Proton NMR of Fish Oils and Lipids

1H and13C NMR of virgin olive oil. An overview

“…The detection of transfatty acids in virgin olive oil is another interesting determination in which NMR spectroscopy can be used as an alternative to official gas chromatographic methods. 16,37 The absence of trans-isomers is considered as a purity index for virgin olive oils : reÐned NMR OF VIRGIN OLIVE OIL S139 isomers were found in virgin olive oils whilst reÐned oils showed a variable level of trans-fatty acids (0.3È1%). For this analytical problem, the methylene region appears to be very useful, owing to the little dependence of the trans-allylic carbon chemical shift (32.5È32.7 ppm) on the double bond position.31 Sensitivity tests were performed using standard triacylglycerol solutions containing 1, 0.5 and 0.1% trielaidate.…”

“…37 The advantage of using allylic carbons is the speciÐc simultaneous detection of all-trans-isomers with an increase in sensitivity and speciÐcity with respect to chromatographic techniques, where di †erent isomers give rise to di †erent small signals that are difficult to quantify accurately.37…”

“…By comparing the signal intensity of free carbonyls resonating at 176È178 ppm with the esteriÐed carbonyls (171È174 ppm envelope) a quantitative measure of free acidity (% mole fraction) can be easily obtained by 13C NMR. 16,17 Diacylglycerols and virgin olive oil quality-freshness. The amount of free fatty acids and the corresponding diacylglycerol proÐle can also be used to deÐne the degree of lipolytic alteration which is correlated with the quality of olives from which virgin olive oil has been produced.…”

An Emerging Powerful Technique: NMR Applications on Quality Assessments of Fish and Related Products

“…Fish feed and raw ingredients [3] HF-NMR Quantification of betaine in mussels Mussels [28] Quantification of n-3 fatty acids, anserine, and lactate Salmon and fish oils [48,59] Study of changes in bioactive components Cod [29] Low molecular weight metabolites Cod and haddock [31] Post-mortem metabolic changes in muscle by 31 Fish oils [34,35] Omega-3 fatty acid content by HR-MAS Salmon [62] Metabolic condition changes upon thermal stress Steelhead trout [37] Metabolic response to long-term handling Salmon [38] Metabolic differences between healthy and hepatic tumour tissues Flatfish [39] Metabolic markers upon toxic exposure Minnow, Chinook salmon, medeka, and rainbow trout [40][41][42][43] Authenticity Wild-farmed salmon fish oils [2,47] MRI Backbone deformations Salmon [5] Belly bursting Herring [52] Salt content by 1 H and 23 Na MRI Salmon and cod [57] Abbreviations: LF-NMR, low-field nuclear magnetic resonance; HF-NMR, high-field NMR; MRI, magnetic resonance imaging; HR-MAS, high resolution-magic angle spinning.…”

“…The biochemical changes (hydrolysis and esterification) in lipids of cod (Gadus morhua) throughout a storage period of 7 days at 4 • C have been studied by 13 C HF-NMR [33]. The analysis of fish oil to determine the content of docosahexaenoic acid (DHA) and omega-3 (n-3 or -3) fatty acids have been performed using the 1 H HF-NMR method [34,35]. Another major application area for HF-NMR would be the employment of phosphorus ( 31 P).…”