RESUMO
A procedure is described for the examination of large numbers of ground beef samples for the 4 most commonly used preservatives. A single sample solution is prepared and aliquots are taken for the various tests. Sulfite is determined colorimetrically with acid-bleached prosaniline. Ascorbic acid is titrated with 2,6-dichloroindophenol. Benzoic and sorbic acids are measured by ultraviolet absorption. Negative samples are rapidly sorted out in this procedure and positive samples are completed for quantitative determination of the preservative. Recoveries are 95% for sodium sulfite, 103% for sodium benzoate, 90% for potassium sorbate, and 81% expected recovery for sodium ascorbate. The limit of detection is 0.005% for potassium sorbate, and 0.001% for the 3 other perservatives.
