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Determination of Insect Infestation in Food: A Semiautomated Calorimetric Analysis for Uric Acid with Immobilized Uricase
Author(s) -
ROY R. B.,
KVENBERG J. E.
Publication year - 1981
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1981.tb04193.x
Subject(s) - uric acid , chemistry , sodium hydroxide , hydrochloric acid , chromatography , reagent , phosphotungstic acid , food science , sodium , biochemistry , organic chemistry , catalysis
A semiautomated differential calorimetric procedure for the determination of uric acid is reported. Samples are treated with hydrochloric acid, incubated at 55–60°C in a water bath, and neutralized with sodium hydroxide. Uric acid is extracted with sodium acetate and is determined with phosphotungstic acid as the color reagent. Uric acid is destroyed with uricase, and the calorimetric analysis is repeated for a blank measurement. The reaction specificity of uricase and its immobilization in a nylon coil contribute to the reliability of the method, which permits analysis of 30 samples/hr. Recovery studies and analyses of actual samples show that uric acid can serve as a chemical index of insect infestation in a variety of foods. The sensitivity of the method is approximately 5 μg uric acid/g of sample and is adequate to ascertain objectionable levels of stored product insect excreta contamination in food products.