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Shen X.L.,Southwest University | Shen X.L.,China Agricultural University | Wu J.M.,Southwest University | Chen Y.,China Rural Technology Development Center | And 3 more authors.
Food Hydrocolloids

Antimicrobial biodegradable films have been prepared with sweet potato starch by incorporating potassium sorbate or chitosan. Films incorporated with potassium sorbate ≥ 15% or chitosan ≥ 5% were found to have an anti-Escherichia coli effect. Staphylococcus aureus could be effectively suppressed by incorporation of chitosan at ≥10%. Whereas potassium sorbate lowers the tensile strength and elongation at break, and raises the oxygen permeability, water vapor permeability and water solubility, chitosan has the opposite effect. Fourier Transform Infrared (FT-IR) spectra analysis revealed that starch crystallinity was retarded by potassium sorbate incorporation and that hydrogen bonds were formed between chitosan and starch. This explained the modification of the mechanical and physical properties of the films by the incorporation of these two antimicrobial agents. © 2009 Elsevier Ltd. All rights reserved. Source

Liu J.-F.,Tianjin University of Commerce | Liu J.-F.,Tianjin Key Laboratory of Food Biotechnology | Liu H.,Chinese Academy of Agricultural Sciences | Tan B.,Academy of State Administration of Grain | And 2 more authors.
Journal of Molecular Catalysis B: Enzymatic

A nanosized support for reversible immobilization of enzymes, magnetic poly(glycidyl methacrylate-ethylene glycol dimethacrylate-hydroxyethyl methacrylate) nanospheres grafted with polyethyleneimine, was prepared and characterized by scanning electron microscopy and vibrating sample magnetometry. The novel support displayed 3.2-fold higher adsorption capacity for Kluyveromyces fragilis β-galactosidase than commercial ion exchange resin DEAE-Sepharose, the maximum amount of the enzyme adsorbed on the support reached 86.7 mg/g with enzyme activity recovery of 92.5%. The adsorbed K. fragilis β-galactosidase showed high catalytic activity and operational stability for synthesis of galacto-oligosaccharide (GOS), 4.5 kg of GOS were produced per gram of adsorbed enzyme from lactose during 15 consecutive batch reactions by reuse of the same biocatalyst, and the immobilized biocatalyst retained about 84.6% of its initial activity after 15 cycles of batch operation. The support could be regenerated and reused, remaining 93.0% of its original adsorption capacity at the end of the twentieth adsorption-desorption cycle. © 2012 Elsevier B.V. Source

Chen L.,Beijing Normal University | Li X.,Beijing Normal University | Wen W.,Beijing Normal University | Jia J.,China Rural Technology Development Center | And 2 more authors.
Renewable and Sustainable Energy Reviews

China is rich in biomass resources, with favorable conditions for the development and utilization of biomass energy. Currently, the main secondary forms of biomass energy utilized in China include biogas, biomass power, bioethanol, biodiesel. By the end of 2010, the annual output of biogas in China had reached 14.3×10 9 m 3; the installed capacity of biomass power had reached 5.5×10 6 kw; the annual output of bioethanol had reached 1.84×10 6 t; the annual output of biodiesel was 400×10 3 t. Although China is very rich in biomass resources, the percentage of biomass energy in the total energy utilized in China is very low. In 2010, the biomass secondary energy accounted for 7.28% of the total renewable energy consumption; and only 0.66% of the primary energy consumption in China. Compared with other types of renewable energy, the biomass energy development remains very slow and even marginalized. The development of secondary sources of energy in China is relatively slow, the reasons for which are many, such as food security, high production costs, obsolete equipment, technological immaturity, insufficient raw materials, and a serious shortage of investments. In fact, the root causes for the slow development of the biomass secondary energy industry are the government's focus on economic development and the private enterprises focus on economic benefits. The lower economic benefits of the biomass secondary energy industry do not intrinsically motivate them to promote its development. Entering the market is crucial to the development of the biomass secondary energy and requires strong implementation and policy guarantees by the government. Biomass secondary energy has a positive role in reducing greenhouse gas emission, reducing waste pollution, and increasing employment opportunities. It is recommended that the government and enterprises should actively promote the development of the biomass secondary energy. © 2012 Elsevier Ltd. Source

Wu S.,Jiangnan University | Zhang H.,China Rural Technology Development Center | Shi Z.,Jiangnan University | Duan N.,Jiangnan University | And 3 more authors.
Food Control

A novel aptamer-based fluorescence biosensor was developed for the detection of chloramphenicol (CAP) using aptamer-conjugated magnetic nanoparticles (MNPs) for both recognition and concentration elements and using upconversion nanoparticles (UCNPs) as highly sensitive signal labels. The bioassay system was fabricated by immobilizing aptamer onto the surface of MNPs, which were employed to capture and concentrate CAP. In the absence of target, MNPs-aptamer hybridizes to its complementary DNA (cDNA) which was modified with UCNPs, form the duplex structure therefore giving a maximum fluorescent signal. Upon CAP addition, the aptamer preferentially bound with CAP and caused the dissociation of some cDNA, liberating some UCNPs-cDNA and leading to a decreased fluorescent signal on the surface of MNPs. Under optimized assay conditions, a wide linear detection range (from 0.01 to 1ngmL-1) was achieved with a detection limit down to 0.01ngmL-1. The proposed method then was successfully applied to measure CAP in contaminated milk samples and validated by a commercially available enzyme-linked immunosorbent assay (ELISA) method. Improved by the magnetic separation and concentration effect of MNPs, the high sensitivity of UCNPs and the high affinity of aptamers, the present method performs with both high sensitivity and selectivity for CAP. Besides, this strategy can be applied to detect other antibiotics. Utilization of the proposed biosensor for quantitative determination of antibiotics in food samples may provide significant improvements in quality control of food safety. © 2014 Elsevier Ltd. Source

Long H.,Beijing Normal University | Long H.,Beijing Academy of Agriculture and Forestry Sciences | Li X.,Beijing Normal University | Wang H.,Beijing Normal University | Jia J.,China Rural Technology Development Center
Renewable and Sustainable Energy Reviews

Biomass and bioenergy potential estimation has been worldwide research highlights in renewable energy field to get comprehensive understand of bioenergy development, especially under the situation of energy crisis. This paper reviews the results of previous studies that investigated biomass resources and their bioenergy potential estimation. It is organized from the perspectives of traditional vs. newly-introduced approaches and present vs. future. First, according to the methods used in relative studies, existing studies were divided into two categories: statistical data based and RS-GIS based. Second, concerning about the future of bioenergy, biomass and bioenergy potential estimation under different scenarios in the future were also reviewed and summarized according to the dominant factor considered in simulation. At last, based on the reviews above, questions and the future of bioenergy potential estimation were proposed so as to provide some instructions for bioenergy development. © 2013 Elsevier Ltd. Source

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