One area of work involves active packaging, which has been directed by Dr. Kay Cooksey for the last 12 years. This work first began with testing the effectiveness of antimicrobial packaging using nisin and has led to testing other antimicrobials including: chitosan, chlorine dioxide, silver ions, organic acids, and rosemary alone or in combination with nisin, which is a natural antimicrobial agent that can be used against a wide variety of undesirable food-borne (pathogenic) bacteria. Nisin alone and in combination with rosemary has been the most effective antimicrobial additive tested and further work has been done to optimize the level of nisin used to reduce the cost.
Release mechanisms and effective methods of measurement using food systems such as ready-to-eat deli and fresh meats have been used. Biopolymers have been used as carriers of the additives and are an effective means of releasing the additives. The antimicrobial agents can be coated onto packaging polymers such as polyethylene or blended and extruded. The antimicrobial packaging materials are meant to serve as an additional method to enhance food safety and are not meant as a replacement for good manufacturing practices.
Other research includes measurement of aroma/flavor components through biopolymer films. Many companies are interested in using biopolymer films as part of a sustainability program but little is known regarding the effects of the films on the product’s shelf life.
Research was recently completed regarding the shelf life of celery packaged in different biopolymer films compared to standard low density polyethylene film. Only one biopolymer was found to be suitable. Another study is nearing completion which involves characterization of the thermal properties of sodium caseinate biopolymer.
Initial studies have found this biopolymer to have suitable properties for extrusion and injection molding. While work on biopolymers has focused on characterization and functionality, testing the material’s ability to degrade in a composting environment using ASTM standards is also possible.
Finally, shelf-life testing is an important area of work. Projects typically begin with establishing the main mode of deterioration for the product and establishing an expected shelf life. Research can involve real-time testing and/or accelerated shelf life testing.
Sensory panels can help establish the end of shelf life and corresponding objective measurements such as texture, moisture content or oxidation can be used to determine final quality. In addition, mathematical models might be developed to help predict shelf life if a change in materials is made in the future. Shelf life testing has been found to be very beneficial for validating quality standards and for product/package development.
Recently a shelf life study was performed for a meal-replacement bar. Two different materials were tested and compared to a control material. Based on the sensory and textural studies, one of the materials (a sustainable material) performed just as well as the existing non-sustainable material. This study provided important information for the client company to use in deciding whether product quality would be affected by changing to a new, sustainable material.
For further information, contact Kay Cooksey, Ph.D. and Cryovac Endowed Chair, Clemson University Department of Packaging Science, at 864/656-4613 or [email protected]