Prediction of Freshness Quality and Phosphate Residue of White Shrimp Products Using Near-Infrared Spectroscopy

The manufacturing of frozen shrimp is an important industry for the economy of Thailand. The objective of this study was to use Near-Infrared (NIR) spectroscopy to determine the freshness quality, including Total Volatile Basic Nitrogen (TVB-N) and Water Holding Capacity (WHC) of white shrimp (whole and chopped shrimp) and phosphate residues of shrimp.

Sixty white shrimp samples of a size of 70-80 shrimp/kg were stored at 4 ˚C. The sample was divided into two groups by soaking in two kinds of phosphate solutions, including Sodium Tripolyphosphate (STPP) and Mixed Phosphate (NAN101). The samples were evaluated using NIR which was performed before freezing and seven days after freezing. Calibration models of the freshness and phosphate residues of fresh and frozen shrimp products were built by Partial Least Square (PLS) regression between the spectral data and the reference methods.

Satisfactory PLS results were obtained from the calibration model of TVB-N of chopped shrimp with a correlation coefficient (R) of 0.94 and Ratio of Prediction to Deviation (RPD) of 3.07. However, the NIR data indicated an unreliable prediction for the WHC (R<0.5). For the determination of phosphate residuals from STPP and NAN 101, the best calibration results were R>0.94 and RPD>3.00.

The NIR spectroscopy was feasible for monitoring the TVB-N as well as phosphate residues of shrimp products.