Fermented Ethiopian Dairy Products and Their Common Useful Microorganisms: A Review

Recently emphasis has been given to produce fermented milk with significant quality and improved health characteristics. In Ethiopia, a large proportion of milk is consumed in the fermented form through the application of traditional fermentation methods. The main fermented milk products include ergo (sour milk), ititu (milk curd), ayib (cottage cheese), neter kibe (spiced butter), kibe (traditional butter), aguat (whey) and arerra (sour defatted milk). In East and South East part of Ethiopia, fermented (suusac) camel milk is widely consumed, while in North West part, fermented Metata Ayib is prepared using traditional cottage cheese with different spices. The objective of this review is to investigate the role of microorganisms in Ethiopian traditional fermented dairy products. With all traditional fermented milk products, lactic acid bacteria (LAB) produce several metabolic products including potential antimicrobial activities, fatty acids, organic acids, hydrogen peroxide, CO and diacetyl. The inhibitory capacity of the acids depends on reduction of pH to levels below the 2 requirement for bacterial growth. Therefore, LAB play a significant role in food fermentation and they have also antagonistic effects against food borne pathogenic microorganisms and help to improve biochemical features of fermented foods. LAB produces specific bacteriocins and proteineous substances which inhibit the growth of pathogens and food bore pathogens. They are also produces different types of compounds that impart characteristic aroma, color and flavor of fermented foods. In fermented Metata Ayib, the combined effect of spices which were incorporated during traditional Metata Ayib preparation and LAB with antagonistic activity can reduce the risk of spoilage and pathogenesis.