Monitorization of Atlantic salmon (Salmo salar) spoilage using an optoelectronic nose

An optoelectronic nose for monitoring Atlantic salmon (Salmo salar) spoilage has been developed. The chromogenic array uses eight sensing materials containing pH and a Lewis acid indicator adsorbed in aluminium oxide or silica gel. Colour modulations as RGB coordinates are measured on day 0 and for the salmon samples held in cold storage for 2, 5, 7 and 9 days. For the same days volatile basic nitrogen (TVB-N) and (mesophilic, psychrotrophic and H2S-producing bacteria) analyses were carried out. Changes in the RGB coordinates in the chromogenic array are processed with qualitative (PCA) and quantitative (PLS) tools. The chromogenic data obtained from the array is correlated with the physico-chemical and microbiological parameters (TVB-N, H2S producing, mesophilic and psychrotrophic bacteria) via PLS statistical studies. The influence of the use of two cross-validation methods (Venetian and Random) and diverse number of data splits (NDS) (2-4) to determine the number of PLS components is discussed. The suitability of the PLS models is also studied via t-u score plots. The results suggest the potential feasibility of this system for S. salar freshness monitoring.