In vitro antifungal activity of residues from essential oil industry against Penicillium verrucosum, a common contaminant of ripening cheeses

•Essential oil industry residues as sources of bioactive compounds.•Phenolic compounds as antifungal substances.•Natural products for the development of cheese covers.•Prevention and control of molds in cheeses.

Essential oil (EO) industry produces a considerable amount of solid residues during the distillation process, which results in pollution, management and economic problems worldwide. However, these wastes are especially rich in high added-value compounds that can be exploited as natural sources of bioactive compounds. In this connection, ethanolic extracts of solid agro-industrial residues from distillation of some Lamiaceae species were chemically and biologically characterized. The phenolic profile of the extracts was tentatively determined by LC-DAD-MS and the antifungal activity against Penicillium verrucosum was established in vitro by means of the broth microdilution M38-A method. As antifungal agents, the most active extracts were those from the solid residues of Hyssopus officinalis, yielding 50% inhibition of fungal development at a concentration around 92 μg mL−1, and Lavandula x intermedia var. Super (248 μg mL−1). The major phenolic compound present in Hyssopus officinalis residue was cyanidin 3-rutinoside, whilst 4-O-β-d-glucosyl-4-coumaric acid and ferulic acid O-glucoside were the most representatives in the Lavandula x intermedia residue. Solid residues from the industrial distillation of aromatic plants contain natural substances that may satisfactorily prevent fungal contamination on cheeses as well as providing a commercial and economical opportunity to agricultural by-products.