Valorização de bagaço de uva para produção de ácido lático, contribuição para a economia circular

The main objective of this project is to start using POM winery residue and finishing producing biobased PLA, a material with increasing applications. It envisages the valorization of grape pomace by developing and optimizing the production of one of the enantiomers L(+) lactic acid or L(-) lactic acid, L- and D-lactic acids respectively, in order to produce lactide and polymerize it to Polylactic acid (PLA). Two molecules of one of these enantiomers form lactide, will be the monomer for the PLA. All the very different steps from the first POM residue until reaching PLA a polymer increasingly sought after for various applications will be investigated by the Team with widely different complemental expertises. The acquired knowhow will be a starting point to potential application to all the other types of POM released in the wineries, according to different varieties of grapes feeding such processes but also due to different types of wines produced. Considering this main purpose, also two main issues are envisaged: a) the total conversion of grape pomace into added value products (lactic acid and oligosaccharides) in a zero waste approach, b) reducing petrochemical-based polymers utilization since an alternative renewable-based PLA is proposed. Lactic acid fermentation is not a new research item but the homofermentative production of D or L lactic acid from wastes to attain such a high purity that allows its polymerization to PLA is a new challenge. To face this challenge and to attain the main objective of this project, the following specific objectives will be accomplished: 1) To study and to optimize the grape pomace biomass fractionation into different fractions. 2) To produce lactic acid by W. coagulans and E. coli JU15 in a small scale, selecting the appropriate experimental conditions. 3) To study R. oryzae lactic acid production not only in submerged fermentation but also in solid state fermentation. 4) To study the scale-up of bacterial fermentations after selecting the best experimental conditions for each bacterium. The 5 L bioreactor will be used for operating in a fed-batch for providing enough fermentation broth for feeding separation and purification processes. 5) To study cell-free lactic acid recovery and purification by combining microfiltration and nanofiltration membrane processes. The purest L or D lactic acid solution will be provided for feeding polymerization. 6) To study the polymerization of L and also D lactic acid for obtaining L or D-lactides and then to polymerize to the isotactic homopolymers of PLLA and PDLA.