Elemental and structural changes associated with white spot formation in sun‐dried Pacific white shrimp shells

Abstract

Structural and elemental properties of dried Pacific white shrimp (WSS) (Litopenaeus vannamei) shell having the white spots were compared with non‐white spot shrimp (NWSS) shell. Based on X‐ray diffraction (XRD) analysis, both samples showed two characteristic peaks representing chitin. However, WSS sample had two additional major peaks at 2θ of 26.65 and 29.53º, which were related to quartz and calcite, respectively. Scanning electron microscope coupled with energy‐dispersive X‐ray spectrophotometer (SEM‐EDX) mapping showed the movement of various elements towards the exo‐ and endocuticle. The Raman spectroscopic study confirmed the formation of calcite crystals in the white spots. The looser chitin matrix was obtained for WSS as compared to that of NWSS as depicted in SEM micrographs. Therefore, the white spots developed in the shell were caused by the formation of calcite, which exhibited different structural arrangements and elemental positioning as compared to shrimp shell without white spots.

Simultaneous determination of multiple quality indices of dried shrimp (Parapenaeopsis hardwickii) during storage using Raman spectroscopy

“…They found that the combination of salt pretreatment (4% w/v) and microwave drying with a power of 500 W was the best drying condition, under which the conversion degree of α‐helices to β‐sheets was the lowest. Singh et al 7 . used Raman spectroscopy to explore the reasons for the appearance of white spots in sun‐dried Pacific white shrimp ( L. vannamei ) shells, which can lead to a drastic reduction in the final market price of the product.…”