• lipid oxidation
• chicken meat
• soybean acid oils

Fats and oils are usually used in animal feeding because they represent the main source of energy and they provide several essential nutrients, such as polyunsaturated fatty acids. On the market, there are many different available fat sources for poultry diets and nowadays there is an increasing interest about searching for new alternative sources. One of these alternative sources is represented by the by-products derived from the refining of edible oils, because some of them (e.g. acid oils and fatty acid distillates) can satisfy the energy and nutritional requirements, and at the same time, their use would contribute to the sustainability of the food chain and reduce the costs.
EU recently defined acid oils and fatty acid distillates and some previous studies have assessed these by-products in order to study quality and safety aspects about their use in animal production, protecting both consumers and animals.
However, there is a lack of information about several aspects of these fat sources: strict composition characterization, nutritional quality, ability to modify lipid composition of foods from animal origin (e.g. meat, fish fillets, eggs), effect on the oxidative stability of these foods, and toxicological or physiological effects of some fat degradation compounds and of some undesirable contaminants.
It is widely known that lipid oxidation is a cause of meat degradation, especially in cooked meat products, and, consequently, responsible of the quality reduction, affecting colour, nutritional value, taste and aroma. Furthermore, it is important to consider that the lipid composition of meat directly depends on the fat source composition used in feed formulations. The main factors involved in the oxidative stability and influenced by diet are fatty acid profile and tocopherols and tocotrienol content. However, other antioxidants and prooxidants present in the diet might have an effect.
The global objective of the whole project is to characterize the acid oils and fatty acid distillates coming from industrial refining and to generate practical information about their use in feeding monogastric animals (including broilers, pigs and basses) and to study the repercussions on the lipid quality of meats and fish fillets. Specifically, the present work focuses on the study of chicken meat composition and their influence on oxidative stability. In the present work it was studied how broiler feed containing soybean acid oils as fat source may affect meat oxidability.
To evaluate the oxidative status of the chicken meat different analytical methods were used to quantify lipid oxidation products. First, the primary lipid oxidation was assessed through the major primary lipid oxidation products, lipid hydroperoxides (measured by FOX method). Then, secondary lipid oxidation was determined by the measurement of malondialdehyde (TBA values) and the content of the volatile compounds was measured by SPME/GC-MS.
Broiler diets have been divided into three groups, depending on the dietary treatment received: crude soybean oil (CS), soybean acid oil (AS) and refined soybean oil (RS), and the meat samples obtained have been divided into three different meat treatments: Fresh, Cooked and Cooked & refrigerated.
Lipid fraction and tocopherols and tocotrienols content were studied, comparing feeds and meats. For PUFA n-3 content, as well as for SFA and MUFA, the differences in dietary treatments are reflected in FA composition of meats. Also tocopherol and tocotrienol values in meats show that, except for the α-T, the content of the tocopherols and tocotrienols reflected the content of the diets. These results demonstrate that dietary treatments directly influence FA and tocopherols and tocotrienols contents of meat. The composition of the different fat sources (CS, AS and RS) used in feeds is reflected in the lipid composition of chicken meat.
The magnitude of the differences found in meat between the different dietary treatments used (CS, AS and RS) is low, in terms of FA profile and tocopherols and tocotrienols content. Consequently, this might explain why no significant differences were found in oxidation parameters of meats, considering the dietary treatment factor.
Results obtained from the analysis of oxidation parameters reveal that oxidative stability is strongly influenced by meat technological treatment (cooking, refrigeration). It is widely studied that heat and storage increment the meat susceptibility to lipid oxidation. The measurements of the main parameters used to evaluate oxidative status of chicken meat (FOX method, TBA values and volatile profile) show higher values regarding Cooked and Cooked & refrigerated meat.

The study of sample clustering by the principal component analysis (PCA), clearly shows a correspondence between the primary and secondary products of lipid oxidation and the meat technological treatments, in which the cooking process and refrigerated storage are involved, further confirm the effect of meat processing on the oxidative status of meat.