Some physicochemical analyses of kefir produced under different fermentation conditions

This study presents physicochemical attributes of kefir under different cultural conditions. Maximum values of kefir biomass and kefiran were achieved when 100 ml of skimmed cows' milk (pH 6)/250 ml glass container was fermented with 5 g fresh kefir grains after stationary incubation at 30 degrees C for 120 h. Amino acids profile in kefir included most types of amino acids except asparagine, glutamine and tryptophan. Analysis of kefir organic acids indicated that lactic acid had highest concentration (7.30 mg/ml), followed by acetic acid (6.50 mg/ml) and maleic acid (4.00 mg/ml). Production of ethanol was high, reaching a concentration value of 0.22\% (w/w). Highest kefir biomass and kefiran concentration were maintained when fermentation process was carried out using a medium formulation composed of: lactose, 40; ammonium chloride, 4.0; KH(2)PO(4), 1.0 and MgSO(4).7H(2)O, 5.0 g/l. Physicochemical analyses of kefir resulted from fermentation of either skimmed milk or medium formulation indicated that both kefiran production and kefir filtrate viscosity were growth associated, while increase in titratable acidity was largely related to lactic acid production.