A novel approach to the rapid assignment of ¹³C NMR spectra of major components of vegetable oils such as avocado, mango kernel and macadamia nut oils

Abstract

Assignment of 13 C nuclear magnetic resonance (NMR) spectra of major fatty acid components of South African produced vegetable oils was attempted using a method in which the vegetable oil was spiked with a standard triacylglycerol. This proved to be inadequate and therefore a new rapid and potentially generic graphical linear correlation method is proposed for assignment of the 13 C NMR spectra of major fatty acid components of apricot kernel, avocado pear, grapeseed, macadamia nut, mango kernel and marula vegetable oils. In this graphical correlation method, chemical shifts of fatty acids present in a known standard triacylglycerol is plotted against the corresponding chemical shifts of fatty acids present in the vegetable oils. This new approach (under carefully defined conditions and concentrations) was found especially useful for spectrally crowded regions where significant peak overlap occurs and was validated with the well-known 13 C NMR spectrum of olive oil which has been extensively reported in the literature. In this way, a full assignment of the 13 C{1H} NMR spectra of the vegetable oils, as well as tripalmitolein was readily achieved and the resonances belonging to the palmitoleic acid component of the triacylglycerols in the case of macadamia nut and avocado pear oil resonances were also assigned for the first time in the 13 C NMR spectra of these oils.

Effect of gamma-ray irradiation on the fatty acid profile of irradiated beef meat

“…Numerous papers have reported the application of 1 H and 13 C NMR mainly for analysis of fish oils 0308-8146/$ -see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2010.12.155 (Igarashi et al, 2000;Sacchi, Medina, Auborg, Paolillo, & Addeo, 1993), vegetable oils (Guillen & Ruiz, 2003;Knothe & Kenar, 2004;Retief, McKenzie, & Koch, 2009;Sacchi, Addeo, & Paolillo, 1997), in particular olive oil (Manina, Sobolev, & Segre, 2003;Mavromoustakos et al, 1997;Vlahov, 1999;Vlahov, Schiavone, & Simone, 2001), and seed oils (Ketshaywang, Holmback, & Yeboah, 1998), however very seldom for analysis of animal fats.…”

Postharvest Parameters of the “Fuerte” Avocado When Refrigerated in Different Modified Atmospheres

“…However, when nuclear magnetic resonance is used to analyze avocados, açaí and olive oil, it clearly shows the presence of triglycerides and the absence of free fatty acids (Retief et al . ; Luo et al . ).…”

“…The fatty acids are converted to volatile fatty acid methyl esters, which are the analytes. However, when nuclear magnetic resonance is used to analyze avocados, açaí and olive oil, it clearly shows the presence of triglycerides and the absence of free fatty acids (Retief et al 1991;Luo et al 2012).…”

Quantification of Fatty Acids and their Regioisomeric Distribution in Triacylglycerols from Porcine and Bovine Sources Using 13C NMR Spectroscopy

“…3. 1 As a sidenote, we observed that there are differences in assignments for C-5 0 and C-6 0 in various sources (Mannina et al, 2000;Retief et al, 2009;Simova et al, 2003), and have chosen to assign C-5 0 at higher field than C-6 0 , in line with the majority of the literature.…”