results showed that the ultrasonic treatment and sequential extractions with alkali and alkaline peroxide under the conditions given led to a release of over 90% of the original hemicelluloses and lignin. This fact as well as the sugar composition and structural features of the isolated seven hemicellulosic fractions indicated that ultrasonication attacked the integrity of cell walls, cleaved the ether linkages between lignin and hemicelluloses, and increased accessibility and extractability of the hemicelluloses. Increasing alkali concentration from 0.5 to 2M and alkaline peroxide percentage from 0.5% to 3.0% resulted in degradation of hemicellulosic backbone as shown by a decrease in their molecular weights from 43,580 to 14,470 and 30,180 to 18,130gmol(-1), respectively. However, there were no significant differences in the structural features of the seven sequential alkali- or alkaline peroxide-soluble hemicellulosic fractions, which are composed mainly of L-arabino-(4-O-methyl-D-glucurono)-D-xylans. Ferulic and p-coumaric acids were found to be chemically linked with hemicelluloses.