Botrytis cinerea is responsible for the gray mold disease, which causes considerable economic losses for winemakers. Its evaluation in wine grapes is commonly performed through visual estimation, which was demonstrated to be prone to assessor bias. Rapid and simple enzymatic carbon screen printed amperometric biosensors were here used to evaluate gluconic acid and glycerol content on wine grapes at different B. cinerea infection degrees. The lower concentrations measurable by screen-printed amperometric biosensors were 3 mg/L for gluconic acid (corresponding to an infection degree lower 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. This study demonstrates the effectiveness of the biosensors for rapid analysis of gluconic acid and glycerol in grapes, confirming their high correlation with B. cinerea degree of …