Valorization of rice straw through aqueous polyphenol extraction: Optimization, scale-up and potential industrial applications.

This study explores the optimization and scale-up of polyphenol extraction from rice straw (Oryza sativa), a lignocellulosic by-product with significant environmental impact. Annually, up to 790 million tons of rice straw are generated worldwide, much of which is improperly disposed of, often through open burning. On the one hand, this practice releases harmful gases, detrimentally affecting environmental quality and human health. On the other hand, the high antioxidant and antimicrobial value of rice straw-derived polyphenols presents a promising solution for repurposing this waste, aligning with circular economy principles.

To maximize the recovery of these bioactive compounds, artificial intelligence was utilized to optimize critical extraction parameters, including temperature, ultrasound energy (J/mL), enzyme quantities and straw-to-water ratios. Laboratory-scale optimization identified conditions yielding high polyphenolic content and antioxidant capacity.

Progressing to a semi-industrial scale, advanced technologies such as steam explosion and affinity resin purification were employed. Equipment such as semi-industrial reactors, plate filters, rotary evaporators and vacuum dryers were integrated to refine and scale the process.

Following the optimization of the scaling-up process, different assays were conducted to determine the polyphenolic content, antioxidant capacity and cosmetic potential of the obtained extracts. The results of these tests confirmed the scalability and industrial feasibility of the aqueous extraction method. The residues and by-products of this process have been also valorized for alternative industrial and value-added applications, adhering to the principles of circular economy and sustainable development.

In this sense, the obtained polyphenol-rich extract demonstrated potential for incorporation into anti-aging cosmetic formulations and as additives in footwear components. Additionally, residual by-products from the process were successfully repurposed into biomaterials for construction applications, further enhancing the sustainability of the system.