*While the full article for this executive summary is currently under peer review, these initial findings are being made available on BeefResearch.org to enable the industry to act on the research, inform the scientific community of ongoing work, and help prevent duplication of research efforts. Once peer review is complete, a link to the published article will be added to this summary.
Key Takeaways
- Discoloration of steaks in retail results in a large amount of food waste from perceived undesired products for consumers
- Amino acid treatments have the potential to reduce discoloration over a longer period of time, as well as reduce the abundance of microbial populations during extended shelf life
- For this study, there were no observed differences in redness from treated to controlled samples, but showed potential for improving color stability without increasing microbial growth
BACKGROUND
Discoloration of beef results in a large amount of food waste because consumers commonly use meat color as an indicator of wholesomeness. The industry has been working on ways to increase the color stability of beef put into retail display counters and has made progress in areas such as packaging and antioxidant application. Novel application mechanisms such as the Agent Delivery MatrixTM tested in the current study could offer an extended activity for potential color-stabilizing compounds such as amino acids and acerola extract (natural antioxidant). The objectives of this study were to (1) evaluate the effect of amino acids on color-stabilizing capability and microbial populations of beef steaks during retail display, and (2) incorporate amino acids into an ADM to increase their color stability and evaluate the impact on beef shelf life. An additional objective was to investigate whether incorporating acerola extract (a known natural antioxidant) into an ADM would enhance its color-stabilizing capability of beef steaks during retail display.
Methodology
Beef muscles (USDA Choice striploin or tenderloin) were fabricated into 4 × 1 × 0.5 inch (10.2 × 2.5 ×1.3 cm) portions, followed by application of treatment solutions or distilled water (positive control) onto the surface of the meat samples. After treatment application, samples were left to dry (10 min) and were then overwrapped and placed in a retail display case (3 ± 1°C). Untreated samples served as a negative control. Steaks were evaluated daily for instrumental color (i.e., lightness, L*; redness, a*; and yellowness, b*). Additionally, untreated samples were analyzed for aerobic plate counts (APC) on day 1 of retail display to determine the microbial load of the meat samples on the day of treatment application. Three amino acids, including arginine, cysteine, and/or glutathione (GSH) were evaluated in three separate studies (Studies A through C) for their beef steak color-stabilizing capability. Testing parameters included different amino acid concentrations (1 mM, 10 mM, 100 mM, 500 mM, 1000 mM), volume of treatment solution applied to the meat surface (150 µL, 250 µL), and retail display day for treatment application (day 1, or during retail display when the steaks started to discolor). In Study D, the color stability during retail display of striploin samples surface-treated with an ADM containing 100 mM GSH and zinc was investigated. Finally, two studies (Studies E and F) were conducted to evaluate the use of acerola extract, either alone or integrated into an ADM, for their color stability effects of striploin steaks and for any impacts on microbial populations (APC) during retail display.
Findings
Results from Studies A through D indicated no notable improvement in the redness (a* value) of beef samples, as compared to the controls, regardless of the type of amino acid, amino acid concentration, day of treatment application, or use of an ADM. Striploins surface-treated with acerola extract (0.25% by final weight of sample) had greater mean a* values than those of control (untreated, distilled water-treated) samples after 12 days of retail display. When acerola extract-GSH was integrated into an ADM, no differences (P ≥ 0.05) were observed between the a* values (redness) of steaks treated with the acerola extract or acerola extract-GSH ADM. Additionally, these treatments did not (P ≥ 0.05) impact microbial growth during retail display. Therefore, acerola extract increased the color stability of striploin samples during retail display, but its effect was not enhanced by ADM incorporation
Implications
The results from this study indicated that direct amino acid applications were not effective in improving meat color stability. However, the acerola application was able to improve the meat color stability without impacting the microbial population.