Characterizing the Flavor Precursors and Liberation Mechanisms of Various Dry-Aging Methods in Cull Beef Loins Using Metabolomics and Microbiome Approaches

Abstract

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.

Metabolic and microbial analyses of the surface and inner part of wet‐aged and dry‐aged beef

“…. Consistent with the present results,Ribeiro et al (2021) andSetyabrata et al (2022) found Lactobacillales, which are anaerobic bacteria, to be the dominant bacteria on wet-aged beef. The authorsTA B L E 2Note: Mean and standard deviation in log CFU/g beef (wet matter).…”

“…The WST with much higher microbial counts (>5 log CFU/g) than DST showed high levels of succinic acid and acetic acid, which are products of microbial metabolism (Pothakos et al, 2015). The results of amino acid and nucleotide concentrations over the aging time in the present study suggested an inhibition of protein degradation and energy metabolism due to the drying process of the surface of the DST and an increase in protein degradation and energy metabolism due to the additional factor of the microbiota in wet-aged beef (Muroya et al, 2020;Oh et al, 2019) explained that these bacteria groups belong to the meat spoilage bacteria and can degrade proteins and lipids into products such as organic acids and amino acids (Casaburi et al, 2015;Ribeiro et al, 2021;Setyabrata et al, 2022). A higher rate of protein degradation may have a positive effect on the tenderness of beef, but microbial growth with a count of 5-7 log CFU/cm 2 and higher can lead to negative changes and off-flavors in meat (Feiner, 2006;Hulánková et al, 2018).…”

“…(2021) and Setyabrata et al. (2022) found Lactobacillales , which are anaerobic bacteria, to be the dominant bacteria on wet‐aged beef. The authors explained that these bacteria groups belong to the meat spoilage bacteria and can degrade proteins and lipids into products such as organic acids and amino acids (Casaburi et al., 2015; Ribeiro et al., 2021; Setyabrata et al., 2022).…”

“…(2022) found Lactobacillales , which are anaerobic bacteria, to be the dominant bacteria on wet‐aged beef. The authors explained that these bacteria groups belong to the meat spoilage bacteria and can degrade proteins and lipids into products such as organic acids and amino acids (Casaburi et al., 2015; Ribeiro et al., 2021; Setyabrata et al., 2022). A higher rate of protein degradation may have a positive effect on the tenderness of beef, but microbial growth with a count of 5–7 log CFU/cm 2 and higher can lead to negative changes and off‐flavors in meat (Feiner, 2006; Hulánková et al., 2018).…”

“…Compared to these literature studies, the samples in this study showed clearly lower microbial growth on dry-aged beef (DST) and slightly lower growth on wet-aged beef (WST). These differences observed may be related to the recirculating air sterilizer with a UV-C lamp in the dry-aging chamber used in this study and, thus, the disinfection of the air in the chamber (Setyabrata et al, 2022). Such microbially clean dry-aged beef can be used even after a long aging period without the problem of microbial contamination (EU, 2005).…”