A preliminary study on the diversity and technological properties of indigenous traditional South African fermented milk

The nutritional and biotherapeutic properties of traditional fermented milks have stimulated research into various aspects of microbial metabolism, microbial composition and fermentation processes of these products. Yeasts were enumerated, isolated and identified from different traditional fermented milks manufactured in households by small-scale dairy farmers in rural areas. A total of 30 yeasts were isolated from 10 sour milk samples and 27 yeasts from seven different kefir samples. The yeast counts for the sour milk samples varied between 103 and 106 CFU per ml and was approximately 108 CFU per ml for kefir. Predominant species found in the fermented milks were Debaryomyces hansenii, Torulaspora delbrueckii and Kluyveromyces marxianus. Other species found were Yarrowia lypolitica and Dekkera anomala. The predominant yeast species in the kefir samples were Saccharomyces cerevisiae and Kluyveromyces marxianus. Other species encountered were Torulaspora delbrueckii, Zygosaccharomyces rouxii and Debaryomyces hansenii. Assimilation of lactate was a common feature for the isolates from fermented milks and several assimilated and fermented lactose an degraded casein. A few were lipolytic. Most isolates could grow in the presence of 10 per cent (w/v) NaCl and a few, including D. hansenii, even in the presence of 20 per cent (w/v) NaCl.