Table 1. Effects of the feeding rate and the concentration of the feeding date juice glucose on the cell growth and lactic acid production.

Feeding rate (mL/h)	Feeding glucose (g/L)	Biomass concentration (g/L)	Final lactic concentration (g/L)	Lactic acid productivity (g/L.h)a	Lactic acid yield (g/g)b	Specific growth rate (μ) (h−1)c
150	62	10.4	56.9	0.80	1.4	0.100
75	62	11.1	75.2	1.00	1.5	0.090
33	62	11.8	89.2	1.30	1.7	0.080
33	62*	8.3	57.8	0.80	1.3	0.076
33	100	9.7	79.4	1.13	1.4	0.078
22	100	10.4	80.4	1.15	1.4	0.076
18	100	10.3	84.9	1.21	1.5	0.075

^*Supplements are the same components as the production medium.

^aThe productivity was calculated using the equation: $\mathrm{\delta }=\frac{P_t{V}_t-P{V}_0}{(t_t-t_0)V_t}$.

^bThe yield was calculated using the equation: $Y_{P/S}=\frac{P_t{V}_t-P_0{V}_0}{S_0{V}_0-S_t{V}_t+(V_t-V_0)S_a}$.

^cThe specific growth rate was calculated using the equation: $\mathrm{\mu }=\left[\text{ln}\frac{VX}{V_0{X}_0}\right]\times \frac{1}{t}$.

P_t: Final lactic acid (g/L). V_t: Final volume of the fermentor (L). V ₀: Initial volume of the fermentor (L). P ₀: Initial lactic acid (g/L). S_a: Glucose concentration of the feeding date juice solution (g/L). S_t: Residual glucose concentration (g/L). X ₀: Initial biomass concentration (g/L). X: Final biomass (g/L).