Boneless ribeye rolls (n = 12) and boneless top sirloin butts (n = 12) were obtained from heavy weight carcasses (mean = 407.8 kg), assigned to one of two aging treatments (dry or wet) and aged for 35 days at a commercial aging facility. Cutting tests were performed at the end of the aging period to determine retail yields. Subprimals were fabricated using the Beef Alternative Merchandising cutting styles, isolating four specific muscles: M. spinalis thoracis, M. longissimus thoracis, M. gluteobiceps, and M. gluteus medius. Retail cutting tests showed wet-aged subprimals had higher (P < 0.0001) total saleable yield percentages with decreased cooler shrink and gross cut loss percentages. This resulted in wet-aged ribeye rolls and top sirloin butts yielding 1.5 times and 1.3 times more saleable product than dry-aged counterparts, respectively. In order to determine palatability characteristics, consumer sensory evaluations and trained panel evaluations were preformed. Palatability related to aging and muscle type resulted in significant differences. From a consumer standpoint, aging treatment influenced OLIKE, FLAV, FLEVEL, and BEEFLIKE but only through the interaction of aging treatment x muscle. Clearly, consumers rated the wet-aged, M. spinalis thoracis highest in each of the previously stated attributes. Aging also affected JUIC, whereas muscle type had a significant (P < 0.0001) effect on FLVBF, TEND, LEVTEND, JUIC, and LEVJUIC. As far as trained sensory attributes were concerned, a more concrete flavor profile of aged beef was obtained. In addition, dry-aged steaks had greater (P < 0.0001) cooking yield percentages when compared to wet-aged steaks.

<p dir="ltr">This research thesis focuses on natural postmortem strategies for improving fresh meat quality. More specifically, it focuses on fresh meat tumbling application in beef and dry-aging methods in bison.</p>

<p>Within the last decade, the popularity and interest in dry-aging have constantly increased among both consumers and producers. Dry-aging is a natural value-adding process where meat is exposed to a controlled refrigerated environment without any protective barrier during the aging process. This process leads to the development of unique flavors in the final meat product. Although the prevalence of this process is increasing, there are inconsistent reports regarding the impacts of dry-aging on meat sensory attributes, especially on the flavor aspect. Given that flavor generation is dependent on the composition and availability of flavor precursors, the presence or absence of these precursors may contribute to the inconsistency observed. Thus the main objective of the research described here was to characterize the flavor precursors in dry-aged meat and elucidate potential factors or mechanisms favoring to their production.</p> <p> To achieve this objective, metabolomics analysis was conducted in conjunction with various chemical analyses (free amino acids, fatty acids, sugar content and volatile analysis), microbiome profiling and meat quality analysis (tenderness, water holding capacity, color stability, oxidative stability, microbial attributes and sensory analysis) to identify the essential flavor precursors and their production process. In addition, similar analyses were conducted using multiple meat sources (grass-fed beef loins, cull cow beef loins and pork loins) aged by wet-aging (WA), conventional dry-aging (DA), dry-aging in bag (DWA) and UV-light dry-aging (UDA) to elucidate the impact of the different aging treatments on meat quality, sensory attributes and flavor precursor availability.</p> <p>Regardless of the meat source, the results demonstrated that dry-aging altered the meat flavor precursor compositions, primarily by increasing the presence of protein-derived precursors (e.g., free amino acids and dipeptides), especially glutamine and glutamate compounds. Additionally, nucleotide and carbohydrate-derived compounds such as adenosine and reducing sugars were greatly increased after the dry-aging process. While the fatty acid profile was minimally affected, metabolomics analysis revealed a decrease in sterol and terpenoid lipids following dry-aging, which could potentially reduce off-flavors development in the meat. Other compounds such as vitamin B and vitamin C were also detected in the dry-aged product, which potentially could contribute to the flavor development.</p> <p>Analysis of the liberation mechanisms demonstrated that dehydration played a role in increasing the concentration of the flavor precursors in the dry-aged product, potentially promoting greater (e.g., Maillard reaction) during cooking. Furthermore, microorganisms might be responsible for further increasing the availability of flavor precursors in dry-aged meat, especially free amino acids, along with the dehydration process. Microbiome profiling found that <i>Pseudomonas</i> spp. are the most prominent bacterial species in microbial communities found on dry-aged meat which could affect the precursor release in dry-aged meat. Metabolomics analysis also indicated increased glutathione metabolism during dry-aging, which could lead to the liberation of glutamine-related compounds. The analysis also identified other compounds such as porphyrin rings (iron-related) and shikimic acid (bacterial metabolism), providing further examples of how metabolomics can identify dry-aged flavor precursors and reveal other potential mechanisms related to flavor development mechanisms.</p> <p>These outcomes demonstrate that dry-aging alters meat flavor precursor composition, mainly by increasing the availability of protein-, nucleotide- and carbohydrate-derived compounds. Such results indicate that the Maillard reaction is likely be the main mechanism in flavor generation in dry-aged meat. The current results provided more insights into the dry-aging flavor development, especially highlighting important flavor precursor such as glutamate and glutamine containing products, likely to contribute to the dry-aged flavor. Future study to identify the impact of different microorganism (especially mold and yeast) on dry-aging flavor development would be of interest. Additionally, impact of different cooking process should also be studies to maximize the dry-aged flavor potential from the product.</p>