Silver Nanoparticle Formation-Based Colorimetric Determination of Reducing Sugars in Food Extracts via Tollens’ Reagent

A simple, sensitive, and nonenzymatic nanospectrophotometric method was developed for the determination of reducing sugars. The silver mirror reaction-assisted method is based on the in situ formation of silver nanoparticles in the presence of reducing sugars. All simple reducing sugars (glucose, galactose, fructose, mannose, maltose, and lactose) examined had perfectly linear regression equations. The detection limit for glucose was 40 nM. The proposed method could be selectively applied to various synthetic mixtures of reducing sugars with polyphenolic compounds, and to honey, milk, and commercial fruit juice as real samples using solid phase extraction as a clean-up process. The developed method was also statistically validated against conventional alkaline CUPRAC (cupric-neocuproine, Cu(II)-Nc) spectrophotometric method using Student's t- and F-tests.