Effect of artificial light on the lipid oxidation of whole, cooked Northern shrimp (Pandalus borealis) during frozen storage

Abstract

In retail, whole, cooked Northern shrimp (Pandalus borealis) is commonly stored in illuminated display freezers for an extended time period. The aim of the present study was to understand how and when light-induced lipid oxidation occurs. Two sizes of cooked shrimp were packed in air and stored frozen with and without artificial light for 84 days. Samples were investigated for oxidative stability (peroxide value (PV), volatile compounds, and tocopherol consumption) and color changes and free astaxanthin.PV only increased significantly for shrimp stored with light (up to 20 meq/kg). α-tocopherol content remained unchanged during the storage period irrespective of the storage condition. Shrimp stored with light showed an increased L*-value and decreased a* and b*-values, whereas these color values did not change significantly in shrimp stored in darkness. The color changes could not be explained by changes in the free astaxanthin content as no significant changes occurred in free astaxanthin content during storage. The formation of volatile compounds depended on the shrimp size and light exposure, but the concentration of e.g. 2-methylbutanal, 3-methylbutanal and 1-penten-3-ol increased significantly more in shrimp stored in light than when they were stored without light. In conclusion, illuminated storage increased lipid oxidation in Northern shrimp.