Nuclear Magnetic Resonance Spectroscopic Analysis of the Evolution of Peroxidation Products Arising from Culinary Oils Exposed to Thermal Oxidation: An Investigation Employing 1H and 1H-1H COSY and TOCSY Techniques

Oxidative Lipidomics to Unravel the Glycerol Core Aldehydes of Three Typical Unsaturated Triglycerides under Simulated Heating Conditions

Glycerol core aldehydes (GCAs) are significant nonvolatile aldehyde compounds generated in heated edible oils, which may pose potential health risks. Utilizing the complementary CID and EAD mass spectrometry data, this study introduced a predict-to-hit strategy, identifying 42 types of GCAs from oxidized OOO, LLL, and LnLnLn. Structural analysis revealed that oxidation occurred at both the sn-2 and sn-1/3 positions of triglyceride (TG), with the Sn-1/3 position exhibiting greater susceptibility as the degree of TG unsaturation increased. As the temperature increases, the concentration of saturated GCAs steadily rises, while unsaturated GCAs exhibit an initial increase, followed by a decrease. During further oxidation, GCAs tend to convert into hydroxyl compounds, monocyclic epoxides, dicyclic epoxides, and polycyclic epoxides, with epoxy groups predominantly forming at the 9,10 positions. These observations enhance our understanding of the formation of GCAs and promote the search for strategies to delay or prevent oxidation.

Effectiveness of different antioxidants in suppressing the evolution of thermally induced peroxidation products in hemp seed oil

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.

High-resolution 1H NMR analysis of continuous and discontinuous thermo-oxidative susceptibility of culinary oils during frying at 180 °C

Lipid oxidations products (LOPs) are reactive mutagenic and carcinogenic species known to be generated in thermally stressed culinary oils. Mapping the evolution of LOPs in culinary oils exposed to standard frying practices - both continuous and discontinuous thermo-oxidation - at 180 °C is vital to our understanding of these processes, and to the development of scientific solutions for their effective suppression. Modifications in the chemical compositions of the thermo-oxidised oils were analysed using a high-resolution proton nuclear magnetic resonance (1H NMR) technique. Research findings acquired showed that polyunsaturated fatty acid (PUFA)-rich culinary oils were the most susceptible to thermo-oxidation. Consistently, coconut oil, which has a very high saturated fatty acid (SFA) content, was highly resistant to the thermo-oxidative methods employed. Furthermore, continuous thermo-oxidation produced greater substantive changes in the oils evaluated than discontinuous episodes. Indeed, for 120 min thermo-oxidation durations, both continuous and discontinuous methods exerted a unique impact on the contents and levels of aldehydic LOPs formed in the oils. This report exposes daily used culinary oils to thermo-oxidation, and therefore, it permits assessments of their peroxidative susceptibilities. It also serves as a reminder to the scientific community to investigate approaches for suppressing toxic LOPs generation in culinary oils exposed to these processes, most notably those involving their reuse.

Ultrasound-Assisted Extraction of Blackberry Seed Oil: Optimization and Oil Characterization

Ultrasound-assisted extraction (UAE) was applied to extract oil from blackberry (BB) seeds. The effect of UAE conditions on oil recovery and quality was investigated. Favorable experimental conditions (ultrasound intensity (UI), extraction temperature, and time) were investigated using response surface methodology (RSM). A Box–Behnken design was used to predict optimized conditions for BB seed oil extraction. These conditions were as follows: 13.77 W/cm2 UI, 45 °C extraction temperature, and 15 min extraction time. The experimental value obtained for extraction efficiency under optimal conditions was 87 ± 0.34%, in good agreement with the optimized predicted value. UAE does not affect the oil composition and confers higher antioxidant values in BB seed oil in comparison with Soxhlet extraction.