Fresh beef has a relatively short shelf-life due to beef lipid’s susceptibility from attacks of free radicals and thus resulting in lipid oxidation. Previous studies have demonstrated that lipid oxidation is enhanced by the hydrolysis of phospholipids by an enzyme known as phospholipase α2 (PLA2) in beef. Anti-phospholipase α2 (aPLA2) is an antibody that has shown to inhibit PLA2 activity, and aPLA2 can be mass-produced in eggs from hens immunized against PLA2. The resulting eggs can be spray- or freeze-dried into egg powder (EP) to preserve the antibody activity. Perhaps, incorporating aPLA2 into ground beef patties may be able to extend fresh beef shelf-life by delaying lipid oxidation.
To test this hypothesis, vacuum-packaged USDA choice striploins from 10 different beef carcasses were obtained from a beef packing plant at 2 days postmortem. The next day, each loin was ground, divided into 4 batches, hand mixed with 0, 0.4, 0.8, or 1.6% of dried EP containing aPLA2 (w/w), vacuum packaged, and stored at 35.6 °F for 14 days. After the storage period, each batch of ground beef was formed into four 0.25 lb patties, overwrapped, and randomly assigned to 1 of the 3 retail display periods (day 0, 4, and 7; Figure 1). Moisture content, protein content, fat content, fatty acid (FA), and phospholipid profiles were measured from samples on day 0 of the simulated retail display across the 4 EP treatments. Percent visual discoloration was determined using a trained panel, and L* (lightness), a* (redness), and b* (yellowness) of the patties were determined using a colorimeter on each day of display for all EP treatments. Finally, lipid oxidation status, antioxidant capacity, and pH were measured on samples from retail display periods of 0, 4, and 7 days across the 4 EP treatments.