Linnea A. Rimmer

This erratum corrects the title and the description of the thawing systems used in the experiment for “Effect of Electromagnetic Field Assisted Thawing on the Quality of Previously Frozen Beef Striploins.”

Skeletal muscle metabolism has implications for swine feed efficiency (FE); however, it remains unclear if the metabolic profile of skeletal muscle changes during postnatal growth. To assess the metabolic changes, samples were collected from the longissimus dorsi (LD, glycolytic muscle), latissimus dorsi (LAT, mixed muscle), and masseter (MS, oxidative muscle) at 20, 53, 87, 120, and 180 days of age from barrows. Muscles were assessed to determine the abundance of several metabolic enzymes. Lactate dehydrogenase (LDHα) decreased in all muscles from 20 to 87 d (p < 0.01), which may be attributed to the muscles being more glycolytic at weaning from a milk-based diet. Pyruvate carboxylase (PC) increased in all muscles at 53 d compared to the other time points (p < 0.01), while pyruvate dehydrogenase α 1 (PDHα1) increased at 87 and 180 d in MS compared to LD (p < 0.05), indicating that potential changes occur in pyruvate entry into the tricarboxylic acid (TCA) cycle during growth. Isolated mitochondria from each muscle were incubated with ¹³C-labeled metabolites to assess isotopomer enrichment patterns of TCA intermediates. Citrate M + 2 and M + 4 derived from [¹³C₃]-pyruvate increased at 87 d in LAT and MS mitochondria compared to LD mitochondria (p < 0.05). Regardless of the muscle, citrate M+3 increased at 87 d compared to 20, 53, and 120 d, while 180 d showed intermediate values (p < 0.01). These data support the notion that pyruvate metabolism is dynamic during growth. Our findings establish a metabolic fingerprint associated with postnatal muscle hypertrophy.

The objective of this study was to evaluate the impact of applying electrostatic field (EF)–assisted thawing on the quality attributes of previously frozen beef striploin. Beef striploins from both sides of 12 USDA Choice carcasses were halved, frozen at −40°C, and thawed under 4 EF voltage treatments: 0 kV (control), 2.5 kV, 5 kV, and 10 kV. After reaching the internal temperature of −1°C, striploins were weighed for yield calculation, swabbed for microbial analysis, fabricated into steaks, and assigned to either 0- or 14-d aging period and retail displayed for 0 or 7 d. Subjective and objective color measurements were taken during the retail display. Upon completion of retail display, Warner-Bratzler shear force (WBSF), cook loss, sarcomere length, troponin-T degradation, muscle fiber spacing, lipid oxidation, antioxidant capacity, pH, and proximate analysis were performed. All EF treatments increased purge loss compared to the control (P<0.05) and did not improve thawing speed, with samples from 10 kV actually taking the longest to thaw (P<0.05). The 2.5 kV and 5 kV samples aged 14 d showed less discoloration than those from 0 kV and 10 kV, and 5 kV samples aged 14 d had higher a* than those from the other treatments (P<0.05). Samples thawed under 10 kV showed a reduction in WBSF compared to the control (P0.05). Overall, our study determined that there was no economic benefit to apply EF during thawing regarding yield and purge loss. However, the application of EF may improve tenderness and extend shelf life of beef during retail display.