Zeta电位的测定及其对抄纸的影响

着重探讨了纸料Zeta电位对填料留着率、施胶度和纸张强度的影响，并对影响Zeta电位测量的因素进行了探讨。结果表明：不管是在酸性造纸还是在中性造纸中，纸料Zeta电位控制在-4～-9mV范围内效果较好。     

不同保守力势能函数的计算及讨论

对重力势能、弹性势能、静电势能等常见的保守力势能所对应的函数进行了计算与讨论，认为势能零点及坐标原点的选取不影响两点间功的计算，但影响计算的繁简程序，因而应尽量选取默认的势能零点及坐标原点。因需要而改变坐标原点或势能零点时，仍需使用势能的一般计算表达式。     

Relationship of iso‐α‐acid content and endogenous antioxidative potential during storage of lager beer

One of the critical issues regarding the quality of beer is the change in its chemical composition that occurs during storage. Decomposition of iso‐α‐acids results in an undesirable decrease in bitterness as well as a deterioration in the sensory profile of the beer. These changes are caused by the susceptibility of iso‐α‐acids to degradation owing to the influence of reactive oxygen species and light. The aim of this study was to investigate the influence of storage conditions (temperature, light) on the degradation of iso‐α‐acids during aging, with the main focus on monitoring the relationship between the turnover of iso‐α‐acids, the sulphur dioxide content and the antioxidative potential of stored beer as measured by electron spin resonance spectroscopy. In agreement with previous investigations, a significant decrease in the content of bitter compounds (up to 18 % relative to the original level, depending on storage conditions) was observed. A significant decrease in the antioxidant potential of beer was recorded simultaneously and the data confirmed a strong correlation between these parameters. The decline in beer bitterness could become a marker for estimating oxidative damage during storage. Copyright © 2014 The Institute of Brewing & Distilling     

Effect of solvent and extraction temperatures on the antioxidant potential of traditional stoned table olives “alcaparras”

This paper reports the first approach to the antioxidant potential evaluation of traditional stoned table olives “alcaparras”. This kind of olives are largely produced and consumed in Trás-os-Montes region (Northeast of Portugal). Different solvents and temperature extraction conditions were employed in order to achieve the best method to obtain phenolic compounds and a higher antioxidant activity. The optimum method (water at boiling temperature) was applied on 10 samples from the traditional market. The total phenol content ranged between 5.58 mg gallic acid equivalents (GAE)/g and 29.88 mg GAE/g and effective concentration (EC₅₀) values were in the range 0.36-1.64 and 0.34-1.72 mg/mL for reducing power and radical scavenging effect, respectively. A significantly negative linear regression was observed between the total phenol content found in the samples and its antioxidant activity.     

Evaluating potential applications of indigenous yeasts and their β‐glucosidases

The potential applications of wild yeast strains with β‐glucosidase activity were investigated by assaying their enzymatic production under simulated oenological conditions, coupled with the exploration of the potential applications of the β‐glucosidases by studying the enzymatic activity and stability under similar oenological conditions. The assay of enzymatic locations revealed that the β‐glucosidase activities from these wild strains occurred in the extracellular fraction, and in whole and permeabilized cells. The effects of different oenological factors on β‐glucosidase production indicated that the F6 Trichosporon asahii strain had higher β‐glucosidase production than the other strains under low pH conditions. However, the F35 Hanseniaspora uvarum strain and the F30 Saccharomyces cerevisiae strain showed higher β‐glucosidase production under high‐sugar conditions. Furthermore, the influence of oenological factors on the activity and stability of the β‐glucosidases revealed that the enzyme from the F6 T. asahii strain had a stronger low‐pH‐value resistance than the other yeast β‐glucosidases. These results suggest that the F35 H. uvarum, F30 S. cerevisiae and the F6 T. asahii β‐glucosidases may have some potentially applicable values in the fermentation industry. Copyright © 2015 The Institute of Brewing & Distilling     

Bioactive compounds and antioxidant potential in fresh and dried Jaffa® sweeties,a new kind of citrus fruit

Bioactive compounds in the edible parts of fresh and dried Jaffa^® sweeties, a new kind of citrus fruit, were analysed and their antioxidant capacities were assessed. Antioxidant‐rich fractions were extracted from fresh and dried sweeties with 1.2 M HCl in methanol/water (1:1 v/v), and the antioxidant activities of these extracts were evaluated. Using the β‐carotene/linoleate model system, the extracts from equivalent quantities of fresh and dried sweeties showed 89 and 87% antioxidant activity respectively. Similarly, using the DPPH radical‐scavenging method, the extracts showed 87 and 85% antioxidant activity respectively. The best correlations were between caffeic acid content and β‐carotene and DPPH antioxidant activity values (r = 0.9849 and 0.9798 respectively, p = 0.005). Both fresh and dried sweeties are bioactive natural products; when fresh fruits are not available, properly dried sweeties could be used as a substitute. Copyright © 2004 Society of Chemical Industry     

Rheology and baking potential of wheat/plantain composite flour

The possibilty of producing bread from wheat/plantain composite flour has been comprehensively assessed. The chemical analysis of the composite flour showed that it contained less protein and higher carbohydrate and minerals than wheat flour. With increasing levels of supplementation with plantain the water absorption capacity and dough development time of the composite flour decreased. However, the mixing tolerance time increased and the mixing quality decreased. It was found that the baking quality decreased with increasing level of supplementation and when unblanched plantain flour was used. The blend with 100 g kg^?1 blanched plantain and 900 g kg^?1 wheat flour was found to be internally and externally better than other blends and the bread was of acceptable quality.     

Measurement of the oxidation-reduction potential of cheddar cheese

ABSTRACT:  The objective of this study was to develop a method to measure the oxidation–reduction (redox) potential of hard cheeses such as cheddar and to investigate the impact on this parameter of measurement temperature, and factors associated with electrochemical cell design such as distance between reference and working electrodes and depth into the cheese of the platinum electrodes. For this purpose, a novel, self-sealing, platinum working electrode was constructed which was thin and flexible enough to be inserted directly into the cheese sample. A calomel electrode was used as the reference electrode and the circuit was completed with a 3 M KCl salt bridge. The physical orientation of electrodes, such as distance between reference electrode and working electrode, had a substantial effect on equilibrium time for redox potential measurement. The time required for redox potential to reach equilibrium was 2 d in cheddar cheese and the optimum distance between the platinum and calomel electrodes was 2.5 cm. The fastest equilibration time was obtained when the working electrode was inserted 5 or 6 cm into the cheese. Temperature also had an important effect on redox potential. The shortest time to reach equilibrium of potential was at room temperature (20 °C), but it was not practical to keep cheese at this temperature for a period of 2 d. Therefore, redox measurement at 12 °C was recommended in spite of the longer equilibration time compared with room temperature. The results of this study suggest that the novel platinum working electrode allows reproducible measurement of the oxidation–reduction potential of cheddar cheese.     

Anti-irritant potential of cosmetic raw materials and formulations

The investigation studied the anti-irritant potential of several substances commonly employed in cosmetic formulations as basic components of the emulsion or as active ingredients, and evaluated the effect of the emulsifier. Five different emulsions were made irritating by addition of croton oil, in sufficient quantity to provoke a clearly adverse reaction in the rabbit, i.e. primary cutaneous irritation index (PII) close to 2. The PII was determined according to the official French methods by applying to symmetrical areas of the back, the irritant base as control and the same base containing the test substance. Fifty-five ingredients were evaluated: gelling agents, plant extracts, molecules defined as healing, anti-inflammatory substances or anaesthesic compounds, etc. The test substances were added to the emulsion at concentrations close to the ones generally found in cosmetics. The qualitative and the quantitative composition of the oil phase was similar for each emulsion.
Several gelling agents, thickeners and polymers which notably reduce skin contact with an irritant, gave good results. Some of the usual healing, anti-inflammatory, local anaesthesic compounds gave the expected results. Some ingredients, though well known, were ineffective. The type of emulsifier, by modifying cutaneous penetration and bio-availability of the active ingredients, may play an important role.
Le potential anti-irritant de constituants de base et compositions cosmétiques     

我国油脂压榨业开发潜力及应对措施

在查阅近几年来我国油脂压榨业相关资料的基础上,结合对国内外生产实际的考察,明确地提出在加入WTO后对油脂压榨业带来的正面与负面影响效应,指出调整、改革和重组是我国油脂压榨业面临的战略性选择,相适应地提出油脂压榨业其产品开发、技术创新、企业管理与产业建设的具体任务.只有这样,才能达标并与国际接轨,强化油脂压榨业的自我策划、自我改造、自我完善和自我发展的能力,建设有中国特色的油脂压榨产业.     

Suitability of pre‐dawn and stem water potential as indicators of vineyard water status in cv. Tempranillo

Background and Aims: Irrigation management requires the collection of up‐to‐date information that allow growers to make rapid decisions, water potential being one of the most used parameters in irrigation scheduling. The goal of this research was to determine whether predawn (Ψpd) and stem (Ψs) water potential can be used equally well, quantifying the effect external factors have on the relationship between them. Methods and Results: Ψpd, mid‐morning (Ψs‐m) and noon (Ψs‐n) stem water potential were measured at seven cv. Tempranillo vineyards. Climatic conditions, vine growth and fruit load affected daily water potential dynamics. A greater decline of Ψs occurred when temperatures were higher and there was no dew formation, as well as under larger canopies and fruit load. While the relative impact of these variables on water potential was not particularly high, it was by no means negligible. Conclusions: Data collected in this study did not favour Ψpd, Ψs‐m or Ψs‐n as a preferred measure to evaluate plant water status. It is important to remark that similar Ψpd values do not necessarily indicate the same level of deficit, and that similar Ψs values do not always mean similar water availability. Therefore, a straightforward interpretation of Ψpd and Ψs can sometimes be misleading. Significance of the Study: The results obtained provide significant explanation to the lack of agreement in the literature regarding the most suitable time to measure water potential. Vineyard managers and scientists should select it according to the level of stress expected, climatic conditions and irrigation frequency.     

"电位活化"现象与金属电沉积初始过程研究简报

针对无氰电镀在镀层结合强度方面还存在的一些问题,用"电位活化"概念给出了理论解释,并从宏观到微观多方位地揭示了电位活化现象的电化学本质:恒电流法电位-时间曲线显示出了金属电沉积初始过程的电位活化平阶和特点;Ar 离子纵向深度溅射与X射线光电子能谱分析(XPS)相结合证实了电镀层结合强度差的原因是电沉积初始过程中镀层/基体界面氧化层的存在.保证电镀层与金属基体良好结合的前提,即实现电位活化的条件是电镀液中金属离子的还原电位必须负于基体金属表面氧化层的活化电位.同时给出了结合强度可与氰化物电镀相近的铁基体上焦磷酸盐直接镀铜工艺.研究表明,镍电极上的电位活化问题也取得了与上述研究一致的结论.     

食用香精的呈味特征结构与潜在危害性分析

食用香精作为一种影响食品口感和风味的特殊高倍浓缩添加剂已经被应用到现代食品工业的各个领域。受天然香料来源、数量、成本的限制,在食品工业中使用的基本都是合成香精、反应香精及天然等同香精。文章对近些年食品香精香味与呈味物质分子结构的关系进行了归纳,并对几种常用香精类型的潜在性危害研究进行了综述。     

Burgundy red wines: Representation of potential for aging

This study was conducted to investigate wine professionals’ perception of aging potential of red wines. In the first experiment, 41 wine professionals assessed sixteen commercial Burgundy red wines via a binary categorization task, an aging potential rating task, and a hedonic rating task and an analytic sensory evaluation including an astringency and a bitterness rating task. The wines were also analyzed by High-Pressure Liquid Chromatography with a UV Detector (HPLC-UV) and their color was evaluated using Hue (H*), Lightness (L*) and Chroma (C*) measurements. Results showed that the wines were split into two clusters on the basis of aging potential judgements indicating that the wine professionals had a collective representation of the characteristics of a wine with a potential for aging. Wines with a potential for aging were characterized by low L* and H* and high C* values, a high astringency and a higher concentration of anthocyanins and polyphenol. In a second experiment, 34 wine professionals performed three potential for aging binary sorting task based on (1) visual assessment only, (2) olfacto-gustatory assessment only and (3) overall assessment (visual plus in-mouth). Results showed that the sensory modalities tested were complementary and that visual or olfacto-gustatory assessments alone were not sufficient to explain overall judgments of aging potential.     

关于解析势能函数的研究

利用一种带相位因子的场方程,给出了适用于双原子分子或分子离子间相互作用的解析势能函数,通过调节相位因子可获得多种常见形态的势能曲线.利用该势能函数,计算给出了He2 分子离子电子基态X2Σ 6、LiH分子电子基态X′Σ 、N2分子电子激发态A3Σu 、Cu2分子、Cu2-分子离子等10多种双原子分子或分子离子的势能曲线,结果在较高的精度范围内与实验曲线相一致;同时计算出了H2分子和H2 分子离子的力常数,与实验测定值符合很好;其次,利用该势能函数给出了由微观参量表示的5种固体材料的杨氏模量的解析计算式.     

蛋白新资源潜在致敏性评价方法的研究进展

食物过敏是指过敏人群摄入含有相应致敏蛋白的食物后导致人体消化系统、呼吸系统、血液系统等出现的一系列变态反应,如呕吐、腹泻、鼻炎、哮喘、水肿、荨麻疹、过敏性皮炎等,严重时可致全身性休克反应。据统计,全球约6%~8%的婴幼儿和2%~4%的成年人被食物过敏所困扰,因此食物过敏已成为国际社会关注的一个食品安全问题。然而,近几年随着食品蛋白新资源在人类消费生活中的应用日益增加,其是否具有潜在的致敏性更是受到国内外的广泛关注,食品蛋白新资源致敏性评价方法和体系的建立也成为国内外研究和关注的热点。本文就现有食品蛋白新资源潜在致敏性的评价方法的研究进展进行了综述,对其现状做出总结。