Journal of Dairy Research (2001) 68 639±652
GRACIELA L. GARROTE, ANALI;A G. ABRAHAM and GRACIELA L. DE ANTONI
Summary. Chemical and microbiological composition of four Argentinean kefirr
grains from different sources as well as characteristics of the corresponding fermented
milk were studied. Kefirr grains CIDCA AGK1, AGK2 and AGK4 did not show
significant differences in their chemical and microbiological composition. In contrast,
protein and yeast content of AGK3 was higher than in the other grains. Although
grain micro¯ora comprised lactobacilli, lactococcus, acetic acid bacteria and yeast,
we found an important difference regarding species. Lactococcus lactis subsp. lactis,
Lactobacillus kefir, Lactobacillus plantarum, Acetobacter and Saccharomyces were
present in all types of kefir grain. While Leuconostoc mesenteroides was only isolated
from grains CIDCA AGK1 and Lactococcus lactis subsp. lactis biovar diacetylactis,
Lactobacillus parakefir and Kluyveromyces marxianus were only isolated from CIDCA
AGK2 grains. All grains produced acid products with pH between 3±5 and 4±0. The
apparent viscosity of AGK1 fermented milk was greater than the product obtained
with AGK4. All fermented milks had inhibitory power towards Escherichia coli but
AGK1 and AGK2 supernatants were able to halt the bacterial growth for at least
25 h. Grain weight increment in AGK1, AGK2 and AGK3 during growth in milk did
not show significant differences. Despite their fermenting activity, AGK4 grains
did not increase their weight
Keywords: Keirr, lactic acid bacteria, kefir microflora
