Thin active packaging films applied directly to fruits and vegetables using atmospheric pressure cold plasma

Abstract

Active thin film packaging is a technology with the potential to provide American consumers with new fruit and vegetable products - if the film can be applied without deactivating the bioactive agents. Active thin film packaging can have a major impact on food safety and food quality. Unfortunately, existing thin film deposition techniques transfer a significant amount of thermal energy to the film as an essential part of the application process. The heat required by current spray/dry technologies alters the form and function of the bioactive molecules in the thin film. A deposition technique not dependent on thermal energy is needed to enable the application of active packaging films to fruits and vegetables. Atmospheric pressure cold plasma (APCP) processing can apply thin film active packaging without using thermal energy. APCP can be used to activate a monomer with concomitant deposition of an organic plasma polymerized film which can incorporate onto the target surface (via adsorption or via chemical bonding) the active packaging's bioactive molecules. APCP thin film processing can take place at or below room temperature. APCP can overcome the “heat barrier” because the APCP process does not use heat to mix the active ingredient into a liquid carrier. There are three specific aims associated with this work: 1) determine if the APCP process preserves or enhances the functionality of the bioactive molecule that is at the heart of the active packaging; 2) determine if the plasma-polymerized matrix material is either toxic to humans or if it is an allergen; and 3) optimize the design of the APCP reactor for this application. The plasma zone in the reactor will be obtained by increasing the voltage on an electrode structure until the electric field in the feed material (Argon + monomer) is sufficiently high to yield electron avalanches. The “corona onset criterion” is used to design the cold plasma reactor. The produce will be placed in a treatment chamber downstream from the activation zone. Results will be described for work that has used Red Delicious apples as the substrate and vanillin as the monomer.