Use of silicon dioxide nanoparticles for β-galactosidase immobilization and modulated ethanol production by co-immobilized K. marxianus and S. cerevisiae in deproteinized cheese whey

•Immobilized β-galactosidase nanoparticles resulted in a higher hydrolysis of whey.•During batch fermentation in cheese whey, co-culture yielded higher ethanol than single culture.•Same Vessel hydrolysis and fermentation process resulted in a decrease in fermentation time.

β-galactosidase from dairy yeast was immobilized on silicon dioxide based nanoparticles for the hydrolysis of whey. The biocatalyst was checked for the optimal thermal and pH stability. Consequently, the immobilized β-galactosidase was recycled 15 times for the hydrolysis of lactose (37 °C and pH 7.0) without loss of a significant amount of catalytic activity. Almost 91% of lactose hydrolysis was obtained from using concentrated cheese whey. Considering the available approaches for efficient bioconversion of hydrolyzed whey into ethanol, co-immobilization strategy was used using Saccharomyces cerevisiae and Kluyveromyces marxianus for fermentation. Same vessel hydrolysis and fermentation process was employed using silicon dioxide nanoparticles based enzyme immobilization along with co-immobilized yeast cell and provided a maximum ethanol titer of 63.9 g/L on concentrated cheese whey (150 g/L). Hence, the nano-biocatalytic system along with immobilized S.cerevisiae could improve the viability of ethanol production from cheese whey.