Consumers prefer the appearance of bright cherry red beef. Beef color is dictated by myoglobin status, where oxymyoglobin and carboxymyoglobin promote surface redness when oxygen (O2) or carbon monoxide (CO) are bound with myoglobin, respectively. Many prior works have evaluated the efficacy of high-oxygen (High-Ox) modified atmosphere packaging and carbon monoxide modified atmosphere packaging (CO-MAP). While High-Ox and CO-MAP may effectively promote beef redness, each has been determined to have drawbacks. For High-Ox, where 80% O2 may be used, there is a significant determinant of flavor due to lipid oxidation. CO-MAP presents issues with “persistent pinking” during and after cooking, which negatively influences consumers' perception of the degree of doneness, especially in ground beef.
To date, few studies have evaluated NO-MAP with beef. However, previous work in research demonstrates that a mixture of 0.4% NO and 99.6% N2 promotes stable red color over a 15-day storage period. This data strongly indicates that NO may bind with myoglobin and promote red color. As a result, when NO is applied to beef, redness will be promoted and stabilized when beef is held under NO-MAP. Literature also indicates that NO limits microbial growth, lipid and protein oxidation. The objective of the study was to evaluate the efficacy of nitric oxide-modified atmospheric packaging as either a mother bag or deep tray system in both ground beef and whole muscle steaks compared to more traditional packaging methods in relation to shelf-life, cooked color and sensory performance.
Separate trials were conducted to evaluate mother bag and deep tray MAP systems across ground beef and whole muscle steaks. For ground beef trials, chubs of 80:20 ground beef were obtained from a commercial purveyor and randomly sorted into 8 batches. Each batch was coarse ground and immediately formed into 0.45 kg bricks. Bricks were randomly assigned to 1 of 5 packaging types: Vacuum (VAC, n=40), Polyvinyl Chloride overwrap (PVC, n=40), 80% O2:20% CO2 (HI-OX, n=40), 0.4% CO:30% CO2: 69.6% N2 (CO, n=40) or 0.4% NO:99.6% N2 (NO, n=40). For trials 1 & 2, bricks allotted to MAP systems were packaged in PVC overwrap and placed in a mother bag and flushed with their designated gas. Bricks designated for MAP systems were placed into 2.5 cm deep plastic trays and flushed with their designated gas for trials 3 & 4. Packages were acclimated for 7 days at 0 - 2°C in the dark. After storage, samples designated to PVC were removed from vacuum and overwrapped. All samples were then placed in a simulated retail display, where descriptive and instrumental color were evaluated every 12 hours for 96 hours. On days 0, 2 and 4 measures of lipid oxidation, metmyoglobin reducing activity and spoilage organisms were conducted. Steaks designated for cooked color, volatile compound analysis or descriptive sensory panels were subjected to 48 hours of retail display.
For trials regarding whole muscle steaks, vacuum packaged beef striploins (n=13) and whole tenderloins (n = 25) were collected from USDA low choice carcasses and aged at 0 – 2 ° C, in the dark, for 7 days. Following aging, subprimals were sliced into 2.54 cm thick steaks representing the Longissimus lumborum (LL) and Psoas major (PM) and allotted to the assigned packaging treatments: Vacuum (VAC, n=40), Polyvinyl Chloride overwrap (PVC, n=40), 80% O2:20% CO2 (HI-OX, n=40), 0.4% CO:30% CO2:69.6% N2 (CO, n=40) or 0.4% NO:99.6% N2 (NO, n=40). Like ground beef, for trials 5 and 6, bricks allotted to MAP systems were packaged in PVC overwrap and placed in a mother bag and flushed with their designated gas. Bricks designated for MAP systems were placed into 2.5 cm deep plastic trays and flushed with their designated gas for trials 7 and 8. After acclimation, samples designated to PVC were removed from vacuum and overwrapped. All samples were then placed in a simulated retail display, where descriptive and instrumental color were evaluated every 12 hours for 8 days. On days 0, 4 and 8 measures of lipid oxidation, metmyoglobin reducing activity and spoilage organisms were conducted. Steaks designated for cooked color, volatile compound analysis or descriptive sensory panels were subjected to 48 hours of retail display.
This research indicates that nitric oxide has the potential to promote redness throughout retail display, especially when flushed in a deep tray MAP system. Generally, NO-MAP samples performed similarly to traditional packaging systems, regardless of muscle. The exception was the HI-OX packaging and off-flavors associated which were enhanced in the Psoas major. While NO-MAP has a marginal impact on the sensory performance of steaks from the Longissimus lumborum or Psoas major, NO-MAP also promotes a unique cooked color possessing greater redness. An increase in redness on both the external and internal cooked surface warrants further investigation to determine the acceptability of NO-MAP for fresh beef..
Nitric oxide modified-atmosphere packaging systems promote the redness of certain meat products throughout retail display. The palatability attributes of NO-MAP were comparable to traditional CO-MAP. Thus, NO-MAP may be a viable alternative when carbon monoxide is not preferred or has regulatory restrictions, such as in EU markets. However, cooked color variation did exist for NO-MAP. The impacts of cooked color variation should be evaluated to determine acceptability among consumers.
ARMS#120525-17