Chemically rheological analysis

Some basic food analytical methods such as determination of °brix, pH, titratable acidity, total proteins and total lipids are basic to food analysis and grounded in procedures which have had wide-spread acceptance for a long time. Others such as analysis of cell-wall polysaccharides, analysis of aroma volatiles, and compressive measurement of solids and semi-solids, require use of advanced chemical and physical methods and sophisticated instrumentation. In organizing the Handbook of Food Analytical Chemistry we chose to categorize on a disciplinary rather than a commodity basis. Included are chapters on water, proteins, enzymes, lipids, carbohydrates, colors, flavors texture/ rheology and bioactive food components. We have made an effort to select methods that are applicable to all commodities. However, it is impossible to address the unique and special criteria required for analysis of all commodities and all processed forms. There are several professional and trade organizations which focus on their specific commodities, e.g., cereals, wines, lipids, fisheries, and meats. Their methods manuals and professional journals should be consulted, particularly for specialized, commodity-specific analyses. 

The starting point in the kinetic analysis of the oxidation of polypropylene is the measurement of the extent of oxidation of the polymer as a function of time. In rheological and processing studies it is difficult to obtain real-time chemical information, and many of the chemical changes are elucidated after processing by analysis of the polymer product... 

The reasons behind the observed differences in rheological behaviour of these TGDDM resins could be determined by analysis of the kinetics of the system and the quantitative analysis of the hydroxyl content by MIR or other methods of chemical analysis. This is a clear example of the effect of chemical purity of the resin on rheological properties. 

The second derivative enables the location of the peaks in the spectra and thus assists in assignment, since it will be negative if the original spectrum has a local maximum, positive if it has a local minimum and a point of inflection when it is zero. Again the baseline drift is eliminated (Shimoyama et al, 1998) and either the first or the second derivative may be used in subsequent data analysis by one of the regression methods. In a comparison of the three correction methods specified above, it was found that MSC was best for the discrimination of the EVA copolymers due to their chemical similarity (Shimoyama et al, 1998), while in a comparison of rheological properties (Vedula and Hansen, 1998) the first-derivative spectra were satisfactory. 

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