In the analysis of wine, how can the Folin Phenol Reagent be utilized in a spectrophotometric method to determine the total phenolic content?

The Folin–Ciocalteu reagent reacts with phenolic compounds in wine, forming a blue complex that absorbs light at around 765 nm; the intensity of this color is proportional to the total phenolic content. First, the wine sample is diluted and mixed with the reagent, then a base (often sodium carbonate) is added to develop the blue color over a set incubation time. After allowing the reaction to complete, the absorbance is measured with a spectrophotometer. By comparing this absorbance to a calibration curve made from known concentrations of a standard phenol, such as gallic acid, the total phenolic content can be calculated. For example, if the absorbance of a wine sample equals that of a 50 µg/mL gallic acid standard, the wine contains about 50 µg/mL of total phenolics.