Identification of sea bass freshness grades using laser-induced breakdown spectroscopy coupled with multivariable analysis

Rapid detection of marine fish freshness is of great importance, as aquatic products are susceptible to spoilage during storage. In this work, for the first time, the laser induced breakdown spectroscopy (LIBS) coupled with multivariable analysis was used for the rapid identification of the freshness of sea bass ( Lateolabrax japonicus ) without using of organic solvents. Results suggested that the principal component analysis (PCA) could accurately differentiate the sea bass samples stored for different days, and the three freshness grades (first-grade, second-grade, and spoilage) of sea bass were separately clustered together. The overall classification accuracy of partial least squares-discriminant analysis (PLS-DA) reached 91.50% ± 1.49% and 97.33% ± 1.90% for differentiating sea bass samples stored for different days, and authenticating different freshness grades, respectively. As storage period increased, the degradation of high-molecular-weight proteins and micromorphology changes were observed in fish muscles using SDS-PAGE and SEM, respectively. In addition, the laser energy absorbed by sea bass increased with the longer storage periods, as shown by the plasma temperature and plasma electron density. The present study demonstrated the capability of LIBS combined with chemometrics for the rapid and eco-friendly identification of marine fish freshness in the food supply chain.