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Abstract
Summary
Identification of meat according to species plays a key role in forensic medicine. The identification of meat species is performed for a variety of reasons, both economic and ethnic and to prevent the adulteration of meat with unsuitable or inferior species, or in religious communities where particular meat is proscribed.
So the study was designed to achieve three goals by using three simple and different methods to identify the meat species of raw meat, to know the possibility of changing the protein profile due to freezing for several months and the possibility of detection the substitution or adulteration of halal meat with other non labeled species of meat.
This study was conducted to evaluate and implement the use of two of biochemical methods and protein fingerprinting method for species verification via analysis of protein of meats.
For this purpose 60 fresh meat samples from sheep, camel , cattle , pig and donkey (12 samples from each species ) were collected and analyzed for total protein concentration , glycogen content and protein pattern using SDS-PAGE. Meat samples were frozen for 6 month and total protein concentration and electrophoretic methods were implemented periodically along the six months to study the effect of time on those parameters.
The results of total protein concentration revealed that the donkey meat was higher protein concentration than other tested animals (96.7 1.85 g/L) followed by cattle (57.1 0.75 g/L), pig (46.8 0.90 g/L), sheep (38.9 0.55 g/L) and camel (28.1 1.61 g/L) respectively. The adulterated samples of halal meat with donkey meat showed significant increase in the total protein concentration of the adulterated sample than the individual animal total protein.
The results of glucose (as a unit of glycogen) content revealed that the pig meat was higher glucose concentration than other tested animals (147.0 0.82 mg/dl) followed by donkey (66.0 0.47) then the sheep (59.9 0.5 mg/dl), cattle (29.3 1.02 mg/dl) and camel (27.8 1.4 mg/dl). The adulterated samples of halal meat with pig meat showed increase the glucose concentration of the adulterated sample than the individual animal glucose.
The application of SDS-PAGE to identify the different tested animal species along 6 month of freezing give 15-16 bands in sheep with 5-6 major bands and 10-11 minor bands while the camel has 16-17 bands with 8-10 major bands and 7-8 minor bands and the cattle has 18 bands with 5 - 7 major bands and 11 - 13 minor bands and the pig has 19-20 bands with 6-7 major bands and 12-13 minor bands and the donkey has 16-17 bands with 6-7 major bands and 9-11 minor bands.
The differences between the total protein concentration or electrophoretic pattern showed no significant differences in different duration of time the procedure applied.
The protein pattern of mixed meat samples were estimated by visual examination with the detection limit of 10% by the intensity of bands and presence of the characteristic bands in the mixed samples. In protein pattern of mixed sample of pig and sheep there are two characteristic bands (No. 1 and 18) belong to pig and these bands are found in mixed sample and did not found in sheep protein pattern . In protein pattern of mixed sample of pig and camel there is a characteristic band No. 18 in pig protein pattern which found in mixed sample and did not found in camel protein pattern. In protein pattern of mixed sample of pig and cattle there is a characteristic band No. 19 in pig protein pattern which found in mixed sample and did not found in cattle protein pattern and band No.18 in cattle protein pattern which found in mixed sample and did not found in pig protein pattern. In protein pattern of mixed sample of donkey and sheep there is a characteristic band No. 1 in donkey protein pattern which found in mixed sample and did not found in sheep protein pattern and bands No. 3, 5 in sheep protein pattern which found in mixed sample and did not found in donkey protein pattern. In protein pattern of mixed sample of donkey and camel there is a characteristic band No. 1 in donkey protein pattern which found in mixed sample at concentration 50% : 50% and did not found in camel protein pattern and other concentrations. In protein pattern of mixed sample of donkey and cattle there are two characteristic bands one of them is band No.18 in mixed sample which represent the band No. 18 in cattle protein pattern and didn’t found in donkey protein pattern and the second is band No. 19 in mixed sample which corresponding to band No. 16 in donkey protein pattern and it didn’t found in cattle protein pattern and there are thicknesses in 2 bands which are No. 12 and 16 in mixed sample due to overlapping of bands of donkey with their corresponding in cattle.
Biochemical methods may be useful in species identification to some extent and they were considered as screening, field, primary tests where, there results need more confirmation. Electrophoresis separation pattern of meat protein using SDS-PAGE method enable to differentiate between the individual investigated species and to detect the possibility of adulteration in mixed samples. This system proved to be a useful tool for protein quantification.