Macaroon-like FeCo2O4 modified activated carbon anode for enhancing power generation in direct glucose fuel cell

Macaroon-like FeCo₂O₄ nanomaterial was prepared and used as electrocatalyst in direct glucose alkaline fuel cell (DGAFC), which exhibited high catalytic activity towards glucose oxidation reaction. Maximum power density of 35.91 W m⁻² was achieved in the DGAFC equipped with a FeCo₂O₄ modified activated carbon (AC) anode, which was almost 151% higher than the control. Physical and electrochemical characterizations were performed to provide further understanding of the origin of its high activity. Our results show that the introduction of FeCo₂O₄ into the AC anode remarkably increase the exchange current density and reduce the charge transfer resistance. It is supposed that there is a synergistic effect between Fe (III) and Co (III), which accelerates electron transfer from glucose to external circuits. This study will promote the development of cost effective and environmentally benign catalysts for electrochemical energy applications.     

The rapid selecting of precursor ions and product ions of thirty-four kinds of pesticide for content determination by GC–EI/MS/MS

Pesticide residues caused great threat to human body health, and all countries protected the health of human body by specifying its upper limit. However, pesticide residues were generally very low, similar to trace analysis and as low as millionth or less, the content determination of pesticide residues was a troublesome problem. With the application and promotion of tandem mass spectrometry, it was able to do trace analysis. GC–EI/MS/MS was a common method for the determination of pesticide residues. The multiple reaction monitoring (MRM) mode was the most common quantitative method used in GC–EI/MS/MS. It has the characteristics of high sensitivity, good reproducibility, high accuracy, strong anti-interference and high ion flux. Multiple-twin precursor ions, product ions and collision energy of thirty-four pesticides were provided for MRM. It could play an important role in developing MRM method for the quantifying of 34 kinds of pesticide. Meanwhile, the development of MRM method for the quantifying of other compounds could also refer to this paper.     

Effect of successive stimuli on sweetness intensity of gels and custards

Variations of tastant concentration during the consumption of food products were shown to enhance taste intensity. The aim of this study was to investigate the relation between the frequency at which tastant concentration is varied during the consumption of products and the occurrence of taste enhancement. For this purpose, the sweetness intensity of sequences of 4 successive sweet stimuli represented by cubes of a semi-solid gel or spoons of a model custard dessert was assessed. The intensity and the order of the stimuli within the sequences were varied to obtain 4 types of sucrose concentration profile (decreasing, increasing, middle peak and boundary peak) at 2 magnitudes of concentration differences (small and large). Sequences of 4 stimuli containing a constant sucrose concentration were used as a reference. The sweetness intensity of the sequences of successive stimuli was assessed using line scale and time-intensity ratings.Line scale ratings showed that the type of sequence had an effect on sweetness intensity. A sweetness enhancement relative to the reference was observed in sequences that ended with high-intensity stimuli, whereas sweetness suppression was observed in sequences that ended with low-intensity stimuli. The observed sweetness enhancement and suppression were attributed to serial position effects (i.e. recency effects).Time-intensity ratings indicated that each stimulus in the sequences was evaluated individually by the assessors. Sequential effects seem to have occurred during the continuous evaluation of successive stimuli, since preceding stimuli in the sequences affected the evaluation of posterior stimuli. Furthermore, the overall sweetness intensity of the different sequences was not enhanced in relation to the reference. The lack of taste enhancement in sequences exhibiting variations of sucrose concentration was attributed mainly to the long period at which sucrose concentration was varied during the evaluation of the sequences. It was confirmed that the frequency of variation of tastant concentration affects the occurrence of taste enhancement.     

Controlled whey protein aggregates to modulate the texture of fat-free set-type yoghurts

The impact of nanoparticulated whey protein aggregates on the texture of fat-free set-type yoghurts was investigated. Monodisperse (MFA) and polydisperse (PFA) fractal aggregates obtained from heated whey protein isolate (WPI) were added to skimmed milk for yoghurt manufacture at four different concentrations (0.2%–1.5%, w/w). The impact of the concentration and the polydispersity of the aggregates on fat-free set-type yoghurts were studied by instrumental measurements (rheology, penetrometry, syneresis and microscopy) and sensory analysis. Yoghurt gel strength and firmness increased with the concentration of WPI, MFA and PFA. However, yoghurts enriched with PFA clearly differed from the yoghurts enriched with WPI. Indeed, yoghurts enriched with PFA were characterised by a weak gel, a low firmness and a low-density of the protein network. Sensory analysis confirmed the results obtained by instrumental measurements. The whey protein aggregates studied are thus promising tools to modulate fat-free yoghurt texture while using milk-derived ingredients.     

Re-understanding the antecedents of functional foods purchase: Mediating effect of purchase attitude and moderating effect of food neophobia

The world market for functional foods has grown dynamically and China is expected to be one of the most promising markets. But little is understood the formation mechanisms of consumers’ purchase attitude and intention toward functional foods in Mainland China. The current study investigates the roles of trust, health consciousness and price in shaping consumers’ purchase intention toward functional foods by focusing on purchase attitude as a mediator and food neophobia as a moderator. Results from the sample of 1144 Chinese suggest that Chinese consumers had moderate purchase intention toward functional foods. Trust in the food system and health consciousness positively affects purchase intention via purchase attitude. Price negatively affects purchase intention; meanwhile, the negative effect could be counteracted by health consciousness. Food neophobia does not directly affect individuals’ purchase attitude or intention, but moderates the relationships between antecedents and them. Consumers with a low level of food neophobia treat higher price as a monetary sacrifice, while their counterparts may regard a higher price as a greater quality signal. The study offers the food industry insights into the development and marketing of functional foods targeted to the Mainland China market.     

Effects of temperatures and storage time on resting populations of Escherichia coli O157:H7 and Pseudomonas fluorescens in vitro

Assessment of microbial interactions is crucial for documenting bacterial growth in pure and mixed cultures and their potential for biological applications. Pseudomonas fluorescens (non-plant pathogenic and non-pectinolytic) has been used as a biocontrol microbe for plant pathogens and food-borne bacteria. We determined the growth of Escherichia coli O157:H7 (Ec) and P. fluorescens(Pf) in monocultures and co-cultures in sterile distilled water (SDW), buffered peptone water (BPW) and trypticase soy broth (TSB). The effects of temperatures (5, 10, 15, 20, 25, 35, and 37 °C) and storage time (0, 2, 4, 6, 24, and 48 h) on bacteria populations were assessed. Bacteria counts in monocultures in SDW ranged from 2.14 to 3.03 and 2.54 to 3.31 Log CFU/ml for Ec and Pf; respectively. In BPW, mean bacteria counts (monocultures) ranged from 3.15 to 6.14 and 2.54 to 6.41 Log CFU/ml for Ec and Pf, respectively. Ec populations in co-culture varied with storage temperatures and time. After 48 h, Ec 43894 monocultures in TSB ranged from 2.17 to 8.75 and 2.31 to 8.85 Log CFU/ml at 20 and 35 °C; respectively. In co-cultures with Pf 2-79, Ec 43894 counts ranged from 1.71 to 5.83 (20 °C) and 1.90 to 9.03 Log CFU/ml (35 °C) in TSB. The reductions of Ec by Pf 2-79 varied among strains and generally ranged from 0.20 to 0.90, 0.63 to 1.18, and 0 to 0.56 Log CFU/ml in BPW (10 °C). Substrate availability, storage temperatures, and time significantly (P < 0.05) impacted Ec populations in co-culture. The liquid substrate experiments indicated suppressive conditions of Ec by Pf, however; the reduction of produce contamination by E. coli O157:H7 during transitory temperature abuse conditions such as the transportation of produce from fields needs further investigation.     

黑果腺肋花楸中白藜芦醇的提取工艺研究

采用超声波技术对黑果腺肋花楸中白藜芦醇的提取工艺进行研究.通过单因素实验和正交试验获得最佳提取工艺参数:乙醇浓度70％、料液比1∶15、提取温度45℃、提取时间50 min,在此条件下,白藜芦醇提取量为1.702 μg/mL.超声波辅助法操作简单,提取时间短,提取率高,可为相关产品的开发提供理论依据.     

Combining effects of TiO6 octahedron rotations and random electric fields on structural and properties in Na0.5Bi0.5TiO3

The structural and dielectric properties of Na_0.5Bi_0.5TiO₃ (NBT) ceramics and crystals have been investigated and are compared to that of Pb(Zr_0.55Ti_0.45)O₃ (PZT55/45) and Pb(Mg_1/3Nb_2/3)_0.72Ti_0.28O₃ (PMNT 72/28) ceramics. X-ray diffraction (XRD) profiles for (100), (110), (111), (200), (220), and (222) (referred to cubic structure) reveal that the monoclinic structure with Cc space group exists both in the NBT single crystal and ceramics. The diffraction profile obtained with high resolution laboratory XRD for the NBT single crystal can be well described, using Cc model instead of R3c model. The dielectric constant of NBT below T_hump shows some similarity to that of PZT45/55 ceramics below 50°C in which oxygen octahedron rotations cause the frequency dispersion of the dielectric constant. The temperature-dependent dielectric constant for NBT can be deconvolved into two independent processes. The lower temperature process shows a typical relaxor characteristic and follows the Vogel-Fulcher relationship. The other process at higher temperature shows less frequency-dependent behavior. Comparing the dielectric constant of NBT with that of PZT55/45 and PMNT72/28 reveals that both oxygen octahedral rotations and random electric fields play an important role in the frequency dispersion of the dielectric constant for NBT relaxor feroelectric.     

Binding of curcumin to β-lactoglobulin and its effect on antioxidant characteristics of curcumin

The binding of curcumin (CCM) to bovine β-lactoglobulin (β-Lg) was investigated by Fourier transform infrared and fluorescence. The effect of binding on antioxidant activity of CCM was determined by using ABTS and hydroxyl radical scavenging capacity and total reducing ability. Our results showed that when CCM binds to β-Lg, it lead to a partial change in protein structure. In fact, CCM was bound respectively to two different sites of protein at pH 6.0 and 7.0 via hydrophobic interaction. CCM–β-Lg complex was formed by one molecule of protein combining with one molecule of CCM. Moreover, the average distance from one binding site to Trp residues in protein is similar with another. This result suggested that fluorescence resonance energy transfer cannot be used as unique method to study the characteristics of binding of ligands to proteins. The antioxidant activity of CCM might be improved by binding with β-Lg.