The effect of cold storage and cooking procedures on the levels of oxytetracycline residues in beef from Dodoma Region, Tanzania

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Sokoine University of Agriculture


Worldwide, there is an increased use of antimicrobial drugs due to occurrence of diseases of human and animals. The general objective was to study the effect of cooking procedures and cold storage on the levels of Oxytetracycline (OTC) residues in beef in Tanzania. The study used a cross-sectional research design whereby both quantitative and qualitative data were collected from Dodoma region, Tanzania. The household survey was conducted to assess knowledge, attitude and practice on beef consumption among 254 residents. The results show that community based health education and promotion of proper antimicrobial use in animals and preventing drug residues is highly recommended to this population. Beef samples were also analyzed by using High Performance Liquid Chromatography Mass-Spectrometry (HPLC-MS). The quantitative data were analyzed using the IBM Statistical Package for Social Science (SPSS) software version 20 and Epi info version 7. A simple and sensitive method for the detection of OTC levels in ready-to- eat beef by HPLC-MS was modified and validated and used for beef analysis in this study. The advantages of the modified method were cleaning by Supelclean ENVI-carb active coal is cheaper compared to solid phase extraction and samples drying using a stream of liquid nitrogen is cheaper and more than six samples can be dried at a time. For the raw beef, the results indicate that the mean concentration level of OTC was very low (0.69 ± 0.09 ng/g). The boiled and barbecued beef, the mean concentration was 69.4 ±41.93 ng/g and 69.40±38.91 ng/g, respectively. The results indicate that one should not count on heat- treatment to eliminate residues of OTC from beef. The effect of the cold storage on the concentration of OTC residues in beef stored at -20 °C for 60 and 120 days showed that the mean concentration of OTC residues before freezing was 191.71 ± 90.21 ng/g. The mean concentration of OTC after freezing at -20 oC for 60 and 120 days were 166.40 ± 86.49 ng/g and 133.50 ± 83.24 ng/g respectively. These results revealed a significant (p<0.05) reduction of OTC residues of 30% after 60 days and 65% after 120 days of freezing at -20 °C.


PhD. Thesis of doctor of philosophy


Cold storage effects, Cooking procedures, Oxytetracycline residues levels, Beef, Dodoma Region, Tanzania