Title: Electronic Nose to Monitor the Freshness of Red Fish (Sebastes marinus) Stored in Ice and Modified Atmosphere Packaging (MAP)

An electronic nose called FreshSense was used as a rapid technique to monitor the freshness of red fish stored in ice and modified atmosphere packaging (MAP). Standard compounds were measured to study the characteristic response of the FreshSense sensors. Volatile compounds produced during storage of red fish were monitored and the results were analysed by multivariate analysis methods. The sensors showed good selectivity, sensitivity and repeatability to standard compounds that are representative of spoilage compounds in fish. The FreshSense could discriminate between standard compounds and their mixtures and was also able to discriminate between fresh samples and spoiled samples of red fish. The CO sensor increases earlier than the other sensors and is most likely responding to short chain alcohols and carbonyls formed during the storage of red fish. The NH3 and H2S sensors are sensitive to amines and sulphur compounds respectively formed in high concentrations at the end of the storage period. A slower spoilage rate was observed in MAP storage than in iced. The electronic nose measurements are generally in agreement with the results of sensory evaluation, but give detailed information about the spoilage pattern and the composition of the headspace of red fish.