Kinetic study of Lactococcus lactis strains (SLT6 and SLT10) growth on papain-hydrolysed whey.

The effect of controlled whey hydrolysis by papain on growth of two lactic acid bacteria isolated from artisanal Leben: Lactococcus lactis var. diacetylactis (SLT6 and SLT10) was investigated. The higher biomass and maximum specific growth rate ( μ) were obtained after 30 min of hydrolysis. HPLC analysis of peptides showed that whey hydrolysis reduced the amount of peptides of MW > 400 Da and increased those peptides of MW < 400 Da. The two studied strains exhibited different peptide requirements. The pH-controlled batch cultures in 30 min hydrolysed whey followed the Monod kinetic for growth and for lactate production. The values of the key kinetic constants were: maximum specific growth rate ( μ), 1.08 and 0.56 h; yield biomass on lactose ( Y), 0.20 and 0.18 g g and saturation constant K, 4.2 and 2.8 g L for SLT6 and SLT10, respectively. When compared with batch experimental data, the model provided good predictions for growth, lactose utilisation and lactate production profiles. [ABSTRACT FROM AUTHOR]