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Author ORCID Identifier

https://orcid.org/0000-0001-8924-1705

Date Available

7-15-2026

Year of Publication

2026

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College

Agriculture, Food and Environment

Department/School/Program

Animal and Food Sciences

Faculty

Surendranath Suman

Faculty

J Alex Pasternak

Abstract

Color is a critical quality attribute that influences consumer purchase decisions for fresh and cooked lamb and is governed by myoglobin's redox chemistry. Wet aging is commonly used to enhance lamb tenderness, while endpoint cooking temperature is the primary determinant of internal cooked color. However, the combined effects of these factors on the color stability of the lamb longissimus lumborum (LL) muscle during refrigerated storage remain unclear. The objective of this thesis was to evaluate the effect of wet aging duration on the color attributes and lipid oxidation of fresh lamb LL chops and endpoint cooking temperature and refrigerated storage on the internal cooked color and myoglobin (Mb) concentration of lamb LL chops. In the first experiment, the influence of wet aging duration on the color attributes and lipid oxidation of lamb LL muscle was evaluated during refrigerated storage. LL muscles were excised 24 h postmortem from both sides of twelve (n = 12) Polypay ram lamb carcasses. The LL muscles were divided into two equal-length sections, vacuum packaged, and randomly assigned to wet aging for 0 (A0), 10 (A10), 20 (A20), or 30 (A30) days at 2 °C. Following aging, muscle sections were fabricated into 2.5-cm-thick chops, overwrapped with oxygen-permeable polyvinyl chloride (PVC) film, and stored under refrigeration (2 °C) for 0, 3, 6, or 9 days. Myoglobin concentration, pH, instrumental color, color stability (R630/580), and lipid oxidation (TBARS) were analyzed. Non-aged chops (A0) exhibited greater (P < 0.05) myoglobin concentration on day 0 than aged chops. Myoglobin concentration decreased (P < 0.05) during storage in A0 and A10, increased (P < 0.05) in A20, and remained stable (P > 0.05) in A30. Chops aged for 10 days exhibited greater (P < 0.05) redness (a* value) and R630/580 than A0 and longer-aged treatments at multiple storage times, although R630/580 decreased (P < 0.05) across all treatments during storage. Lipid oxidation increased with aging, and A30 exhibited greater (P < 0.05) TBARS values throughout storage. These findings suggest that 10 days of wet aging may optimize surface redness and color stability of lamb LL chops. In the second experiment, LL muscles were excised 24 h postmortem from both sides of eight (n = 8) Polypay ram lamb carcasses, vacuum-packaged, and wet-aged for 10 days at 2 °C. After aging, muscles were fabricated into 2.5-cm-thick chops and randomly assigned to refrigerated storage (2 °C) for 0, 3, 6, or 9 days. On each day of storage, chops were cooked to internal endpoint temperatures of 54 °C (C54), 63 °C (C63), or 72 °C (C72). Cooked samples were cooled, sectioned parallel to the cooking surface, and evaluated for instrumental color, color stability (R630/580), and Mb concentration. Endpoint cooking temperature and storage duration influenced (P < 0.05) Mb concentration, L*, a*, b*, and R630/580. There was a progressive decrease in Mb concentration, a*, b*, and R630/580 with increasing endpoint cooking temperature, whereas C63 exhibited greater L* than C54 and C72. Storage affected color parameters, decreasing (P < 0.05) a* and R630/580 from day 3 of storage. Myoglobin concentration and b* remained overall steady over 9 days of storage. These findings suggest that endpoint cooking temperature is the primary determinant of internal cooked color and myoglobin concentration of lamb LL chops, whereas refrigerated storage exerted a more limited influence.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2026.351

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Funding Information

This work was supported by the U.S. Department of Agriculture - Agricultural Research Service, National Program 101, Food Animal Production (ARS Project 5042 32630-003-00D).

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