Studies on the effects of gamma irradiation on the chemical and microbial parameters of chilled minced beef meat

Changes in quality parameters of minced beef meat samples treated with different doses of gamma irradiation [0, 3, 5, 7 and 9 KiloGray [KGy]] were followed to assess acceptability during refrigeration storage at 4°C. The obtained results indicated that irradiation improved the organoleptic quality and delayed deterioration of chilled minced meat. Application of irradiation resulted in development of off flavour which was more pronounced at high doses specially at 7 and 9 kGy but slightly dissipated after exposure to air. Application of gamma irradiation reduced the rate of development of all deteriorative changes. Irradiation with different doses had a slight significant changes in chemical analysis. Moisture content was decreased. Protein content slightly increased by increasing the irradiation doses and decreased with the progress of storage, while fat% and ash% increased with storage and irradiation doses. pH values of irradiated samples were lower than those of unirradiated samples. Application of ionizing radiation resulted in a remarkable increase in thiobarbituric acid [T.B.A.] content in chilled minced meat samples followed by a proportional increase during refrigeration storage. Total volatile basic nitrogen was decreased specially at doses of 7 and 9 KGy. The microbial load of chilled minced meat was affected by the exposure to different doses of irradiation as well as the reduction of bacterial counts were observed by increasing the irradiation doses. In conclusion, irradiation of minced meat can be effectively used as a supplement to refrigeration process and for increasing the acceptability, safety of the products and shelf life of chilled minced meat

Organochlorine pesticide residues in meat and edible offals

Samples were collected from 350 carcasses of slaughtered animals [175 beef, 150 buffalo and 25 mutton]. Moreover, 200 samples of fresh and frozen livers were taken. With regard to chickens, skin, abdominal fat, liver, kidney and gizzard samples were collected from 50 carcasses. One hundred samples of fish flesh, 50 from each of Clarias lazera and Tilapia nilotica were collected. The collected samples were examined for organochlorine residue by using thin layer chromatoplate. The incidence and the detectable level of organochlorine residues were varied dependent on the species of animals, type of tissue examined as well as the degree of accumulation of these compounds. None of examined fat samples of slaughtered animals exceeded the permissible limits of DDT, while beef muscle and fat as well as buffalo fat showed high level of lindane residue. Broiler carcasses showed no detectable level of any pesticide residues, while the detectable level in laying hen carcasses did not exceed the permissible limits of aldrin and dieldrin. There is no detectable level of organochlorine residues in frozen liver as compared with fresh ones which contained low residual levels of aldrin, dieldrin, lindane and DDT. Clarias lazera contained higher level of dieldrin than other pesticide residues, while none of detectable levels of pesticides in Tilapia nilotica exceeded permissible limits. The sources of contamination to animals, chicken and fish with organochlorine pesticides were discussed

Histamine levels in imported scombroid fishes

A total of 100 imported scombroid fish samples, 50 of each frozen mackerel and canned tuna, were used in this study for determination of pH value, histamine content as well as isolation of histamine producing bacteria. pH values in imported frozen mackerel ranged from 5.4 to 6.8 with a mean value of 6.1, while they ranged from 5.6 to 6.8 with a mean value of 6 in canned tuna. 86% of mackerel samples and 16% of canned tuna showed that histamine content exceeded the permissible level [10 mg/100 g], while 10% of imported frozen mackerel and 2% of canned tuna exceeded 25 mg/100 g. None of the examined samples reached the hazard action level of histamine [50 mg/100 g]. Proteus species, followed by Klebsiella pneumoniae and Enterobacter aerogenes could be detected in high frequency as compared with other isolated organisms. The health hazard effect of histamine and suggestive measures for reducing the risk were discussed