Rapid discrimination of three marine fish surimi by Tri-step infrared spectroscopy combined with Principle Component...

A Tri-step infrared spectroscopy (Fourier transform infrared spectroscopy (FT-IR) integrated with second derivative infrared (SD-IR) spectroscopy and two-dimensional correlation infrared spectroscopy (2DCOS-IR)) combined with Principal Component Regression (PCR) were employed to characterize and discriminate three marine fish surimi (white croaker surimi (WCS), hairtail surimi (HS) and red coat surimi (RCS)). The three surimi had similar IR macro-fingerprints (similarity>0.7) especially for the absorption bands of amide groups. Compared to the other two surimi, however, RCS had a middle strong characteristic peak of lipids at 1745 cm(-1), indicating that RCS had the highest content of lipids. SD-IR spectra of the three surimi enhanced the spectral resolution and amplified the small differences, especially at about 1682 cm(-1), 1679 cm(-1), 1656 cm(-1) and 1631 cm(-1), suggesting that the three had different profiles of proteins. Moreover, evident differences were observed in 2DCOS-IR spectra of 1500-1800 cm(-1). WCS had one strong (1620 cm(-1)) and three weak auto-peaks (1520 cm(-1), 1552 cm(-1), 1706 cm(-1)). HS had three strong (1621 cm(-1), 1648 cm(-1), 1708 cm(-1)) and two weak auto-peaks (1523 cm(-1), 1553 cm(-1)), whereas RCS had one strong (1623 cm(-1)) and three weak auto-peaks (1525 cm(-1), 1709 cm(-1), 1738 cm(-1)). Furthermore, sixty batches of surimi (twenty for each surimi) were objectively classified by PCR. It was demonstrated that the Tri-step infrared spectroscopy combined with PCR could be applicable for discrimination of precious marine fish surimi in a direct, rapid and holistic manner.