Upcycling waste apples into platform chemicals: pilot-scale production of lactic and succinic acids

The conversion of renewable biological resources into value-added products is essential for supporting the transition to a sustainable bioeconomy. This study explores the use of waste apples—a byproduct generated in large quantities along the fresh apple supply chain—as feedstock for the production of two industrially relevant platform chemicals: lactic acid (LA) and succinic acid (SA). A screening identified Heyndrickxia coagulans A203 and Actinobacillus succinogenes DSM 22257 as the most suitable strains for LA and SA production from apple biomass. A simplified procedure, omitting costly centrifugation and sterilization steps between enzymatic liquefaction and fermentation, was successfully scaled up, resulting in 73.8 g∙L − 1 LA with a yield of 0.91 g∙g − 1 and 36.8 g∙L − 1 SA with a yield of 0.69 g∙g − 1 . The results demonstrate the potential of waste apples as a low-cost, effective feedstock for the biotechnological production of high-value platform chemicals, contributing to the valorization of agri-food waste within a sustainable and circular bioeconomy.