An exploration of renewable resources for biobased chemicals and materials

Valorisation of unavoidable food supply chain (UFSC) waste through circular, zero-waste principles is an important driver in the transition from petroleum-based to biobased refineries for chemicals, materials, and bioenergy. This work explores the valorisation of UFSC wastes, namely, blackcurrant pomace (BC), ginger pomace (GP), aeroponically grown coriander (CR) and Thai basil (ThB) roots, into biobased chemicals and materials.

Microwave hydrothermal (MHT) and acid-assisted treatment of BC yielded low methoxy pectin (Degree of esterification up to 21.1%). Low-temperature MHT (100 °C) produced the highest anthocyanin-rich fraction among all aqueous conditions. Subsequent MHT at 160 °C, followed by alkali bleaching, enabled the production of hydrogel-forming defibrillated celluloses (DFC). Incorporation of BC-derived fractions into sodium alginate (NaAlg) films enhanced antioxidant activity. NaAlg–BCP films were able to detect ammonia, with NaAlg–BCP50 showing the most distinct colour change. Differential scanning calorimetry showed that the films are suitable for high-temperature applications (up to 187 °C), with antifogging properties and high-water vapour permeability, supporting their use in packaging for highly perishable foods and spoilage indicators.

Supercritical CO2 extraction of GP, CR, and ThB recovered essential oil- and lipid-rich extracts. CR and ThB extracts were rich in fatty acids, while GP extracts contained high phenolics. Microwave-assisted extraction produced soluble proteins at temperatures below 100 °C, whereas temperatures ≥ 80 °C yielded soluble starch from GP with yields up to 37% and high amylose content (41-46%). Further MHT of residues produced DFC with high thermal stability and water-holding capacity. However, only GP-derived DFC formed stable hydrogels, while CR- and ThB-derived DFC were unable to gel due to the presence of highly crystalline calcium oxalate and lignin.

Overall, this work demonstrates an integrated biorefinery approach for converting diverse agro-industrial and agricultural wastes into functional biobased products, contributing to waste reduction, resource efficiency, and sustainable material development.