Kinetics of drosopterin release as indicator pigment for heat-induced color changes of brown shrimp (Crangon crangon)

Heat-induced color changes of crustaceans are commonly described as the release of astaxanthin. In this study on Crangon crangon, it was found that astaxanthin plays a minor role in the (dis)coloration. By LC-HRMS, two polar, process dependent pigments were found. One pigment was identified as riboflavin and one as drosopterin (level-2 certainty). Thermal treatments had highest effect on drosopterin concentration changes and were chosen as indicator for a kinetic study of heat-induced color changes. The kinetic data fitted a consecutive step model (r2 = 0.971), including a first step in which drosopterin was released (kd,85°C = 0.95 ± 0.09 min−1; Ead = 105 ± 4 kJ/mol) and a second step where drosopterin is degraded (kb,85°C = 0.02 ± 0.002 min−1; Eab = 190 ± 15 kJ/mol). The kinetic model shows that shrimp should be heated at lower temperatures (<80 °C) than the heating temperatures used by fishermen (86-101 °C), creating opportunities for quality optimization. Therefore, this study delivers essential information needed in a comprehensive quality optimization study of the cooked brown shrimp.