Determinations of the peroxidative susceptibilities of cod liver oils by a newly-developed 1H NMR-based method: resistance of an antioxidant-fortified product isolated from pre-fermented sources

Authors

• B. C. Percival, De Montfort University
• R. Zbasnik, University of Nebraska-Lincoln
• V. Schlegel, University of Nebraska-Lincoln
• M. Edgar, University of Loughborough
• J. Zhang, Green Pasture Products
• M. Grootveld, De Montfort UniversityFollow

ORCID IDs

http://orcid.org/0000-0003-1502-3734

Document Type

Article

Date of this Version

2-12-2020

Citation

The Author(s) 2020.

Comments

Percival et al. BMC Res Notes (2020) 13:73

Abstract

Objective: To explore the molecular composition and antioxidant status of four natural (unrefined) cod liver oil (CLO) products, three of which (Products 1–3) were non-fermented, whilst one (Product 4) was isolated from pre-fermented cod livers, and hence was naturally antioxidant-fortified. Potential antioxidants and aldehyde-scavenging agents were determined by recommended and/or 1H NMR methods; peroxyl radical-specific oxygen radical absorbance capacity (ORAC) values were measured fluorimetrically. The activities of such antioxidants were also investigated by assessing the susceptibilities/resistivities of these CLOs to thermo-oxidation by 1H NMR analysis, which monitored the time-dependent evolution of aldehydic lipid oxidation products at 180 °C.

Results: Product 4 displayed much higher, albeit variable ORAC values (mean ± SEM 91.4 ± 19.5 mmol. trolox equivalents/kg) than those of Products 1–3, an observation arising from significant levels of peroxidation-blocking and/ or aldehyde-consuming collagenous polypeptides/peptides, flavonones, biogenic amines, total phenolics, tannins, and ammoniacal agents therein. All of these agents were undetectable in Products 1–3. Quantitative considerations indicated that collagenous gel agents (present at ca. 1.5% (w/w)) were the most powerful Product 4 antioxidants. Significantly lower levels of aldehydes were generated in this product when exposed to thermal-stressing episodes. Results confirmed the enhanced peroxidative resistivity of a pre-fermented, antioxidant-rich natural CLO over those of corresponding non-fermented products. Product 4: Green Pasture Blue IceTM fermented cod liver oil.