Quality changes during the frozen storage of the crustacean lobster krill (Munida spp.)

Abstract

This study focused on the quality changes of an undervalorised and underutilised crustacean, lobster krill (Munida spp.) during its frozen storage (10 months at −18°C). Fresh lobster krill specimens were previously soaked in aq. 0.75 and 0.25% sodium metabisulphite (SMB) solutions (0.75‐SMB and 0.25‐SMB conditions, respectively). Comparisons with individuals soaked in water (water control, WC condition) and unsoaked (blank control, BC condition) were carried out. Better sensory acceptance (namely, external colour and flesh odour and taste) was obtained with SMB presence in previous soaking; BC samples were rejected (external odour as limiting factor) at month 10, while the remaining batches were still acceptable. Additionally, a sensory quality enhancement was accomplished by water soaking. Increases in secondary lipid oxidation compound formation were observed in SMB‐treated lobster krill; however, chemical assessment of non‐enzymatic (tertiary lipid oxidation) and enzymatic browning showed a marked inhibition in lobster flesh previously soaked under both SMB conditions when compared with their counterpart blanks (BC and WC). As a result, no effect on the polyene index could be concluded. Finally, previous SMB soaking increased the formation of trimethylamine and inhibited lipid hydrolysis (free fatty acid content) in lobster flesh.Practical applications: The marine food industry is actually suffering from dwindling stocks of traditional species as a result of drastic changes in their availability. Consequently, marine technologists and trade have turned their attention to some unconventional sources of raw material. Among them, lobster krill, also called squat lobster, a decapod crustacean belonging to the Genus Munida (Family Galatheidae, Order Decapoda), represents a relevant choice. Currently, lobster krill has no commercial value, but it is occasionally caught and discarded at sea during fishing targeted to commercial fish species. The results presented in this study open the way to the potential commercialisation of lobster krill as frozen product. Moreover, a simple preservation step, such as sodium metabisulphite soaking previous to freezing, was successfully applied to retain its quality. Further research is needed to reinforce the commercial and technological possibilities to provide the consumer with such a new, attractive and nutritious seafood species.Quality changes during the frozen storage of the infravalorised crustacean lobster krill (Munida spp.)