Factors influencing the production and stability of xanthylium cation pigments in a model white wine system

The influence of various wine parameters on the production and stability of xanthylium cation pigments in a wine-like medium is reported. The xanthylium pigments have an absorbance maximum in the visible region at 440 nm that is close to the measured absorbance used by the wine industry to indicate the browning of wine (i.e. 420 nm). The results of this study show that iron is more efficient than copper in both the colouration and production of xanthylium cation pigments in wine-like solutions of tartaric acid and (+)-catechin. The non-flavonoid caffeic acid can inhibit the accumulation of the xanthylium cation pigments, despite the presence of metal ions, and also influence the stability of the pigment. Sunlight leads to a decrease in the concentration of xanthylium cation pigments while a temperature difference of 20 ^oC in the absence of light was observed to have little influence on concentration. The results suggest that the xanthylium cations are more likely to be a transitory species during white wine oxidation rather than accumulating pigments based on their instability with caffeic acid.     

COMPARISON OF PEROXIDASES FROM BARLEY KERNEL (Hordeum vulgare L.) AND WHEAT GERM (Triticum aestivum L.): ISOLATION AND PRELIMINARY CHARACTERIZATION

Peroxidases (POD) of crude extracts from barley and wheat germ were separated, partially purified using salt fractionation, ion-exchange and hydrophobic interaction chromatographies and their properties examined. Barley and wheat germ POD contained basic, neutral and anionic isoforms as confirmed by isoelectric focusing. Toyopearl-Butyl 650 M chromatography resolved POD into four cationic fractions. Chromatography of wheat germ extract on CM-Sepharose isolated an anionic and a neutral fraction. Following chromatography on Concanavalin-A Sepharose, enzymes from both cereals showed differences in their elution properties. Optimum pH ranges were 4.0 to 5.5 (barley) and 5.3 to > 6.3 (wheat germ) and POD reacted differently under acidic or basic conditions. Their catalytic behavior in the presence of calcium also differed. Kinetics of POD were of Michaelian type with a ping-pong mechanism and Michaelis constants of guaiacol oxidation in the presence of hydrogen peroxide varied from one enzymatic group to another.     

POLYPHENOLIC SUBSTRATES OF CATIONIC AND NEUTRAL/ANIONIC PEROXIDASES FROM BARLEY AND MALT USING A CHRONOMETRIC METHOD FOR THE DETERMINATION OF POD ACTIVITY

4-methylcatechol, phenolic acids from the benzoic and cinnamic series, flavan 3-ols and L-tyrosine were tested to determine the catalytic behavior of barley peroxidases (POD) at the expense of hydrogen peroxide. A chronometric assay using L-ascorbic acid was described for determining the peroxidatic activity of basic and neutral/anionic enzymatic fractions. The effects of hydrogen donors H₂O₂, and Ca⁺⁺ ion concentrations and pH were studied to set maximal conditions for POD measurement. The sensitivity to endogenous phenolic compounds (ferulic and p-coumaric acids, (+) catechin) along with caffeic acid for POD fractions was investigated and compared with their response versus guaiacol. Under the conditions tested, syringic and sinapinic acids as well as L-tyrosine were very weakly oxidized by POD from barley, whereas ferulic and caffeic acids were rapidly transformed. Levels of POD activity extracted from barley, green malt and kilned malt crude extracts were thereafter compared.     

PERFORMANCE EVALUATION OF GLAZED AND UNGLAZED COLLECTORS/REGENERATORS IN A LIQUID ABSORBENT OPEN-CYCLE ABSORPTION COOLING SYSTEM

The performance of two collectors/regenerators, one glazed and the other unglazed, was studied when tested side-by-side under the meteorological conditions of Tempe, Arizona. One half of an 11 m by 11 m roof structure was covered with a series of seven Tedlar panels, each measuring 1.76 cm by 4.88 m, and the other remained unglazed. When the performance of the collector/regenerator (C/R) was expressed in terms of the quantity of water evaporated from it, which in effect was a measure of the cooling capacity of the system, the unglazed C/R performed better than the glazed C/R under the climatic conditions considered here. Nondimensional correlations for heat and mass transfer were developed from the experimental data for subsequent use with a performance model. The glazed C/R was found less sensitive to changes in independent variables and its regeneration efficiency was, on the average, 7.6% lower than the unglazed C/R. The performance of the glazed C/R approaches that of unglazed C/R at a larger height of the glazing.     

利用井筒稳定性分析确定砂岩安全钻井液密度窗口

以伊朗西南部某油田Asmari组砂岩储集层为研究对象,研究其中一口垂直井的井筒稳定性,利用FLAC3D软件,根据钻遇地层地质力学特征建立井筒的有限体积模型,监测井壁岩石塑性状态的形成以确定砂岩层安全钻井液密度的上限值和下限值。评估了岩石强度特性、井筒周围主要地应力和孔隙压力对该井安全钻井液密度窗口的影响,敏感性分析结果表明,井壁岩石内聚力和内摩擦角的减小会导致安全钻井液密度窗口大幅变窄;孔隙压力和最大水平应力与最小水平应力之比的减小则会使安全钻井液密度窗口显著增大。此模型便于量化安全钻井液密度窗口的变化,可作为一种油气井钻井方案设计和监测工具。图11参50     

SODIUM BICARBONATE AND THE MICROSTRUCTURE, EXPANSION AND COLOR OF EXTRUDED BLACK BEANS

Seed microstructure provides complementary information to physicochemical determinations. Scanning electron micrographs of cross sections of black bean extrudates illustrated the increase in volume expansion, with an increase of sodium bicarbonate (NaHCO ₃ ) in the extrudate. This increase in volume expansion is attributed to the increase in air cell size and corresponding decrease in air cell wall thickness with additional concentrations of NaHCO ₃ . The measured increase in diameter and expansion ratio of extrudates with NaHCO ₃ addition may be explained by the increase in number of air cells within the extrudate and the increase in pores in the gelatinized starch matrix of air cell walls. Extrusion conditions, which involved the use of heat and moisture, provided the necessary conditions for the release of CO ₂ from NaHCO ₃ during processing. Expansion ratio increases between the control extrudate, and extrudate with 0.5% NaHCO ₃ addition were twofold at the node and 1.8‐fold at the area between the nodes. Statistical analysis of color data exhibited no significant change in L*, hue or chroma across concentrations of NaHCO ₃ for nonextruded flours. A simple linear regression adequately described changes in L* and hue for extruded flours. However, a curvilinear relationship was needed to explain changes in chroma versus NaHCO ₃ for extruded flours, making changes in chroma measurements less easy to interpret. The color data in this study serve as primary information for future establishment of cut‐off values of color for the development of an acceptable legume snack.     

Muscle Protein Structure-Function Relationships and Discrimination of Functionality by Multivariate Analysis

Functional (gel strength, cook loss, emulsifying, fat and water binding capacities) and physicochemical properties of mince and salt-extractable proteins were analyzed. Factor analysis identified three principal components which accounted for over 75% of data variance and distinguished between mechanically and hand-deboned meat and fish samples. Stepwise discriminant analyses classified samples with good, intermediate and poor functionality. Regression analyses yielded equations to predict functionality from physicochemical properties. Generally, samples with superior thermally induced functionality possessed (1) higher protein, lower fat and pH in the mince; (2) higher solubility and sulthydryl and lower hydrophobicity in unheated salt-extractable proteins; and (3) greater decrease in solubility and increase in hydrophobicity after heating.     

Corporate Downsizing and the Rise of 'Problem-solving Suppliers: the Case of Hadco Corporation

In re-examining the supply chain relationships of American firms,investigators usually confine their studies to the outsourcingstrategies of original equipment manufacturers (OEMs). A fewauthors meanwhile have examined how small and medium size manufacturers(SMMs) fit within the vertical supply chain. This study exploreshow these suppliers develop new opportunities for increasingthe volume and breadth of product which they source to OEMsand how these SMMs develop ways to collaborate with their OEMcustomers and manage appropriate technologies. The study developsa strategic supplier typology with transaction cost economicsproviding the conceptual basis and a survey sample of 200 SMMsoffering the relevant data. The focus is on Hadco Corporation,an electronic parts manufacturer, that has taken special advantageof OEM strategic outsourcing decisions within the computer industry.Conclusions support the general proposition that structure followsstrategy. Survival in a strategic outsourcing environment requiressuppliers to hone competency skills and organizational formsthat allow for adaptation and quick customer demand responsethrough inter-organizational linkage, networks, partnershipsor strategic alliances.     

SCHOOL SCHEDULING USING THRESHOLD ACCEPTING

In this paper, we focus on solving problems modeled after a real-world high school timetable problem. It includes multiple objectives and a variety of constraints. It mainly involves producing an optimal schedule for each teacher and for each class. The conventional integer programming approach seems to have some difficulties with solving such problems. The versatility of our proposed heuristic based on a modification of the threshold accepting method is exemplified through our problem solving. For comparison sake, simulated annealing was also used to solve the same problems.