Beef Carcasses Aged at Mild Temperature to Improve Sustainability of Meat Production

Abstract

Beef carcass aging, which enhances tenderness and flavor through proteolysis, is traditionally costly and slow, requiring long-term storage at temperatures near 0 °C. To reduce energy consumption, a new technique using moderate cooling room temperatures was tested. Six carcasses of Holstein bulls were used. From each carcass, two shoulders were processed in different ways: one was refrigerated at 8 °C (W), and after spraying with a solution with calcium chloride and sodium chloride, was coated with sodium alginate. The other shoulder was stored at 2 ± 1 °C as a cold control (C). After five days of aging, the shoulders were dissected, and two muscles (Caput longum triceps brachii and Supraspinatus) were subjected to physico-chemical analysis, microbiological safety assessment, and sensory testing. The remaining samples of both muscles were stored in domestic conditions for an additional 5 days at various temperatures (2, 4, 8 °C), where the same physic-chemical and sensory tests were conducted. The results showed that moderate aging temperature improved meat quality, significantly reducing the shear force (p = 0.001) and increasing sarcomere length, the myofibrillar fragmentation index, and sensory tenderness (p = 0.042, p = 0.039, and p = 0.027, respectively). However, domestic storage post-dissection should not exceed 4 °C to prevent rapid lipid oxidation, as observed at 8 °C for both muscles (p < 0.001). Mild aging temperature maintained legal safety standards, enhanced certain meat qualities, and promoted enzymatic activity similar to traditional dry aging while reducing high energy consumption.

1. Introduction

When considering the environmental impact and sustainability of meat production, it is important to expand the focus beyond animal breeding alone. While much attention has been focused on the environmental consequences of livestock farming, it is crucial to recognize that the entire supply chain, including storage, handling, and processing, significantly contributes to environmental impact, particularly through the maintenance of the cold chain [1]. Sustainability in beef carcass maturation is a complex, multifaceted concept that integrates economic viability, environmental stewardship, and social responsibility. Central to this approach is minimizing the ecological footprint while ensuring food safety, quality, and economic efficiency [2].

Traditional refrigeration systems in meat storage, although crucial for preserving quality [3], are often energy intensive, contributing to the meat industry’s carbon footprint. Adopting energy-efficient refrigeration technologies, harnessing renewable energy sources, and optimizing storage conditions are pivotal for reducing energy consumption and greenhouse gas emissions [4], and there are numerous hypothesized solutions for efficient energy saving and increased use of renewable energy sources. However, despite the measures already adopted, modern systems still show significant potential for improvement [5]. From a social perspective, sustainable carcass conservation entails maintaining strict hygiene standards to prevent contamination and spoilage, which can have serious public health implications. Furthermore, there is growing consumer demand for transparency in the meat production and storage process, pushing the industry towards more ethical and sustainable practices [6,7,8].

Economic feasibility is also vital for sustainable carcass conservation. Practices such as long-time dry aging, though energy intensive, can increase the market value of meat products. Balancing the higher costs of sustainable technologies with the potential for higher quality and value of end products is crucial [9].

Meat is a perishable product, and low-temperature storage, essential in meat aging processes, involves maintaining carcasses at temperatures just above freezing, typically within the range of 0 °C to 2 °C [3]. This method is strategically employed not only to inhibit bacterial activity [10] and extend shelf life but also reduce evaporation loss [8] and stabilize meat color [11]. Calculating the thermal power required to maintain the cooling rooms at temperatures close to zero is a thermodynamics problem based on three fundamental factors as follows:

• The volume of the room to be refrigerated;
• The dispersion coefficient (K), which depends on the insulation of the building and affects the power absorbed by a cold room;
• The temperature difference between the outside and the inside (∆T1).

The energy consumption mentioned above is largely determined by the design and construction of the slaughter plant, which must consider global warming and employ efficient insulation systems [12] to handle an ever-increasing temperature differential (ΔT1).

Additionally, the temperature drop required to cool carcasses within 24 h after slaughter to approximately 7 °C at the carcass center involves a temperature difference of 30–33 °C (∆T2). The rate of carcass refrigeration is influenced by factors such as room ventilation, fat cover, volume and muscularity of the carcass, and its different regions [13,14]. Furthermore, this calculation must also account for temperature losses due to cold room door openings.

The efficiency of this refrigeration system is measured in terms of the coefficient of performance (COP), defined as the ratio of useful energy output to energy input [15]. Moreover, as climate change significantly raises average ambient temperatures, the heat load on all cold chain systems will increase. Raising the carcass refrigeration temperature affects both ∆T values by approximately 6–7 degrees. If we also add to this calculation the shorter time required to achieve meat aging, we estimate an energy saving of 12–15 kW per day for each carcass.

Moreover, carcass refrigeration is not merely a storage activity, it constitutes a true maturation process characterized by a complex interplay of biochemical reactions driven by enzyme activities under controlled environmental conditions [3]. These enzymatic reactions, primarily involving endogenous proteolytic enzymes, such as calcium-dependent calpains and cathepsins, play a crucial role in the breakdown of muscle fibers, thereby enhancing meat tenderness [11]. The duration of aging determines the extent of enzymatic activity and, consequently, the degree of tenderization and flavor development [16].

However, extended aging periods can lead to increased weight loss in meat due to water evaporation and drip loss [6]. Additionally, as previously reported, longer aging requires more energy to maintain the meat at controlled temperature and humidity levels, contributing to higher energy consumption. This creates a paradox, as the concept of sustainability is challenged by consumer expectations for culinary excellence and premium beef quality.

Attempts to increase the temperature to accelerate meat maturation and enhance tenderness have been studied in the past; however, these experiments have yielded limited success, primarily due to excessive microbial growth [17,18,19]. Elevated temperatures in meat aging act as a double-edged sword; while they improve tenderization, they also increase risks related to oxidation and microbial stability. Jacob and Hopkins [11] demonstrated that aging at 15 °C for 24 h enhances tenderness (p < 0.05) compared to standard refrigeration (1–4 °C) but also raises lipid oxidation (p < 0.01 via TBArs), which compromises color stability. Alternative approaches in temperature modulation, such as initial high temperatures up to 35 °C around rigor mortis for limited periods [20], show promise but remain challenging to balance for microbial control, tenderness, and flavor. Practical applications in large-scale facilities are limited, despite promising experimental results.

To address these challenges and improve meat quality, active films or compounds with strong bacteriostatic and antioxidant properties have recently been utilized, such as lactic acid and ascorbic acid. The application of these compounds has been further enhanced using innovative methods, like electrostatic spraying [21].

Additionally, practices across the entire meat supply chain, from breeding to distribution and consumption, should be carefully analyzed to identify opportunities for improvement and to implement innovative strategies that mitigate environmental harm and economic loss.

In response to the growing demand for sustainable beef carcass aging and the reduced energy inputs in meat production, a technique involving moderate cooling room temperatures during aging was investigated. To optimize the positive effects of the aging process, models that consider the effects of factors such as temperature, pH, and enzyme activity are necessary. This approach aligns with the concept of “smart-aging” as described by Kim et al. [22], which could potentially enable precise control over all aspects of the aging process.

Post-mortem interventions to enhance meat tenderness can be applied not only through physical methods, such as increasing storage temperature, but also through chemical means. For instance, the application of calcium chloride is designed to boost the activity of calcium-dependent proteolytic enzymes. This enzymatic activation facilitates the solubilization of myofibrillar proteins, thereby improving the meat’s water retention capacity and overall tenderness [23]. The aim of this research was to increase the cooling room temperature in a slaughterhouse from 2 °C to 8 °C to reduce energy consumption, further protecting the meat with sodium chloride and alginate and using calcium chloride, presumably acting to accelerate proteolysis. Additionally, this study aimed to evaluate the shelf life of the meat under domestic storage conditions by simulating a range of typical household refrigerator temperatures. This will allow us to assess any potential negative effects on meat stored at mild temperature, which, although not apparent at the time of dissection, could emerge later during domestic storage. The analysis will focus on possible changes in quality, including alterations in texture, flavor, and microbiological stability over time.

2. Materials and Methods

2.1. Sampling

Six carcasses from Friesian young bulls, similar in terms of live weight and carcass weight (on average 550 ± 14.5 kg and 308.5 ± 10.7 kg, respectively, for all animals), were classified under the SEUROP beef carcass classification system as conformation class “R” and fat score “3” [24]. This study was conducted in two consecutive cycles, with three carcasses per cycle.

As per standard slaughterhouses practices, after recording the live weight, followed by stunning and bleeding, the carcass was divided into half sides and labeled to ensure traceability. Subsequently, the two shoulders were removed from each side and hung on hooks. The shoulder weight was, on average, 19 ± 1.3 kg, and was approximately 61.7% meat and 14.6% fat.

One shoulder from each carcass was stored at 8 °C (referred to as W = warm). At about 24 h post-slaughter, this W shoulder was treated by spraying with a solution of 2% calcium chloride (CaCl₂), to activate proteolytic enzymes, and 2% sodium chloride (NaCl) in sterile water, to inhibit bacteria spoilage. Each solution was prepared fresh for each cycle, with a spray distance of 20 cm. After spraying, shoulders were coated with a sodium alginate solution (1.5%) and glycerine (10%), applied with a silicone brush, to form a protective film. The other shoulder (referred to as C = cold) was stored at 2 ± 1 °C without any additional treatment. Both storage rooms were adjacent to the same slaughterhouse.

Five days post-slaughter, at dissection, microbiological surface samples were collected, and two muscles for each shoulder, Caput longum triceps brachii (CL) and Supraspinatus (SS), were harvested. A small sample from each muscle for both the C and W treatments was minced for proximate chemical composition analysis. After determining the dry matter, samples were vacuum stored at −70 °C for approximately 1 month. Given the assumed similarity in composition, proximate composition analysis was only performed on the C treatment muscles, with dry matter (DM%) analysis conducted immediately after muscle dissection for both treatments. Simultaneously, two slices of approximately 3 cm were cut from both muscles in the C and W shoulders. One unfrozen slice of 3 cm was used for physical analyses, including pH, shear force, the myofibrillar fragmentation index (MFI), sarcomere length, thiobarbituric acid reactive substance assays (TBArs), and color. The second slice was frozen at −70 °C and later used for sensory panel testing.

The remaining portions of the two muscles, for both the C and W shoulder treatments, were divided into three samples and were weighed and stored in vacuum bags for an additional five days, simulating domestic storage conditions (2 ± 1 °C, 4 ± 1 °C, and 8 ± 1 °C). After this storage period, samples of both muscles were removed from the vacuum bags, gently swabbed dry, and re-weighed to determine drip losses. The samples were subsequently analyzed for physico-chemical and sensory characteristics (Figure 1).

From six carcasses, the shoulders after slaughter were aged at two temperatures, one at 2 °C (cold = C) and one at 8 °C (warm = W), to reduce the energy impact. Subsequently, after 5 days of aging, from the two shoulders (C and W), two muscles, Caput longum triceps brachii (CL) and Supraspinatus (SS), were sampled and stored in domestic settings for an additional 5 days at three different temperatures (2, 4, 8 °C).

2.2. Analysis

The analytical methods used are briefly described below.

2.2.1. Proximate Chemical Analysis

The proximate composition of the two muscles was performed according to the methods reported in AOAC [25] to determine the dry matter (DM, method 934.01), ether extract (EE, method 920.39), ash (method 942.05), and crude proteins (CPs), which were obtained by differences.

2.2.2. Microbiological Analysis

For each shoulder in the cold and warm groups, respectively, two types of microbiological samples were collected: superficial (at 1 and 5 days without the superficial coating on the W shoulder) and deep determination on day 5. For superficial sampling, an area of 100 cm² was swabbed with a sponge soaked in peptone water (PW-Oxoid, Thermo-Fisher Scientific, Waltham, MA, USA). For deep sampling carried out at dissection, 5 days after slaughter, 25 g of muscle tissues from the Caput longum triceps brachii (CL) were aseptically collected in both the C and W aging treatments. This muscle was chosen due to its deep structure within the shoulder, lower susceptibility to external contamination, and abundance compared to the other. The samples were homogenized using a peristaltic device (Stomacher, VWR International, Radnor, PA, USA) for approximately 2 min, while the deep samples were homogenized for 5 min. After homogenization, the samples were allowed to rest for approximately 10 min. Serial dilutions (1:10) were prepared with sterile PW using the maximum legal dilutions for bovine carcasses as a reference. The resulting samples were plated in duplicate on Petri dishes with specific media as follows: total viable count, using plate count agar medium (Oxoid Thermo-Fisher Scientific, Waltham, MA, USA) and incubated at 30 °C for 48–72 h; fecal coliforms, using Rapid Coli Medium (BIO-RAD, Hercules, CA, USA) and incubated at 37 °C for 24 h; and Escherichia coli, using Rapid Coli Medium (BIO-RAD, USA) and maintained at 44 °C for 24 h.

2.2.3. Physical and Chemical Analysis

The pH was measured approximately 24 h post-mortem after rigor mortis in the most rounded part of the shoulder in the muscles sampled at dissection 5 days post-slaughter and after domestic storage, where a portion of the two muscles was maintained at different temperatures. Measurements were performed by a “Hanna Hi 98240 (Woonsocket, RI, USA)” pH meter. The probe, equipped with a blade for easier penetration, was inserted approximately 2 cm into the muscles. The final pH value represents the average of 3 pH readings taken at different points of each sample.

The loss of liquids by dripping (drip loss) was determined according to the method proposed by Honikel [26]. A slide that was 1 cm thick was taken from both muscles, weighed, and placed in a polyethylene bag, into which air was blown to prevent the plastic from adhering to the sample. It was hung with a plastic cord to avoid absorption of the liquids by capillarity and excessive evaporation losses. The bag with the meat was stored in a cold room for 2 days at 2 ± 1 °C. The sample was then reweighed to calculate the weight loss expressed as a percentage of the difference. For samples stored at different temperatures after dissection, drip loss was determined by calculating the weigh differences before and after five days of vacuum storage at domestic storage.

Cooking loss was determined as the difference in weight on a meat slide of about 2.5 cm thick, which was cooked in a water bath at 80 °C until the internal temperature reached 75 °C, cooled under running water for 2 h, and expressed as a percentage of the difference.

Shear force was measured on cooked meat using the same meat samples of cooking loss. A Warner–Bratzler Shear Force (WBSF) device with dynamometer Instron 5543 Single Column Table Top Tensile Tester System (Instron, Norwood, MA, USA) was used on a 2 × 1 × 1 cm thick sample cube with a crosshead speed set at 100 mm/min and a cut force of 50 kg, as reported with more detail in [27]. Data were expressed in kilogram force (kgf).

Sarcomere length, used to determine the meat fiber shrinkage rate, was measured on a 1 × 1 cm thick cube of meat, free of fat and connective tissue, homogenized, and fixed for one hour in phosphate-buffered glutaraldehyde. A drop of the homogenate was placed on a slide and observed under an optical microscope with oil immersion a 100× objective (Zeiss Axioplan of Zeiss company, Oberkochen, Germany). Ten bands (sarcomeres) were counted in four groups of myofibrils located on four different sectors of the slide, and their average length was expressed in μm.

The same procedure was performed on samples at dissection and after further domestic storage under vacuum in polyethylene bags for 5 days. All physical analyses were performed on a no-frozen slide of meat.

The myofibrillar fragmentation index (MFI) was determined following the method used by Culler et al. [28]. It is based on separation through polyethylene filters with a pore diameter of 18 mesh of portions of myofibrils of different sizes. Briefly, 5 g of muscle, free of fat and connective tissue, was homogenized with a phosphate buffer and EDTA and centrifuged to separate the structural part of the muscle. The pellet was suspended with a phosphate buffer and separated with polyethylene filters with a pore of 18 mesh. Total soluble proteins were determined on the suspension, obtained from filtering, with a biuret assay. After, the suspension with myofibrils prepared a sample with approximately 0.5 mg/mL of proteins, and the myofibrils were read on the spectrophotometer at 540 nm.

Lipid oxidation was determinate by thiobarbituric acid reactive substance assays (TBArs), as reported in Valerio et al. [29], measuring the level of malondialdehyde (MDA). Briefly, the meat sample was homogenized with water and ethanolic BHT to avoid further oxidation, and the proteins were precipitated using trichloroacetic acid (TCA) 10%. After centrifugation, the supernatant was incubated with thiobarbituric acid (TBA) at 90 °C for 30 min and then detected by an HPLC instrument with a C18 column (150 × 4.4 mm) and read in fluorescence ex = 515 nm and em = 543. The MDA sample peak was identified by comparison with the MDA standard peak and TBArs expressed as mg of MDA/kg.

Meat color was assessed after one hour of the blooming period. L* (lightness), a* (redness), b* (yellowness), chrome, and hue in the CIELAB space [30] were determined using a Konica Minolta CM-3600 D (Sensing, Inc., Osaka, Japan) spectrophotometer with a D65 illuminant, characterized by the same spectral emission of the natural light (6504°K, daylight with clear skies). More details are reported in Ripoll et al. [31].

2.2.4. Sensory Test Analysis

A 2.5 cm thick slice of meat from both CL and SS muscles was thawed at 2–5 °C for 24 h. The meat slices were then cooked on a griddle until an internal temperature of 75 °C was reached. Subsequently, the surfaces in contact with the griddle, along with parts rich in connective tissue and fat, were removed. The cleaned, cooked meat was divided into small cubes of 1.5 cm thickness, and each piece was wrapped in aluminum foil to retain aroma and heat.

The samples were evaluated by 8 semi-trained panelists who assessed tenderness, juiciness, and flavor using an 8-point scale, where 1 represented extremely hard, dry with no aroma, or an unpleasant flavor, and 8 represented extremely tender, juicy, and rich in pleasant flavor.

A total of six batches (each batch contained five samples: two aging temperatures per two muscles plus a repeated sample to test the panelists’ evaluative capacity) were examined over three different days, with two sessions per day. Samples were randomly labeled with a code number (1 to 5) and evaluated in a randomized order.

Furthermore, the panelists evaluated the meat samples stored in a domestic refrigerator at three different temperatures. Sensory tests were conducted over six days, with two sessions per day. Each session compared six samples labeled with a code number (1–6) and tested in a randomized order.

Samples were examined at individual stations under natural light, with room temperature maintained at 20 ± 1 °C.

2.3. Statistical Analysis

Before statistical analysis, microbial counts were converted to log CFU/cm². Data below the detection limit of 0.5 CFU/cm² were considered as 0 log units.

The data recorded were analyzed by ANOVA (analysis of variance). For the data obtained after aging time (5 days), a bifactorial model with interaction was used, considering the muscles and aging temperatures as fixed factors.

The data recorded after dissection were analyzed using a trifactorial model considering the two muscles, the aging temperatures, and the three domestic storage temperatures as fixed factors.

To identify significant differences among means, Tukey’s test was used, with a significance threshold set at p < 0.05. The statistical analysis was carried out with SAS Systems statistical software v.9.4 (SAS Institute Inc., Cary, NC, USA).

To assess the reliability of the sensory test, both distribution analysis and box plot analysis were conducted for each sensory attribute. Descriptive statistics (mean, median, standard deviation, and range) were calculated to determine the central tendency and dispersion of scores. Histograms were generated to visualize score distributions and normality (data were reported in Figures S1 and S2).

Ethical review and approval were not required for this study because the shoulders were collected randomly at slaughterhouses where legal directives were followed, without any interference with animal health and welfare. The data on weight and SEUROP classification were obtained through a digital classification process, as is standard in an EU-approved slaughterhouse.

3. Results and Discussion

The dry matter (DM%) content of the two muscles (CL and SS) taken from shoulders C and W and analyzed on fresh meat showed no significant difference, with DM% contents of 23.82 ± 0.53 and 23.27 ± 0.84 for the average of the two muscles from shoulders C and W, respectively. This lack of difference was probably because the muscles were not separated from the shoulder during aging. The proximate chemical composition of the two muscles analyzed did not differ significantly, as shown in

Table 1. Proximate composition of two muscles at dissection time.

	CL	SS	p-Value	RMSE
DM%	24.04	23.60	0.182	0.53
Protein%	20.65	20.26	0.327	0.65
Fat%	1.89	1.69	0.252	0.27
Ash%	1.51	1.64	0.311	0.22

CL = Caput longum triceps brachii; SS = Supraspinatus; DM = dry matter; RMSE = root mean square error.

, indicating chemical similarity between the two muscles at the time of dissection (five days after slaughter). Similarly, Pereira et al. [32] highlighted that the proximate composition of lean within the beef carcass may not exhibit significant differences.

3.1. Microbiological Results

Temperature is a significant factor that affects microbial growth. The majority of microorganisms are classified as mesophilic, with some bacteria exhibiting a preference for low temperatures and classified as psychrophilic bacteria. As the meat industry continues to evolve and the trade of slaughtered animals expands, low-temperature preservation generally is the most preferred method to minimize microbial growth.

European Regulation 2073/2005 sets a lower limit and a cut-off point for bacterial count. A value is considered acceptable when it lies below the lower limit, tolerable when it remains within limits, and unacceptable if it exceeds the safety limit. The microbiological count of total viable bacteria (TVC) remained below the legal limit for up to 5 days after slaughter in both C and W aging (

Table 2. Effect of the different aging temperatures on microbiology parameters in superficial and CL muscle.

Treatment	TVC Log UFC/cm2	Escherichia coli Log UFC/cm2	Total Coliforms Log UFC/cm2	Salmonella
C 1 d	2.38	-	-	-
C 5 d	2.81	-	-	-
W 1 d	2.31 b	-	-	-
W 5 d	4.05 a¥	0.84 ± 0.04 ¥¥	-	1.67 ¥
C-CL	1.87 b	0.37 ¥	-	-
W-CL	3.02 a	1.23 ± 0.08 ¥¥	-	-
RMSE for C and W	0.75	-	-	-
p-value C vs. W	0.043	-	-	-
p-value 1 d vs. 5 d	0.008	-	-	-
RMSE for CL	0.805	-	-	-
p-value for CL	0.037	-	-	-

C 1 d = cold shoulder at 1 day of aging; C 5 d = cold shoulder at 5 days of aging; W 1 d = warm shoulder at 1 day of aging; W 5 d = warm shoulder at 5 days of aging; C-CL = cold shoulder, muscle Caput longum triceps brachii; W-CL = warm shoulder, muscle Caput longum triceps brachii; TVC = total viable count. ^¥ one sample exceeded the legal limits, ^¥¥ two samples exceeded the legal limits; ^a,b = significant differences for p < 0.05; RMSE = root mean square error.

). Only one sample exhibited non-conformity in the W group after 5 days on the shoulder surface.

Coliforms consistently remained below the lower limit for both C and W conditions on the surface and in the CL muscles analyzed at dissection. Escherichia coli was detected in only two replicates after 5 days on the shoulder on both the surface and within the CL muscle under W conditions. These samples likely experienced environmental contamination during slaughter [33].

In slaughterhouses, hygienic conditions are constantly challenged by the presence of animals. Camargo et al. [34] evaluated microbial contamination in a slaughterhouse and analyzed four critical points in the slaughtering process and found that many microorganisms present in the animals can easily transfer to the carcass.

Comparisons of microbial populations indicated that when counts on the animal’s skin were high, the populations remained elevated throughout evisceration up to the cleaned carcass, suggesting that the hygiene status of the animal’s skin before slaughter may play a role in carcass contamination [35]. Additionally, factors such as storage temperature, pH, and water activity (aw) can accelerate microbial proliferation [36].

The total microbial load on the surface of the shoulder one day post-slaughter did not show significant differences between the shoulders assigned to the two different experimental groups. This load increased in both groups during aging; however, after 5 days, group C exhibited a modest increase of +15% compared to a +43% rise in group W, indicating significant differences from the TVC value at slaughter (p = 0.008). The microbial load within the CL muscle was of less concern.

Among Enterobacteriaceae, Escherichia coli was much better controlled and remained well below the legal limits for all categories considered. It is important to note that the samples were taken from the shoulder, the anatomical region of the carcass most compromised microbiologically, as it may incidentally come into contact with eviscerated contents during the removal of the rumen and intestines.

The values we observed are consistent with those reported by Kinsella et al. [37], who documented an increase of 2 log CFU/cm² in TVC when beef was stored at 10 °C for 72 h, whereas the increase was only 0.4 log CFU/cm² at 5 °C. In the same study, the authors also highlighted an increase in Enterobacteriaceae.

The presence of a surface coating, as used in our experiment with the addition of NaCl, could partially inhibit microbial proliferation during storage at mild temperatures. This effect was demonstrated in a study by Yu et al. [21], which used a surface coating supplemented with organic acids that were much more effective than salt alone. In fact, the organic acids, maintaining the carcass at 10 °C, completely controlled bacterial proliferation.

However, microbial growth during dry aging could pose a potential food safety issue. It is important to consider that the carcass is protected by the adipose tissue, and exposed parts harden due to surface dehydration, forming a crust with very low water activity. This process reduces and inhibits aerobic bacterial growth [22]. Furthermore, these layers of lean meat exposed to the adipose tissue are usually discarded during dissection.

The population of Enterobacteriaceae generally increases with meat storage. These are Gram-negative bacteria and facultatively aerobic bacteria associated with beef, playing a role in food spoilage by causing unwanted flavors and discoloration, thereby reducing the meat’s shelf life. Therefore, limiting their proliferation before dissection ensures the maintenance of the meat’s quality [33].

3.2. Physical and Chemical Results

The shoulders were not excessively globous, and the limited fat coverage allowed for greater heat exchange with the cooling room [3]. Approximately 12 h post-slaughter, the temperature of the C shoulders reached around 9 ± 2 °C, while the W group still maintained a temperature of 15 ± 2 °C. This difference would allow for better enzymatic activity of calpains in the W group, as the optimal temperature range for maximizing proteolytic activity in the pre-rigor phase is between 22 and 30 °C [19].

Carcass size influences the rate of temperature decline, as more rounded carcasses generally retain higher internal temperatures, which in turn affect post-mortem metabolism [35]. Therefore, post-mortem management practices should consider carcass weights and the thickness of the adipose tissue to optimize meat quality.

The heat exchange between muscle and the environment is not just a physical component but also involves a metabolic aspect. As muscles enter rigor mortis, their temperature decreases due to the reduction in muscle energy metabolism, which is also influenced by the myofibrillar characterization [38].

A rapid drop in temperature caused by a cooling room environment close to 0 °C before the pH reaches around 6 could lead to cold shortening, increasing muscle toughness and resulting in darker meat. Conversely, high temperatures during aging accelerate metabolic processes, causing a rapid drop in pH and increased proteolysis, which impairs the muscle’s ability to retain moisture, denatures color, leads to texture loss, and inhibits proper meat maturation [39]. Therefore, the temperature/pH ratio must follow specific decline ranges to maintain a good balance. There is an optimal window for the temperature/pH ratio (between 35 and 12 °C the pH should remain around pH 6), as reported by Cadavez et al. [40], within which the meat undergoes proper maturation and achieves desirable organoleptic characteristics.

The pH values measured 24 h post-slaughter (5.66 ± 0.11 and 5.63 ± 0.09 for carcasses C and W, respectively, measured by inserting the pH meter directly into the shoulder) confirmed that no pH anomalies were observed in any of the shoulders.

After 5 days of aging, at the time of dissection, the pH was measured in the CL and SS muscles, showing no significant differences related to either muscle type or aging temperature. This suggests that the temperature variation between the two treatments was not substantial enough to significantly impact the glycolytic processes.

Physical and chemical analysis (

Table 3. Effect of the different aging temperatures on some physical parameters and lipid oxidation of CL and SS muscles.

	CL		SS		p-Value
	Cold	Warm	Cold	Warm	CL vs. SS	C vs. W	RMSE
pH	5.60	5.54	5.63	5.59	0.227	0.166	0.08
Drip loss %	1.06 b	1.20 a	1.04	1.13	0.388	0.017	0.11
Cooking loss %	32.31	33.34	30.64	32.19	0.506	0.542	4.06
WBSF (kgf)	6.04 a	5.26 b	6.17 a	5.32 b	0.471	0.001	0.36
Sarcomer length (µm)	1.77 b	1.89 a	1.78	1.82	0.603	0.042	0.09
MFI	62.14 b	76.38 a	44.77 b	64.43 a	0.071	0.039	14.07
TBArs (mg MDA/kg)	0.29	0.31	0.30	0.33	0.127	0.195	0.07

CL = Caput longum triceps brachii; SS = Supraspinatus; C = cold aging; W = warm aging. MFI = myofibrillar fragmentation index; TBArs = substance of lipid oxidation that reacts with Tio barbituric acid expressed in mg MDA/kg (MDA = malondialdehyde); WBSF = Warner–Bratzler Shear Force. ^a,b = significant differences for p < 0.05; RMSE = root mean square error.

) did not reveal any significant differences between the muscles, whilst for the myofibril fragmentation index (MFI), there was a tendency (p = 0.071) for greater degradation in the CL muscle in both the C and W shoulders.

In contrast, the differences due to aging temperatures were significant across several parameters analyzed. Particularly, significant differences were observed in drip loss in the CL muscle (Table 3), probably because this muscle, having a larger volume than the SS, cooled more slowly in the W group compared to the C group. This slower cooling led to more pronounced proteolysis, resulting in a loss of protein ionic strength, and, consequently, a reduced ability to retain water [22]. Furthermore, the larger surface area of the CL muscle led to greater absorption of calcium chloride compared to the SS muscle, prematurely activating calcium-dependent enzymes. This clearly demonstrates that there are no substantial differences in fluid retention between the two aging temperatures, as cooking loss did not show a significant difference. These findings align with Choe et al. [6], who reported an increase in drip loss in certain muscles aged at 7 °C, and, occasionally, a non-linear relationship between drip loss and higher aging temperatures was observed [19].

A clear effect of the aging temperature was observed in Warner–Bratzler Shear Force (WBSF) on cooked meat for both the CL and SS muscles, with the C shoulders showing +18% of the WBSF value. The combined effect of higher temperature increased calcium from the CaCl₂; coating likely enhanced proteolytic activity, resulting in greater tenderness in the muscles from the W shoulders at 5 days. In the C shoulders, both muscles (+11% for CL and approximately +13% for SS) were tougher. According to consumer perceptions, Destefanis et al. [41] classified beef with WBSF values exceeding 5.37 kgf as tough. Elevated shear force values were still evident in the two muscles from the C shoulders, even after an additional 5 days of vacuum storage, except for those maintained at 8 °C (Table 3), where the value significantly decreased.

Tenderness is a crucial meat quality characteristic highly valued by consumers. The biological, structural, and physiological mechanisms underlying meat tenderness have been extensively studied [42,43].

The myofibril fragmentation index (MFI) is an indicator of the extent of myofibrillar protein degradation during the post-mortem aging of meat, specifically reflecting the breakdown of proteins in the I-band of the myofibril [44]. Supporting the accelerated myofibrillar degradation, the MFI value was significantly higher in the W shoulders compared to the C (p = 0.039), despite considerable variability in the data. The susceptibility of myofibrillar proteins, particularly myosin, is influenced by pH and temperature, which can vary significantly between muscles within a carcass due to differences in glycolytic metabolism that release energy as heat during the post-mortem period [39].

Most studies suggest that higher aging temperatures rapidly activate the calcium-dependent protease isoforms, μ-calpain, and m-calpain in the presence of free calcium ions, leading to a quicker degradation of myofibrillar proteins. However, the progression of degradation by calcium-dependent enzymes quickly depletes the calcium availability in muscle cells and rapidly denatures the enzymes [16,19]. Therefore, the use of calcium chloride may prolong enzymatic activity by reducing the rapid autolysis of these enzymes.

The effect of temperature was also significantly evident in the sarcomere length of the CL muscle. Generally, high storage temperatures combined with a rapid drop in pH can inhibit meat tenderization through a phenomenon known as “heat-induced toughening”, where the sarcomere contracts excessively during rigor mortis, preventing the complete subsequent release. However, this phenomenon is usually observed at temperatures above 35 °C during rigor mortis, although contrasting patterns are noted by Kim et al. [39].

Extremely low storage temperatures near freezing during rigor mortis can also cause excessive sarcomere shortening, which cannot be resolved in the subsequent aging phases, leading to negative consequences for meat tenderness [39].

No temperature-related effects on TBArs were observed (p = 0.195), confirming that moderate temperatures did not compromise lipid oxidation during storage conditions of meat.

The color of meat, for all components studied (

Table 4. Effect of the different aging temperatures on color parameters of CL and SS muscles at 5 days after slaughter.

	CL		SS		p-Value
	Cold	Warm	Cold	Warm	CL vs. SS	C vs. W	RMSE
L*	41.98	41.23	41.48	41.24	0.920	0.837	5.75
a*	12.82	13.37	12.48	12.82	0.515	0.871	1.63
b*	12.34	12.12	12.73	12.19	0.820	0.708	2.47
Chrome	18.24	17.70	17.86	17.71	0.868	0.754	2.67
Hue	42.22	42.67	45.42	43.71	0.223	0.711	4.12

CL = Caput longum triceps brachii; SS = Supraspinatus; C = cold aging; W = warm aging. L* = lightness, a* = redness, b* = yellowness; RMSE = root mean square error.

), showed no significant differences between the muscles or between the two different aging systems. Some authors have reported a degradation of the red index and an increase in hue at high storage temperatures with low pH [45]. The lighter color and reduced color stability of meat subjected to a rapid pH drop and high temperatures may be due to the denaturation of sarcoplasmic proteins (particularly myoglobin) and/or myofibrillar proteins, resulting in structural changes and altered oxygen consumption by endogenous oxidative enzymes [20]. However, in our study, the W aging temperature was moderate, and although it slowed down the carcass cooling process, it did not cause a rapid pH decline, and thus did not affect color stability.

The physical characteristics of meat are undoubtedly influenced by numerous factors during farming and the pre- and post-slaughter periods, as well as during aging, which are also dependent on the structural and metabolic characteristics of the two muscles. Nevertheless, the results often stem from changes in muscle protein structure and their spatial arrangement [20].

The muscles dissected from the carcasses at 5 days post-mortem were maintained for an additional 5 days under vacuum in controlled storage, following a maturation process at different temperatures. The use of vacuum packaging aimed to protect the muscle from microbial proliferation and prevent excessive dehydration, especially for the samples stored at 8 °C.

No significant differences were found between the two muscles for any of the parameters considered (

Table 5. Effect of the different domestic storage temperatures on some physical parameters of the CL and SS muscles.

Treatment	pH	Drip Loss %	Cooking Loss %	WBSF (kgf)
C-CL-2	5.59	1.16 b	33.21	5.78 a
C-CL-4	5.60	1.34 ab	34.82	5.47 a
C-CL-8	5.64	1.50 a	35.41	5.13 b
W-CL-2	5.55	1.26 c	34.10	5.03 a
W-CL-4	5.57	1.67 b	35.86	4.81 a
W-CL-8	5.61	1.94 a	36.85	4.46 b
C-SS-2	5.63	1.06 b	32.03	6.00 a
C-SS-4	5.64	1.29 ab	33.74	5.75 a
C-SS-8	5.67	1.43 a	34.63	5.31 b
W-SS-2	5.61	1.23 c	32.98	5.15 a
W-SS-4	5.65	1.54 b	34.50	4.91 a
W-SS-8	5.67	1.90 a	35.51	4.53 b
RMSE	0.06	0.25	4.09	0.31
p-value CL vs. SS	0.087	0.284	0.237	0.214
p-value C vs. W	0.201	0.001	0.304	0.001
p-value Temperatures	0.113	0.001	0.102	0.001

C-CL-2, C-CL-4, C-CL-8 = cold shoulder, muscle Caput longum triceps brachii, domestic storage at temperatures of 2°, 4°, 8 °C; W-CL-2, W-CL-4, W-CL-8 = warm shoulder, muscle Caput longum triceps brachii, domestic storage at temperatures of 2°, 4°, 8 °C; C-SS-2, C-SS-4, C-SS-8 = cold shoulder, muscle Supraspinatus domestic storage at temperatures of 2°, 4°, 8 °C; W-SS-2, W-SS-4, W-SS-8 = warm shoulder, muscle Supraspinatus domestic storage at temperatures of 2°, 4°, 8 °C. ^a,b,c = significant differences for p < 0.05; RMSE = root mean square error.

). The slices of both muscles had the same thickness and were cut perpendicular to the fibers.

The pH for all three temperatures considered did not show abnormal values, with the minimum value observed in the CL muscle aged at a moderate temperature and then stored at 2 °C (5.55), and the maximum in the SS muscle (for both aging types) stored at 8 °C (5.67). This variability indicates that pH slightly increased during the subsequent aging stages, particularly at 8 °C storage. Although this trend was not significant, it could be due to the degradation of proteins by endogenous enzymes, producing free amino acids and alkaline compounds, such as amines and ammonia [22].

Drip loss increased with the length of storage time and depended on the aging system. In both muscles, there was a significant difference between the samples from the C aging compared to W (p = 0.001). The lower water-holding capacity observed immediately after dissection persisted between the two treatments. No difference was found in drip loss in meat stored at 2 °C and 4 °C if it came from C aging. However, if the muscles from the shoulder belonged to W, they showed a progressively significant increase in loss as storage temperature increased from 2 °C to 4 °C and 8 °C, with the maximum average value for the two muscles being 1.92%. The accelerated degradative effect from the higher aging temperatures (W) was not halted at a storage temperature of 4 °C.

Excessive drip loss can negatively affect the appearance of the meat, influencing the consumer’s willingness to purchase the product, and can promote greater microbial growth [46].

Furthermore, protein denaturation exposes previously folded hydrophobic amino acid residues, negatively affecting the protein’s water-binding capacity [22]. As with the muscles analyzed at dissection, no significant differences in cooking loss were observed.

The subsequent vacuum storage further improved the tenderness of the meat, with a significant decrease in shear force values at 8 °C observed for both muscles and both aging methods. The increased proteolysis initiated by the higher temperatures during the aging period continued during storage, showing an acceleration when the meat was stored at 8 °C. The tenderization rate varied depending on the storage temperature but followed a similar pattern for both aging types (W and C) and both muscles. The WBSF values were reduced by approximately 17% compared to the values observed at dissection for muscles stored at 8 °C, 8% at 4 °C, and about 3.5% at 2 °C under vacuum storage.

Sarcomere length did not differ significantly even during vacuum storage at different temperatures). Generally, the sarcomere tended to be longer (p = 0.086) as the storage temperature increased (+9%). This phenomenon became more pronounced in CL muscle from the W aging process, where sarcomere length increased by 12% when moving from 2 °C to 8 °C in domestic storage. These results reflect findings in the literature that suggest sarcomere length results are conflicting across various studies and not always correlated with shear force [16]. Specifically, when sarcomere length is within the range of 2.0–2.5 μm, there is no correlation with meat tenderness, and it remains unaffected by changes in storage temperature, as indicated by Holdstock et al. [47].

Myofibrillar degradation (MFI) became severe at 8 °C storage (Figure 2), particularly for meat from the W aging process. The CL muscle from W aging showed significant differences at 4 °C compared to storage at 2 °C. The effect of temperature (p < 0.001) was significantly more pronounced than the effect of muscle type, which showed no significant differences (p = 0.311). The excessive myofibrillar degradation observed at 8 °C in meat aged at warm temperatures, reaching values as high as 100, led to substantial protein breakdown and inconsistency in meat texture, which could result in low consumer acceptability.

The significant level of myofibrillar degradation observed was accompanied by general oxidation of the meat, as indicated by an increase in malondialdehyde levels (TBArs) with rising storage temperatures. Significant differences (p < 0.001) were observed between 8 °C and the other temperatures across all muscles examined (Figure 3). This trend was particularly evident when the muscles were aged at warm temperatures. Lipid oxidation is characterized by an auto-oxidative process [28]; indeed, the low variations between W and C observed during dissection (Table 3) became more pronounced after an additional five days of domestic storage at 8 °C.

The relationship between oxidation and reduced shelf life at higher storage temperatures, even under vacuum packaging, is well established in the scientific literature [32], underlining the importance of maintaining low temperatures to prevent spoilage and oxidation during storage. Higher temperatures can accelerate these detrimental processes.

The different storage temperatures tested indicate the need to find a balance between oxidative deterioration and the organoleptic improvement obtained through prolonged proteolysis of meat stored at higher temperatures. Achieving the right physical and biochemical balance is fundamental to developing the concept of smart aging.

In a recent study, Yu et al. [21] highlighted, consistent with our findings, that rapid tenderization can be achieved by maintaining the temperature close to 10 °C without subsequently observing any degradative effects or qualitative instability.

The use of a dynamic temperature approach, which involves lowering the cooling room temperature from 9 °C to 3 °C within 24 h, has been shown to enhance meat tenderization, as studied by Nunes et al. [48]. However, this method likely results in higher energy consumption compared to the approach used in this experiment.

Mild aging temperatures and preservation using an alginate coating, followed by vacuum packaging, did not significantly alter the meat color of the two shoulder muscles studied (

Table 6. Effect of the different storage temperatures on color parameters of the CL and SS muscles.

Treatment	L*	a*	b*	Crome	Hue
C-CL-2	39.37	13.37	12.42	18.30	43.12
C-CL-4	38.01	13.75	12.58	18.68	42.41
C-CL-8	38.76	13.95	12.62	18.83	42.45
W-CL-2	40.45 a	12.28	11.41	16.80	43.01 a
W-CL-4	39.13 ab	13.82	11.76	18.15	40.40 ab
W-CL-8	37.53 b	14.01	11.82	18.35	40.12 b
C-SS-2	40.53	12.33	10.78	16.40	41.36
C-SS-4	40.76	12.30	10.49	16.17	40.39
C-SS-8	39.44	12.53	11.30	16.88	42.14
W-SS-2	39.34	12.26	10.59	16.22	40.65
W-SS-4	39.16	12.55	11.05	16.74	41.47
W-SS-8	38.65	13.00	10.84	16.95	39.86
RMSE	2.87	2.06	1.59	2.40	2.74
p-value CL vs. SS	0.278	0.037	0.001	0.006	0.236
p-value C vs. W	0.961	0.918	0.230	0.547	0.183
p-value Temperature	0.662	0.386	0.754	0.491	0.577

C-CL-2, C-CL-4, C-CL-8 = cold shoulder, muscle Caput longum triceps brachii, domestic storage at temperatures of 2°, 4°, 8 °C; W-CL-2, W-CL-4, W-CL-8 = warm shoulder, muscle Caput longum triceps brachii, domestic storage at temperatures of 2°, 4°, 8 °C; C-SS-2, C-SS-4, C-SS-8 = cold shoulder, muscle Supraspinatus domestic storage at temperatures of 2°, 4°, 8 °C; W-SS-2, W-SS-4, W-SS-8 = warm shoulder, muscle Supraspinatus domestic storage at temperatures of 2°, 4°, 8 °C. L* = lightness, a* = redness, b* = yellowness. ^a,b = significantly different for p < 0.05; RMSE = root mean square error.

). Values for lightness, redness, yellowness, chroma, and hue showed no significant differences due to the storage temperature after dissection, except for the CL muscle from the W aging type, which exhibited a significant decrease in lightness and hue at 8 °C. This reduction in lightness and hue is likely due to enhanced oxidative processes during storage, as increased temperatures can accelerate oxidation and color changes in meat [49]. Research has shown that meat color stability is highly dependent on storage conditions, including temperature and packaging. Oxidation can lead to myoglobin denaturation and discoloration, especially at higher storage temperatures [38]. The decrease in lightness and hue observed in the CL muscle aged at 8 °C aligns with findings that oxidative instability can be more pronounced in muscles with higher volumes and varying anatomical portions [39]. Proper management of storage temperature is crucial in maintaining the desired color stability and overall quality of meat during aging.

3.3. Sensory Test Results

Tenderness, juiciness, and flavor are currently the primary attributes of beef palatability, with tenderness being considered the most influential factor for beef palatability [18]. The sensory characteristics perceived by the panelists did not differ significantly between muscles (

Table 7. Effect of the different aging temperatures on sensory quality of CL and SS muscles.

	CL		SS		p-Value
	Cold	Warm	Cold	Warm	CL vs. SS	C vs. W	RMSE
Tenderness	4.59 b	5.25 a	3.76 b	4.52 a	0.079	0.027	0.69
Juiciness	4.85 b	5.39 a	4.77 b	5.26 a	0.452	0.034	0.50
Flavor	4.85	5.13	4.90	5.09	0.626	0.462	0.82

CL = Caput longum triceps brachii; SS = Supraspinatus; C = cold aging; W = warm aging. ^a,b = significant differences for p < 0.05; RMSE = root mean square error.

). However, there was a tendency (p = 0.079) for the CL muscle to be perceived as more tender. The aging temperature did not significantly affect the flavor of the meat, likely due to greater variability in the data. Flavor is a multi-component olfactory sensation, influenced by free fatty acids and other molecules, such as peptides or oxidation and cooking products [50]. Flavor sensations depend on numerous factors that can be contrasting, and panelists may weigh them differently, resulting in varied judgments.

It is noteworthy that the addition of the external coating based on salt and calcium chloride did not cause any olfactory changes, and the higher temperature did not accentuate oxidation or off-flavors. However, the aging temperature significantly affected tenderness (Table 7 and

Table 8. Effect of the different domestic storage temperatures on sensory quality of the CL and SS muscles.

Treatment	Tenderness	Juiciness	Flavor
C-CL-2	4.82	4.99	4.98
C-CL-4	5.09	4.81	5.13
C-CL-8	5.44	5.48	5.24
W-CL-2	5.51 b	5.38 b	4.93 b
W-CL-4	6.05 ab	5.44 ab	5.11 ab
W-CL-8	6.35 a	6.25 a	5.60 a
C-SS-2	3.91	4.55	4.48
C-SS-4	4.06	4.71	4.50
C-SS-8	4.12	5.01	4.78
W-SS-2	4.70 b	4.90	4.63 b
W-SS-4	4.93 ab	5.10	4.75 a
W-SS-8	5.34 a	5.54	5.05 a
RMSE	0.75	0.78	0.66
p-value CL vs. SS	0.001	0.118	0.121
p-value C vs. W	0.001	0.008	0.043
p-value Temperatures	0.001	0.053	0.032

C-CL-2, C-CL-4, C-CL-8 = cold shoulder, muscle Caput longum triceps brachii, domestic storage at temperatures of 2°, 4°, 8 °C; W-CL-2, W-CL-4, W-CL-8 = warm shoulder, muscle Caput longum triceps brachii, domestic storage at temperatures of 2°, 4°, 8 °C; C-SS-2, C-SS-4, C-SS-8 = cold shoulder, muscle Supraspinatus domestic storage at temperatures of 2°, 4°, 8 °C; W-SS-2, W-SS-4, W-SS-8 = warm shoulder, muscle Supraspinatus domestic storage at temperatures of 2°, 4°, 8 °C. ^a,b = significant differences for p < 0.05; RMSE = root mean square error.

). Tenderness is defined as the ease with which the consumer can chew and is considered the primary factor influencing perceived quality. It is strongly correlated with the shear force measured instrumentally but is also driven by sensations originating from the chemical composition of the meat, such as collagen and fat content, as well as granularity [51].

The average tenderness value expressed by the panelists was higher in meat aged at warm (8 °C) temperatures (p = 0.027). This aligns with the proteolytic action on myofibrillar degradation, as previously discussed in relation to the shear force value.

Juiciness also showed significant differences between the two aging methods (p = 0.034). Despite greater fluid loss being recorded with one aging method (W), this did not affect the sensation of juiciness, likely because there were no significant differences in cooking loss. Juiciness refers to the amount of fluid released from the meat, as well as the saliva stimulated during chewing [51]. It is influenced not only by the presence of liquids and fat in the meat but also by tenderness, a phenomenon known as the “halo effect” [39]. Additionally, it has been found that juiciness increases with proteolysis and the early activation of calpain-2 [52].

The sensory characteristics were also studied in meat stored at different temperatures after dissection (Table 8). Post-dissection, the two muscles showed significant differences in tenderness (p < 0.001). The CL muscle was found to be more tender than the SS muscle. This sensation is likely correlated with the greater abundance of collagen fibers in the SS muscle, which contains more epimysial, perimysial, and endomysial connective tissue [53], resulting in greater toughness.

Therefore, Ree et al. [54] highlighted, through the analysis of 11 different muscles from the carcass, that there are substantial differences among muscles regarding the tenderization process. These differences depend on muscle globularity, the presence of fat infiltration, and likely the varying metabolism of glycolytic and oxidative fibers. The Caput longum triceps brachii is perceived as more tender compared to the Supraspinatus muscle, which is confirmed by our data.

The other two parameters evaluated did not show significant differences between the muscles. The effect of aging temperature also had a significant impact on subsequent storage, with differences being more attributable to the aging process itself than to the subsequent vacuum storage process. In fact, when considering the meat from the two muscles aged in group C, there were no significant differences in tenderness, juiciness, and flavor at different storage temperatures for both the CL and SS muscles.

The sensory analysis successfully highlighted differences between the meat aged at 2 °C compared to that aged at 8 °C, but it did not significantly detect differences due to the varying storage temperatures within the group. Generally, while sensory evaluation remains a valuable investigative tool, as it consolidates various sensory perceptions into a single judgment, it tends to reduce the significant differences perceived instrumentally, bringing the data closer to the average [55].

For the meat aged at 8 °C (W), the effect of subsequent storage temperatures was evident in both muscles, particularly for tenderness, flavor, and juiciness. However, for juiciness, the Supraspinatus muscle did not show significant differences between the different temperatures, even with aging at 8 °C. The proteolytic process, which was more strongly activated in the shoulder muscles with W aging, during the first 5 days of aging continued clearly at storage temperatures of 4 °C and 8 °C. At 2 °C, it appears that the proteolytic process initiated during aging was halted. The increased proteolysis in the W muscles stored at temperatures above 2 °C also affected the flavor due to the formation of peptides and free amino acids, along with the previously mentioned “halo effect” associated with tenderization.

The radar chart (Figure 4) clearly highlights the impact of aging type on sensory characteristics. Meat from both muscles aged at moderate temperatures exhibits greater tenderness, juiciness, and enhanced flavor, particularly when subsequently stored at 8 °C. However, sensory perception does not always account for proteolytic and lipolytic processes, which may have detrimental effects. The formation of peptides and free fatty acids imparts an olfactory bouquet to the product, enhancing the organoleptic profile but limiting the shelf life [56]. The chart also demonstrates that the CL muscle aged using the W method and stored at 4 °C displays desirable sensory characteristics with superior preservation qualities.

4. Conclusions

This study demonstrates that aging beef carcasses at mild temperatures can be an effective strategy to improve the sustainability of meat production. By maintaining the aging process at 8 °C, meat tenderness and juiciness were significantly enhanced due to increased proteolytic activity, while still adhering to microbiological safety standards. The mild aging temperature also led to a more efficient use of energy compared to traditional near-freezing aging processes, potentially offering an environmentally friendly alternative that reduces the overall energy consumption in meat production.

However, it was observed that the subsequent storage temperature plays a crucial role in preserving meat quality. Storage temperatures should not exceed 4 °C post-dissection to prevent rapid lipid oxidation and maintain optimal sensory qualities, such as flavor and juiciness. This study confirmed that while aging at mild temperatures can accelerate tenderization, it is essential to find a balance between the benefits of proteolysis and the risk of oxidative deterioration to ensure meat quality and safety.

Overall, this approach to beef aging provides a promising method for achieving high-quality meat while reducing the carbon footprint of the meat industry. Further research into refining these methods and understanding their implications across different types of meat and storage conditions could enhance their application in sustainable meat production.