Alpha-tocopherol stereoisomer analysis as discriminant method for distinguishing Iberian pig feed intake during the fattening phase

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

“…Function 1 had the highest correlation ( R 2 = 0.82) and was mainly explained by γ ‐tocopherol concentration, whereas α ‐tocopherol concentration had more influence on function 2. These results are similar to those obtained in a previous study using raw fat, although the discriminant functions were obtained using three variables ( RRR‐α ‐tocopherol, α ‐tocopherol and γ ‐tocopherol) …”

“…The FREE‐RANGE and FREE‐FEED feeding groups are difficult to differentiate, and merging them into one category reduces the classification errors to 13% in dry‐cured shoulders. This success rate is close to the one achieved in raw fat samples (90%), which included the stereoisomer profile of α ‐tocopherol to distinguish between the four feeding categories of pigs . Hence, if the stereoisomer proportion of samples cannot be quantified, γ ‐ and α ‐tocopherol quantification in dry‐cured muscle samples may be used as an adequate quality control method of the final product.…”

“…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 . When the number of feeding categories was reduced to three (by joining the FEED‐OUT and FEED groups because of their low levels of γ ‐tocopherol, which is the main discriminant variable), the prediction ability of the model increased, with an 87% success rate.…”

“…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. In a previous study carried out on raw fat samples, it was found that samples from the group fed a fat‐enriched diet supplement and allowed to feed outdoors had similar α ‐tocopherol concentrations to the free‐range group . Using a stereoisomer analysis of α ‐tocopherol, these authors confirmed that α ‐tocopherol in this group was not only provided by the natural ingredients but also came from synthetic α ‐tocopherol supplementation .…”

“…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.…”