The apparent paradox of a decrease in S.thermophilus counts after d 14 and an increase after d 28 is a fact that, indeed, frequently occurs in studies that employ commercial cultures of bacteria, especially those employed in yoghurt making, likely because of the presence of a bouquet of bacteria with slight peculiarities in the ability of growth and survive under different conditions of the media. Being so, that group of bacteria grown under the initial conditions and survived likely became old and less adapted to the subsequent changes in pH, acidity and nutrients.