Antifungal Effect of Thymol and Carvacrol Added on Starch Coatings on Tropical Fruits (Mango and Papaya)

Introduction:  The incorporation antimicrobial compounds to edible coatings, such as essential oils and its derivates, can notably improve antimicrobial properties for coatings in tropical fruits. In this case, coating applications can also affect consumer sensory appreciation and adequate design of the composition, including the antimicrobial agents, needs to be considered, taking into account the compatibility of the compound with each food application.

Purpose: The aim of this work was to analyze the antifungal effect of thymol and carvacrol added to starch coatings on mango (Mangifera caesia) var. ataulfo and papaya (Carica papaya L.) var. maradol throughout 15 days of storage at 20ºC. 

Methods: Four different treatments were performed on mangoes and papayas: fruits without treatment as a control, only starch coating fruits, Formulation 1: starch coated fruit with 1125 ppm of carvacrol and 375 ppm of thymol, and Formulation 2: starch coated fruit with 750 ppm of carvacrol and 750 ppm of thymol. After coating fruits were stored at 20ºC on a dry place for 15 days, every day fungal growth (log CFU/cm²) was measured on fruits surfaces. Growth curves were adjusted to Gompertz parameters. 

Results: There were significant differences (P < 0.05) in fungal growth for all coatings in relation to control; there is evidence that coatings with thymol and carvacrol are able to controlfungal development. Formulation 1 was the most efficient in delaying surface fungal growth and therefore deterioration, lag phase are increased. 

Significance:  Edible starch coatings added with thymol and carvacrol are a good alternative for mango and papaya preservation, improving shelf life with a fungistatic effect.