81-3 |
Lighting effects on packaged foods |
J. C. ACTON, Dept. of Food Science & Human Nutrition, Clemson Univ., PO Box 340371, Clemson, SC 29634-0371 and L. K. Cook, Cryovac Div., Sealed Air Corp., 100 Rogers Bridge Rd., Bldg. A, PO Box 464, Duncan, SC 29334-0464. Food products packaged in transparent and translucent films can deteriorate during retail light display due to changes in sensitive pigments or lipids. Oxidation of these constituents leads to fading or discoloration and off-flavor development. While modified atmosphere packaging or use of barrier films may reduce the rate of product deterioration, lighting environments, similar to temperature environments, will provide energy for oxidation to occur. In most photooxidation reactions, results show that varying the light intensity has an Arrhenius-type effect on the reaction rate and is also oxygen dependent. Only under conditions of temperature control and near complete elimination of oxygen, such as through the application of in-film or in-package scavengers, or use of appropriate oxygen-barrier films does product shelf life extension occur. Current retail display lighting for foods and lamp selection are neither standardized between stores nor within stores in a particular food chain. Spectral irradiance of lamps relating to ultraviolet (UV) energy output is of public concern and provides an indication of potential energy available to detrimentally affect food products. Plastic lens diffusers or coated cover glass on lamps effectively reduce UV output. Similarly, for "worst case" products that are extremely sensitive to the UV portion of the lighting spectrum, UV-absorbing substances may be incorporated into the packaging film. While reduction or elimination of UV energy is important, most food pigments of animal or plant origin do remain sensitive over time, albeit to a lesser degree, to light energy in the visible spectral region.
Session 81, Maximizing shelf life through product formulation and packaging
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