Tannin in Common Beans: Methods of Analysis and Effects on Protein Quality

Condensed tannins and related phenols in 13 samples of red Guatamalan common beans (Phaseolus vulgaris) were determined by four chemical assays. The results were highly correlated although the degree of variation among the samples differed greatly according to the assay. In rat feeding trials, tannin content was negatively correlated with net protein ratio, a measure of protein quality, and positively correlated with protein digestibility. Neither correlation was statistically significant due primarily to the low tannin content of the diet. Methionine supplementation not only improves the protein quality but may also play a role in metabolic detoxification of tannin.     

Electrolysis of Soda-Lime Silicate Glass in Water

Thin glass bulbs made of commercial soda-lime glass were electrolyzed in aqueous solution. Ratios of mobilities of sodium and hydronium ions in the glass were calculated and compared to results of inter diffusion experiments with these ions. The results showed that a combination of electrolysis and ion exchange measurements can be used to test theories of the diffusion-controlled step in the reaction of water with glass, and that an interionic diffusion mechanism with complete ionization of the ions from SiO groups in the glass is the preferred mechanism.     

CHARACTERIZATION AND INACTIVATION BY THERMAL AND PRESSURE PROCESSING OF STRAWBERRY (FRAGARIA ANANASSA) POLYPHENOL OXIDASE: A KINETIC STUDY

Polyphenol oxidase (PPO) was isolated from strawberries (Fragaria ananassa) and some of its biochemical characteristics were studied. The optimum pH for strawberry PPO activity was pH = 5.0. K_mand V_maxvalues were 5.95 mm and 133.8 A_420nm/min using a 50 mm catechol substrate solution. Kinetic studies showed that the thermal inactivation of strawberry PPO followed biphasic kinetics, resulting in an activation energy of 314.1 kJ/mol for the labile fraction and 321.3 kJ/mol for the stable fraction. Pressure/temperature inactivation of the stable fraction of strawberry PPO can be adequately described by a first‐order model. Pressure and temperature were found to act synergistically, except in the high temperature–low pressure region where an antagonistic effect was observed. A second‐degree polynomial model was successfully applied to describe the temperature/pressure dependence of the inactivation rate constants of the stable strawberry PPO fraction.     

THE MEASUREMENT OF HEALTH IN URBAN COMMUNITIES

This paper discusses weaknesses of the available indicators of community health. These weaknesses derive from conceptual as well as methodological confusion. Although complex interrelationships among key variables (ability to function, biomedical condition, individual perception, and social or cultural setting) make measurement difficult, the lack of a conception of health makes choice among indicators impossible, except by methodological convenience. It is proposed that an adequate definition of health should focus on the ability and will of the individual to perform needed tasks, i.e. to produce and reproduce, in an environment over the span of a lifetime. Measures should be developed to measure health directly, rather than indirectly. A number of leads for indicators are suggested for the major stages of the human life cycle.     

The Influence of Unlined Boreholes on Groundwater Chemistry: A Comparative Study Using Pore-Water Extraction and Packer Sampling

In the consolidated formations which form most of the major aquifers in the UK, many monitoring boreholes are left unlined (open) for their effective length. They therefore provide pathways for groundwater to flow from one part of the aquifer to another.
A borehole was core-drilled through Triassic sandstones into Permian mudstones at a site in North Yorkshire. Pore water was extracted from the core and compared with conventional depth samples and with samples taken from intervals isolated using packer systems: (a) during drilling, (b) about one month after drilling, and (c) two years after drilling.
The study revealed that natural flow down the borehole led to rapid changes in the quality of water in some parts of the formation.
The implication is that open boreholes can act as conduits to allow flow to take place from one part of the aquifer to another. They are therefore not reliable as sampling points, and may actually accelerate the vertical spread of pollutants. However, this last effect should not be over-stated; in this study, the flow down the borehole was equivalent to the natural flow through only a relatively small area of land.     

Concrete and the Engineered Picturesque: The Parc des Buttes Chaumont (Paris, 1867)

Influential developments in landscape architecture paralleling those in architecture, industrial design, and engineering occurred during the French Second Empire (1851–1870). The civil engineer J.C.A. Alphand oversaw the design and construction of the Parc des Buttes Chaumont located in Paris's 19th arrondissement. The park opened concurrently with the Exposition Universelle on April 1, 1867; it is the only extant installation associated with the exposition. The park demonstrated advances in landscape design through numerous innovations in construction and materials, particularly concrete. Alphand's theoretical treatise and the physical presentation of the park as an engineered landscape fundamentally shifted the practice of landscape design.     

THERMAL AND HIGH PRESSURE INACTIVATION KINETICS OF VICTORIA GRAPE POLYPHENOL OXIDASE: FROM MODEL SYSTEMS TO GRAPE MUST

Polyphenol oxidase (PPO) was extracted from white grapes (var. Victoria, South Africa) and partially purified by ammonium sulfate precipitation. Detailed kinetic studies on thermal and high‐pressure inactivation of grape PPO were preformed in McIlvaine buffer (pH = 4.0), in reconstituted grape must and in grape must. Thermal inactivation of PPO in McIlvaine buffer followed a first‐order model while in reconstituted grape must and grape must a biphasic inactivation behavior has been observed. Under all conditions investigated, a first‐order kinetic model could describe the pressure inactivation data. It was found that PPO is more thermostable and pressure‐stable in must than in reconstituted grape must and McIlvaine buffer at the same pH = 4.0.