Milk technological properties and fermentation products of human origin Lactobacillus rhamnosus IF3 and L. paracasei ssp paracasei IF10 as single culture

Abstract

The growth and metabolism of two probiotic strains were studied in pasteurized milk at different temperatures with no supplement. The probiotic strains from infant faeces were Lactobacillus paracasei ssp. paracasei IF10 and L. rhamnosus IF3. Fermentation was followed for 24 h at 32, 37 and 42 degrees C, and the samples were analyzed for pH, titratable acidity, acetaldehyde, diacetyl, exopolysaccharide (EPS), viscosity and for viable counts (log cfu/ml). After 24 h of incubation the two strains reduced pH from 6.6 to between 3.86 and 4.78; however, all strains showed cell levels between 6.18 and 8.93 log cfu/ml. Lactic acid (%), EPS (mg/L) and viscosity (cP) produced varied according to strain between 0.46-0.81, 43-127 and 350-950, respectively. While L. rhamnosus IF3 produced detectable levels of acetaldehyde and diacetyl, L. paracasei ssp. paracasei IF10 formed only acetaldehyde at all temperatures after 24 h of incubation.