Effect Of Cooking Methods( Boiling - Grilling) And Processing Using Some Natural Foods On The Concentrations Of Heavy Metals In Fresh Meats

The purpose of this  study was to estimate some  heavy metals such as Lead "Pb" ,Mercury "Hg" ,Cadmium "Cd" Nickel "Ni" ,Copper "Cu" and Cobalt "Co" in fresh meats (Btello "small veal" ,Kndoz "Beef" and Danni "sheep" ) also to investigate the effects of some  cooking methods boiling and grilling  on these selected heavy metals in fresh meats, finally to investigate the protective effect of soaking  fresh meats precooking in natural foods (tomato juice ,lemon juice, onion juice and yogurt) on these heavy metals.
A total of 330 random samples were selected of fresh meats (Btello, Kndoz and Danni )  from the local markets in Damietta governorate 110 samples  of each type of meats to evaluate their content of lead, mercury, cadmium, copper, nickel and cobalt. The samples of each kind of meats were divided as follows:
Group 1: contains 10 samples of fresh meats.
Group 2: contains 10 samples that were just boiled
Group 3: contains 10 samples that were just grilled
Group4: contains 10 samples soaked in 100% tomato juice  for 2    hours before boiling
Group 5: contains 10 samples soaked in100% lemon juice for 2 hours before boiling
Group 6: contains 10 samples soaked in  100% onion juice for 2 hours before boiling
Group 7: contains 10 samples soaked in 100% yogurt for 2 hours before boiling                                                                                     
Group8: contains 10 samples soaked in 100% tomato juice for 2 hours before grilling
Group 9: contains 10 samples soaked in100% lemon juice for 2 hours before grilling                                                                          
Group10: contains 10 samples soaked in 100% onion juice for 2 hours before grilling
Group11:contains 10 samples soaked in 100% yogurt for 2 hours before grilling
         The main results declared that the concentrations of selected heavy metals were: Cd: 0.81+0.01 , 0.69 + 0.02  ,0.37 +0.01 ppm, Cu : 1.60+0.19, 1.20+0.10, 1.20+0.21 ppm, Co: 0.20+ 0.06, 0.15+0.02, 0.18+ 0.01 ppm  and Ni: 0.40+ 0.08, 0.24+0.12 ,0.47+0.01 ppm  in Btello ,Kndoz and Danni meats respectively and the concentrations of pb, Hg in all samples were found negligible. This indicates that the investigated samples of fresh meats Btello ,Kndoz and Danni are safe from lead and mercury. The  obtained results were concluded that mostly the values of heavy metals in fresh meats samples were lower than recommended maximum acceptable levels and the concentration of Pb and Hg were not detectable.                                                                                         
Results also showed that cooking methods had an important effect on these  selected heavy metals concentrations. Boiling increased Cu concentrations (1.62+0.05 ,1.68+0.08 ,1.68+ 0.01 ppm) but reduced Cd ( 0.26+ 0.02 ,0.05+ 0.01, 0.06+0.02 ppm), Co (0.16+0.02 , 0.09+0.01,0.17+0.01  ppm)  and Ni(0.21+ 0.01, 0.20+ 0.02, 0.26+0.02 ppm) concentrations in Btello ,Kndoz and Danni meats respectively, as well Grilling increased Cu concentrations ( 2.53+0.20, 2.15+0.11, 1.83+0.02 ppm) but reduced Cd ( 0.31+0.01, 0.08+0.01, 0.08+0.01 ppm), Co (0.18+0.02,0.09+0.01,0,16+0.02 ppm)  and Ni(0.24+0.02, 0.22+0.02, 0.27+0.01ppm) concentrations in Btello ,Kndoz and Danni meats respectively.
In this study it was found that soaking  fresh meats (Btello .Kndoz and Danni)precooking in natural foods (tomato juice ,lemon juice, onion juice and yogurt) reduced selected  heavy  metals Cd, Cu, Co and Ni.
The present study recommends that fresh meats should be processed before cooking with the natural foods studied in order to reduce the contamination of heavy metals and overcome their health problems.