Growth potential and inhibition of bacillus cereus and staphylococcus aureus during the souring of ergo; a traditional Ethiopian fermented milk

ABSTRACT

The growth potential of bacillus cereus and staphylococcus in milk in non-smoked and smoked containers was assessed. In non-smoked containers both organisms reached a level of about 10[7] cfu/ml within 24 hours. A marked retardation of growth of the organisms was achieved until 24 hours (10[3] cfu/ml) by smoking the containers. In souring Ergo; pH fell to -4.3 and titratable acidity increased to more than 0.73 in 24 hours in milk in non-smoking containers and the organisms were completely inhibited within 24 to 36 hours. Although rate of pH drop and increase in titratable acidity was slightly lower in souring Ergo in smoked containers; complete inhibition of the test organisms was detected within 24 hours. Smoking containers and inoculating a heat-treated milk with an old Ergo starter is recommended to obtain a wholesome product