A practical approach for fish freshness determinations using a portable electronic nose

A portable electronic nose was developed and applied to fish freshness determinations of Argentinean hake. The applied methodology differs from the typical ones based on the headspace method or glass syringe manipulation. In the present study, a weighted piece of fish is introduced into a sensor's chamber and the signals of the sensors due to the fish emissions are recorded as function of time. Commercial gas sensors, based on tin dioxide, were used. Analysis of the individual sensor signals and of the array's pattern was performed. An increase of the signals was observed with increasing storage days and the mass of the hake pieces (up to 50 g). The obtained response patterns are independent of the weight but change after some days of storing, indicating the rottenness of the sample. Two different patterns are obtained. associated to rotten and non-rotten samples, respectively. These patterns are independent of storage conditions; for example, the pattern of a rotten sample is the same independently if the piece was stored several days in a refrigerator or if was kept out for 1 day. Hence, it is quick and easy to identify between fresh and old samples. These results were confirmed by performing principal component analysis (PCA). (C) 2001 Elsevier Science B.V. All rights reserved.