Effect of Nigella sativa and salt on the growth and survival of E. coli O157:H7 during manufacture and storage of Damietta cheese [electronic resource].

Includes references.

Damietta cheese was prepared from pasteurized milk inoculated with E. coli O157:H7 and contained 5% , 10% sodium chloride. Nigella sativa seeds (1 %, 3%) were added. Cheeses were stored in their whey, at room (25 % 2°c) and refrigerator (5 % 2°c) temperatures. Cheese samples were examined periodically for E. coli O157:H7 count, acidity, salt and moisture content. The results indicated that counts of E coli O157:H7 increased rapidly during storage of control cheese at room temperature reaching 8x 105 cfu/g by the end of the first week, then decreased gradually till the fourth week. E. coli O157:H7 could survive until the end of the third week of storage in control cheese stored at refrigerator. However, the organism was not detectable after three and two weeks in cheeses containing Nigella sativa and stored at room and refrigerator temperatures respectively. There was a decrease in moisture content while, acidity and salt contents increased. Nigella sativa seeds were found to have antimicrobial activities against E. coli O157:H7. The results recommended the use of 5% salt and 1 % Nigella sativa to produce a new type of Damietta cheese. Key Words: Nigella sativa, E. coli O157: H7, Damietta cheese.

Summary in Arabic.