Both Hemocyanin\nand β‑1,3-Glucan-Binding\nProtein from the Shrimp Shell of Litopenaeus vannamei Are Responsible for Its Color Change from Brown to Red during Thermal\nProcessing

Because of the composition and structural\ncomplexity of crustacean\nshells, their color change mechanism during thermal processing remains\nunclear. This study identified and characterized two intrinsic protein\ncomponents, hemocyanin (Lv-Hc) and β-1,3-glucan-binding protein\n(Lv-BGBP) from Litopenaeus vannamei shrimp shells by a combination of ion-exchange chromatography, gel\nfiltration, and mass spectrometry. It was found that a mixture of\nLv-Hc, a gray protein, and Lv-BGBP (which is a natural astaxanthin-binding\nprotein with a red color) is responsible for the brown color of fresh\nshrimp shells. Upon heating to 100 °C, the mixture of these proteins\nturned red, mimicking the color change observed in cooked shrimp shells.\nThis transition is attributed to the extremely high thermal stability\nof Lv-BGBP, which has the ability to protect astaxanthin from thermal\ninduced degradation. These findings provide significant insights into\nthe molecular mechanism governing shrimp shell coloration, advancing\nour understanding of crustacean biochemistry.