Browsing by Author "Ampem, Gilbert"

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    Effectiveness of different antioxidants in suppressing the evolution of thermally induced peroxidation products in hemp seed oil
    (Elsevier, 2024-05-03) Ampem, Gilbert; Le Gresley, Adam; Grootveld, Martin; Naughton, Declan Patrick
    Several scientific studies have warned that the ingestion of dietary lipid oxidation products (LOPs) may initiate or exacerbate the development of several chronic non-communicable diseases in humans. Indeed, the constantly increasing consumption of culinary oils by larger global populations indicates the need for scientific techniques to suppress the evolution of LOPs in thermo-oxidised oils. This study employed a 600.13 MHz frequency NMR spectrometer in evaluating the effect of 10, 50, and 100 ppm concentrations of chemical compounds reported to have antioxidant properties in continuously-stirred and thermally stressed polyunsaturated fatty acid (PUFA)-rich hemp seed oil at a frying temperature of 180℃ for 180 min. Research data acquired showed that the antioxidants α- and γ-tocopherol, γ-oryzanol, β-carotene, eugenol, resveratrol, ascorbyl palmitate, gentisic acid, and L-ascorbic acid all played a vital role in suppressing the evolution of secondary aldehydic lipid oxidation products in hemp seed oil. However, the most ineffective LOP-suppressing agent was L-lysine, an observation which may be accountable by its poor oil solubility. Nonetheless, trends deduced for compounds acting as antioxidants were mainly unique for each class of agent tested. Conversely, the antioxidant capacity of resveratrol was consistently higher, and this effect was found to be independent of its added amounts. This report provides a direct approach in developing scientific methods for the suppression of LOPs in thermo-oxidatively susceptible PUFA-rich cooking oils.
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    Evaluations of the Peroxidative Susceptibilities of Cod Liver Oils by a 1H NMR Analysis Strategy: Peroxidative Resistivity of a Natural Collagenous and Biogenic Amine-Rich Fermented Product
    (MDPI, 2020-03-12) Percival, Benita; Wann, Angela; Zbasnik, Richard; Schelgel, Vicki; Edgar, Mark; Ampem, Gilbert; Le Gresley, Adam; Wilson, Philippe B.; Naughton, Declan; Grootveld, Martin; Zhang, Jie
    High-resolution 1H nuclear magnetic resonance (NMR) analysis was employed to molecularly screen the lipid, lipid oxidation product (LOP), and antioxidant compositions of four natural (unrefined) cod liver oil (CLO) products. Products 1–3 were non-fermented CLOs, whilst Product 4 was isolated from pre-fermented cod livers. Supporting analytical data that were acquired included biogenic amine, flavanone, tannin, phenolic antioxidant, α-tocopherol, and oxygen radical absorbance capacity (ORAC) determinations by recommended HPLC, LC/MS/MS, or spectrophotometric methods. SDS-PAGE, HPLC, and 1H NMR analyses investigated and determined collagenous antioxidants and their molecular mass ranges. 1H NMR analysis of aldehydic LOPs was employed to explore the susceptibilities/resistivities of each CLO product to peroxidation that is induced by thermal stressing episodes (TSEs) at 180°C, or following prolonged (42 day) storage episodes at 4 and 23 °C. Product 4 displayed extremely high ORAC values, which were much greater than those of Products 1–3, and that were predominantly ascribable to significant levels of peroxidation-blocking and/or aldehyde-consuming collagenous polypeptides/peptides and ammoniacal agents therein. Significantly lower levels of toxic aldehydes were generated in the pre-fermented Product 4 during exposure to TSEs, or the above long-term storage episodes. These results confirmed the enhanced peroxidative resistivity of a fermented, antioxidant-fortified natural CLO product over those of non-fermented unrefined products. Product 4: Green Pasture Blue Ice™ Fermented Cod Liver Oil.
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    Real-World Evaluation of Lipid Oxidation Products and Trace Metals in French Fries From Two Chain Fast-Food Restaurants
    (Frontiers, 2021-02-05) Ampem, Gilbert; Le Gresley, Adam; Grootveld, Martin; Naughton, Declan; De Mars, Simon
    Differences in lipid oxidation products (LOPs) and trace metal concentrations of French fry samples found between two global chain fast-food restaurants in the UK were investigated using high-resolution proton nuclear magnetic resonance (1H NMR) and inductively coupled plasma-optical emission spectrometry (ICP-OES) analyses, respectively, of extracts derived therefrom. Over the course of 3 days and 3 different diurnal time periods, samples of French fries (FFs) were analyzed, and comparisons of two different oil extraction methods were undertaken for the two restaurants involved. The magnitude of concentrations of LOPs extracted from FFs is discussed. Significant differences between 6/7 aldehyde classifications, and aluminum, manganese, vanadium, lead, iron, copper and nickel levels between samples from the two restaurants are also reported. Redox-active transition and further trace metal concentrations inversely correlated with FF oil sample LOP contents; this suggested an antioxidant rather than a pro-oxidant role for them.
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    The Role of Polydimethylsiloxane in Suppressing the Evolution of Lipid Oxidation Products in Thermo-Oxidised Sunflower Oil: Influence of Stirring Processes.
    (Frontiers, 2021-08-10) Le Gresley, Adam; Ampem, Gilbert; Grootveld, Martin; Naughton, Declan
    Suppressing the evolution of lipid oxidation products (LOPs) in commercially available culinary oils is considered to represent a valuable health-promoting incentive since these agents have cytotoxic and genotoxic properties and have been implicated in the pathogenesis of several chronic disease states. One agent used to suppress LOPs formation is polydimethylsiloxane (PDMS). In this study, proton nuclear magnetic resonance (1H NMR) analysis was employed to evaluating the influence of increasing PDMS concentrations (6.25 × 10−7 , 1.0 × 10−5 , 0.025, 0.05, 0.1, 0.5, 1.0, 5.0, and 10.0 ppm) in either stirred or unstirred refined sunflower oil exposed to thermal stressing episodes continuously at 180◦C for 300 min with no oil replenishment. Results acquired showed that the extent of blockage of LOPs generation was correlated with increasing concentrations of PDMS. The minimal level of added PDMS required to provide a statistically significant protective role for both stirred and unstirred culinary oils when exposed to high frying temperatures was only 6.25 × 10−7 ppm. Furthermore, stirring at 250 rpm was experimentally determined to reduce the functional role PDMS. This is vital in a real world setting since the boiling process of frying may ultimately reduce the LOPs suppression activity of PDMS.
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    The impact of partial oil substitution and trace metal ions on the evolution of peroxidation products in thermally stressed culinary oils.
    (Elsevier, 2021-12-15) Ampem, Gilbert; Le Gresley, Adam; Grootveld, Martin; De Marsa, S.; Naughton, Declan
    Suppressing toxic aldehydic lipid oxidation product (LOP) generation in culinary oils is now considered vital, since the deleterious effects arising from their ingestion are implicated in a wide range of disease conditions. Partial substitution involves the replenishment of thermally-stressed culinary oils with corresponding unheated ones. This technique was tested by employing 10%, 25%, 50%, and 75% (v/v) partial substitutions of coconut, olive, rapeseed, and sunflower oils at 180℃ for a 300 min continuous thermo-oxidation duration. Oil samples were analysed by proton nuclear magnetic resonance (1H NMR) spectroscopy. Trace metal levels, including oxidation-reduction (redox)-active metal ions credited with enhancing cooking oil oxidation were also analysed using inductively coupled plasma-optical emission spectroscopy (ICP-OES). As expected, the degree of oil unsaturation, and the % partial substitutions significantly influenced their susceptibility to thermo-oxidation. In view of the very low polyunsaturated fatty acid (PUFA) and monounsaturated fatty acid (MUFA) contents of coconut oil, both the class and concentrations of evolved LOPs were found to be least affected by this partial substitution process. Aldehydic LOPs were greatly suppressed in partially-substituted rapeseed oil. The % suppression activity of LOPs evaluated for the partially substituted oils were generally high making partial oil substitutions an effective chemical-free method in suppressing LOPs at both industrial and commercial levels. In general, the % partial oil substitutions were directly related to the dilution effect observed for LOPs quantified in the oils. Furthermore, trace metal ion concentrations measured in the culinary oils did not influence the evolution of LOPs in the oils.