3 April 2010

2 minute read

Introduction

Modified atmosphere packaging (MAP) systems with a high oxygen (80%) level are widely used in retail meat markets because the bright red color of meat in this packaging system attracts consumers. However, high oxygen levels are likely to increase the incidence of oxidative changes in the meat, thus negatively affecting meat quality characteristics. Further, it may cause more quality problems for some beef round muscles, which have traditionally been underutilized because of commonly noted tenderness and discoloration defects. The objectives of this study were to determine effect of different packaging systems (HiOx-MAP and VAC) on color stability, and lipid oxidation, and sensory attributes of beef round cuts.

Materials and Methods

Ten market weight beef cattle (A-maturity) were slaughtered at the Iowa State University Meat Laboratory. The longissimus lumborum (LL; control muscle), semimembranosus (SM), and adductor (AD) muscles were removed from each carcass at 24 hours after slaughter. Steaks (2.54-cm thick) were cut from each muscle and randomly assigned to either HiOx-MAP (80% O2, 20% CO2) or VAC for packaging. Steaks were displayed for 9 days at 1°C under 2150 lux of fluorescent light. Surface color (Hunter), pH, thiobarbituric acid reactive substance (TBARS) values, star probe, and sensory analysis were measured on steaks at the beginning and at the end of display. Results were analyzed using the Mixed procedure of SAS.

Results and Discussion

HiOx-MAP packaged beef steaks had significantly lower tenderness and juiciness scores compared to steaks in VAC. HiOx-MAP packaged beef steaks had an increase (P < 0.05) in lipid oxidation during display, and also increased off-flavor development. The AD in HiOx-MAP had the greatest increase of lipid oxidation during display followed by SM and LL suggesting that these beef round muscles are more susceptible to oxidation than LL. In contrast, the steaks packaged in VAC did not develop lipid oxidation during display time. The surface redness values of steaks packaged in HiOx-MAP rapidly decreased during display, and AD had the greatest decrease (P < 0.05) in surface redness (indicating more myoglobin oxidation) followed by SM and LL. However, VAC steaks had no significant change in redness during display. These data suggest that HiOx-MAP can create more oxidative conditions, which negatively affects myoglobin and lipid oxidation stability, meat juiciness and flavor. Further, the results support the hypothesis that conditions that promote oxidation are detrimental to improvement in tenderness with postmortem aging.

Authors

Yuan Kim, postdoctoral research associate;
Steven Lonergan, professor;
Elisabeth Huff-Lonergan, professor,
Department of Animal Science, Iowa State University

April 2010