In the last year we produced glutenin and gliadin edible films obtained from wheat gluten. Gliadin-rich films were extracted with 70 percent ethanol at pH 6.4. The insoluble part was solubilized in 50 percent ethanol at acid pH and at 60°C. Films were transparent, glossy, and smooth. Glutenin films were stronger and better barrier than gliadin films.

We completed the barrier and mechanical characterization of high barrier films used for high pressure processing (HPP). We also measured the sorption properties of the multilayer films at HPP conditions. Results indicated that HPP did not affect the flavor scalping power of polymers.

We are studying the use of plastic materials for olive oil containers. In this project we identified 5 compounds as indicators of the oxidation state of the oil. This method could be valuable to the olive oil industry to characterizing and monitoring shelf life of packaged oil.

In the area of Modified Atmospheric Packaging (MAP) we work closely with the Horticulture Depatment. We  have determined the permeation and sorption (with and w/o cyclodextrines) of methylcyclopropane (MCP)and the use of MPC on tomato. 1 to 5 percent of beta- and alpha-cyclodextrin were blended with LLDPE and converted into films. One percent of cyclodextrin was found to increase water vapor and oxygen permeability of LLDPE film in the 10-40°C range. The activation energy did not change. Sorption isotherms, free energy, entropy, and enthalpy, of MCP sorbed by selected agents were determined by IGC at 50-80C. Silica gel, Tenax, and clay were used as the stationary phases. The interaction between MCP and the adsorbing agents followed the active binding site theory. Silica gel had much larger number of binding sites than Tenax-TA, or clay.

Storage temperature and MCP treatment for tomato fruit were effective in retarding the ripening process: 1) tomato ripening process with MCP was retarded regarding color change and firmness, 2) daily treatment of MCP was more effective than with single treatment, and 3) tomato fruit at 10C retarded more color and firmness compared to treatment at15-20°C. MCP inhibited ethylene response binding to the ethylene receptors.

Polycaprolactone (PCL) is a biodegradable material with potential applications in packaging. With the Chemical Engineering Department we investigated the feasibility and optimal conditions of film production, measured its mechanical properties, and determined barrier properties for linear and branched PCL. Films were fabricated using a 1" extruder in a range of temperature-pressure, and tensile stress analysis was performed. Permeability coefficients were determined for oxygen, water vapor, and carbon dioxide. Usable films were obtained in the ranged of 135-190°C and between 12-14 MPa. Compared to LDPE, PCL had higher tensile strength and lower elongation.
Permeability was higher for all permeants.

Polylactic acid (PLA) is also a biodegradable and compostable. The properties of PLA for food packaging are not well understood. Funded by Kraft Foods, we made films from two PLA resins and measured tensile, thermal, and permeability properties for CO₂, O₂, and H₂O. Values for PLA resins were compared to those of polystyrene and PET measured at the same conditions.