Influence of freezing and oxygen‐free packaging methods on lipid oxidation and other flesh quality parameters of Norway lobster (Nephrops norvegicus)

Abstract

By adapting oxygen‐free systems, the use of modified atmosphere packaging (MAP) appears increasingly attractive and of commercial global interest for (sea)foods products. Moreover, when combined with other preservation methods, MAP continues to show high promise in tackling a wide range of deterioration aspects affecting fishery products. This study was therefore purposed to apply freezing and oxygen‐free (vacuum as well as modified atmospheres of 50% N2‐50%CO2‐ and 100% N2) packaging methods onto Norway lobster (NL) (Nephrops norvegicus) and resultant data compared with conventional preservative treatment of sulphite together with control (untreated). The specific objective was to determine the influence of the (above‐mentioned) treatments on lipid oxidation (thiobarbituric acid {TBA}) and other flesh quality parameters (total volatile base (TVB) nitrogen, pH, free amino acids (FAAs), proximal composition, as well as melanosis scores) during the inspected storage period of up to 12 months. The result showed that across treatments, whilst the TBA values were little coincidental with significantly changing pH plus superficially fluctuating proximate composition(s), the TVB‐N values seemed unaffected except some increases in 100% N2‐treated NL samples at the second half of frozen storage. Whilst individual FAAs per treatment considerably varied, the trends of total FAAs between treatments seemed relatively unvaried. Additionally, the treatments of 50% N2‐50%CO2‐ and 100% N2‐ to apparently delay the melanosis formation in NL samples indicated oxygen‐free treatment methods herein with high promise to replace the sulphite ones. To best of our knowledge, this is the first study about freezing combining oxygen‐free packaging treatment methods specifically applied to NL samples.Practical applications: Norway lobster (NL) is among crustacea species receiving increasing global interest given its economic value together with the promising market status. But lipid damage together with other freshness restraints continually affects its post‐harvest shelf. Modified atmosphere packaging (MAP) adapts oxygen‐free system which when combined with other preservation methods offers real‐time and tested food storage success. Amid the advances in MAP to‐date, relevant information about freezing combined with oxygen‐free packaging atmospheres applied to Norway lobster species has not been found. Occupying a space within the state‐of‐the‐art of extant knowledge, this current study has showed that freezing and oxygen‐free packaging atmospheres can capably influence the lipid oxidation and other flesh quality attributes of a crustacean product such as NL samples.The lipid oxidation of oxygen‐free (vacuum as well as modified atmospheres of 50% N2‐50%CO2‐ and 100% N2) packaged Norway lobster samples measured by thiobarbituric acid (TBA) and presented in mg MDA/kg in comparison to conventional preservative treatment of sulphite together with control (untreated). The image symbols include: (▪) vacuum; (▴) N2‐CO2; (Δ) N2; (•) sulphited; (□) control. Image shows that lipid oxidation of NL samples, although it appears somewhat affected during the first 6 months of frozen storage compared to the much‐reduced effects the remaining months, it should still be considered as trivial given the low MDA values that continuously prevailed throughout the inspected frozen storage period in the range of between ∼0.10 and 0.25 mg MDA/kg.