Research

Improving the oxidative stability of guts from cod filleting by antioxidant dipping – a route to better seafood side-stream utilization

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Abstract

There is a growing interest for sustainable food production and increased utilization of existing food raw materials. In the cod filleting industry up to 60% of the weight ends up as side-streams, e.g. guts, heads and frames. At the moment, the majority of these side-streams ends up as low value products for feed. To increase utilization for food applications, new preservation solutions are needed to maintain a high quality of the side-stream before further processing. The aim of this study was to evaluate the effect of antioxidant dipping of cod guts on the oxidative stability during subsequent storage. Selection of antioxidants was based on earlier findings with commercial formulations of rosemary extracts for preservation of herring solid side-streams (Wu et al., 2020). The following treatments were evaluated: no dipping, dipping in 0.9% NaCl, dipping in 2% Duralox MANC (commercial rosemary preparation fortified with ascorbic acid, α-tocopherol and citric acid), or dipping in 0.05% and 0.2% lipophilic rosemary extract having a carnosic acid content 15 times higher than that in Duralox-MANC. After antioxidant dipping, the guts were drained and minced to obtain homogeneous samples after which they were subjected to short- and long-term storage (5 oC for 7 days and -20 oC for 6 months). The effect of the antioxidant treatment was evaluated by regularly measuring peroxide value (PV) and TBA-reactive substances (TBARS) during storage. Results from the short term storage show a positive effect of the antioxidant dipping on the oxidative stability of cod guts. Duralox MANC inhibited the formation of PV throughout the storage and TBARS was inhibited for 4 days. Rosemary extract (0.2%) also inhibited the formation of PV for 7 days, however, the inhibition of TBARS was 2 days. For the control, PV and TBARS already increased after 1 day of storage. Duralox MANC was most efficient followed by rosemary extract applied in 0.2% (the high concentration evaluated).