Comparison and integration of different electronic noses for freshness evaluation of cod-fish fillets

For the instrumental analysis of fish freshness, several different methods have been proposed based on different principles (such as mechanical, elect rical, and optical). Although, it is well-known that the headspace composit ion changes greatly during the spoilage process, the difficulties in sampli ng and measuring the headspaces with traditional analytical chemistry techn iques makes the practical implementation of this principle not viable. Rece ntly, the advent of sensor array technology has given the possibility to re consider the headspace variation for instrumental applications. In this pap er the use of measurements of two electronic noses, based on different sens or technologies and sampling methodologies, to detect freshness of cod-fish fillets is illustrated and discussed. Over a period of 17 storage days, th e two sensor systems have shown different resolution, while the combination of them achieves the best performances allowing an almost complete evaluat ion of the freshness of samples. Trimethylamine (TMA) and total volatile ba sic nitrogen, measured with conventional techniques, show a non-monotonic b ehaviour, that induces the possibility of large errors in freshness estimat ion, as shown by the electronic noses. (C) 2001 Elsevier Science B.V. All r ights reserved.