Contribution of Lipids to Volatiles Generation in Extruded Corn-Based Model Systems

Volatile compounds generated by model systems of zein, corn amylopectin and corn oil extruded at barrel temperatures of 120°C and 165°C were analyzed by GC and GU/MS. The largest quantities of lipid oxidation products were detected in systems containing all three components. In each system, the quantity of 2,4-decadienal was low relative to the quantities of hexanal, heptanal, and benzaldehyde. Identification of the Maillard reaction products, 2-methyl-3(or 6)-pen-tylpyrazine, 2-methyl-3(or 6)-hexylpyrazine, and 2,5-dimethyl-3-pen-tylpyrazine, suggested that lipid-derived aldehydes might be involved in the formation of substituted pyrazines.     

旋光性氰醇的酶催化合成

综述了酶催化立体选择性合成及动力学折分制备旋光性氰醇的几种方法。     

Design of a robust estimator for nonlinear kinetic modelling

A biased estimator for nonlinear kinetic modelling is studied. The proposed estimator contains two easily tuned parameters that enable the estimator to possess robustness in dealing with the problem of a nearly singular design matrix. The robustness of the estimator is discussed in detail, and the asymptotic normality of the estimator is proved concisely but rigorously. The regularity conditions imposed to obtain the results are fairly weak in engineering applications. Three examples presented demonstrate that the estimator is significantly better than the least-squares (LS) estimator and the ridge estimator in both estimate accuracy and convergence speed     

An assessment of quality management in the US/Mexico export processing industry

The focus of this analysis is on the critical issues of quality performance and management in manufacturing facilities operating under the co-operative US/Mexico export processing system. Results of the study reveal that a multi-faceted, proactive approach is extensively used in achieving world-class quality levels, and that quality management methods and techniques can be successfully transferred and implemented between First and Third World socioeconomic environments. Adjustments to the quality management methods are necessary to account for differences in ownership and in mode of operations.     

Haze Development in Aerobically or Anaerobically Produced Clarified Apple Juices

Haze production in aerobically or anaerobically produced Red Delicious apple juice was assessed following heating, aeration, and protein addition. Stored aerobic juice produced haze in 6 wk, but anaerobic juice was haze-free unless oxygen was introduced. Phenolic material was incorporated into haze in both systems. HPLC (detection at 420 nm) of concentrated juice and addition of 100 mg/L BSA suggested the presence in both juices of ‘reactive’ material which could complex and precipitate during storage. Phenolic compounds, heating, and especially oxidation during processing (and storage) appear to be major determinants of ‘haze potential’ in clarified apple juice.     

Changes in Soluble and Bound Peroxidase—IAA Oxidase During Tomato Fruit Development

Soluble peroxidase activity increased dramatically during the early stages of tomato fruit development, reaching a maximum at the mature-green stage. Ionically and covalently bound peroxidases were also observed, and the activities of these fractions increased steadily throughout fruit development. IAA (indoleacetic acid) oxidase activity was observed in both soluble and bound fractions and paralleled the peroxidase activity. Tissue homogenates from juvenile fruit caused an extended induction period in IAA oxidation reactions catalyzed by the purified tomato fruit peroxidase, suggesting the occurence of a high concentration of phenolic-type auxin protectors in this tissue. As the fruit developed, tissue homogenates showed a reduction in the amount of auxin protectors as the IAA oxidizing capacity of the fruit increased.     

Correlation of Ethanol Concentration with Sensory Classification of Decomposition in Canned Salmon

Canned salmon samples of four species (sockeye, pink, coho, and chum) were analyzed for ethanol content. A highly significant correlation (r = 0.71, p < 0.001, Pearson;r = 0.80, p = 0.001, Spearman) was found between the ethanol content and the sensory classification of decomposition in canned salmon. This relationship has potential use as a means of objectively confirming the initial sensory classification of canned salmon.     

PSYCHOLOGICAL TESTING THROUGH THE LOOKING GLASS OF YOUTH.

ATTEMPTED "TO EXAMINE HOW MUCH YOUNG AMERICANS (I.E., HIGH SCHOOL STUDENTS) KNOW ABOUT TESTING, THE EXTENT OF THEIR EXPOSURE TO VARIOUS TYPES OF PSYCHOLOGICAL TESTS, AND THEIR BELIEFS ABOUT THE EFFICACY OF THESE TESTS . . . . DATA ARE (ALSO) PRESENTED ON THEIR ATTITUDES TOWARD TESTING IN GENERAL AND IN THE SPECIFIC AREAS OF SCHOOL AND INDUSTRY." CERTAIN DEMOGRAPHIC VARIABLES RELATED TO THE ABOVE ARE CONSIDERED. 16,000 55-ITEM QUESTIONNAIRES WERE SENT TO THE PURDUE OPINION PANEL, WHICH CONSISTS OF 113 COOPERATING HIGH SCHOOLS. THERE WERE 12,000 RESPONDENTS. IT IS CONCLUDED THAT "WHILE ATTITUDES TOWARD PSYCHOLOGICAL TESTING ARE NOT OVERWHELMINGLY FAVORABLE IN THIS SAMPLE, THEY DO SEEM TO BE REASONABLY POSITIVE, AND HIGH SCHOOL STUDENTS DO EXPRESS CONSIDERABLE BELIEF IN THE UTILITY AND IMPARTIALITY OF PSYCHOLOGICAL TESTING." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular Dynamic Calculations of A Sodium Borosilicate Glass Structure

The structure of seven sodium borosilicate glasses was calculated using molecular dynamics. Consistent with Zachariasen's rules of glass formation, silicon and boron were found to form a continuous near-random network of SiO₄, BO₃, and BO₄ polyhedra linked to each other at corners, whereas sodium ions occupied interstitial sites only. The most probable coordination of oxygen around sodium was five. There were roughly six oxygen atoms around an oxygen, nearly independent of the glass composition. The trigonal to tetrahedral conversion of boron with the addition of sodium agreed with the NMR results. The glasses studied showed no tendency to form boroxol groups.