Green metrics for sustainability of biobased lactic acid from starchy biomass vs chemical synthesis

The interest in the biotechnological production of lactic acid has increased due to the prospects of environmental friendliness and of using renewable resources instead of petrochemicals. Besides, this type of lactic acid is important for polylactic acid (PLA) production, as it is not toxic as packaging in food application while monomers of many fossil polymers are. However, lack of information can be found about the efficiency of fermentative production of lactic acid from biomass in compare with its production in a chemical way. The present paper reviews some of our recent studies concerning metrics relevant to the development of a cost-effective and sustainable viable processes for lactic acid production. In particular, the following metrics were taken for consideration: (i) material efficiency; (ii) total energy efficiency, (iii) economic added value and (iv) land use. Higher economical effect has been found by using biological conversion of wheat biomass to lactic acid vs chemical synthesis by increasing the energy efficiency by 47% and decreasing the total costs by 17%. Chemical synthesis from petrochemical resources always results in a racemic mixture of D/L-lactic acid, which is a major disadvantage of this approach, while fermentation-derived lactic acid mixtures of poly D(-) and poly L(+) give the high crystalline melting point (T-m), which is a very important criteria for improving PLA applicability for bioplastics production. Conversely, microbial lactic acid fermentation offers an advantage in terms of utilization of renewable carbohydrate biomass, low production temperature, low energy consumption, and the production of optically high pure lactic acid by selecting an appropriate strain. (C) 2014 Elsevier B.V. All rights reserved.