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

1H LF-NMR Self-Diffusion Measurements for Rapid Monitoring of an Edible Oil's Food Quality with Respect to Its Oxidation Status

The food quality of edible oils is dependent on basic chemical and structural changes that can occur by oxidation during preparation and storage. A rapid and efficient analytical method of the different steps of oil oxidation is described using a time-domain nuclear magnetic resonance (TD-NMR) sensor for measuring signals related to the chemical and physical properties of the oil. The degree of thermal oxidation of edible oils at 80 °C was measured by the conventional methodologies of peroxide and aldehyde analysis. Intact non-modified samples of the same oils were more rapidly analyzed for oxidation using a TD-NMR sensor for 2D T₁-T₂ and self-diffusion (D) measurements. A good linear correlation between the D values and the conventional chemical analysis was achieved, with the highest correlation of R² = 0.8536 for the D vs. the aldehyde concentrations during the thermal oxidation of poly-unsaturated linseed oils, the oil most susceptible to oxidation. A good correlation between the D and aldehyde levels was also achieved for all the other oils. The possibility to simplify and minimize the time of oxidative analysis using the TD NMR sensors D values is discussed as an indicator of the oil’s oxidation quality, as a rapid and accurate methodology for the oil industry.

Time Domain (TD) Proton NMR Analysis of the Oxidative Safety and Quality of Lipid-Rich Foods

Food safety monitoring is highly important due to the generation of unhealthy components within many food products during harvesting, processing, storage, transportation and cooking. Current technologies for food safety analysis often require sample extraction and the modification of the complex chemical and morphological structures of foods, and are either time consuming, have insufficient component resolution or require costly and complex instrumentation. In addition to the detection of unhealthy chemical toxins and microbes, food safety needs further developments in (a) monitoring the optimal nutritional compositions in many different food categories and (b) minimizing the potential chemical changes of food components into unhealthy products at different stages from food production until digestion. Here, we review an efficient methodology for overcoming the present analytical limitations of monitoring a food's composition, with an emphasis on oxidized food components, such as polyunsaturated fatty acids, in complex structures, including food emulsions, using compact instruments for simple real-time analysis. An intelligent low-field proton NMR as a time domain (TD) NMR relaxation sensor technology for the monitoring of T₂ (spin-spin) and T₁ (spin-lattice) energy relaxation times is reviewed to support decision-making by producers, retailers and consumers in regard to food safety and nutritional value during production, shipping, storage and consumption.

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

This study aimed to investigate the effects of in ovo feeding (IOF) and dietary addition (DA) oils on growth, development and immune function of broiler chickens. In experiment 1, a total of 500 eggs were randomly assigned to 3 treatments: non-injected group (CON) with 100 eggs; soybean oil injected group (SO) with 200 eggs and linseed oil injected group (LO) with 200 eggs. Results showed that there were no detrimental effects of IOF of oils on embryonic development. In experiment 2, a two factor experimental design was adopted. After hatching, 120 chicks which came from each oil-injected group were divided into 2 treatments with 6 replicates, and chickens were fed soybean oil diet and linseed oil diet, respectively. The results showed that DA linseed oil increased final body weight (FBW) of broilers at d 21 post hatch, IOF of linseed oil decreased average daily feed intake (ADFI) and feed conversion ratio (FCR) of broilers from d 1 to 21 (P < 0.05), while the plasma leptin level of 21-day-old broilers was increased by IOF or DA linseed oil (P < 0.05). Main effect analysis showed that DA linseed oil increased the spleen index and mRNA expression of IFN-γ in spleen of broilers at 7 d of age (P < 0.05). IOF of linseed oil upregulated the mRNA expression of IFN-γ in the spleen of chicks at 1 d and mRNA expression of IL-2 and IL-4 in spleen of broilers at 21 d (P < 0.05), and the interaction effect showed that IOF and DA linseed oil synergically increased the expression of IL-2 and IL-4 in spleen of broilers at 21 d. Compared with SO group, LO increased the Shannon index of hatching-day cecum microflora (P < 0.05). Principal co-ordinates analysis (PcoA) showed that LO group clearly separated from CON and SO groups. Finally, Spearman correlation analysis also manifested that Alkalicoccus was significantly correlated with spleen index and mRNA expression of IL-2, and Phreatobacter was significantly correlated with the mRNA expression of IL-2 and IFN-γ in spleen, Acinetobacter had a positive correlation with thymus index (P < 0.05). In conclusion, IOF of linseed oil reduced the ADFI and FCR of broilers and increased the species diversity and changed the structure of cecal microflora of chicken embryos at the 19th day of incubation (E19). Immune function of broilers spleen was also regulated by IOF and DA linseed oil.

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

The nutritional characteristics of fatty acid (FA) containing foods are strongly dependent on the FA’s chemical/morphological arrangements. Paradoxically the nutritional, health enhancing FA polyunsaturated fatty acids (PUFAs) are highly susceptible to oxidation into harmful toxic side products during food preparation and storage. Current analytical technologies are not effective in the facile characterization of both the morphological and chemical structures of PUFA domains within materials for monitoring the parameters affecting their oxidation and antioxidant efficacy. The present paper is a review of our work on the development and application of a proton low field NMR relaxation sensor (¹H LF NMR) and signal to time domain (TD) spectra reconstruction for chemical and morphological characterization of PUFA-rich oils and their oil in water emulsions, for assessing their degree and susceptibility to oxidation and the efficacy of antioxidants. The NMR signals are energy relaxation signals generated by spin–lattice interactions (T₁) and spin–spin interactions (T₂). These signals are reconstructed into 1D (T₁ or T₂) and 2D graphics (T₁ vs. T₂) by an optimal primal-dual interior method using a convex objectives (PDCO) solver. This is a direct measurement on non-modified samples where the individual graph peaks correlate to structural domains within the bulk oil or its emulsions. The emulsions of this review include relatively complex PUFA-rich oleosome-oil bodies based on the aqueous extraction from linseed seeds with and without encapsulation of externally added oils such as fish oil. Potential applications are shown in identifying optimal health enhancing PUFA-rich food formulations with maximal stability against oxidation and the potential for on-line quality control during preparation and storage.