Bread residues conversion into lactic acid by alkaline hydrothermal treatments

Bread residues can be converted into a suitable feedstock for chemicals production due to their high starch content. The present study was focused on the production of lactic acid from bread residues using alkaline catalysts. NaOH, KOH, Ca(OH)(2), LiOH and K2CO3 were used at 300 degrees C, 30 min and 0.5 M catalyst concentration. The preliminary experiment showed that KOH, NaOH and Ca(OH)(2) are the best catalyst. Using these catalysts further experiments were carried out varying the catalyst concentration at the same operation conditions. The maximum yields of lactic acid from bread residues (% respect to the total initial raw material) were obtained at 300 degrees C, 30 min by using 0.4 M of KOH (38.11 +/- 0.2%), 0.6 M of NaOH (34.46 +/- 0.21%) and 3.5 M Ca(OH)(2) (72.90 +/- 4.45%). (C) 2014 Elsevier B.V. All rights reserved.