Effect of nitrogen sources and neutralizing agents on D-lactic acid production from Kodo millet bran hydrolysate: comparative study and kinetic analysis

Abstract

D-lactic acid (DLA) serves as a key monomer enhancing both the mechanical and thermal properties of Poly(lactic) acid films and coatings, extensively used in the food packaging industry. Economically viable production of optically pure DLA by Lactobacillus delbrueckii NBRC3202 was achieved using a low-cost carbon source, Kodo millet bran residue hydrolysate (KMBRH) and nitrogen source (casein enzyme hydrolysate (CEH) resulting in a high DLA yield of 0.99 g g -1 and KMBRH conversion to final product (95.3%). The optimum values for kinetic parameters viz., specific growth rate (0.11 h -1 ), yield coefficient of biomass on KMBRH (0.10 g g -1 ) and DLA productivity (0.45 g L -1 h -1 ) were achieved at 5 g L -1 of CEH dosage under controlled pH environment. A comparative study and kinetic analysis of different neutralizing agents (NaOH, NH 3 , CaCO 3 and NaHCO 3 ) under pH controlled environment for KMBRH based DLA production was addressed effectively through bioreactor scale experiments. Maximum cell concentration (1.29 g L -1 ) and DLA titer (45.08 g L -1 ) were observed with NH 3 as a neutralizing agent. Kinetic analysis of DLA production under different neutralization agents demonstrated that the logistic derived model predicted biomass growth, KMBRH consumption and DLA production efficiently (R 2 [ 0.92).

Steps toward a digital twin for functional food production with increased health benefits

“…The logistic equation represents classic kinetic model techniques during batch cultivations that describe biomass development. A logistic model considering only cell growth variables and therefore independent of the substrate was applied to predict the biomass and is given in Equation (3) ( Balakrishnan et al, 2020 ). …”

Production of L (+) Lactic Acid by Lactobacillus casei Ke11: Fed Batch Fermentation Strategies

“…It is very likely that if the fermentation had not been interrupted in 48 h, greater L (+) lactic acid production could have been obtained with this fermentation, as production with exponential feeding was only 112.71 g/L L (+) lactic acid in 48 h when pH was controlled by NaOH 10 N and CaCO 3 (Figure 8c). Balakrishnan et al [21] found that although lactic acid production and yield was better when using CaCO 3 to control pH compared to NaHCO 3 , the latter is more indicated because at lower cost and e solubility of sodium lactate is higher which led to an easier separation of LA.…”

“…gardening residues [17], crystal sugar [18,19], municipal biopulp [20], Kodo millet bran hydrolysate [21,22], bakery waste and lucerne green juice [23], sugarcane bagasse [24][25][26] and sugar beet pulp [27].…”

A Simple Biorefinery Concept to Produce 2G-Lactic Acid from Sugar Beet Pulp (SBP): A High-Value Target Approach to Valorize a Waste Stream

“…Considering the recent literature, López-Gómez et al [22] produced 61.1 g/L of l-lactic acid from hydrolyzed municipal solid waste on a batch mode, noticing a high positive impact of yeast extract addition on the media. Balakrishnan et al [23] produced 45.08 g/L of d-lactic acid from hydrolyzed millet bran residue and hydrolyzed casein, with a productivity of 0.45 g L −1 h −1 . Tian et al [24] produced 114.6 g/L of lactic acid from purified sweet sorghum juice and soybean hydrolysate with a productivity of 2.61 g L −1 h −1 on a simple batch mode.…”