Rapid Assessment of Gray Mold (Botrytis cinerea) Infection in Grapes with a Biosensor System

Botrytis cinerea is the causative agent of gray mold disease, which causes considerable economic losses to winemakers. The extent of gray mold infection of winegrapes is commonly visually estimated, a method that is prone to assessor bias. Here, we used rapid and simple enzyme-based screening consisting of carbon-electrode, screen-printed amperometric biosensors to estimate gluconic acid and glycerol concentration in winegrapes infected with different degrees of B. cinerea. The lower limits of quantification of the screen-printed amperometric biosensors were 3 mg/L for gluconic acid (corresponding to an infection rate of less than 1%) and 35 mg/L for glycerol; the response times with a flow rate of 0.5 mL/min were in a range of 0.5 to 2 min in the linear ranges of the two assays. This study demonstrates the efficacy of amperometric biosensors for rapid analysis of gluconic acid and glycerol in grapes. The measurements confirmed that concentrations of both compounds are highly correlated with the rate of B. cinerea infection (R-2 = 0.98). Thus, the biosensor developed to measure gluconic acid in grapes (or must) was more precise and gave a faster response than methods that currently exist for determining the rate of B. cinerea infection of grape berries.