Low‐Field Nuclear Magnetic Resonance Time Domain Characterization of Polyunsaturated Fatty Acid–Rich Linseed and Fish Oil Emulsions during Thermal Air Oxidation

Abstract

Linseed contains high levels of polyunsaturated fatty acids (PUFA), such as α‐linolenic acid (> 50% ALA‐18:3), that are naturally protected against thermal oxidation by their encapsulation within linseed oil bodies (OB) by multiple components including antioxidant proteins and mucilage emulsifying agents. Linseed OB emulsions (LSE) can be produced by grinding linseed seeds, adding water, adjusting pH, and sonication. This is a process that can encapsulate externally added PUFA to minimize their thermal oxidation, as it does for the intrinsic ALA PUFA. Fish oil (FO) encapsulation into this LSE platform to form linseed fish oil emulsions (LSFE) offers the possibility of a nutritive delivery system of the biologically essential FO PUFA eicosapentaenoic acid and docosahexaenoic acid. In this study, 1H low‐field nuclear magnetic resonance (LF‐NMR) is used to characterize LSE's and LSFE's chemical and structural properties as well as their stability and changes under thermal oxidation (55 °C for 96 hours). 1H LF‐NMR data processing was developed to generate one‐dimensional (1D) T1 (spin–lattice), 1D T2 (spin–spin), and 2D (T1 vs. T2) relaxation time spectra that can characterize OB emulsions and monitor their time domain fingerprints (spectrum peaks) of chemical and structural changes during the oxidation process. The 1H LF‐NMR analysis were further supported and correlated with conventional peroxide value test, self‐diffusion, droplet size distribution, zeta potential estimation of surface stability, and gas chromatography–mass spectrometry analysis of fatty acid profile changes under thermal oxidation conditions. The 1D and 2D LF‐NMR relaxation spectra showed that the LSE and LSFE did not suffer intense oxidation process, due to PUFA assembly in OB oxidative protection. These results were further confirmed by the supportive analytical methodologies. The results of this study demonstrate the efficacy of 1H LF‐NMR methodology to monitor PUFA's rich oil and emulsion thermal oxidation.

Proton Low Field NMR Relaxation Time Domain Sensor for Monitoring of Oxidation Stability of PUFA-Rich Oils and Emulsion Products

“…However, not all peroxidation reactions generate MDA, therefore TBA data may be misleading. GC-MS is another common methodology used in the assessment of PUFA's degree of oxidation, that requires a complex sample preparation characterized by lipid extraction and subsequent derivation steps, which are very time consuming [37].These and other spectroscopic methods such as HF 1 H NMR and FTIR are limited in the resolution they can achieve of the different chemical and morphological states of PUFA oils and emulsions [7,41]. Hwang [7] suggested the development of methods that combine the concomitant detection of multiple oxidation products for the consistent assessment of lipid oxidation.…”

“…Linseed O/W emulsions (LSEs) of the present study are made from linseed oleosomes (oil bodies, OB) as described in detail by Resende et al [41]. In Section 2.2 the structural organization of LSE vesicles was described as oil encapsulated on the inside by different interfacial components such as polar head groups of amphiphiles, with their hydrophobic tails within the vesicle's core isolated from the continuous aqueous matrix environment.…”

Effects of in ovo feeding and dietary addition oils on growth performance and immune function of broiler chickens

“…Based on these result, we speculate that in ovo injection of PUFA in the yolk sac will have great potential to influence the embryonic development and broilers performance. Meanwhile, the study shown that n-6 PUFA in soybean oil accounts for about 51% and n-3 PUFA is about 6.8% ( Messina et al, 2021 ), while the linseed oil contains α-linolenic acid, which belongs to one of the n-3 PUFAs, more than 50% ( Resende et al, 2021 ). Hence, this study was conducted to explore the effects of IOF and dietary supplement of soybean oil (rich in n-6 PUFA) or linseed oil (rich in n-3 PUFA) on performance and immune function of broilers from 19 d incubation to 21 d post-hatch.…”