PubMed · 5761947
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D V Barker, B Greenwood, C C Ingrey. 1969. A microscope warm stage.. https://pubmed.ncbi.nlm.nih.gov/5761947/
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The effect of ionic strength (I) on the formation of thermally induced aggregates by the 7S globular storage protein of soya, beta-conglycinin, has been studied using atomic force microscopy. Aggregates were only apparent when I> or =0.1, and had a fibrous appearance, with a height (diameter) of 8-11 nm. At high ionic strength (I=1.0) the aggregates appeared to associate into clumps. When aggregate formation was studied at I=0.2, it was clear that aggregation only began at temperatures above the main thermal transition for the protein at 75 degrees C, as determined by differential scanning calorimetry. This coincided with a small change in secondary structure, as indicated by circular dichroism spectroscopy, suggesting that a degree of unfolding was necessary for aggregation to proceed. Despite prolonged heating the size of the aggregates did not increase indefinitely, suggesting that certain beta-conglycinin isoforms were able to act as chain terminators. At higher protein concentrations (1% w/v) the linear aggregates appeared to form large macroaggregates, which may be the precursors of protein gel formation. The ability of beta-conglycinin to form such distinctive aggregates is discussed in relation to the presence of acidic inserts in certain of the beta-conglycinin subunits, which may play an important role in limiting aggregate length.
Stimulated acoustic relaxation emissions from maize starch tablets after compression were detected and recorded in the audible region. Stimulation was found to enhance the detected acoustic emission and to maintain recordable acoustic emission level longer. Based on the fact, that the stimulation by a halogen lamp and a preheated chamber produced similar results, the effect of stimulation on acoustic relaxation emission is proposed to be connected to the temperature rather than the visible emission. A mathematical model of acoustic activity and its dependence on stimulation temperature is also introduced.
Based on reaction kinetics and thermodynamic considerations a mathematical model was developed to describe the thermal death rate of microbes as a function of environmental factors such as temperature, water activity, pH and redox potential. The mathematical model is discussed and validated by fitting to data sets of heat destruction of Lactobacillus brevis and Lactobacillus plantarum. The mathematical analysis of the kinetic model and the parameters of the model fitting demonstrate its applicability both for the prediction of the heat destruction rate and estimation of the thermodynamic parameters of heat destruction.