Lactic Acid Bacteria Incorporated into Edible Coatings to Control Fungal Growth and Maintain Postharvest Quality of Grapes

Lactic acid bacteria (LAB) have been shown to prevent the growth and activity of several postharvest pathogen fungi in fruit and vegetables because of their ability to produce antimicrobial metabolites. Edible coatings (ECs) can be used as carriers of LAB and could provide an alternative natural preservation method. The effectiveness of Lactobacillus plantarum against fungal decay on grapes applied together with EC was studied. Different formulations with or without L. plantarum were considered, using pregelatinized potato starch (PS) or sodium caseinate (NaC) as main components of the coating matrices. In some of the formulations, oleic acid (OA) was added as a surfactant. The population dynamics of the bacterium and its ability to control fungal decay were studied together with the assessment of fruit quality. NaC-based formulations improved survival of L. plantarumon fruit surface after 7 days of storage in comparison with a water control. On the other hand, L. plantarum in PS-based formulation without OA reduced Botrytis incidence more than when applied in NaC formulation or in water. Coatings had little effect on berry quality (weight, color, firmness, and soluble solids content) of grapes throughout storage, although some of the coated samples maintained acidity and maturity index during storage better than others. Therefore, LAB applied in ECs could provide a viable biocontrol method for postharvest disease in grapes.