Effect of Oil Source, Cooking Method and Storage Time on Lipid Oxidation in Ground Beef Patties from Nellore Cattle

The aim of this study was to evaluate the effects of feeding vegetable oil sources (sunflower - SU; linseed - LO and soybean - SO) in lipid oxidation of raw and cooked beef patties stored for 0 and 90 d. Ninety-six Nellore steers were fed for 82 d with diets containing 3.5% of vegetable oils (DM basis). After 82 d on feed, animals were harvested and samples of Longissimus muscle and subcutaneous fat were collected to prepare 40 hamburger patties per treatment (100 g each). Patties were prepared utilizing a commercial formulation (85.4% meat, 12% fat, 2% salt, 0.3% garlic and 0.3% emulsifier) and packaged in oxygen permeable plastic bags, then immediately frozen at −18°C and stored for 0 and 90 d. The patties were evaluated raw and cooked. The cooked patties were grilled at 170°C for 4 min on each side (internal temperature 70°C). Lipid oxidation was estimated as thiobarbituric acid-reactive substances (TBARS) and measured as mg of malonaldehyde (MDA)/kg. The data was analyzed as a completely randomized design in a 4 × 2 × 2 factorial arrangement (3 oil sources plus control × 2 storage time × raw and cooked) using a mixed model (MIXED procedure of SAS), including the fixed effects of oil source, storage time, cooking method, and the interaction between the treatments. There was an interaction between storage times, cooking methods and oil source (P<0.0001). There was an increase of TBARS values after 90 d for all oil sources (P<0.0001). For both 0 and 90 d, LO and SU were higher in MDA than SO (P<0.0001), the same happened for both raw and cooked patties (P<0.0001). The TBARS values were higher in cooked samples as compared with the raw patties for the control treatment (P=0.013), smaller for SU (P<0.0001) and no effect for LO (P=0.7785) or SO (P=0.7949). There was an increase of TBARS values after 90 d for the raw samples (P<0.0001) but there was no effect for those that were cooked (P<0.0001). When the patties were compared at 0 d, those that were raw had lower concentrations of MDA compared to the cooked samples (P<0.0001), however at 90 d the raw samples had higher concentrations of MDA than cooked (P<0.0001). In conclusion, storage time and cooking method increase lipid oxidation in beef patties and the use of soybean oil would result in less lipid oxidation compared with the other treatments.