A practical study on the feasibility of alpha and gamma-tocopherol quantification for distinguishing Iberian pig feeding systems

Abstract

RESUMEN Estudio práctico de la fiabilidad de la cuantificación de alfa y gamma-tocoferol para diferenciar los sistemas de alimentación del cerdo ibéricoEste estudio se llevó a cabo para comprobar la fiabilidad del uso de la cuantificación de alfa y gammatocoferol en grasa y músculo para establecer una clasificación correcta de los cerdos ibéricos de acuerdo a su alimentación. Las muestras se obtuvieron durante tres campañas diferentes procedentes de cuatro categorías de cerdos según se descri be en la norma de calidad (FREEOUT: «bellota», FREE OUTFEED: «recebo», FEEDOUT: «campo» y FEEDIN: «cebo»). Se calcularon funciones discriminantes con los da tos obtenidos de las campañas 1 y 2 y se validaron. La clasi ficación de las muestras de grasa y músculo obtenidas de la tercera campaña en las cuatro categorías de acuerdo a las funciones discriminantes calculadas alcanzó un rango medio de éxito del 76% para diferenciar el origen de las muestras. La cuantificación en el músculo pareció tener una mayor ca pacidad de predicción. Las ecuaciones de regresión para cuantificar el peso ganado en montanera en función de la concentración de gammatocoferol tuvieron un mayor R 2 pa ra el músculo que para la grasa (R 2 = 0.81 vs. 0.62). La unión de alguna de las categorías de alimentación establecidas en la norma de calidad podría incrementar la fiabilidad del méto do de cuantificación de los tocoferoles alfa y gamma hasta entre un 89 al 98%. PALABRAS CLAVE: Alfa-tocoferol -Cerdo ibérico -Diferenciación de la alimentación -Gamma-tocoferol. SUMMARY A practical study on the feasibility of alpha and gamma-tocopherol quantification for distinguishing Iberian pig feeding systemsThis study was undertaken to test the feasibility of using alpha and gammatocopherol quantification in fat and muscle to establish a correct classification of Iberian pigs according to their feeding background in practical situations. Samples were obtained over three different seasons from the four categories of pigs described in the Industry Quality Policy (FREEOUT "bellota"; FREEOUTFEED "recebo"; FEED OUT "campo"; and FEEDIN "cebo"). Linear discriminant functions were calculated with data obtained from seasons 1 and 2 and validated. The classification of fat and muscle samples from season 3 in the four feeding categories according to the calculated discriminant functions achieved an average of 76% success rate in distinguishing the true origin of pig samples. Quantification in muscle seemed to have higher prediction ability. Regression equations to quantify weight gained depending on the gammatocopherol concentration had higher R 2 values for muscle than for fat (R 2 = 0.81 vs. 0.62). Merging of the feeding categories established by the Quality Policy could raise the accuracy of the alpha and gammatocopherol quantification method to up to between 89% and 98%.

Quantification ofγ- andα-tocopherol isomers in combination with pattern recognition model as a tool for differentiating dry-cured shoulders of Iberian pigs raised on different feeding systems

“…The separation of these groups was made mainly by function 1. This separation of feeding groups was similar to that observed in raw muscle . Also in raw fat, when using the RRR stereoisomer profile together with γ ‐ and α ‐tocopherol quantification, a comparable distribution pattern was obtained .…”

“…In a previous study the authors reported a 78% success rate for γ ‐ and α ‐tocopherol quantification in raw muscle and fat when distinguishing between the four feeding categories of Iberian pigs, with muscle being a better predictor than fat . In the present study the percentage of incorrect classifications was similar or slightly lower than in the study using raw tissues (20 vs 22%) . It is also interesting to note that the success rate for the FEED and FEED‐OUT groups was similar (100 and 70% respectively) compared with the previous study using raw fat samples, but which included the proportion of α ‐tocopherol stereoisomer as a variable to improve the classification results .…”

“…This is the first study to examine the classification capacity of tocopherols in dry‐cured shoulders by using pattern recognition techniques such as linear discriminant analysis. In a previous study the authors reported a 78% success rate for γ ‐ and α ‐tocopherol quantification in raw muscle and fat when distinguishing between the four feeding categories of Iberian pigs, with muscle being a better predictor than fat . In the present study the percentage of incorrect classifications was similar or slightly lower than in the study using raw tissues (20 vs 22%) .…”

“…The FREE‐FEED group (known as ‘recebo’) showed α ‐tocopherol concentrations that fell between animals fed under free‐range conditions and those fed outdoors with a fat‐enriched diet supplement (FEED‐OUT). Grass has been found to provide tocopherol mainly in the α form, while the proportion of γ ‐tocopherol is much lower than in acorns . The high concentration of α ‐tocopherol in the FEED‐OUT groups, which was sometimes higher than the levels found in free‐range groups, was probably due to the high α ‐tocopherol content of the oil used in formulating the diet and to additional α ‐tocopherol supplementation in the diet.…”

“…Previous studies using tocopherol quantification to distinguish between the four feeding categories of pigs used only raw muscle or fat samples. However, the tocopherol content of the four existing market categories has not been reported in dry‐cured shoulders.…”