Steak dry aging: a strategy to reduce trimming losses and improve yield in beef dry aging process

Abstract

This study aimed to develop an innovative approach for the production of dry-aged beef, named steak dry aging (StDA), by applying the stepwise dry/wet aging method to steaks from Nelore and F1 Angus×Nelore cattle, and evaluating its effects on technological, microbiological, and amino acid quality. Additionally, the impact of prior freezing on the performance of the StDA protocol was investigated to verify its potential to accelerate the process while maintaining the technological and microbiological viability of dry-aged beef. In the first article, beef longissimus thoracis samples were subjected to four treatments: non aged (NMat), dry-aged for 28 days (DA), and two StDA protocols in which steaks were first dry-aged (until an average 15% mass loss) and subsequently wet-aged for 14 days (StDA14) or 28 days (StDA28). In the second article, the effect of pre-freezing and thawing on the StDA protocol was evaluated for both breeds, comparing six treatments: NMat, DA, and four StDA protocols — two without freezing (NF) and two with freezing (FT), each aged for 14 (NF14d and FT14d) or 28 days (NF28d and FT28d). The StDA protocol eliminated the need for trimming, resulting (P < 0.05) in at least a 35% increase in final yield compared to DA. DA samples exhibited higher pH, myofibrillar fragmentation index (51.18 vs. 37.68), and cooking losses (21.58 vs. 17.66%), as well as lower shear force (37.45 vs. 35.54 N) than StDA. Despite a darker and less intense color, no significant differences were observed in total free amino acid content, proximate composition, lipid oxidation, water activity, or total bacterial count. The amino acid profile was similar among aged samples, with a higher proportion of glutamine in StDA28 and taurine in DA. Pre-freezing accelerated the mass loss during the initial dry-aging stage, reducing by one day the time required to reach the target dehydration level while maintaining an 83% yield in StDA samples. Lipid oxidation in FT28d samples (P > 0.05) was similar to DA (~0.38 mg MDA/kg), with higher oxidation in DA samples from F1 Angus than from Nelore. Freezing intensified proteolysis (higher MFI) in StDA samples, resulting in shear force values comparable to DA. Total bacterial counts were lower in NF14d and FT14d and similar among NF28d, FT28d, and DA. A brownish color, associated with a higher metmyoglobin proportion, was observed in NF14d and FT14d samples. NF28d and FT28d samples showed similar hue (h*) values but were darker (lower L*) and less intense (lower C*) than DA. It is concluded that pre-freezing can be incorporated into the StDA process as a strategy to shorten the drying phase and enhance proteolysis while maintaining technological and microbiological viability. The StDA protocol with a total aging period of 28 days, with or without pre-freezing, is a technically feasible and scalable alternative that preserves the quality of dry-aged beef while providing a substantial increase in industrial yield.