Noncontact Salt and Fat Distributional Analysis in Salted and Smoked Salmon Fillets Using X-ray Computed Tomography and NIR Interactance Imaging

Abstract

To be able to monitor the salting process of cold smoked salmon, a nondestructive imaging technique for salt analysis is required. This experiment showed that X-ray computed tomography (CT) can be used for nondestructive distributional analysis of NaCl in salmon fillets during salting, salt equilibration, and smoking. The combination of three X-ray voltages (80, 110, and 130 kV) gave the best CT calibrations for NaCl, with a prediction error (root mean square error of cross-validation, RMSECV) of 0.40% NaCl and a correlation (R) of 0.92 between predicted values and reference values. Adding fat predictions based on NIR interactance imaging further improved the NaCl prediction performance, giving RMSECV = 0.34% NaCl and R = 0.95. It was also found that NIR interactance imaging alone was able to predict NaCl contents locally in salted salmon fillets with RMSECV = 0.56% and R = 0.86.