Another well-known fermented milk produced with a natural yeast microflora is koumiss. Koumiss is like a milk wine with an alcohol percentage around 2 and a final pH about 4. In the beginning of the 1900 century koumiss was described as the greatest of the fermented milks as reviewed by Steinkraus (1996). Koumiss originates from Khazakstan and is traditionally made from mare's milk but variants made from cows milk has been reported (Steinkraus 1996). The dominating microflora in koumiss is thermophilic lactic acid bacteria and Saccharomyces spp. especially S. unisporus and K. marxianus (Montanari et al. 1996).
Yeast are also present in several indigenous African fermented milk products such as amasi/hodzeko from Zimbabwe (Gadaga et al. 2001), banik from Senegal (Gningue et al. 1991), rob from Sudan (Abdelgadir et al. 2001), nono from Nigeria (Okagbue and Bankole 1992), and ergo and ititu from Ethiopia (Gonfa et al. 2001). All traditional fermented milks are prepared by allowing raw milk to spontaneously ferment at ambient temperature. Lactic acid bacteria and yeast with S. cerevisiae, K. marxianus, K. lactis, and C. kefyr as dominating yeast are part of the natural microflora and it is assumed that yeast play an important role in the microbial interactions between the different microorganisms and development of the characteristic aroma in these products. Traditional fermented milks are made in many households daily. These milks products represent an important source for human of energy, protein, vitamins, and minerals (Loretan et al. 1998). Because of the socioeconomic changes that are taking place in Africa some of the traditional fermentation technologies might be lost together with the related microflora (Loretan et al. 1998). Therefore, interest in traditional African fermented milk is increasing, especially examination and identification of the high number of lactic acid bacteria and yeast and exploration of their role in the fermentation process of the milk (Loretan et al. 1998).
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