Rapid Determination of Total Conjugated Linoleic Acid Content in Select Canadian Cheeses by¹H NMR Spectroscopy

Abstract

The application of (1)H nuclear magnetic resonance (NMR) spectroscopy to the measurement of conjugated linoleic acid (CLA) content in the lipid fraction of dairy products is both a novel and inviting alternative to traditional methods such as gas chromatography (GC), which can require time-consuming sample derivatization. In this work, a newly developed, rapid, and reliable lipid extraction protocol was combined with simple, nondestructive (1)H NMR spectroscopic analysis to measure the total CLA content in CLA standards and in various Canadian cheeses from conventional, organic, and grass-fed dairy sources. The total CLA concentrations (mg/g cheese) obtained using these new extraction and analysis methods were consistent with amounts found using the modified Folch extraction and GC analysis (correlation coefficient of 0.948). Results showed that cheeses from exclusively grass-fed dairy cows were significantly higher in total CLA content than either conventional or organic cheese.

Conjugated Linoleic Acid and Cholesterol Oxidative Products Generated in Hot Boned Beef Semimembranosus Muscle as Affected by Rigor Temperature, Ageing and Display Time

“…This also applied to GC-FID, as all the CLA isomers co-eluted, thereby having the same retention times. The analysis of CLA concentration from both analytical techniques showed a high correlation (R 2 = 0.9682, Figure 2) and was in agreement with the results reported by Manzano et al [4] on beef lipids and the results of Prema et al [26] on selected Canadian Cheeses. These resonances do not overlap with the chemical shifts representing other fatty acids, simplifying the quantitation of total CLA content in meat lipid using 1 H NMR [25,29].…”

“…The CLA concentrations in beef lipid were analyzed using the methods of Prema et al [26] and Manzano et al [4] with modifications on the selected internal standard used. The 1 H NMR spectra were acquired using a Varian/Agilent 400 MHz NMR spectrometer with a Oneprobe and Varian /Agilent 7600AS robot (Palo Alto, CA, USA) with a magnet of 9.4T; CDCl 3 was used as the solvent and the residual protons as an internal reference (7.26 ppm).…”

“…It is important to consider the high possibility of 3 fatty acid (FA) groups esterifying on the same glycerol moiety [26], so the molecular weight of triacylglycerol reflects the maximum number of possible FAs that can attach to the glycerol [27]. The calculated MW TAG of 864.5 g mol −1 was determined to represent an average of fatty acid composition in beef [27,28].…”

Evaluation of antioxidant properties of the different tissues of vine tea (Ampelopsis grossedentata) in stripped canola oil and sunflower oil

“…The conditions were: 12,335.5 Hz of spectral width, 16 of number of scans, 2.656 s of acquisition time, and 25 °C of analysis temperature. Chemical shifts were recorded as ppm based on the reference of tetramethylsilane at δ = 0 ppm with MestreNova 5.3.1 software (Prema et al., 2013).…”

Total and Free Fatty Acids Analysis in Milk and Dairy Fat

“…In all cases, the NMR assignments allow for quantifying FA that are in high concentration. More recently, Prema et al [125] quantified total CLA in the lipid fraction of select Canadian cheeses by 1 H NMR spectroscopy. In all these works, NMR analysis was applied to the lipid fraction of the dairy product.…”