Edible and water-soluble corn zein coating impregnated with nisin for Listeria monocytogenes reduction on nectarines and apples

Abstract

A corn zein based water-soluble coating formulation impregnated with nisin at 1 g L−1 (CoZWN), or without nisin (CoZW), was evaluated for performance against Listeria monocytogenes as edible coating on nectarines and apples. In comparison to uncoated (NC) control and coating with conventional petroleum-based wax (Wax), CoZWN coated nectarine showed higher reduction of L. monocytogenes population after storage for 2 d at 2.2 °C in simulation of refrigerated transportation, followed by additional 2 d at 22 °C in simulation of retail display. L. monocytogenes populations were reduced by 1.3 or 1.1 log in comparison to uncoated controls when coating was applied before or after L. monocytogenes inoculation, respectively. The performance of this nisin-impregnated corn zein formulation was further validated as a post-contamination coating using Gala apples stored at room temperature (22 °C) for up to 10 d in simulation of retail display. Gala apples coated with CoZWN accelerated the decline of L. monocytogenes populations during the early stage of simulated storage, and outperformed Wax through the entire period against L. monocytogenes. CoZWN did not significantly impact the survival and growth of molds and yeasts on nectarines but performed comparably to Wax against molds and yeasts on Gala apples. Data presented in this study indicated that nisin-impregnated corn zein coating is a promising strategy for mitigating L. monocytogenes contamination on fresh produce. It also demonstrated that this water-soluble coating could be impregnated with other natural antimicrobials to target a wide range of foodborne pathogens.