Temperature-activated films keep produce fresh.

Apio, the food technology unit of Landec Corp., Menlo Park, Calif., has developed a breathable membrane for fresh produce bags that has a built-in temperature-activated "switch" that adjusts its permeability to oxygen and CO2 to compensate for the increased respiration rate of produce as it gets warmer. The temperature "switch" is reversible because it is based on a physical rather than chemical change.

Apio's BreatheWay film uses Landec's patented Intelimer SCC (sidechain crystallizable) acrylic copolymer, which changes from a solid to a gel over a narrow temperature range of a few degrees Fahrenheit (tuneable by varying copolymer composition). A thin film of copolymer is coated onto a proprietary porous substrate using melt or solvent casting, depending on coating thickness. When the copolymer changes from solid to gel, the physical change removes the crystalline gas barrier and doubles the CO2 and O2 permeability.

Apio's first commercial BreatheWay product was introduced in the 1990s for fresh broccoli and cauliflower. A brand-new application is bags for Chiquita bananas distributed to 200 convenience stores in Southern California and expected to reach 5000 stores nationwide this year. Landec: [phone] * PTDirect: 453DX

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