Unstructured kinetic modeling of growth and lactic acid production by Lactobacillus plantarum NCDC 414 during fermentation of vegetable juices

- Model to predict the kinetics of cell growth, lactic acid production, and sugar consumption in Lactobacillus plantarum.
- Secondary modelling showed maximum specific growth rate and relative maximum cell concentration depend on the sugar concentration.
- From an industrial point of view, this study is a first step in the development of novel vegetable based functional foods.
- A set of equations for the optimization of large-scale production of probiotic cultures.

Unstructured Gompertz and Logistic models were developed to describe growth, substrate utilization and lactic acid production by Lactobacillus plantarum NCDC 414 in juices of bitter gourd (Momordica charantia), bottle gourd (Lagenaria siceraria) and carrot (Daucus carota). These vegetable juices have considerably good quantities of total sugars that allowed the growth of L. plantarum for 24 h at 37 °C, after which the cell numbers begin to decline. Kinetics of cell growth, lactic acid production and sugar consumption were evaluated. The viable cell counts increased from 4 × 105 CFU/ml to 7 × 1010 CFU/ml after 24 h of fermentation. The lactic acid increased by about 4.5 times in 24 h and about 44% w/v reduction in sugar content was observed during growth of L. plantarum. Significant lactic acid production occurred during the growth phase as well as stationary phase. With the kinetic model proposed by R. Luedeking and E.L. Piret for lactic acid production rate, the growth associated and non growth associated coefficients were determined. The model was demonstrated for batch growth of L. plantarum in vegetable juice.