Using an electronic nose for determining the spoilage of vacuum-packaged beef

The use of an electronic nose in the quantitative determination of the degr ee of spoilage of vacuum-packaged beef was evaluated. Beef from four differ ent slaughterhouses was sliced, vacuum-packaged and stored at 4 degrees C f or 8 weeks. Samples were withdrawn for bacterial (aerobic bacteria, lactic acid bacteria, Brochothrix thermosphacta, Pseudomonas and Enterobacteriacea e) and sensorial analyses and analysis of the volatile compounds during the storage period. A trained panel was used for the sensorial evaluations. Th e volatile compounds were analysed using an electronic nose containing a se nsory array composed of 10 metal oxide semiconductor field-effect transisto rs, four Tagushi type sensors and one CO2-sensitive sensor. Four of the 15 sensors were excluded due to lack of response or overloading. Partial least -squares regression was used to define the mathematical relationships betwe en the degree of spoilage of vacuum-packaged beef, as determined by the sen sory panel, and the signal magnitudes of the sensors of the electronic nose . The mathematical models were validated after 6 months using a new set of samples. The stability of the sensors during this period was examined and i t was shown that the sensitivity of five of the 11 sensors used had changed . Using the six remaining sensors, the signal patterns obtained from the me at from the different slaughterhouses did not change over a period of 6 mon ths. It was shown that the degree of spoilage! as calculated using a model based on two Tagushi sensors, correlated well with the degree of spoilage d etermined by the sensory panel (r(2) = 0.94). (C) 1999 Elsevier Science B.V . All rights reserved.