2023 Volume 14 Issue 1 Pages 98-105
The crayfish (Procambarus clarkii) is an invasive alien species consumed as a food source worldwide. However, there is an extremely low demand for it as a food resource in Japan, and it is typically targeted for extermination. One reason for the lack of progress in considering crayfish a sustainable food resource is limited education on the issue during secondary education programs. It is well known that astaxanthin is the pigment responsible for the body color of common red crayfish and crustaceans such as shrimp and crabs. At the same time, while there are ample study materials on plant pigments in the science education curriculum in junior high and high schools in Japan, there are no such materials to our knowledge that focus on animal pigments. Therefore, this research sought to develop teaching materials to deepen understanding of color as a food component of crayfish through an experiment involving extracting and separating their pigments. Using pigments extracted from red crayfish exoskeletons, we developed experimental teaching materials to observe astaxanthin by employing thin-layer chromatography and high-performance liquid chromatography. In addition, an experiment was conducted to observe the effect of different foods on crayfish body color. For the experiment, food was developed to make crayfish bodies white (decolorized) and orange. When the decolorized crayfish were fed norbixin or bixin, which are components of the orange annatto pigment, norbixin tended to accumulate as orange in the exoskeleton more than bixin based on the apparent body color change, color extraction from images, and thin-layer chromatography. These findings are expected to be useful for science and nutrition education, supporting the development of the students’ awareness and understanding of crayfish as a food resource.
