Effect of antioxidants on lipid oxidation in herring (Clupea harengus) co-product silage during its production, heat-treatment and storage

Mursalin Sajib,Ingrid Undeland,Markus Langeland

doi:10.1038/s41598-022-07409-8

Abstract

Provided high product quality, ensilaging can be used to valorize fish filleting co-products into a silage suitable for food applications. However, a documented challenge for products from hemoglobin-rich fish raw materials is the high susceptibility to lipid oxidation, calling for stabilization by antioxidants. In a comparison among different rosemary-containing antioxidants and isoascorbic acid, we here found that the commercial mixture Duralox MANC-213 (MANC) provided the best protection against peroxide value and 2-thiobarbituric acid reactive substances (TBARS) development during ensilaging of herring filleting co-products (0–7 days, 22 °C), and also during subsequent heat-treatment (30 min, 85 °C). Increasing MANC concentration from 0.25 and 0.75 to 1.25% lowered TBARS values from 43.53 and 25.12 to 18.04 µmole TBARS/Kg silage, respectively, after 7 days of ensilaging. During storage at 4 °C/22 °C in presence of MANC, 1.25% provided the highest protection with 87–90% and 66–73% lower TBARS, at 4 °C and 22 °C, respectively, at 6 months compared to the controls. At this time point, heat-treated silages had lower protein degree of hydrolysis and free amino acids values than the non-heat-treated one. Regardless of antioxidant addition, total volatile basic nitrogen (TVB-N) formation still increased during the storage, but, overall, TVB-N values in silages were below the acceptable limit of 30 mg TVB-N/100 g fish for human consumption. Together with lipid oxidation data, this suggest that herring silage produced in presence of antioxidants can be used both for high quality feed and food applications.

Highlights

Provided high product quality, ensilaging can be used to valorize fish filleting co-products into a silage suitable for food applications
Both peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) increased significantly (p < 0.05) over time in silage without antioxidant added, and this sample had the highest levels of both PV and TBARS at the end of ensilaging, i.e. 935.95 μmole peroxide/kg silage and 286.99 μmole TBARS/kg silage, respectively
Duralox MANC-213 provided the highest protection against both PV and TBARS development, while BORDANTIX antioxidants were effective primarily against TBARS development (Fig. 3)

Summary

Introduction

Provided high product quality, ensilaging can be used to valorize fish filleting co-products into a silage suitable for food applications. Given the ban on mink farming in 2020 to stop Covid-19 transmission, and the highly energy-demanding processes required to produce meal and oil, ensilaging—preservation under acidic conditions—could provide a cost-efficient process to valorize fish filleting co-products into high value peptide ingredients ensuring a circular approach (Fig. 1)[5]. This process can be considered as a “green” process because it does not generate any waste and does not comprises any harmful solvents[6]. Very little is known about the effect of heat-treatment on lipid oxidation at low pH (pH ~ 3.50), and the same is true for the effectiveness of antioxidants under such conditions

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