Correlation of Bioelectrical Impedance With Freshness Quality Attributes of Beef Longissimus Lumborum Steaks

The quality attributes of beef longissimus lumborum during 15 d of retail display were assessed using surface bioelectrical impedance analysis (S-BIA) and internal bioelectrical impedance analysis (I-BIA). Beef loins (N = 18) were obtained from 3 commercial processors with 3 postmortem (PM) ages (27, 34, and 37 d). Loins were fabricated into twelve 2.54-cm-thick steaks, subdivided into 6 consecutively cut pairs, and randomly assigned to one of 6 display days (DD): 0, 3, 6, 9, 12, or 15. Steaks were assessed for S-BIA and I-BIA. Three locations were analyzed within each steak: top, middle, and bottom. Microbiological analysis, BIA, pH, instrumental color, proximate composition, and lipid oxidation were measured. There was a location × PM day × DD interaction (P < 0.05) for longissimus lumborum steaks for S-BIA. Among all 3 locations, steaks aged 27 d had higher (P < 0.05) S-BIA values on day 9 and 12 than steaks aged 34 and 37 d. There were no location × PM day × DD or two-way interactions (P > 0.05) for I-BIA. Display day affected (P < 0.05) all instrumental color data regardless of PM aging times. Among all PM aging times, steaks aged 27 d were 13% and 7% higher for a* and b*, respectively, compared with 34 and 37 d PM. There was a PM day × DD interaction (P < 0.05) for aerobic plate counts (APC). From day 0 and 9 of display, APC of steaks aged 27 d PM were 1 to 2.0 log colony-forming units/cm² lower than steaks aged 34 and 37 d. Quality attributes, including a*, b*, APC, and thiobarbituric acid reactive substances, were correlated (r = 0.70, −0.64, −0.56, and 0.69, respectively) with S-BIA. Overall, BIA values increased on aerobically packaged longissimus lumborum steaks and were correlated with various freshness quality parameters.