RESUMEN
The complexity of determining the composition of animal tissue lipids is greatly increased by the presence of plasmalogens in which the alkyl chain is linked to glycerol by an enol ether bond instead of being esterified. Acidic methanolysis of animal tissue lipids provides the simultaneous scission of acyl and alkenyl ether moieties, but the complexity of the products of reaction poses a great challenge in their gas chromatographic analysis. Two-dimensional gas chromatography with online reduction (GC-OR × GC) provided the resolution of all components contained in acid methanolyzed animal lipids, taking advantage of the selective hydrogenation of alkenyl ether methanolysis products prior to the second-dimension separation (2D). In this study, we also studied the chemical transformations occurring during the acidic methanolysis of animal lipids and the subsequent gas chromatographic analysis. In particular, we observed that using methanolysis reagents contaminated with water resulted in the undesired formation of fatty aldehydes, and we made recommendations on how to avoid these side reactions using proper methanolysis conditions. Products of acidic methanolysis were studied by GC-OR × GC, GC-MS, NMR spectroscopy, and GC with flame ionization detection (GC-FID). We defined the GC-FID elution order of animal lipid acidic methanolysis products using 100 m × 0.25 mm 100% bis(cyanopropyl)siloxane columns and two different set of elution conditions: isothermal elution at 180°C, and a temperature program optimized for dairy fats. A simple procedure for isolating dimethyl acetals (DMA) prior to GC analysis is also described.
Asunto(s)
Técnicas de Química Analítica/métodos , Cromatografía de Gases , Lípidos/química , Acetales/aislamiento & purificación , Tejido Adiposo/química , Animales , Hidrogenación , Metabolismo de los Lípidos , Espectroscopía de Resonancia Magnética , Plasmalógenos/química , Plasmalógenos/metabolismo , Siloxanos/química , TemperaturaRESUMEN
The objective of the present study was to assess the fatty acid composition of horse-meat available at the retail market in northern Spain. Horse steaks (Longissimus thoracis et lumborum muscle; n=82) were purchased from butcher-shops and large grocery stores throughout six northern regions of Spain in two different seasons. Fat content differed significantly among regions (1.12 to 2.77%). Samples with higher intramuscular fat content presented the highest percentages of total monounsaturated fatty acids and the lowest contents of dimethylacetal and polyunsaturated fatty acids (PUFA), while the opposite was found in the leanest samples. A high variability was observed in the muscle and subcutaneous n-3 PUFA content. Overall, total n-3 PUFA content ranged between 1.17% and 18.9% in muscle fat and between 1.52% and 27.9% in backfat. Interestingly, almost 5% of surveyed loins from horse carcasses (4 out of 82) contained over 300mg of linolenic acid per 100g of meat which could have been marketed as a "source" of n-3 FAs according to Commission Regulation (EU) No 116/2010.
Asunto(s)
Ácidos Grasos/análisis , Caballos , Carne/análisis , Animales , Grasas de la Dieta/análisis , Ácidos Grasos Monoinsaturados/análisis , Ácidos Grasos Omega-3/análisis , Ácidos Grasos Insaturados/análisis , Análisis de los Alimentos , Músculo Esquelético/química , Valor Nutritivo , EspañaRESUMEN
The consumption of horse-meat is currently not popular in most countries, but because of its availability and recognized nutritional value consumption is slowly increasing in several western European countries based on claims that it could be an alternative red meat. In this review, horse-meat production, trade and supply values have been summarized. In addition, the advantage of horse production is noted because of its lower methane emissions and increased uptake, particularly of n-3 polyunsaturated fatty acids (PUFAs), which is based on its digestive physiology. Of particular interest in this review is the unique fatty acid composition of horse-meat with its high level of the nutritionally desirable PUFAs in both the adipose and muscle fat. Because of its large frame size and digestive physiology, the horse can be considered an alternative to bovine meat, with large advantages regarding the maintenance of less favored mountain grazing areas and its facility to transfer PUFA from feed to meat.