Cross‐linked tannase‐carbon nanotubes composite in elevating antioxidative potential of green tea extract

Multi‐walled carbon nanotubes (MWCNT)‐tannase composite was investigated as an immobilized biocatalyst on the basis of its facile preparation, low cost, and excellent aqueous dispersibility. Cross‐linked tannase enzymes, obtained in the presence of glutaraldehyde, were composited with MWCNT via physical adsorption. Multiple techniques were applied to investigate, and corroborate the successful adsorption of cross‐linked tannase onto the MWCNT structure. Green tea infusion extract post‐treatment using the composite preparation showed elevated radical scavenging activities relative to the control. Green tea infusion extract exhibited a markedly reduced EC50 value on 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radicals following its treatment with the enzyme composite, which represents 20%–34% enhancement in its free radical scavenging capacity. Stoichiometry and number of reduced DPPH were determined and compared. The antioxidative potential of a widely consumed, health‐beneficial green tea is elevated by the treatment with MWCNT‐tannase composite. Practical applications Cross‐linked tannase enzymes were composited with pristine multi‐walled carbon nanotubes via simple physical adsorption. The composite presents key advantages such as low specific volume compared to other well‐known immobilization media, inert, facile enzyme composition, and ease of recovery for repeated use. The work demonstrated carbon nanotube prosthetic utility in the biotransformation of food‐based health commodity sought after for its nutritional benefits. The approach is of both industrial‐ and agricultural importance, and is a promising and viable strategy to obtain a natural, functional food supplement for the multi‐billion dollar well‐being and health‐related industries. Cross‐linked tannase‐carbon nanotubes composite exhibits facile preparation, minute specific volume and excellent aqueous dispersibility. It is applied in the biotransformation of green tea infusion to obtain elevated free radical scavenging activities, which augments the beverage nutritional benefits. The composite can be easily separated from the end product, and reuse for multiple times.