The objective of this study was to characterize and compare the dry-aging flavor precursors and their liberation mechanisms in beef aged with different methods. Thirteen paired loins were collected at 5 days postmortem, divided into four sections, and randomly assigned into four aging methods (wet-aging (WA), conventional dry-aging (DA), dry-aging in a water-permeable bag (DWA), and UV-light dry-aging (UDA)). All sections were aged for 28 days at 2 °C, 65% RH, and a 0.8 m/s airflow before trimming and sample collection for chemical, metabolomics, and microbiome analyses. Higher concentrations of free amino acids and reducing sugars were observed in all dry-aging samples (p < 0.05). Similarly, metabolomics revealed greater short-chain peptides in the dry-aged beef (p < 0.05). The DWA samples had an increase in polyunsaturated free fatty acids (C18:2trans, C18:3n3, C20:2, and C20:5; p < 0.05) along with higher volatile compound concentrations compared to other aging methods (aldehyde, nonanal, octanal, octanol, and carbon disulfide; p < 0.05). Microbiome profiling identified a clear separation in beta diversity between dry and wet aging methods. The Pseudomonas spp. are the most prominent bacterial species in dry-aged meat, potentially contributing to the greater accumulation of flavor precursor concentrations in addition to the dehydration process during the dry-aging. Minor microbial species involvement, such as Bacillus spp., could potentially liberate unique and potent flavor precursors.

The objective of this study was to determine the effect of various dry-aging methods on meat quality and palatability attributes of cull cow beef loins. Paired bone-in loins (m. longissimus lumborum) from 13 cull cow carcasses (Holstein, 42þ mo) were obtained at 5 d postmortem, divided into 4 equal sections, and randomly assigned into 4 aging methods (wet-aging [WA], conventional dry-aging [DA], dry-aging in water-permeable bag [DWA], and ultraviolet light dry-aging [UDA]). The beef sections were aged for 28 d at 2°C, 65% relative humidity, and 0.8 m/s airflow. Following aging, surface crusts and bones were removed, and loin samples were collected for the meat quality, microbiological, and sensory analyses. Results indicated that all dry-aged loins had greater moisture and trimming loss compared with WA (P < 0.05), while DWA had lower loss than DA and UDA (P < 0.05). No differences in shear force, cook loss, or both lipid and protein oxidation across all treatments were observed (P > 0.05). Among all treatments, DWA exhibited the least color stability indicated by rapid discoloration observed in the sample, while UDA had color attributes comparable with WA throughout the whole display. Microbial analysis indicated that UDA had lower microbial concentration on the surface than the other samples (P < 0.05). The consumer panel analysis found that all loins were acceptable, and the trained panel analysis indicated that DA loins decreased sourness and animal fat flavor (P < 0.05) and had a trend of decreasing oxidized flavor (P = 0.07). The results indicate that dry-aging can potentially be utilized as an effective natural process by nullifying some of well-known off-flavor attributes associated with cull cow beef while not compromising other meat quality attrib- utes or microbiological shelf life.

This study evaluated the effect of dry-aging on quality, palatability, and flavor-related compounds of pork loins. Ten pork loins were obtained at 7 days postmortem, divided into three equal portions, randomly assigned into three different aging methods (wet-aging (W), conventional dry-aging (DA), and UV-light dry-aging (UDA)), and aged for 21 days at 2 °C, 70% RH, and 0.8 m/s airflow. The results showed similar instrumental tenderness values across all treatments (p > 0.05), while DA and UDA had a greater water-holding capacity than WA (p < 0.05). Both DA and UDA were observed to have comparable color stability to WA up to 5 days of retail display (p > 0.05). Greater lipid oxidation was measured in both DA and UDA at the end of display compared to WA (p < 0.05). The UV light minimized microorganisms concentration on both surface and lean portions of UDA compared to other treatments (p < 0.05). The consumer panel was not able to differentiate any sensory traits and overall likeness between the treatments (p > 0.05). Metabolomics analysis, however, identified more flavor-related compounds in dry-aged meat. These findings suggested that dry-aging can be used for pork loins for value-seeking consumers, as it has a potential to generate unique dry-aged flavor in meat with no adverse impacts on meat quality and microbiological attributes.

The objective of this study was to determine the effect of different aging/freezing sequences combined with different freezing rates on quality attributes of beef loins (M. longissimus lumborum). Loins from 1 side of 8 beef carcasses (USDA Low Choice grade) were obtained at 2 d postmortem, cut into 10 steaks (2.54 cm), and randomly assigned into 5 treatments, where factorial combinations of 2 aging/freezing sequences (aging first then freezing/thawing [AFT] and freezing first then thawing/aging [FTA]) and 2 freezing rates (fast freezing [FF] and slow freezing [SF]) were used and compared to an aged only (AO) treatment as a control. Samples frozen using the FF condition were found to have a critical freezing time (Tc) of 21.5 min while the SF counterpart had a Tc of 175 min. Histological observation showed more visually enlarged gaps between muscle fibers in the SF samples, regardless of aging/freezing sequence. The SF-FTA samples had a significantly higher purge/ thaw loss followed by FF-FTA, while the loss from FF-AFT, SF-AFT, and AO were not different from each other (P > 0.05), suggesting that freezing rate effect might be more profound when applied in FTA. Cook loss was higher in AO compared to both FTA treatments (P < 0.05); however, it was not different when compared to AFT (P > 0.05). A lower shear force value and higher troponin-T protein degradation were found in both AFT and FTA compared to AO (P < 0.05), which would be attributed to the ice-crystal damage due to freezing. These results suggest that aging/freezing sequence could be an overriding factor in determining major meat quality attributes of frozen/thawed meat over freezing rate. However, fast freezing could negate some quality defects associated with the FTA process.

This study evaluated the effects of dry-aged beef trimmings inclusion on quality and flavor precursors of ground beef patties. Lean and fat trim were collected from beef loins aged for 28 d using 4 different methods: wet aging (WA), dry aging (DA), dry aging in water-permeable bag (DWA), and UV-light dry aging (UDA). Trimmings were ground and incorporated with ground fresh beef top rounds and subcutaneous fat (3 d postmortem) to make patties (80% lean and 20% fat) with different formulations: fresh beef and fat (CON), fresh beef and DA fat only (DA-FAT), and mixtures of 50% fresh lean along with 30% aged lean and 20% aged fat from different aging treatments (WA, DA, DWA, and UDA). Patties were manufactured in 3 independent batches (n = 3) to conduct pH, cooking loss, texture analysis, lipid oxidation, 5 d aerobic display color, trained sensory evaluation, volatile compounds, and metabolomics analyses. The inclusion of aged beef trimmings did not impact the pH and cook loss of the patties (P > 0.05). DWA trimmings lowered chewiness compared to CON (P < 0.05) and induced greater product discoloration compared to all other treatments at the end display (P < 0.05). The addition of DA and UDA trimmings in ground beef reduced bloody flavor and promoted more volatile production compared to other treatments (P < 0.05). Metabolomics profiling revealed different flavor precursor profiles from the inclusion of trimmings aged differently, demonstrating that the addition of the lean trim portion influenced the flavor profile more significantly than the fat trim portion after cooking. Cooking significantly altered the metabolite profile, reducing variations between the different treatments and explaining the observed flavor changes. The results suggested that aged trimmings modify the flavor precursor profile in ground beef products. Further research to identify the impact of different cooking methods on the flavor generation potential of dry-aged trimming inclusion products would be beneficial.

Metabolomics has recently emerged as a powerful tool for evaluating meat quality by characterizing biochemical changes at the molecular level. This review synthesizes metabolomics studies spanning pre-harvest animal factors, post-mortem metabolism, and processing conditions to elucidate the biochemical or metabolic bases of meat quality development. Specifically, this article compiles metabolite classes repeatedly associated with key meat quality characteristics (e.g., color, water-holding capacity, tenderness, flavor, pH, and shelf-life/microbiological traits) influenced by antemortem factors such as animal diet, genetic background, and animal handling and stress, as well as postharvest processing factors including fermentation, dry-curing, smoking, storage/aging conditions. In addition, this review addresses metabolomics profiling of emerging alternative protein products, such as plant-based and cell-cultured meat, and discusses the potential of metabolomics for meat authentication and adulteration detection. Collectively, the reviewed data indicate that meat quality traits, traditionally assessed independently, are regulated by multiple interconnected metabolic pathways, highlighting the importance of integrated pathway-level metabolomic analyses in meat science. Across multiple studies, postmortem energy metabolism is strongly associated with several meat quality traits, reflecting its central role in the rate and degree of postmortem glycolysis, redox balance, and protein-water binding throughout the conversion from muscle to meat. In addition to these advances, this review critically discusses current methodological challenges, limitations, and strengths of metabolomics approaches.