Introduction: Consumption of fresh cut fruits has been associated with foodborne outbreaks; therefore, the application of natural alternatives e.g., essential oils and alcoholic beverages may reduce the risk of pathogens growth and survival on these products.
Purpose: To evaluate the effect of sodium alginate coatings containing cinnamon and mastic gum essential oils (EOs)—alone or in mixtures— and their flavored liqueurs, on inhibition of Listeria monocytogenes growth on cut fruits under modified atmosphere packaging (MAP).
Methods: Fresh cut apples, pears and bananas were inoculated (103-104 CFU/g) with 3-strain L. monocytogenes mixed culture. Fruits were coated with 1% w/v sodium alginate (EC) with 0.7% (v/v) cinnamon EO (ECC); 0.7% (v/v) mastic gum EO (ECM), 0.7% (v/v) ECC+M (1:1); mastic gum liqueur (2 EC:1 liqueur) (ECML); cinnamon liqueur (2:1) (ECCL), and 25% ethanol (2 EC: 1 Ethanol) (ECE) (both liqueurs had 25% (v/v) alcohol) or left uncoated C. Samples were packaged under MAP (80%N2: 20% CO2) and stored at 10 °C. Enumeration of L. monocytogenes and total viable counts (TVC) were carried out on PALCAM and TSAYE, respectively, (n=4). PH, gas composition of package headspace and sensory properties (odor, appearance) of fruits were recorded.
Results: Maximum growth populations of L. monocytogenes were obtained at 13th storage day for controls (7.1 log CFU/g on apples and 8.5 CFU/g on pears and bananas). ECM had no significant inhibitory effect on pathogen growth, nor in TVC, ECCL maintained the levels of L.monocytogenes on apple 2.5 log CFU/g lower than the respective control on day 13, while ECC and ECE samples, remained 2 log CFU/g lower than the control on pears. ECC, ECML and ECE were the most effective for banana causing (all three of them) an inhibition of approx. 1.5 log CFU/g compared to control). PH values slightly increased in most samples (ca up to 0.8 pH units) until 13th day. No significant changes in O2 or CO2 content were observed.
Significance: The combined use of antimicrobial edible coatings and MAP could be a natural preservation method to control growth of L. monocytogenes on fresh cut fruits.