Valorization of cheese whey to eco-friendly food packaging and biomethane via a biorefinery

Non-degradable packaging and cheese whey are two widely produced items, disposal of which causes severe environmental issues. This study tried to address the problems by innovatively valorizing cheese whey to cleaner products including fungal chitosan, biomethane, and novel biopolymer-based films, aiming at green food packaging via a two-stage biorefinery. As the first stage, chitosan was extracted from the biomass of Mucor indicus, an edible filamentous fungus cultivated on cheese whey, resulting in 6.11 g chitosan-rich fungal biomass per 1 L of whey. The obtained fungal chitosan was embedded in wheat starch at varying portions, and further analyses investigated the characteristics of the films. ATR-FTIR and XRD results revealed the good compatibility and synergic effect of the components. The blend film with 6 wt% chitosan showed the least water swelling index (63.8%) and oxygen permeability (similar to 0.5 Barrer (10(-10)cm(3) cm/cm(2).s.cmHg)). The film also had acceptable optical performance with similar to 1.0 A(600)/mm opacity. In the second stage, the effluent of fungal cultivation underwent anaerobic digestion, producing 498.2 mL/g VS biomethane. Overall, 1 m(3) of cheese whey yielded 0.733 Kg chitosan, 17.0 m(3) biomethane, and 89.6% COD removal. The applied cleaner approach, on the whole, provided a biopolymer with the potentiality to produce sustainable packaging that could alleviate plastic pollution, in addition to generating green energy and leaving eco-friendly wastewater.