Abstract
This study used visible/near-infrared hyperspectral imaging (HSI) technology combined with chemometric methods to assess the freshness of pearl gentian grouper. The partial least square discrimination analysis (PLS-DA) and competitive adaptive reweighted sampling-PLS-DA (CARS-PLS-DA) models were used to classify fresh, refrigerated, and frozen–thawed fish. The PLS-DA model achieved better classification of fresh, refrigerated, and frozen–thawed fish with the accuracy of 100%, 96.43%, and 96.43%, respectively. Further, the PLS regression (PLSR) and CARS-PLS regression (CARS-PLSR) models were used to predict the storage time of fish under different storage conditions, and the prediction accuracy was assessed using the prediction correlation coefficients (Rp2), root mean squared error of prediction (RMSEP), and residual predictive deviation (RPD). For the prediction of storage time, the CARS-PLS model presented the better result of room temperature (Rp2 = 0.948, RMSEP = 0.255, RPD = 4.380) and refrigeration (Rp2 = 0.9319, RMSEP = 1.188, RPD = 3.857), while the better prediction of freeze was by obtained by the PLSR model (Rp2 = 0.9250, RMSEP = 2.910, RPD = 3.469). Finally, the visualization of storage time based on the PLSR model under different storage conditions were realized. This study confirmed the potential of HSI as a rapid and non-invasive technique to identify fish freshness.
Highlights
The quality and price of fish depend largely on the freshness [1]
Some peaks occurring near infrared region be well overtone andbroadband combination vibrations of in the near infrared region cansuch be well explained by the overtone and combination vibrathe molecular chemical bonds, as O-H, C-H, and
The gradient from dark blue topredark ated, and time, frozen–thawed pearland gentian grouper, and realized the rapid and accurate red represents the extension of storage time, and different colors represent different days
Summary
The quality and price of fish depend largely on the freshness [1]. Refrigeration is the main method of short-term storage of fish. Fish experienced three stages of rigidity, autolysis, and corruption, which led to a continuous decline in their quality. Freezing is a commonly used effective method for long-term storage of fish [2]. In order to make more profits, some illegal traders sell frozen–thawed fish as fresh fish. It is necessary to study a fast and effective method to identify fresh and frozen–thawed fish and detect the storage time of fish
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