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Investigating the drying kinetics, quality attributes, proteome profile and the generation of aroma compounds during dry-ageing of grass-fed beef
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Date
2024
Authors
Álvarez Hernández, Sara
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Publisher
University College Cork
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Abstract
Beef quality influences the consumer’s eating experience and their purchase intentions. Eating quality is impacted by many factors, such as, genetics and production systems, slaughtering management, post-mortem interventions, meat ageing, and packaging of meat products (Álvarez, Mullen, et al., 2021). Ageing consists of a subsequent series of biochemical events that start once the rigor sets in (when the meat reaches its maximum toughness after the slaughter of the animal) and finishes once the beef is ready for consumption. During this tenderisation period, muscle proteolytic enzymes (e.g. calpains, cathepsins, caspases) break down myofibrillar and cytoskeletal proteins, contributing to the degradation of the muscle structure and the improvement of meat tenderness (Bhat et al., 2018a). This thesis focuses on the study of ageing or tenderisation phase, particularly on the process known as dry-ageing, which has been significantly investigated over the last two decades.
Dry-ageing of beef consists of storing carcasses, primals or sub-primal cuts without protective packaging in a chamber or unit under controlled refrigerated air conditions (relative humidity of 70-80%, temperature of 0-4 °C, and airflow of 0.5-2.5 m/s) for 14-35 days (Koutsoumanis et al., 2023). However, restaurants and retailers may use longer ageing times than 35 days if safety of the meat is demonstrated (Point 2a of Chapter VII in Section I of Annex III, Regulation (EC) No 853/2004 amended on 14th of December 2023; See more details in Appendix I of this thesis). Dry-ageing is a value-adding process that improves meat tenderness and results in a product with unique flavour characteristics. For a long time, dry-ageing was the only method of ageing available to meat processors and was considered a craft process where each meat processor would use different ageing days and air conditions, developing unique dry-aged meat products. Following the development of new packaging and processing technologies in the 1970s, wet-ageing (where meat is vacuumed-packaged using water-impermeable films and aged) progressively replaced dry-ageing, since it overcame some of the disadvantages associated with dry-ageing (Savell, 2008), such as the higher moisture and trimming losses, longer processing times, and higher production costs (Terjung et al., 2021).
There is a general agreement that dry-ageing generates tender beef with unique flavour nuances, for which niche markets are willing to pay premium (Berger et al., 2018; Sitz et al., 2006). This signature “dry-aged beef” flavour has been described as nutty, aged, beefy, and brown roasted, and obtained higher liking scores than wet-aged beef (Campbell et al., 2001; Kim et al., 2016; Li et al., 2014; Stenström et al., 2014; Warren & Kastner, 1992). The development of a dry-aged beef flavour is influenced by a number of factors, such as dehydration, endogenous proteolysis, lipid oxidation, and the enzymatic activity of microorganisms on the beef surface (Zhang et al., 2022). These factors contribute to the generation of taste- and aroma-related precursors during ageing, which can further take part in complex reactions during cooking, such as the Maillard reaction, the thermal oxidation/degradation of lipids, and the interaction of these two pathways to produce high flavour-impacting compounds (Zamora & Hidalgo, 2011;Zamora et al., 2015). In addition, dehydration during dry-ageing favours the concentration of the above-mentioned flavour-related compounds (Lee, Choe, et al., 2019) and the lower moisture content and water activity may also enhance the Maillard reaction during ageing (Gardner & Legako, 2018; Li et al., 2021).
The potential of dry-ageing to produce a unique premium product has increased the interest of purveyors and retailers in dry-aged beef in recent years (Dashdorj et al., 2016). Likewise, research on dry-ageing has increased in recent years and focused on aspects such as its impact on the meat quality attributes (Berger et al., 2018), understanding the generation of flavour precursors and volatile compounds during dry-ageing (Setyabrata, Vierck, et al., 2022), as well as, the characterisation of the microbiome in dry-aged beef (Oh et al., 2019). Despite moisture evaporation being an intrinsic part of dry-ageing, research focusing on dehydration dynamics is scarce. There is also a lack of research in the proteomic changes occurring during dry-ageing and the impact of post-mortem interventions on the final product attributes. In this context, the present thesis addresses several aspects of dry-ageing in order to increase our fundamental understanding of the process with a view to facilitating improvements in the efficiency and sustainability of the process while maintaining product quality. Therefore, the main objectives of this research work are as follows:
▪ To investigate the drying dynamics during dry-ageing of grass-fed beef. The outcomes obtained from this research will help meat processors to understand how water evaporates during dry-ageing, and may assist in optimisation of the ageing time.
▪ To study the proteome evolution during dry-ageing and understand the biochemical changes that determine the development of dry-aged beef products. In addition, this project aims to identify potential biomarkers that may further help in tailoring ageing time and meat quality attributes of dry-aged beef products
▪ To assess the application of a post-mortem intervention, namely UV treatment prior dry-ageing to improve process efficiency (by influencing drying rate) while maintaining desirable quality attributes.
▪ To explore the flavour chemistry by identifying and quantifying the aroma compounds that contribute to the unique dry-aged flavour of grass-fed beef. This work also investigates the influence of UV treatment before dry-ageing on the aroma profile of dry-aged beef.
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Keywords
Dry-ageing , Beef , Volatiles , Muscle proteome , Proteomics , Meat quality , Grass-fed , Drying kinetics
Citation
Álvarez Hernández, S. 2024. Investigating the drying kinetics, quality attributes, proteome profile and the generation of aroma compounds during dry-ageing of grass-fed beef. PhD Thesis, University College Cork.