Abstract: Food waste valorization is crucial for achieving zero-waste initiatives and implementing waste management strategies. Carbon chain elongation, particularly for producing medium-chain carboxylic acids like caproate, presents a promising biorefinery pathway for converting food waste into value-added chemicals. Among the various approaches, lactate-mediated chain elongation has garnered significant interest due to its potential advantages, including enhanced process controllability and high electron donor utilization efficiency. Although lab-scale research has confirmed the feasibility of this technology and demonstrated progress, challenges impede its transition to industrial-scale application. This review summarized the current status of lactate-mediated chain elongation for caproate production and critically analyzed the key bottlenecks hindering its scale-up. Major challenges identified include limitations in adaptability to and microbial utilization of complex substrates, difficulties in achieving precise process control and real-time monitoring, insufficient efficiency and stability of the functional microbial communities, and significant economic constraints imposed by high chemical and energy consumption. Addressing these critical issues is key to advancing this technology towards industrial-scale implementation.

Key words: chain elongation, lactate, caproate, food waste, scale-up bottlenecks