Evaluation of Morphological Changes in Grapes Coated with a Biosurfactant Extract Obtained from Corn Steep Liquor

In this work, grapes were coated with a multifunctional biosurfactant extract obtained from corn steep liquor after liquid–liquid extraction with ethyl acetate. This biosurfactant extract has been demonstrated to not only possess a surfactant capacity but also antimicrobial activity. Hence, it could be an excellent preservative for fruits, as it is more biodegradable and more biocompatible than chemically synthetized preservatives. However, before applying this biosurfactant as a preservative on fruits, it is necessary to study the changes in the surface properties of fruits produced by the addition of this bioactive compound. Therefore, in this work, grapes coated with an aqueous solution containing 1 g/L of the biosurfactant extract were subjected to surface analysis using non-invasive technologies, including profilometry. 2D digital photographs of the surface and parametric roughness of grapes were obtained. They revealed that the biosurfactant extract decreased the roughness of the grape surface compared with non-coated grapes and reduced the changes in the shape of the grapes over time. Moreover, it was observed that the biosurfactant extract increased the hydrophobicity of the grape surface observing higher contact angle compared with non-coated grapes.