C19 | Assessment of the effect of two thawing methods on the shelf life of cephalopod molluscs

L. Casalino¹, S. Alesio², M. Di Paolo², A. Sardo², G. Fiore², C. Cabato², R. Marrone². | ¹Sostenibilità e Agenda ESG, Universitas Mercatorum, Roma; ²Dip. di Medicina Veterinaria e Produzioni Animali, Università degli Studi di Napoli Federico II, Napoli.

Purpose. The purpose of this study was to evaluate the effect of two thawing techniques, one slow (performed in a refrigerated chamber at 0-4°C for 24 hours) and one rapid (performed with a water thawing machine at <7°C for 30 minutes) on the shelf life of two fish species belonging to the cephalopod class (Octopus vulgaris and Illex argentinus) stored at +4°C for up to 48 hours after thawing. Methods. To evaluate the shelf life up to 48 hours, instrumental sensory analyses were performed using an electronic nose-PEN3 IOMS (Instrumental Odour Monitoring System) and QIM tests, physical-chemical analyses (pH, TBA test, ABVT, TMA, CIEL^* a^* b^* colour) and microbiological (mesophilic CBT, Enterobacteriaceae, Coliforms, coagulase-positive Staphylococci) analyses were carried out on four samples: Octopus vulgaris thawed using the rapid (PV) and slow (PL) methods and Illex argentinus thawed using the rapid (TV) and slow (TL) methods. The analyses were carried out in triplicate for each of the three sampling times examined: T0 (day of thawing), T1 (24 hours after thawing), T2 (48 hours after thawing). Results. The results of the QIM test showed more favourable scores in the slowly thawed cephalopod samples. The Total Volatile Basic Nitrogen (TVBN) and Trimethylamine (TMA) parameters were low in all samples, with statistically higher values (p <0.001) in PL and TL compared to PV and TV at T2. This data was confirmed by the results of instrumental analyses using the IOMS (Instrumental Odour Monitoring System), which evaluates the odour mixture through the olfactory fingerprint chromatogram to identify the presence of undesirable molecules, such as nitrogen and ammonia, associated with product deterioration. The lipid oxidation values (TBA test) were below the limit considered critical in the literature. Microbiological results showed that the total mesophilic count was significantly lower in PL and TL (p <0.001) during all three sampling times. Staphylococci, Enterobacteriaceae and Coliforms showed values within the limits, particularly in PL and TL. Conclusions. The results of this preliminary study showed that slow thawing limited bacterial proliferation, while rapid thawing more effectively preserved the chemical and sensory characteristics. Octopus vulgaris proved to be more sensitive to rapid thawing methods than Illex argentinus, highlighting the importance of optimising rapid protocols and adapting procedures to individual species. This evidence could offer fish companies the opportunity to re-evaluate the marketing of these products even beyond 24 hours, as indicated by Ministerial Note 0010026-P-02/08/2007 DGSRN, reducing food waste and strengthening the competitiveness of the sector.