1. Irradiation and counting
BRAZILIAN MEAT COMPOSITION
Avelar A.C. a, Veado J.C.C. b, Mingote R.M. c, Floresta D.L. c ,Veado M.A.R.V. a
a CCTN -Department of Nuclear Engineering UFMG Av. do Contorno 842, CEP , Belo Horizonte, Brazil
b Department of Clinic and Surgery Veterinary , Veterinary College UFMG Brazil,
c Centro de Desenvolvimento da Tecnologia Nuclear -CDTN/CNEN, Comissão Nacional de Energia Nuclear Brazil
In the present work, values of the mineral composition of bovine tissues (muscle, liver and kidney) from Argentina, Mexico, Chile, U.S.A. and Brazil are presented; the data of Argentina, Chile and Mexico are supplied by F.A.O.; the data of U.S.A. are supplied by U.S.D.A.. Brazilian data were obtained with the use of INAA, at the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN/MG), Brazil. K, Na, Zn and Fe experimental values showed coherence with the data of those other countries. The findings of this study indicated that INAA can be an useful instrument in nutrition and health studies.
I. INTRODUCTION
Appropriately accurate food composition data is a prerequisite for decision making in research and regulatory sciences. It is essential to examine the mineral composition of food from the aspects of nutrition and toxicology. Further, analytical data on various tissues must be used in environmental studies as monitoring guide.
At the international level, FAO (Food and Agriculture Organization) and USDA (United States Department of Agriculture) have a long and successful history of producing and disseminating food composition data. USDA has a broad range of North-American foods only, which is available in own web site. FAO’s web site has food composition tables by nation of Latin America. However, at 2001 first semester, FAO’s Regional Office for Latin America and Caribe has showing no data of inorganic elements in Brazil’s page for cattle specimens.
II. MATERIAL AND METHODS
Samples and Biological Reference Material
The cattle specimens (muscle, kidney and liver) were acquired in Curvelo City riverine region, frozen at -70C in external freezer during 12 hours, and lyophilized (freeze dried) in the Labconco Benchtop Freeze Dry System. Their drying times were the same: 24 hours. The traceability of element level determinations was established by using reference materials: Bovine Muscle Powder (NIST-SRM 8414) and Bovine Liver Powder (NIST-SRM 1577b).
Irradiation and counting
Three procedures were used for irradiations. Irradiations of four minutes at Rotary Specimen Rack of TRIGA MARK I IPR-R1, at CDTN-CNEN, with thermal neutron flux of n.cm-2.s-1 used for determining the elements Cl, Mn, Mg, Cu e Al. Four hours irradiation at the same position and flux, for determining the Br, K e Na . Sixteen hours irradiation at the same position and flux, for determining Fe, Zn, Cr e Rb. After irradiation, samples, references and standard waited appropriate decay time, and then their activities were measured using HPGe hyperpure Ge detector with resolution 0.77 keV for a 122 keV gamma-ray of 57Co and 1.63 for 1332 keV of 60Co. Genie2000® and Maestro® were utilized for gamma spectroscopy. The k0 Method was chosen for calculating the content of the respective elements. Complex calculation was accomplished by a PC software, which uses half-lives and k0 Parameters taken from De Corte (1987) tables.
III. RESULTS AND DISCUSSION
Overall accuracy range in 5-10% was obtained for certified elements in reference materials (Bovine Muscle Powder and Bovine Liver Powder). Biological variation of elemental composition is noted for Zn and Fe. That could be credited to the variation of animal age, variable input and output inorganic elements, inhomogeneous composition of tissues and local water and soil conditions. Must be remembered the variation of methods of measurement results in the variation of analytical data.
IV. CONCLUSION
The goal of this endeavor was to develop a procedure for mineral composition analysis in animal tissues. It was obtained because a good agreement between international organizations values and Brazilian analytical data was found, also achieved the required quality data. INAA was shown as an effective method in inorganic food composition.