Effect of thermal processing on the level of malachite green residues in Oreochromis niloticus with special references to its public health significance [electronic resource].

Includes references.

A total of 150 samples of Oreochromis niloticus were collected during summer season of 2011 from different intensive fanns previously known be infected and treated by disinfectant at Kafr El-Sheikh, Governorate. The samples were assessed for the detennination of malachite green residual levels in fresh, scalded (boiled) and microwave by HPLC. Malachite green residues not detected in 81.33% (122) of the examined Oreochromis niloticus samples. The mean concentrations of the malachite green residual level in the fresh Oreochromis nilotiells muscle was 2.20 ± 0.50 ppb. On study of the effect of thennal processing. the reduction percentage in the levels of malachite green in the scalding (boiling) and microwave treated samples were 52.51% and 59.98% respectively. From the sum of the examined fresh Oreoehromis nilotieus samples 81.33% (122) were agree with the pennissible limit established by FDA for malachite green, while 18.66% (28) of the fresh samples that treated by scalding (boiling) and microwave exceeded the permissible limit. This indicates that cooking by scalding (boiling) and microwave reduces the level of malachite green but not removed it from fish muscle. The relationship between the levels of malachite green in fresh, scalding and microwave treated samples as well as the public health significance of these residues were discussed.

Summary in Arabic.