Artificial phylloplanes resembling physicochemical characteristics of selected fresh produce and their potential use in bacterial attachment/removal studies

The recurrence of food-borne outbreaks caused by consumption of fresh produce highlights the importance of a good understanding of the interactions between bacteria and produce leaf surfaces. To facilitate investigations into such, a platform that can produce, for instance, reproducible sanitation results and eliminate natural variations of fresh produce properties will be advantageous. In this study, we proposed and developed a doublecasting method to fabricate artificial phylloplanes that mimic both the topographical and epicuticular characteristics of fresh produce. Two of the most consumed fresh produce commodities in the U.S., i.e. 'Romaine' lettuce and Carmel' spinach, were used as the model surfaces. The surface hydrophobicity of the artificial phylloplanes was modified with addition of a non-ionic surfactant with different hydrophilic-lipophilic balance values to match the hydrophobicity of produce leaves. The key epicuticular wax compounds identified from the natural spinach and lettuce leaves were coated on the leaf replica to reproduce the chemical composition of the natural leaf surfaces. The surrogate surfaces were used to study the attachment Escherichia coli O157:H7 and Listeria innocua. In addition, these surfaces are reusable, and have surface hydrophobicity, surface roughness values and epicuticular wax compositions similar to that of fresh produce. The new artificial phylloplanes of fresh produce could be used for studying the interactions between human pathogens with produce surfaces and for developing new produce sanitation strategies.