Stability of red food colours in the presence of nitrite in canned pork luncheon meat

The stability of nine red food colours in pork luncheon meat products in the absence and presence of nitrite has been investigated. The extracted dyes were examined by visible and u.v. spectrophotometry and paper chromatography for changes due to processing and to the presence of nitrite. All the colours were destroyed to some extent but with nitrite more of the food colour survived. Subsidiary dye components and colourless fluorescent products were formed as a result of heat processing and in certain cases additional products were observed in the presence of nitrite.     

Polarization energy calculations in molecular crystals

The self-consistent polarization field (SCPF) and Fourier transform methods of calculating the polarization energy of excess charges are compared. The SCPF method is extended (i) to treat molecules as a set of submolecules rather than single points in the inner region around the charge, and (ii) to treat the outer region around the charge as an anisotropic dielectric continuum rather Ethan an isotropic one. The contribution to the polarization energy from the outer region depends on the average ^–1, where is the dielectric tensor. These extensions allow the SCPF method to be used for elongated molecules, with potential applications to various systems lacking translational symmetry.     

Hydroxy unsaturated oils. II. Preparation and characterization of methyl dimorphecolate and methyl lesquerolate fromDimorphotheca andLesquerella oils

An evaluation was made of several procedures for the preparation and purification of methyl dimorphecolate and methyl lesquerolate. An anhydrous anion exchange resin in the methoxide form was a catalyst for the methanolysis of the glyceride oils. Liquid-liquid partitioning between acetonitrile and commerical pentane is suitable for purifying large quantities of methyl dimorphecolate. Methyl lesquerolate can be purified by distillationin vacuo as well as by liquid-liquid partitioning. Chromatography and low-temperature crystallization also were tried. W. Utiliz. Res. and Dev. Div., ARS, USDA.     

The measurement of the anisotropy field of single "tape" particles

The uniaxial anisotropy field Haof nominally single acicular particles was measured by three different methods, and the coercivity was also found. A very dilute suspension was made in a viscous liquid, and a particle observed with the microscope. Various types of magnetic field were then applied, and the particle's change in orientation enabledH_{a}, H_{c}and/or Hrto be determined. One method gave anomalously low values for Ha, but it was possible to reconcile the results. The larger values lay in a range consistent with the chain-of-spheres and prolate ellipsoid models. There was a linear relationship between Haand Hr(or Hc). The results suggested new reversal mechanisms.     

Recent research on safflower,sunflower, and cotton

Journal of the American Oil Chemists' Society - Research on safflower shows the following: a) levels of greater than 80% oleic acid and linoleic acid will be achieved with few effects by...     

Crystalline 3-phospho-d-glycerate kinase from horse muscle

Phosphoglycerate kinase has been isolated in crystalline form from horse muscle. A convenient isolation procedure is described that yields homogeneous enzyme of specific activity 700 units/mg (30 degrees C). The enzyme is monomeric, and has a molecular weight 47 000. Of the eight cysteine residues in the protein, two react rapidly with Nbs21 with the concomitant loss of the catalytic activity. Since the isolation of phosphoglycerate kinase from yeast (Bücher, 1955) there have been several reports of purification methods yielding enzyme approaching molecular homogeneity, from rabbit muscle (Beisenherz et al., 1953; Czok and Bücher, 1960; Rao and Oesper, 1961; Avramov and Repin, 1965; and Scopes, 1969) and from chicken muscle (Gosselin-Rey, 1965). Crystalline material has been isolated from human erythrocytes (Hashimoto and Yoshikawa, 1962), and from yeast and rabbit muscle (Krietsch and Bücher, 1970). Cystallographic work on phosphoglycerate kinase from horse muscle by Blake et al. (1972) and Blake and Evans (1974) has prompted mechanistic interest in the enzyme, and we report here a simplified isolation procedure and some properties of the crystalline material from this source.     

Variation in the xanthophyll and carotene content of lucerne,clovers and grasses

The xanthophyll and carotene contents of eleven lucerne clones were found to be higher during September and November than during June and July. Both carotenoids reached a maximum at or before first flowering and then declined as blossoming progressed. Lutein decreased in November while violaxanthin increased. Six grasses and four legumes were analysed for the principal leaf xanthophylls, lutein, violaxanthin and neoxanthin, as well as total xanthophyll and carotene.     

Energetics of triosephosphate isomerase: deuterium isotope effects in the enzyme-catalyzed reaction

The effect of isotopic substitution of the specifically labilized hydrogen in the substrates of triosephosphate isomerase on the steady-state rates of the enzyme-catalyzed reaction has been examined. The k cat value for the enzyme-catalyzed transformation of [1(R)-2H] dihydroxyacetone phosphate is 2.9 times smaller than that for the 1(R)-1H compound. Because of the rapid loss of 2H to solvent from the enzyme-enediol complex, this factor represents the full kinetic isotope effect of the proton abstraction step. The values of k cat and of Km for D-[2-2H]glyceraldehyde 3-phosphate are indistinguishable from those of the 2-1H material. This arises from the rapid loss of 2H from the enzyme-enediol intermediate, which results in 1H rather than 2H transfer in the rate-limiting step. The steady-state kinetic results reported in this paper qualitatively confirm and quantitatively extend the results from the previous papers on the variation of the free energy along the reaction path.     

Cement from magnesium substituted hydroxyapatite

Brushite cement may be used as a bone graft material and is more soluble than apatite in physiological conditions. Consequently it is considerably more resorbable in vivo than apatite forming cements. Brushite cement formation has previously been reported by our group following the mixture of nanocrystalline hydroxyapatite and phosphoric acid. In this study, brushite cement was formed from the reaction of nanocrystalline magnesium-substituted hydroxyapatite with phosphoric acid in an attempt to produce a magnesium substituted brushite cement. The presence of magnesium was shown to have a strong effect on cement composition and strength. Additionally the presence of magnesium in brushite cement was found to reduce the extent of brushite hydrolysis resulting in the formation of HA. By incorporating magnesium ions in the apatite reactant structure the concentration of magnesium ions in the liquid phase of the cement was controlled by the dissolution rate of the apatite. This approach may be used to supply other ions to cement systems during setting as a means to manipulate the clinical performance and characteristics of brushite cements.