Effects of protein on green tea quality in a milk-tea model during heat treatment: Antioxidant activity, foaming properties, and unbound small-molecule metabolome.

Tea drinks have a long history and milk is often added to enhance the taste and nutritional value, whereas the interaction between the tea bioactive compounds with proteins has not been systematically investigated. In this study, a milk-tea model was prepared by mixing green tea solution with milk and then heating at 100°C for 15 min. The milk tea was then measured using biochemical assay, antioxidant detection kit, and microscopy, as well as HPLC-quadrupole time-of-flight-MS/MS after ultrafiltration.

Glucose oxidase, horseradish peroxidase and phenothiazine dyes-co-adsorbed carbon felt-based amperometric flow-biosensor for glucose.

To develop an amperometric flow-biosensor for glucose, the stabilizing effect of methylene blue (MB) toward adsorbed glucose oxidase (GOx) on carbon felt (CF) was successfully applied to prepare the GOx-modified CF-based enzyme reactor combined with a horseradish peroxidase (HRP)-modified CF-based HO detector. Upon mixing MB in the GOx-adsorption solution, the O-dependent GOx-activity was significantly increased with increasing concentration of MB in the GOx-adsorption solution. The GOx-immobilization protocol on CF is very straightforward [, adsorption of the GOx/MB mixed aqueous solution for 5 min under ultrasound (US)-irradiation].

Shield, Anchor, and Adhesive Roles of Methylene Blue in Tyrosinase Adsorbed on Carbon Felt for a Flow Injection Amperometric Enzyme Biosensor for Phenolic Substrates and Inhibitors.

Methylene blue (MB) acted as a stabilizer for preventing surface-induced denaturation of tyrosinase (TYR) adsorbed on a carbon felt (CF) surface, which is based on shield and anchor roles preventing the unfavorable conformational change of TYR on the hydrophobic CF surface. Furthermore, MB acted as an effective adhesive for TYR immobilization on CF. The resulting TYR and MB coadsorbed CF (TYR/MB-CF) worked as an excellent working electrode unit in an electrochemical detector in a flow injection amperometric biosensor, which allowed highly sensitive consecutive determination of not only TYR substrates but also competitive inhibitors.