Microstructure of Silica in the Presence of Iron Oxide

The microstructures that are developed when iron oxide reacts with excess silica at elevated temperatures are described. Compacts of powdered quartz and iron oxide were heated to various temperatures and under selected conditions of oxidation to determine the effect of these parameters on microstructure. The results show that temperature has a small but measurable effect on the geometry of the silica and liquid phases. The oxidation level does not have an effect on the geometry of the phases in this system other than to reduce the liquid content by introducing magnetite as a secondary phase. The strength of silica brick in the presence of high liquid contents probably arises from the interfacial-energy relations which maintain considerable solid-to-solid contact at elevated temperatures.     

PROTEIN-PHYTATE INTERACTIONS IN SOYBEANS. II. MECHANISM OF PROTEIN-PHYTATE BINDING AS AFFECTED BY CALCIUM

Phytate and bovine serum albumin were used in a model system to investigate the mechanism of their binding. Ultrafiltration studies using response surface design showed the association of protein and phytic acid to be highly pH dependent. Under acid conditions, the protein formed an insoluble complex with phytic acid. At pH 3.0, a binding constant of 2.3 times 10⁵ was obtained and it was calculated that there are 78 binding sites of the total 93 basic amino acid residues potentially available. This low pH complex was not disrupted at high temperatures but the presence of calcium ions caused dissolution of the precipitate. Calcium produced different effects at higher pH (> 6). Soluble protein-calcium-phytic acid complexes were formed which were less stable to heat and dissociated above pH 10 at high ionic strength. Since this interaction occurred only in the presence of calcium, a salt linkage is implicated in which divalent cations simultaneously bind to the protein and phytic acid in the form of a soluble complex. It is proposed that either the addition of divalent cations at low pH or sequestering agents at high pH would best effect the removal of phytate from soy products by ultrafiltration.     

A new universal and variable flash device for visual examination and photomicrography: VISUFLASH

A recently developed illumination device for microscopes, VISUFLASH, is a universal and variable flash steering device for visual examination, photomicrography and cinematomicrography. The spectral energy distribution of light from the flashtube is suitable for UV- visible- and IR-light examination. Furthermore it is, with the aid of the customary filters, possible with this light source to carry out microscopic examinations with transmitted and incident light, and make observations when use is made of dark-field illumination, phase contrast (+ and -), interference contrast, INTERPHACO®, fluorescence contrast and polarized light. Problems in connection with ultra-short-time-effect and the Schwarzschild effect do not occur. In comparison to existing gas discharge light sources VISUFLASH is economical.     

A REVIEW OF FUNDAMENTAL AND ENGINEERING ASPECTS OF EXTRUSION OF BIOPOLYMERS IN A SINGLE-SCREW EXTRUDER

A review of fundamental and engineering aspects of extrusion in a single-screw is given. Attention is focussed on flow patterns, flow rates, residence time distributions and power consumption as a function of extruder design and screw rotation speed. The relationship for these engineering variables in extrusion of a purely Newtonian liquid and a power law liquid are reviewed. Where possible these relationships are compared with experimental results from the literature (corn-grits) and with our own measurements on biopolymers (corn-grits, defatted soy flour, modified di-amylopectin).     

A COMPARISON OF PROCEDURES FOR MEASUREMENT OF PIGMENT CONCENTRATION IN PORK

Pigment concentration of pork with known quality defects was evaluated using different methods. In Experiment 1, protein denaturation (induced by postmortem incubation at 5-35C) did not affect the pigment values. However, all methods yielded different absolute pigment values. When using the various procedures on a myoglobin standard, the alkaline haematin method and haematin-chloride method yielded similar results. In Experiment 2, loin samples identified as either PSE (Pale Soft Exudative), RSE (Red Soft Exudative), RFN (Red Firm Non-exudative) and DFD (Dark Firm Dry) based upon drip losses, L-values and ultimate pH, were analyzed for pigment concentration. The methods yielded different absolute pigment values. Moreover, depending on the method, the pigment concentration of meat from these four quality groups was either similar or significantly different. It is concluded that the lower pigment concentration reported for PSE pork may be due to the method used.     

High-Temperature Firing of Basic Refractories

An investigation was conducted to determine the hot modulus of rupture strength, the tendency to burst under iron oxide attack, the tendency to creep, and the hot-load-bearing strength of chromite-bearing basic refractories fired from 1400° to 2000°C. Petrographic examination was employed to define the mechanisms of improved bonding which resulted from firing at high temperatures. The results of these physical and chemical tests and the observed microstructure indicated that a greatly improved, highly stabilized basic refractory could be obtained by proper brick design and firing to temperatures of approximately 1700°C. Control of design features such as total silica content, chromite/periclase ratio, and chromite sizing was found to be necessary to achieve superior properties through high-temperature firing.