Oxidation processes of Longissimus dorsi from pigs supplemented with linseed oil and antioxidants

The aim of this study was to determine the effects of pig fodder supplementation on lipid oxidation of Longissimus dorsi (L. dorsi) after frozen storage at -20 degrees C +/- 1 degrees C for nine months. Fodder additives included 3% linseed oil (L1) or 3% linseed oil and antioxidants containing 100 mg vitamin E/kg and 1 mg organic selenium/kg (L2). The oxidation processes were evaluated by measuring thiobarbituric acid reactive substances (TBARS) and analyses of a profile of volatile organic compounds (VOC). The VOC were determined using an electronic nose based on ultra-fast gas chromatography. The level of TBARS for diets was 1.88 +/- 0.52 to 2.30 +/- 1.10 mg malondialdehyde/kg of meat. The results indicated that the diet of pigs from L1 and L2 groups had no impact on the TBARS value of L. dorsi pork frozen for nine months. On the other hand, aldehydes, which are regarded as compounds characteristic of oxidation processes, were identified in all samples. Volatile aldehydes contributed approximately 10%, 12%, and 15% of total detected volatiles for L2, L1, and the control group, respectively. Moreover, the data showed that propanal and benzeneacetaldehyde were at the same level, regardless of the animal's diet, which is in accordance with the TBARS level. These volatile aldehydes resulted from the oxidation of polyunsaturated fatty acids (PUFAs) and may be considered indicators of lipid oxidation for meat enriched with PUFAs. The results show that supplementation of the pigs' diet with linseed oil (L1 group), which is a source of PUFAs, is recommended for meat intended for long-term freezing storage. However, supplementation with antioxidants is unnecessary, because it has no effect on lipid oxidation of L. dorsi pork after long-term freezing storage.