Evaluating Ground Beef Formulated with Different Fat Sources

Abstract

Objectives were to evaluate effects of fat source and formulated fat percentage on fatty acid composition, lean color stability, lipid oxidation, and aerobic microbial load during simulated retail display of ground beef patties. In Experiment 1 beef carcasses (n = 30) were chilled for 2 d and then fabricated. M. semimembranosus muscles were removed along with 2 fat sources (kidney and pelvic = KP and subcutaneous = S from the same carcass) and ground to achieve 75 and 95% lean. Fatty acid profile and thiobarbituric acid reactive substances (TBARS) were determined over a 7 d simulated retail display period. Saturated fat differed (P = 0.0004) by fat source, with KP having a higher percentage than S. Thiobarbituric acid reactive substances were higher for (P < 0.05) for patties made with S compared to KP. In Experiment 2 beef carcasses (n = 20), were fabricated and blended into ground beef as described in Experiment 1. After designated display time patties were removed and instrumental color measurement, myoglobin concentration, TBARS, and aerobic plate counts (APC) were collected. Oxymyoglobin (OMb) percentage decreased (P < 0.0001) by storage day and had source x formulated fat percentage interaction (P = 0.011). Inversely, storage day increased metmyoglobin (MMb) percentage (P < 0.0001) where d 1 < d 3 < d 5 < d 7, respectively. Changes in myoglobin form contributed to decreased a* values (P < 0.0001) over time. However, APC did not differ (P > 0.05) for d, fat source, or fat percentage. Discoloration in ground beef over 7 d of retail display was more a function of muscle pigment oxidation (OMb to MMb) than aerobic microbial spoilage.

The Relationship between Lipid Content in Ground Beef Patties with Rate of Discoloration and Lipid Oxidation during Simulated Retail Display

“…The increase of the L* value could be attributed to the increase in the light-scattering properties associated with fat particles [ 40 , 41 ]. In agreement, numerous previous investigations [ 9 , 33 , 35 , 39 , 42 , 43 , 44 ] have documented that an increase in fat content generated a lighter visual appearance of ground beef. In addition, there was a weak positive correlation (r = 0.32; p < 0.01) observed between the lipid content and the change in the L* value during retail display ( L* Δ Day-7–Day-0 ).…”

“…A strong positive correlation (r = 0.73; p < 0.01) was observed between lipid content and initial yellowness ( b* Day-0 scores), suggesting beef patties formulated with greater fat had a greater b* value. This observation was expected based on numerous previous research studies [ 32 , 33 , 35 , 39 , 48 ], which have documented greater initial yellowness for higher fat ground beef formulations. Similar results also have been reported in pork sausages [ 40 , 53 ].…”

“…Similarly, Shivas et al [ 38 ] reported that ground beef samples formulated with 25% fat underwent visual discoloration at a faster rate than counterpart samples formulated with 20% fat after 5 days of retail display. Likewise, Callahan et al [ 35 ] observed a more rapid visual discoloration in ground beef samples formulated with 25% fat than 5% fat counterpart samples after 7 days of simulated retail display. In partial agreement, an interaction between fat level and retail display time was observed for visual discoloration by Pietrasik et al [ 39 ], who reported that lean (15% fat) beef patties experienced greater visual discoloration on day 1 and day 2 of display, whereas regular (30% fat) beef patties exhibited greater visual discoloration on day 3 of display.…”

“…Likewise, Cooper et al [ 48 ] observed that ground beef formulated with 25% fat demonstrated lower a* values than counterpart samples formulated with 5% fat during 7 days of retail display. On the contrary, Pietrasik et al [ 39 ] and Callahan et al [ 35 ] reported a greater initial a* value in beef patties formulated with lower fat content. In addition, Reynolds et al [ 49 ] documented that ground beef samples formulated with 5% fat demonstrated a greater a* value than the 25% fat counterpart samples after 7 days of retail display.…”

“…Kerth et al [ 9 ] reported the fatty acid profile for 80% lean and 20% fat ground beef samples prepared from the round primal as 48.23% MUFA and 42.99% SFA when expressed as a percentage of total fatty acids. Additionally, Callahan et al [ 35 ] documented greater SFA content (52.17% of total fatty acids) compared to MUFA content (37.59% of total fatty acid content) in ground beef samples formulated to targeted levels of 25% fat. Overall, results from this population of samples were consistent with the typical fatty acid composition expected in beef fat, which is considered as approximately 46% SFA, 51% MUFA, and 3% PUFA when expressed as a percentage of total fatty acids [ 34 , 36 , 37 ].…”