Impact of edible chitosan–cassava starch coatings enriched with Lippia gracilis Schauer genotype mixtures on the shelf life of guavas (Psidium guajava L.) during storage at room temperature

The effect of edible chitosan–cassava starch (CH–CS) coatings containing a mixture of Lippia gracilis Schauer genotypes (EOM) on the shelf life of guavas during storage at room temperature for 10 days was studied. Sixteen formulations were prepared with a range of chitosan and essential oil mixtures concentrations, and the in vitro antimicrobial activity was tested. Formulations containing 2.0% cassava starch, 2.0% chitosan and 1.0%, 2.0% or 3.0% EOM were most effective in inhibiting the growth of the majority of bacteria. The edible CH–CS coating and CH–CS with 1.0% (CH–CS–EOM1) or 3.0% EOM (CH–CS–EOM3) were added to guavas and the shelf life was evaluated. On the tenth day of storage, total aerobic mesophilic bacteria and mould and yeast counts were statistically lower (p < 0.05) in the CH–CS–EOM1- or CH–CS–EOM3-coated fruits than CH–CS-coated fruits. In addition, fruits coated with CH–CS or CH–CS–EOM showed no significant changes of total soluble solids content, while CH–CS–EOM-coated fruits showed lower titratable acidity than CH–CS-coated fruits at the end of storage. CH–CS–EOM3-coated guavas showed lower a∗ and b∗ values and higher L∗ and hue values than those with other coatings.