Abstract
Biogenic amines are formed in ras cheese (Egyptian hard cheese) during ripening process, as a result of degradation of proteins by proteolysis. Therefore, biogenic amines pattern in ras cheese during ripening at room temperature for 90 days were studied using HPLC. Three batches of Ras cheese were manufactured using Egyptian conventional method. From each batch, Samples were collected at 1, 7, 14, 21, 30, 60 and 90 days after cheese manufacture. The overall results indicated that the levels of biogenic amines increased during ripening periods at room temperature. Histamine increase gradually by time from 3.27±0.27 mg/100g at the 1st day of manufacturing until reach to 15.0± 0.53 mg /100g at 90th day of manufacturing. Regarding tyramine, increased gradually by time from 5.83± 0.35 mg/100 g at 1st day of manufacturing until reach to 20.27± 0.35 mg/100 g at 90th day of ripening. Cadaverine increase gradually from 1.40± 0.21 mg/100g at 1st day of manufacturing until reach to 7.70± 0.43 mg/100 g at 90th day of ripening. Putrescine increase gradually by time from 2.03± 0.33 mg/100 g at 1st day of manufacturing until reach to 9.80± 0.38 mg/100 g at 90th day of manufacturing. Tryptamine failed to be detect in ras cheese during ripening. It is concluded that, biogenic amine formation increase during ripening period. Therefore, to protect cheese from being contaminated with amine producing bacteria and to safeguard consumers from biogenic amines poisoning, the factors that enhance biogenic amines formation should be minimized during cheese processing

Key words: Ras cheese, biogenic amines, Tyramine, Histamine, HPLC