Determinação de proteínas totais de piracuí: comparação entre duas metodologias de análise e locais distintos de aquisição na cidade de Santarém Pará

Abstract

The objective of this study was to evaluate two protein determination methodologies. The samples of piracuí were acquired in two distinct commercial warehouses of the city of Santarém-PA. The analyzes were performed in triplicate. The biuret and Kjeldahl methods were evaluated. For the bioret method a 5% solution of the sample was prepared, allowed to stand for 24 hours, the test tubes were labeled with 50 μL of the supernatant of the sample, the standard with 50 μL of standard commercial laboratory solution and the blank with 50 μL of water distilled, then 2.5 ml of biodegradable Labtest Diagnostica reagent were added, left in a water bath for 10 minutes at 37 ± 1 and read in a spectrophotometer at 545 nm, the blank was used and the concentrations were determined by equations . The total protein was determined by the Kjeldahl analysis (AOAC, 2005) - using a nitrogen conversion factor of 6.25. The data were submitted for comparison using the ASSISTAT statistical program version 7.7, in which the assumptions of analysis and comparison of means by the t-test were verified in 5% of probability. The total protein values were higher in the Kjedahl methodology, with values of 41.10 ± 1.66%, and 10.20 ± 1.32%, by the Biureto method. Values of 1 for the biuret method were 11.33% and Kjedahl of 42.52% and at location 2, biuret was 9.06% and Kjedahl 39.68%. Kjedahl's method is more accurate. The location may change the protein value.