Integrated cost-efficient itaconic acid production from waste potatoes via a holistic upstream-to-downstream approach

Abstract

Itaconic acid (IA) holds enormous potential in the polymer industry as a green substitute for several valuable chemicals derived from fossil fuels. However, its full potential is limited by high production costs, resulting from the use of expensive feedstocks and downstream processing approaches. In this context, this study strategizes an inexpensive approach for the efficient production and recovery of IA using damaged/defective waste potatoes, a major food waste across the globe. Initially, the optimized acidic saccharification process (1.5 % HCl, 20 % w/v solid loading) yielded 170 g glucose/kg potato. The fermentation of activated charcoal-treated potato hydrolysate by Aspergillus terreus DSMZ 23081 resulted in 32 g/L IA with a yield and productivity of 0.21 gIA/gGlu (36.2 gIA/kgWPB) and 0.17 g/L/h, respectively. The downstream processing was performed by implementing a salting-out extraction approach. Among various solvent-salt combinations, maximum IA extraction efficiency was observed when 25 % (w/v) Na2SO4 was used as a salting-out agent with sec-butanol as the extractant. Optimizing the physicochemical parameters (pH, solvent volume, shaking time, etc.) led to 92 % recovery from pure IA solution. Finally, when the process was applied to potato-based fermentation broth, 80.5 % IA was recovered with 85 % purity. By integrating valorisation of a low-cost agro-industrial waste with an optimized salting-out extraction strategy that overcomes key limitations of conventional IA purification, the developed bioprocess demonstrates a simple and economically feasible end-to-end strategy for sustainable IA production.