46E-26 |
Differentiation between fresh and frozen-then-thawed meat by electrophoretic mediated microanalysis |
B. VALLEJO-CORDOBA1, M. A. Mazorra-Manzano, and A. F. González-Córdova. (1) Departamento de Tecnología de Alimentos de Origen Animal, Centro de Investigación en Alimentación y Desarrollo, A.C. (CIAD, A.C.), Carretera a La Victoria, Km. 0.6, P. O. Box. 1735, Hermosillo, Sonora, 83000, Mexico Although freezing inhibits microbiological growth and extends the shelf-life of meat, it also causes some deterioration in its organoleptic quality bringing a drop in its price. Methods available for the differentiation between fresh and frozen-then-thawed meat present some disadvantages, thus there is need for the development of rapid and reliable methods. b-hydroxydroxyacyl CoA-dehydrogenase (b-HADH), which is a significant mitochondrial enzyme in food muscle may be determined by an electrophoretic mediated microanalysis (EMMA). This techique combines the use of an in-tube enzyme assay and capillary electrophoresis and may present some advantages over available methods. The objetives of this work were to develop an EMMA method based on b-HADH activity determination for the differentiation between fresh and frozen-then-thawed meat and to apply this method to evaluate samples collected from the local market. Meat samples were collected from a local slaughter house and frozen-then-thawed (-20 °C/ 72 h - 4 ºC / 12 h). Commercial beef meat samples were collected from the local market. Juice collected from meat samples was used for the analysis. The enzymatic assay and the separation of the reaction products in EMMA were carried out using a plug-plug reaction mode at variable potential. For the quantification of b-HADH activity, the rate of conversion of NADH to NAD+ was calculated by determining NAD+ at 260 nm. A calibration curve for NAD+ concentration versus normalized area showed a highly significant (p < 0.001) linear relationship (R2=0.993). The assay was reproducible since coefficients of variation of less than 6.2% were calculated for triplicate analyses. From five commercial beef meat samples analyzed, four were frozen-then-thawed and one was fresh, although all five samples were retailed as being fresh. The developed method proved to be useful for the differentiation between fresh and frozen-then-thawed meat and could be used for regulatory purposes.
Session 46E, International
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