Predicting sensory score of cod (Gadus morhua) from visible spectroscopy

Freshness is regarded as one major parameter for the quality of fish and fishery products. However, at present there is no instrumental method for freshness determination that has attained commercial credibility. Currently one of the most wholesome and straightforward ways of describing freshness is a standardised sensory assessment method; the quality index method (QIM). However, sensory methods may be considered costly and not always practical for large-scale commercial purposes. In this work it is shown that visible spectroscopy could be used to predict the freshness of cod according to the QIM by prediction of QIM score. The feasibility of the method for cod of different conditional state caught by different catching methods was also addressed. Visible spectroscopy can be used to predict the QIM score of cod caught both by longline and gillnet, and the QIM score for cod of both categories may be predicted from the spectra by use of one model only. It is also shown that a relatively narrow band in the mid-visible spectral range is sufficient to use when measuring freshness.