Light-induced changes in packaged cheeses - a review

This review presents current knowledge on light-induced effects on packaged cheeses. As research in this area is somewhat limited and involves highly non-standardized light exposure conditions, the review includes, if deemed necessary, effects observed in other dairy products. Most of these effects may be explained by general lipid oxidation mechanisms combined with knowledge on the spectral balance between the singlet oxygen quencher, beta-carotene, and the sensitizer, riboflavin. As determined by Lambert-Beer's law, beta-Carotene absorbs light in a concentration-dependent manner, which would otherwise be absorbed by riboflavin, thereby inducing quality changes. Consequently, these processes may be prevented by total exclusion of light and by storage in an oxygen-free atmosphere. Unfortunately, quality changes are apparent at residual oxygen levels even as low as 0.5% in headspace, which is often considered an acceptable residual oxygen level in industry. For a given product composition, spectral distribution and photon flux of the light source determine the extent of quality changes, since photochemical processes have limited temperature dependence, in contrast to the consecutive lipid autoxidation process. Hence, precautionary measures include changes of light source and targeted prevention of photon flux relative to the cheese by use of creative packaging. In order to optimize packaging and display conditions, a substantial need exists for analytical methods, which reflect the sensory perception of the consumer. Once established, optimization to include marketing and consumer aspects will harbor no major obstacles. (C) 2003 Elsevier Ltd. All rights reserved.