Decaffeination of fresh green tea leaf (Camellia sinensis) by hot water treatment

Hot water treatment was used to decaffeinate fresh tea leaf in the present study. Water temperature, extraction time and ratio of leaf to water had a statistically significant effect on the decaffeination. When fresh tea leaf was decaffeinated with a ratio of tea leaf to water of 1:20 (w/v) at 100 °C for 3 min, caffeine concentration was decreased from 23.7 to 4.0 mg g⁻¹, while total tea catechins decreased from 134.5 to 127.6 mg g⁻¹; 83% of caffeine was removed and 95% of total catechins was retained in the decaffeinated leaf. It is considered that the hot water treatment is a safe and inexpensive method for decaffeinating green tea. However, a large percentage of tea catechins was lost if rolled leaf and dry tea were decaffeinated by the hot water treatment and so the process is not suitable for processing black tea.     

Determination of caffeine content in tea based on poly(safranine T) electroactive film modified electrode

Safranine T was electropolymerised on a glassy carbon electrode and then characterised by scanning electron microscope (SEM), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). This uniform electropolymerised film was crystallisable and showed a high electrocatalytic ability towards the oxidation of caffeine. To avoid the interferences of the anions, Nafion was covered on the surface of poly(safranine T) film modified glassy carbon electrode. As a new voltammetric sensor, this modified electrode is sensitive, selective and stable to determine caffeine content in tea. The peak current increased linearly with the concentration of caffeine in the range of 3 × 10⁻⁷–1 × 10⁻⁴ M, with a detection limit of 1 × 10⁻⁷ M. All of these make it a useful tool for determining caffeine content in tea. What’s more, it produces much less organic waste compared with other analytical techniques.     

Methoxy poly(ethylene glycol)-grafted-chitosan based microcapsules: Synthesis, characterization and properties as a potential hydrophilic wall material for stabilization and controlled release of algal oil

Methoxy poly(ethylene glycol)-grafted-chitosan (mPEG-g-CS) was synthesized in an attempt to increase the water solubility of CS, and it was applied as wall material to microcapsulate algal oil (AO). Both Fourier transformed-infrared (FT-IR) spectra and solubility test confirmed that mPEG had been successfully grafted onto CS. The larger particles showed smooth surfaces, whereas smaller ones presented surface folds. The amount of free and total oil were 2.73 and 47.87 g/100 g, respectively, with high encapsulation efficiency of 94.30%. Fourteen fatty acids were detected in free algal oil (FAO) and microcapsulated algal oil (MAO), and the important fatty acids were preserved after microcapsulation. AO contained within microcapsules was protected from UV-light and heat compared with FAO. Release rate of AO was initially rapid and then followed by controlled release with the erosion mechanism playing a dominant role. The mPEG-g-CS proved to be a promising wall material with excellent solubility and film forming ability, and therefore supplied great potential applications in food industry.     

基于微旋流装置的大米淀粉吸附亚甲基蓝性能研究

以大米淀粉为吸附剂,在微旋流器中吸附亚甲基蓝水溶液模拟的印染废水。通过单因素试验分析淀粉浓度,分流比和进料流量对吸附效率和分离效率的影响规律。运用响应面分析法,对试验参数进行优化。结果表明:淀粉浓度、分流比和进料流量对吸附效率和分离效率均有影响,对吸附效率影响的大小顺序为淀粉浓度分流比进料流量,对分离效率影响的大小顺序为分流比进料流量淀粉浓度。综合考虑吸附效率和分离效率后得到最佳参数条件为:淀粉浓度1. 0%,分流比19%,进料流量1 080 kg/h,该条件下吸附效率为69. 2%,分离效率为74. 3%。     

Improving the dyeability of poly (lactic acid) fiber using octa (aminophenyl) POSS nanoparticle during melt spinning

Disperse dye structure affects the dyeability of poly (lactic acid) (PLA) fiber due to the low dyeing temperature and the short dyeing time. Thus, the dye uptake value of PLA fiber is low for some disperse dyes and needs to be improved. In this study, the dyeability of PLA fiber is improved with the addition of synthesized octa (aminophenyl) polyhedral oligomeric silsesquioxane (OAP-POSS) nanoparticle during the melt spinning process. The effects of dyeing conditions including dyeing temperature and time, OAP-POSS concentration, disperse dye types, and concentrations are investigated on the dyeability properties of PLA fiber samples. The tensile, thermal, and morphological properties of the fiber samples are also characterized by tensile testing, differential scanning calorimetry, scanning electron microscopy, and transmission electron microscopy. It is concluded that the percent crystallinity and the tensile strength of pure PLA fiber decrease as the added amount of OAP-POSS increases. According to the dyeing results, OAP-POSS, which behaves as a good sorbent for the disperse dyes used in this study, greatly improves the dyeability of PLA fiber, especially for disperse dyes with low dye uptake values.     

Influences of degree of hydrolysis and molecular weight of poly(vinyl alcohol) (PVA) on properties of fish myofibrillar protein/PVA blend films

Biodegradable blend films based on fish myofibrillar protein (FMP) and poly(vinyl alcohol) (PVA) were prepared and characterized. PVA with different degrees of hydrolysis (DH) and molecular weights (MW) had the impact on properties of FMP/PVA (1:1, w/w) blend film. The blend films with higher MW of PVA were more tensile resistant, as indicated by the greater tensile strength (TS) and elongation at break (EAB), while the films with PVA of lower DH were more flexible. The blend film with PVA-BP26 (DH: 86–98% mol; MW: 124,000–130,000 g/mol) exhibited the greatest tensile performance and the lowest water vapor permeability (p < 0.05), compared with other films. SEM and FTIR results revealed that FMP and PVA were compatible and their intermolecular interaction was enhanced, providing the blend film with desirable properties. Therefore, incorporation of PVA with appropriated DH and MW could improve the properties of the FMP-based film.     

Preparation and characterization of electrically semi-conductive polyfuran-coated poly(ethylene terephthalate) fibers

One of the most important textile materials, poly(ethylene terephthalate) (PET) fiber, was coated with a semi-conductive polyfuran (PFu) by in situ oxidative polymerization using FeCl₃ oxidant in solvent mixture of acetonitrile–chloroform. The effects of polymerization conditions such as volume ratios of acetonitrile/chloroform, monomer concentration, and oxidant/monomer mol ratio were investigated on PFu content (%) of the composites. It was observed that pretreatment of PET in dichloromethane increased PFu content and its coating continuity before polymerization. The highest PFu content (12.0%) was obtained using FeCl₃/furan mol ratios of 3.5 in acetonitrile/chloroform mixture (5/1). The density values of the composites with different PFu contents were measured. Composite fibers were also subjected to doping processes with HCl and I₂ vapors, separately, and it was observed that the surface resistivity of PFu/PET (10¹² Ω/cm²) reached to 53 Ω/cm² after doping with I₂. The structural, thermal, and morphological characterization was performed with FTIR, XRD, TGA, and SEM, respectively.     

海藻酸丙二醇酯对馒头品质的影响研究（网络首发、推荐阅读）

将不同浓度的海藻酸丙二醇酯（PGA）加入小麦粉中，探究PGA对小麦粉糊化特性、面团流变性、微观结构及馒头质构和感官品质的影响。结果显示，添加PGA后小麦粉的糊化温度由58.8 ℃升高至59.5 ℃、最大拉伸阻力由518 EU增加至597 EU，增加了近15%，同时水分在面团中的分布更加均匀，面团的硬度增加、流变特性中的损耗角的正切值tanδ（G''/G"）持续增加，最终导致馒头的比容、光泽度和咀嚼性增加。实验结果表明，当小麦粉中PGA浓度为500~1 000 mg/L时的馒头品质最佳，过量的PGA会缩小馒头体积，使馒头口感变硬。PGA的亲水亲油性质促使水分更加均匀分布在面团结构中，显著影响面团的操作特性，促进馒头品质提升。     

UV resistance graft modification of poly(p-phenylene-l,3,4-oxadiazole) fiber with polyhedral oligomeric silsesquioxane

Using the reaction of amino and acyl chloride generated amide bond, poly(p-phenylene-1,3,4-oxadiazole) (p-POD) fiber was pretreated with sulfuric acid solution and was acyl chlorinated with dichloromethane and thionyl chloride. Then octa-ammonium polyhedral oligomeric silsesquioxanes (POSS-NH₂) linked on the fiber surface with the amide bond, which was as UV absorbent to retard UV photoaging. Under the existing experimental conditions, a higher sulfuric acid solution concentration, a higher temperature or a longer time was beneficial for increasing the fixed amount of POSS and prevent the UV accelerated aging of the fiber. The surface morphology, tensile strength, crystallinity, degree of orientation of fibers, and intrinsic viscosity of polymer solution were characterized in detail. This graft process with POSS-NH₂ introduced silicon elements onto the fiber surface. Changes in the surface morphology and chemical composition are not obvious, except that part of the oxadiazole rings were opened. After UV-accelerated aging, the degree of orientation and the crystallinity of the fiber and the intrinsic viscosity of polymer solution were well maintained. The condensed and macromolecular structures of the fiber were well protected.     

茶多酚对籼米淀粉回生抑制作用的研究

研究了天然抗氧化提取物茶多酚（TPLs）对籼米淀粉回生的影响。采用差示扫描量热仪（DSC）、X-射线衍射仪（XRD）和扫描电镜（SEM）评价茶多酚对淀粉回生的抑制作用。结果表明,淀粉的糊化温度和焓值随着TPLs添加量的增加而明显降低,添加16%TPLs（基于淀粉重）淀粉样品的糊化To、Tp和Tc分别提前8.93、5.69和5.13℃,糊化焓值则降低2.27J/g;在4℃下贮存,淀粉的回生焓值和重结晶随着TPLs添加量的增加逐渐降低,添加16%TPLs（基于淀粉重）的糊化淀粉样品贮存15d后没有出现回生焓值以及重结晶。在SEM相同放大倍数下回生淀粉颗粒形貌显示,随着TPLs添加量的增加颗粒逐渐减小并呈网孔状。以上结果证明,茶多酚对籼米淀粉回生有显著抑制作用。     

Precise control of repeating unit composition in biodegradable poly(3-hydroxyalkanoate) polymers synthesized by Escherichia coli

The composition of medium-chain-length (MCL) poly(3-hydroxyalkanoate) (PHA) biopolymers is normally an uncontrollable random mixture of repeating units with differing side chain lengths. Attempts to generate MCL PHA homopolymers and control repeating unit composition have been published in native PHA-producing organisms but have limited ranges for the different sizes of repeating units that can be synthesized. In this study, a new Escherichia coli-based system that exhibits control over repeating unit composition for both MCL PHAs and short-chain-length (SCL) PHAs has been developed, covering an unprecedented range of repeating units. The fadB and fadJ genes from the β-oxidation pathway were eliminated from the chromosome of E. coli LS5218. The subsequent blockage in β-oxidation caused a buildup of enoyl-CoA intermediates, which were converted to PHAs by an (R)-specific enoyl-CoA hydratase (PhaJ4) and PHA synthase [PhaC1(STQK)] expressed from a plasmid DNA construct. Fatty acid substrates were converted to PHAs with repeating units equal in the number of carbon atoms to the fatty acid substrate. The broad substrate specificities of the PhaJ4 and PhaC1(STQK) enzymes allowed for the production of homopolymers with strict control over the repeating unit composition from substrates of four to twelve carbons in length. Polymers were purified and analyzed by GC, GC-MS, and NMR for structural composition and by DSC, TGA, and GPC for thermal and physical characteristics. This study marks the development of the first single biological system to achieve consistent repeating unit control over such a broad range of repeating units in PHAs.     

不同分子质量聚乳酸立体复合物的结晶性能及球晶形貌

同等质量的L-乳酸(PLLA)和D-乳酸(PDLA)共混后,能够形成立体复合聚乳酸(PLA)。研究了5种不同相对分子质量(0.6×10~4~1.2×10~5)的PLLA和PDLA共混物的热性能、结晶动力学以及球晶的形态结构。聚合物均是通过L-LA或D-LA熔融-固相聚合相结合的方法获得。与相应的均聚物比较,PLLA和PDLA溶液共混后形成的立体复合PLA具有更好的结晶性能和更高的熔点。分别以5、10、20、30℃/min为降温速率进行结晶动力学研究,发现较高分子质量样品具有更好的结晶速率,可能是因为样品中分子链在结晶发生之前具有更快的链复合能力。最后,通过偏光显微镜成功地在较低分子质量sc-PLA球晶结构中观察到了可逆的裂纹现象,证明裂纹的出现与结晶过程中形成的晶体间内应力有关。     

纺粘非织造用聚乳酸/聚(3-羟基丁酸-co-3-羟基戊酸共聚酯)的可纺性

为获得高质量的聚乳酸/聚(3-羟基丁酸-co-3-羟基戊酸共聚酯)(PLA/PHBV)双组分生物降解纺粘非织造材料,对PLA/PHBV母粒的相对分子质量及分布、熔体指数、热力学、结晶和流变性能进行了研究,并对PLA/PHBV纺粘纤维的热力学和结晶性能进行了探讨。结果表明:PLA/PHBV母粒重均分子质量约为120 000,分布指数为1.99;热失重起始热分解温度为285℃,适宜纺粘非织造挤出加工,合适的纺粘加工温度约为210℃。PLA/PHBV熔体在剪切速率小于1 000 rad/s时,表观黏度对剪切速率变化敏感;熔体对温度的敏感程度随着剪切速率的增大而降低。纺粘加工工艺对PLA/PHBV原料的热力学和结晶性能影响显著。与PLA/PHBV母粒相比,纺粘纤维结晶度下降明显,但非晶区取向程度提高。     

Biocompatible green tea extract-stabilised zinc nanoparticles encapsulated by poly(butyl-2-cyanoacrylate) with control release profile and antioxidative capacity

Green tea extract-stabilised Zn nanoparticles (GT-Zn NPs) encapsulated by poly(butyl-2-cyanoacrylate) (PBCA@GT-Zn NPs) were developed for control release of Zn. The crucial parameters, concentrations of GT-Zn NPs and the monomer n-butyl-2-cyanoacrylate (BCA), which affected the size, polydispersity indexes (PDI) and encapsulation efficiency (EE %), were evaluated to achieve the smaller size, higher EE (%) and stably and uniformly dispersed NPs. The optimised PBCA@GT-Zn NPs with <100 nm diameter (46.38 ± 3.46 by SEM, 86.91 ± 3.66 by DLS), PDI (0.159 ± 0.042), zeta potential (−20.56 ± 2.53 mV) and EE (89.31 ± 1.09 %) were obtained. In vitro release of Zn ions was conducted at pH 7.4, showing that Zn from the self-made tablets and lyophilised PBCA@GT-Zn NPs is released significantly slower than that of GT-Zn NPs. Additionally, the PBCA@GT-Zn NP tablets are pH-responsive, non-toxic and antioxidative, suggesting that they could be used as safe food material or drug carriers, contributing to relieve Zn deficiency.     

锰(Ⅱ)-OP-5-Br-PADAP极谱络合吸附波研究

建立简便、快速的锰的极谱分析法,采用线性扫描极谱法对锰-2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP)-聚乙二醇辛基苯基醚(OP)体系进行研究。结果表明:在Na2B4O7-NaOH(pH11.0)缓冲溶液中,锰-2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP)-聚乙二醇辛基苯基醚(OP)络合物在-0.73V(vs.SCE)左右产生一灵敏的吸附波,该波的二阶导数峰峰电流在0.10～0.32μg/mL范围内与锰质量浓度呈线性关系(r=0.9989,n=10)。检出限为0.05μg/mL。经多种电化学方法证明该波为络合物吸附波,其电极过程为不可逆过程,电子转移数为2,此外还验证了多种离子对峰电流Ip'的影响。所拟方法用于大米中锰含量的测定,回收率在94.1%～101.0%之间,相对标准偏差为1.9%。     

Taxonomic characterization and metabolic analysis of the Halomonas sp. KM-1, a highly bioplastic poly(3-hydroxybutyrate)-producing bacterium

In a brief previous report, the gram-negative moderately halophilic bacterium, Halomonas sp. KM-1, that was isolated in our laboratory was shown to produce the bioplastic, poly(3-hydroxybutyrate) (PHB), using biodiesel waste glycerol (Kawata and Aiba, Biosci. Biotechnol. Biochem., 74, 175-177, 2010). Here, we further characterized this KM-1 strain and compared it to other Halomonas strains. Strain KM-1 was subjected to a polyphasic taxonomic study. Strain KM-1 was rod-shaped and formed colonies on a plate that were cream-beige in color, smooth, opaque, and circular with entire edges. KM-1 grew under environmental conditions of 0.1%-10% (w/v) NaCl, pH 6.5-10.5 and at temperatures between 10°C and 45°C. The G+C content of strain KM-1 was 63.9 mol%. Of the 16 Halomonas strains examined in this study, the strain KM-1 exhibited the highest production of PHB (63.6%, w/v) in SOT medium supplemented with 10% glycerol, 10.0 g/L sodium nitrate and 2.0 g/L dipotassium hydrogen phosphate. The intracellular structures within which PHB accumulated had the appearance of intracellular granules with a diameter of approximately 0.5 μm, as assessed by electron microscopy. The intra- and extra-cellular metabolites of strain KM-1 were analyzed by capillary electrophoresis mass spectrometry. In spite of the high amount of PHB stored intra-cellularly, as possible precursors for PHB only a small quantity of 3-hydroxybutyric acid and acetyl CoA, and no quantity of 3-hydroxybutyl CoA, acetoacetyl CoA and acetoacetate were detected either intra- or extra-cellularly, suggesting highly efficient conversion of these precursors to PHB.     

酿酒废弃葡萄皮渣对Cr(VI)的吸附能力研究

利用酿酒后废弃葡萄皮渣(WGP)作为吸附剂,对溶液中六价铬离子Cr(Ⅵ)进行吸附试验,研究了吸附时间、粒径、用量、溶液pH、Cr离子浓度对吸附率的影响。结果如下:WGP对Cr(Ⅵ)的吸附4 h就基本达到平衡,吸附率为87.97%;粒径小于60目的WGP表现出更强的吸附能力;吸附率与WGP用量正相关,用量1 g以上吸附率趋于稳定在88%左右;WGP对Cr(VI)的吸附率随着pH值增加而下降,直至pH为3时,吸附率趋于平衡;溶液中Cr浓度越高,葡萄皮渣对Cr(Ⅵ)的吸附率越高。研究表明:酿酒后葡萄皮渣具有较强吸附铬Cr(Ⅵ)的能力,可作为铬吸附剂,用于废水治理。     

Decolorization of Japanese soy sauce (shoyu) using adsorption

A systemic adsorption study was conducted to find an appropriate process to decolorize Japanese soy sauce (shoyu) without changing the sensory quality, using activated carbon (AC), activated clay (ACL), diatomaceous earth (DE), magnesium oxide (MGO), and silica gel (SG). The AC, ACL, and SG processes exhibited decolorizing ability, but the DE and MGO processes did not. The decolorizing ability of AC was 30 times that of ACL, at the same time the decolorizing ability of ACL was 3 times that of SG. AC-, ACL-, and SG-processed soy sauces had similar characteristic curves in plots of Δa^∗ against Δb^∗ and ΔC^∗ against ΔL^∗. When the decolorizing degree was the same, a major quality index (e.g., total nitrogen (TN), unsalted soluble solid content (USSC), ethanol, and pH) was maintained with AC but not with ACL (especially pH), while SG maintained the quality index except for ethanol. AC and SG did not reduce amino acids or organic acids (e.g., lactic acid and acetic acid), indicating contained sensory quality.     

Cold Plasma Synthesis of Poly(ethylene glycol)-like Layers on Stainless-Steel Surfaces to Reduce Attachment and Biofilm Formation by Listeria monocytogenes

ABSTRACT Poly(ethylene glycol) (PEG)-like structures were generated on stainless steel under di(ethylene glycol) vinyl ether (DiEGVE) radio frequency-plasma environments. Electron spectroscopy for chemical analysis and attenuated total reflectance Fourier transform infrared spectroscopy indicated a PEG-like deposition, which was stable to cleaning, sanitizing, and storage for up to 2 mo. Atomic force microscopy and water contact angle analysis indicated that the modified stainless-steel surfaces were less rough and more hydrophilic than the unmodified surfaces. Listeria monocytogenes attachment and biofilm formation on modified surfaces decreased more than 90% compared with the unmodified stainless steel ( P < 0.01). DiEGVE cold plasma was demonstrated to be a promising technique to reduce bacterial contamination on surfaces encountered in food-processing environments.