E-nose based control charts for fish freshness evaluation.

Freshness is a key indicator of fish quality, making it essential to monitor throughout the food supply chain, particularly during distribution. A rapid, straightforward analytical method for assessing fish quality can provide valuable insights when products reach distribution centers or are commercialized. This study aims to develop a simplified approach based on an electronic nose (e-nose) system to evaluate the freshness of fish products within the distribution chain. The study monitored five seafood products - cuttlefish, red mullet, Atlantic cod, Atlantic mackerel, and mantis shrimp - throughout their shelf life, from arrival and packaging at the distribution centers to beyond their expiration dates. A portable electronic nose, composed by four selected metal oxide semiconductor sensors, a photoionization detector and two electrochemical cells, was used to assess the products, alongside traditional microbial analyses (Total Viable Count). The proposed method identified warning and control limits based on e-nose data, which were further confirmed by microbial testing. Control charts were developed and externally validated to assess product quality through odor intensity measurements by e-nose.