Inter-relationships between the metrics of instrumental meat color and microbial growth during aerobic storage of beef at 4°C

Comparison of physiochemical attributes, microbial community, and flavor profile of beef aged at different temperatures

Beef aging for tenderness and flavor development may be accelerated by elevated temperature. However, little to no research has been undertaken that determines how this affects other important meat quality characteristics and microbial community. This study aims to decrease aging time by increasing temperature. Beef were aged and vacuum packaged at 10 and 15°C, and the effects of increased temperature on meat physiochemical attributes, microbial community, and flavor profile were monitored. The shear force decreased with aging in all temperature and showed the higher rate at elevated temperatures compare to 4°C. The beef aged at elevated temperatures (10 or 15°C) for 5 days showed equivalent shear force value to the beef aged at 4°C for 10 days (p  >  0.05), however, the final tenderness was not affected by the elevated temperature. The beef aged at elevated temperatures showed a significantly higher cooking loss and less color stability compared to 4°C (p  <  0.05). The total volatile basic nitrogen and aerobic plate count increased (p  <  0.05) faster at elevated temperatures compare to 4°C. Carnobacterium, Lactobacillus and Hafnia-Obesumbacterium were the dominant genus in the beef samples aged at 4, 10, and 15°C, respectively. In addition, the contents of isobutyraldehyde, 3-methylbutyraldehyde, 2-methylbutyraldehyde, and 3-methylbutanol were higher than aged at 4°C (p  <  0.05). Therefore, these results suggest that application of elevated aged temperatures could shorten required aging time prior while not adversely affecting meat quality. In turn, this will result in additional cost savings for meat processors.

Vacuum Packaging Can Extend Fresh Color Characteristics of Beef Steaks during Simulated Display Conditions

Packaging technology is evolving, and the objectives of this study were to evaluate instrumental surface color, expert color evaluation, and lipid oxidation (TBARS) on beef longissimus lumborum steaks packaged in vacuum-ready packaging (VRF) or polyvinyl chloride (PVC) overwrap packaging. Paired strip loins (Institutional Meat Purchasing Specifications # 180) were cut into 2.54-cm-thick steaks and assigned randomly to one of two packaging treatments, VRF or PVC. Steaks packaged in VRF were lighter in color (p < 0.05) as the display period increased, whereas steaks packaged in PVC became darker (p < 0.05). Redness (a*) values were greater (p < 0.05) for PVC steaks until day 5, whereas VRF steaks had a greater (p < 0.05) surface redness from day 10 to 35 of the display period. Calculated spectral values of red to brown were greater (p < 0.05) for steaks in VRF than PVC. In addition, expert color evaluators confirmed VRF steaks were less brown and less discolored (p < 0.05) from day 5 to 35 of the display. Nonetheless, lipid oxidation was greater (p < 0.05) for PVC steaks from day 10 through day 35 of the display. Results from this study suggest that the use of vacuum packaging for beef steaks is plausible for maintaining surface color characteristics during extended display periods.

A comprehensive insight into the effects of microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation on the discoloration of rabbit meat during retail display

The effects of the retail display temperature (8 °C, 3 °C and - 1 °C) on the discoloration of the Longissimus thoracis et lumborum of rabbits and the associations among such effects with microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation were investigated. The total aerobic count, total volatile basic nitrogen content, metmyoglobin content, protein carbonyl content, and contents of thiobarbituric acid-reactive substances steadily increased during retail display. Moreover, the lightness and redness of the rabbit meat significantly (P < 0.05) declined over time, whereas the yellowness increased considerably (P < 0.05) with prolonged retail time. Canonical correlation analysis suggested that microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation jointly affected rabbit meat color. Linear mixed models further revealed that microbial spoilage, myoglobin autoxidation, lipid oxidation and protein oxidation positively affected yellowness, and they inversely impacted lightness and redness.

Quality and Acceptability of Fresh and Long-Term Frozen In-Bag Dry-Aged Lean Bull Beef

In-bag dry-aged lean beef was produced using a stepwise ageing process. Lean bull beef striploins were dry-aged at 2°C, 75% RH under three different air velocities: 0.5, 1.5, and 2.5 m·s−1for 7 days followed by wet-ageing for 14 days. The quality and acceptability of the dry-aged beef were compared with equivalent beef dry-aged for 21 days at 0.5 m·s−1which served as a control. Two portions of the dry-aged beef (7/21 days) were randomly selected and held frozen at −18°C for 12 months. Shear force, drip, and cook loss decreased significantly (p<0.05) with dry-ageing time. Increased air velocities accelerated dehydration process with no negative impact on the meat quality, microbiological safety, and consumer acceptability compared to the control (p>0.05). Frozen storage for 12 months had little or no effect on the quality and acceptability of the dry-aged lean beef (p>0.05). Dry-aged lean beef of equivalent quality and palatability, with a lower level of surface microorganisms and higher yield compared to the control, could be produced using the stepwise ageing process.