Animal Science Department

 

First Advisor

Chris R. Calkins

Date of this Version

12-2019

Citation

Henriott, M.L. 2019. Impact of myoglobin oxygenation state on color stability of beef steaks during frozen storage and thawed retail display. Master's thesis, University of Nebraska-Lincoln, Lincoln, NE.

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science,Under the Supervision of Professor Chris R. Calkins. Lincoln, Nebraska: December, 2019.

Copyright (c) 2019 Morgan L. Henriott

Abstract

Meat color is the most important product characteristic that impacts consumer purchasing decisions. Therefore, the major objectives of this thesis were to determine the impact of myoglobin oxygenation level and frozen storage duration on both frozen and thawed beef color. USDA Choice strip loins (n=36) were aged for 4 d or 20 d and cut into steaks. Steaks were randomly assigned to a myoglobin oxygenation level [deoxymyoglobin (DeOxy; immediately packaged), oxygenation (Oxy; oxygenated in air for 30 minutes), or high oxygenation (HiOxy; packaged for 24 h in 80% O2)]. Steaks were then vacuum packaged in oxygen permeable or impermeable film and immediately frozen (-5o C). Following either 0, 2, 4, or 6 months of frozen storage, steaks were removed from the packaging and either immediately measured for frozen meat color (frozen steaks) or placed under simulated retail display (RD) conditions (thawed steaks). Steaks were analyzed for oxygen penetration, instrumental color (colorimeter and spectrophotometer), subjective discoloration, and lipid oxidation. The frozen steak study showed that the HiOxy steaks had greater oxygen penetration and the highest a* values compared to DeOxy and Oxy steaks, regardless of frozen storage packaging (P < 0.0005). Redness and percent oxymyoglobin were greatest for HiOxy steaks within each storage period (P < 0.0002). Conversely, HiOxy steaks that were frozen for 6 months and thawed in RD had the lowest amounts of percent oxymyoglobin than all other treatments on days 4-7 of RD (P < 0.05). The HiOxy steaks had greater delta E values, discoloration, and lipid oxidation compared to Oxy and DeOxy for steaks thawed in RD (P < 0.05). Overall, frozen meat color for the HiOxy steaks was greater or similar when compared to Oxy steaks, but HiOxy steaks experienced more detrimental quality effects when frozen storage was extended out. For the steaks thawed in RD, the HiOxy steaks frozen for under 6 months and through the first few days of RD provided optimal meat color under RD, similar to that of DeOxy and Oxy. However, with extended frozen storage and RD, HiOxy steaks had worse color characteristics compared to the other myoglobin oxygenation levels.

Advisor: Chris R. Calkins

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