The present work relates to a method for determining the degree of freshness of fish by monitoring the production of spoilage products. This method comprises the global detection of the spoilage products including biogenic amines resulting from the degradation of fish by using arrays of voltammetric sensors chemically modified with phthalocyanines. The performance of an array of screen-printed electrodes (SPE) has been compared with that of an array formed by classic carbon paste electrodes (CPE). The sensors have shown good sensitivity towards model solutions of biogenic amines (ammonia, dimethylamine, trimethylamine, cadaverine and histamine). It has been evidenced that the electroactivity and basic character of amines influences considerably the electrochemical behaviour of the electrodic material.
The pattern of responses provided by the array has been successfully used to evaluate fish freshness and to determine the post-mortem period. An increase of the signals associated to biogenic amines and other spoilage products is observed with increasing storage days. Signals provided by classical CPE are better resolved and show better sensor-to-sensor reproducibility than SPE. However, the modification of SPE enables simple mass-production of low-cost and miniaturised sensing units with good sensibility and repeatability. The capability of discrimination demonstrated by Principal Component Analysis (PCA) and the capability of prediction of fish freshness calculated by Partial Least Squares-Discriminant Analysis (PLS-DA) is similar in both cases.
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