Some physicochemical analyses of kefir produced under different fermentation conditions

Abstract

This study presents physicochemical attributes of kefir under different cultural conditions. Maximum values of kefirbiomass and kefiran were achieved when 100 ml of skimmed cows’ milk (pH 6)/250 ml glass container was fermented with 5 gfresh kefir grains after stationary incubation at 30°C for 120 h. Amino acids profile in kefir included most types of amino acidsexcept 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 aconcentration value of 0.22% (w/w). Highest kefir biomass and kefiran concentration were maintained when fermentation processwas carried out using a medium formulation composed of: lactose, 40; ammonium chloride, 4.0; KH₂PO₄, 1.0 and MgSO₄.7H₂O,5.0 g/l. Physicochemical analyses of kefir resulted from fermentation of either skimmed milk or medium formulation indicated thatboth kefiran production and kefir filtrate viscosity were growth associated, while increase in titratable acidity was largely relatedto lactic acid production.