Evaluating cork coating homogeneity using hyperspectral imaging and texture analysis: a comparative study of stationary and mobile pneumatic pistol coating applications

Cork stoppers are vital for wine bottle packaging, allowing the sealing of the wine in the bottle. Cork stoppers are coated with a treatment to increase impermeability and lubrication, ensuring the quality and longevity of bottled wines. This coating, typically made of hydrophobic polymers, is applied during the final stages of cork production. The application of the coating material to the cork surface takes place in a drum and can be applied using two methods, a stationary or a mobile pneumatic pistol. In this study, cork coating homogeneity is evaluated using hyperspectral imaging to investigate which coating application method, a stationary pneumatic pistol, or a mobile pneumatic pistol, gives higher coating homogeneity on the cork surface. Partial least squares-discriminant analysis on hyperspectral images and texture analysis algorithms showed that there is more coating homogeneity when coating is applied with the mobile pneumatic pistol method than when coating is applied with the stationary pneumatic pistol method. This result is advantageous for industry as they can potentially optimize coating methods and choose the coating application method which achieves greater coating homogeneity on their cork samples.