Chemical scores

The PIIS has been calculated as a total score, which is the sum of a chemical score and a process score (Table 1). The chemical score consists of inventory, flammability, explosiveness and toxicity. The process score includes temperature, pressure and yield. Some of the scores are based on similar tables in the Dow and Mond Indices. Others have been constructed by dividing the domain of values of a parameter into ranges and assigning a score to each range. They are supposed to be modified in the future. 

Prototype Index of Inherent Safety (PUS) Chemical score inventory, flammability, explosiveness and toxicity Process score temperature, pressure and yield Total score sum of the chemical and process scores... 

To achieve sufficient essential amino acids or a better amino acid balance (chemical score), plant proteins must be consumed in larger quantities or be blended with other complimentary proteins. 

The substitution of the seed flours for cowpeas or wheat flour increased the percentage protein (Table IV) in all food products and increased the chemical scores of the limiting amino acids, methionine and cystine, for all foods. 

Although there was a difference in the most limiting amino acids between the blends, they were close in chemical score. The chemical score is the score of the most limiting essential amino... 

Jones TD, Walsh PJ, Zeighami EA. 1985. Permissible concentrations of chemicals in air and water derived from RTECS entries A "rash" chemical scoring system. Toxicol Ind Health 1 213-234. 

Protein hydrolysis in 6N HCl and subsequent analysis to determine amino acids (except tryptophan, which is acid labile) chemically present is a first step in protein quality evaluation. The chemical score and the EAA index represent attempts to use this information to chemically estimate nutritional quality of protein their obvious limitation is their disregard for amino acid availability. The chemical score is obtained by evaluating the percent of the limiting amino acid in comparison to that amino acid in whole egg protein ). The EAA index is the geometric mean of the ratios of each of the essential amino acids to those amino acids occurring in whole egg (4). 

Additional factors that may affect the reliability of the chemical scoring methods lie with the inherent difficulties of amino acid analysis. The analytical procedure for amino acid analysis can affect both the recovery and reliable quantitation of amino acids. Proteins must first be hydrolyzed to amino acids before analysis. Hydrolysis methods affect the amino acid recovery. Cystine, methionine, tryptophan, threonine, serine, and tyrosinecan bedestroyed during hydrolysis. Valine and isoleucine are released slowly and may not be completely... 

Chromatographic separation of amino acids in the test protein is required for chemical scoring methods. The selectivity and sensitivity of chromatographic methods vary and comparing results of more than one method may be required, particularly when proteins with unusual amino acid profiles are being tested. 

Values for a test protein will be lower than for the reference protein. The reliability of results for chemical scoring methods depends upon the accuracy of the amino acid determinations that form the basis for these assays. Chemical scoring and animal bioassays tend to provide similar relative rankings of protein quality however, the actual values may be different. Chemical scoring methods should not replace a bioassay for testing the quality of a food protein for which there is very little nutritional information. 

Seligson, F.H., and Mackey, L.N. 1984. Variable predictions of protein quality by chemical score due to amino acid analysis and reference pattern. J. Nutr. 114 682-691. 

Chemical scoring, 133-139 Chemical stresses impacting emulsion stability, 592 (fig.)... 

TABLE VIII. Effect of thermal processing on the chemical score of hard red wheat flour... 

Bryan TR, Ross RH. 1988. Chemical scoring system for hazard and exposure identification. J Toxicol Environ Health 1 119-134. 

In the derivation of regression-based empirical scoring schemes, on the other hand, penalty terms have traditionally not been included. However, some situations like obvious electrostatic and steric clashes can be avoided by guessing reasonable penalty terms or by importing them from molecular mechanics force fields. An example of this is the chemical scoring function available in the docking program This function is a modified van... 

Jones, T.D., P.J. Walsh, A.P. Watson, B.A. Owen, L.W. Barnthouse, and D.A. Sanders. 1988. Chemical scoring by a rapid screening hazard (RASH) method. Risk Anal. 8 99-118. 

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