Influence of aging temperature and duration on spoilage organism growth, proteolytic activity, and related chemical changes in vacuum-packaged beef longissimus

Authors: HERNANDEZ, M SEBASTIAN - Texas Tech University; WOERNER, DALE - Texas Tech University; BROOKS, J CHANCE - Texas Tech University; Wheeler, Tommy; LEGAKO, JERRAD - Texas Tech University

Submitted to: Meat and Muscle Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2022
Publication Date: 7/13/2022
Citation: Hernandez, M., Woerner, D.R., Brooks, J., Wheeler, T.L., Legako, J.F. 2022. Influence of aging temperature and duration on spoilage organism growth, proteolytic activity, and related chemical changes in vacuum-packaged beef longissimus. Meat and Muscle Biology. 6(1). Article 13724. https://doi.org/10.22175/mmb.13724.
DOI: https://doi.org/10.22175/mmb.13724

Interpretive Summary: Storing meat at refrigerated temperatures is common in the beef industry to enhance beef eating quality, primarily tenderness and flavor. Enzymes in the meat degrade the structural proteins increasing tenderness and developing flavor compounds. However, excessive storage time is expensive and beef flavor can deteriorate if stored too long. The length of time and the temperature of the storage affects these important traits, but the optimal combination has not been fully studied. This study evaluated the impact of three storage temperatures and four storage times on important meat tenderness and flavor traits. Flavor was impacted by microbial growth which increased during storage but was dependent on storage temperature. Storage temperature influenced the rate of protein degradation and subsequent tenderness and flavor. Protein degradation continued through 56 days of storage, but tenderness peaked at 42 days. Retailers and purveyors who intend to store product more than 28 days should store product at 28F to prevent spoilage. Most traits were optimized at 42 days of storage at 28F.

Technical Abstract: The objective of this work was to evaluate the influence of wet-aging temperature, duration, and the interaction of these factors on spoilage organism growth and indicators of proteolytic activity and resulting beef tenderness. Paired strip loins were collected from 60 USDA Low Choice beef carcasses (n=60). Each carcass was assigned to a storage temperature (-2, 0, 4'). Strip loins were portioned into half loins and assigned to an aging duration (14, 28, 42, 56 d) and vacuum packaged. Loins were aged in commercial upright refrigerators. At each aging interval, loin portion packages were aseptically opened and loins were surface swabbed for microbial analysis before fabrication into 2.54 cm strip steaks. Steaks assigned to slice shear force (SSF) were cooked to 71'. A raw steak was used to track proteolytic activity, free amino acid content, and volatile compounds. Two-way interactions were observed for all spoilage organisms (P < 0.001). Aging for 42 and 56 d at -2' produced lower microbial counts compared to 4' (P < 0.05). Loins aged for 14 d at 4' had increased desmin and troponin-T degradation compared to aging for 14 at -2 and 0' (P < 0.05). Loins aged in 4' environments produced more tender steaks compared to -2 and 0', according to SSF values (P = 0.001). Steaks aged for 42 and 56 d possessed the lowest SSF values (P < 0.05). Aging for 56 d at 4' produced the greatest amount of total free amino acids (P < 0.001). Aging for 56 d increased alanine, histidine, lysine, serine, and tryptophan content (P < 0.05). Two-way interactions were observed for 7 compounds (alcohols, aldehydes, carboxylic acids, ketones, and sulfur containing; P < 0.05). Aging for 56 d at 4' had the greatest ethanol concentration compared to all other treatments (P < 0.05). These data indicate aging at 4' increases the rate of proteolysis and subsequent tenderness development and flavor precursor accumulation. However, extended aging at 4' resulted in increased microbial counts. Many traits peaked at 42 d of aging.