Food Science and Quality Management www.iiste.org ISSN 22246088 (Paper) ISSN 22250557 (Online) Vol 6, 2012 12 Ketut Suriasih 1,* Wayan Redi Aryanta 2 Gede Mahardika 1 Nyoman Mantik Astawa 3 1. Faculty of Animal Husbandry, Udayana University ,PO box 80237, Bali, Indonesia. 2. Faculty of Agricultural Technology, Udayana University, PO box 80237, Bali, Indonesia. 3. Faculty of Veterinary Science, Udayana University, PO box 80237, Bali, Indonesia. * Email of the corresponding author ketutsuriasih@ymail.com Information regarding to microbiological and chemical characteristics, and incubation time is crucial in developing kefir prepared using Bali cattle milk. This study was intended to investigate microbiological and chemical properties of the kefir prepared of Bali Cattle milk and Indonesian kefir grains after 24, 48 and 72 hours incubation periods. A completely randomized design, with 3 treatments, and 9 replicates were undertaken. Kefir samples were taken at the end of incubation period for determination of total lactic acid bacterial and yeast counts, pH, titratable acidity, lactose percentage and protein content. The result of this research showed that the total lactic acid bacterial counts were 10 8 – 10 9 cfu/ml, while yeast counts were ranging from 10 5 – 10 6 cfu/ml, no coliform and Escherichia coli were detected in any kefir samples in this research. Identification of the lactic acid bacteria and yeast revealed that the ssp. was the predominant species found in the kefir samples, followed by and the yeast . Chemical analysis of the kefir samples showed that, protein, lactose, titratable acidity and pH of the kefir samples were in the range of 5.68 6.26%, 3.98 4.67%, 0.89 1.73% and 3.38 4.35, respectively. The result also indicated that the incubation period significantly affected the microbial counts and chemical composition of Bali Cattle milk kefir. Kefir, Bali cattle milk, Lactic acid bacteria, Yeast, Protein, Lactose Kefir is a fermented milk beverage which has a slightly acidic taste and some effervescence due to lactic acid, carbon dioxide and a minute (<2%) concentration of alcohol resulting from the action of microorganisms present in kefir grains used to cultured the milk. Kefir grains are small, gelatinous, yellowish in color, and appear as small clamps of irregularly shaped cauliflower. The kefir grain is believed originated from the region of Caucasian mountains (Farnworth, 2005). The grains contain a mixture of complex microflora such as lactic acid bacteria, yeast and sometimes acetic acid bacteria which are lodge by a polysaccharide matrix calls “kefiran”. These microorganisms, called probiotics ( Farnworth and Mainville, 2003; Powell, 2006), which consist of lactobacilli, such as and ; lactococci including sbsp sbsp sbsp and a variety of yeast such as and sp. (Oberman and Libudzisz, 1998). Microbial activity in kefir fermentation is a symbiotic metabolic activity of a number of bacteria and yeast species, which degrade milk constituents to lactic acid, acetic acid, ethanol, carbon dioxide and other flavor compound such as acetaldehyde result in a distinctive flavor of the kefir beverage (Farnworth and Mainville, 2003). The beverage also contains easily digestible proteins and essential amino acids that help the body healing and maintenance functions ( Otles and Cagindi, 2003) Generally, kefir is made of cow’s milk, but many types of milk such as goat, ewe, mare, buffalo, camel is also can be used. Bali Cattle is an Indonesian indigenous cattle which yield a high meat quality. Besides, Bali cattle also produce milk about 1.5 2.5 litter/head/day. Bali Cattle milk contains around 5.19% protein, 7 8% fat, 5.18% lactose, 0.21% calcium, 0.18% phosphor and 18 19% total solid (Sukarini, 2000), while other cows milk such as Holstein cows milk, composed of 3.3%, 4.0%, 5.0%, 0.12%, 0.095% and 12.1% protein, fat, lactose, calcium, phosphor and total solid respectively (Campbell and Marshall, 1975). The chemical components of Bali Cattle milk was 50 – 75%