Itaconic acid production from kitchen food waste with Aspergillus terreus

The rising demand for sustainable platform chemicals has intensified interest in valorizing organic waste streams through microbial bioprocesses. This study investigated the production of itaconic acid (IA) from kitchen food waste (KFW) hydrolysate using Aspergillus terreus NRRL 1972, with systematic evaluation of substrate optimization, detoxification strategies, mineral regulation, and downstream recovery. Enzymatic hydrolysis of defatted KFW yielded a fermentable hydrolysate, which exhibited significant fermentation inhibition in its untreated form. Mineral screening revealed that nitrogen limitation and elevated Ca²⁺ concentration enhanced IA accumulation, while excess Na⁺ and K⁺ impaired metabolic flux toward IA biosynthesis. Among detoxification strategies evaluated, activated charcoal at 10% (w/v) selectively removed inhibitory compounds, including phenolics, furans, and Maillard reaction products, while preserving fermentable sugars, outperforming ion-exchange resin treatment, which caused approximately 70% sugar loss despite effective ionic reduction. The sequential combination of activated charcoal detoxification and calcium chloride supplementation achieved a maximum IA titer of 30.03  g/L with a yield of 0.48  g/g, representing a substantial improvement over untreated hydrolysate (1.6 g/L). Downstream recovery via salting-out assisted liquid-liquid extraction using sodium sulfate and sec-butanol achieved crystalline IA with an extraction efficiency of 81% and purity of 86%, as confirmed by Fourier Transform Infrared and Nuclear Magnetic Resonance spectroscopy. Overall, the study demonstrates that strategic detoxification and mineral regulation are critical for unlocking the biotechnological potential of KFW as a low-cost substrate for sustainable, high-purity IA production within a circular bioeconomy framework.