Chemical Composition of the “Galo de Barcelos” (Barcelos Rooster Raw Meat)

Simple Summary The assessment of traditional products is important for the sustainability of agricultural systems and the preservation of a unique gastronomic heritage. The present study aims to determine the chemical composition of “Galo de “Barcelos”” (“Barcelos” Rooster) raw meat, used in the preparation of the typical Portuguese dish “Roasted Rooster from “Barcelos””, in order to evaluate and protect this gastronomic and cultural tradition. The influence of the genotype on the final product was verified, concerning total protein, and fat contents, and a favorable ratio of n-6/n-3 fatty acids of the Sasso line was compared to the “Amarela” breed, contributing to the promotion of its gastronomic potential. Abstract Ten roosters produced according to “Barcelos Confraria” rules and ten roosters of autochthonous “Amarela” breed, reared on a similar traditional production system, were analyzed, and the chemical profile of two of the most significant meat portions, breast and drumstick, was determined. The results demonstrated that the “Barcelos” rooster raw meat is rich in proteins (22.3%) and fat (4.31%), particularly in monounsaturated fatty acids (39.1%). Significant differences (p ≤ 0.01) were observed, with the breast having a higher protein content (25.1 vs. 19.7%) and less fat (1.9% vs. 6.7%), compared to the drumstick. The fatty acid profile revealed (SFA 30.0%, MUFA 39.1%, and PUFA 24.6%) a similar composition to the roosters reared in the traditional or organic production systems, such as the “Amarela” autochthonous rooster. The “Barcelos” rooster can be regarded as a highly nutritional meat, with an interesting chemical profile ensuring a high-quality traditional product to consumers.


Introduction
Meat is one of the most nutritious foods, and poultry meat is known for its nutritional quality as it contains a significant amount of high-quality proteins, is highly digestible, has a high content of vitamins and minerals, and has a low portion of saturated fat.
Chicken meat is highly recommended for all age groups, and its consumption has been privileged by consumers, causing a significant increase in its production [1,2]. In Portugal, in 2018, poultry meat consumption per capita (kg/inhabitant) was 42.8 kg/inhabitant/year, the second-most consumed meat, after pork (about 44.7 kg/inhabitant/year) [3].

Analytical Determinations
The chemical composition of the roosters' breast and drumstick portions was determined. The meat samples were prepared in the laboratory, consisting of the removal of the skin and bones and then homogenization for 2 min (Grindomix GM200, Retsch, Haan, Germany). The parameters were determined in duplicate according to the AOAC [14].
The pH of the samples was measured using a digital portable pH-meter (FC2022/ HALO TM , Hanna Instruments, Eibar, Spain) equipped with a penetration probe, according to the ISO 2917:1974 method [15]. Moisture, following the drying method up to a constant weight at 105 • C in a stove, was quantified according to the ISO recommended standard 1442:1997 [16]. Ash content was estimated via incineration (muffle B150, Nabertherm, Germany) of the samples, for 6 h and at a temperature of 550 • C ± 25 • C, according to ISO 936:1998 method [17].
The total fat content was quantified following the Soxhlet (behr ED) method with ether petroleum solvent. The fatty acid profile was determined according to the procedure described by Cruz et al. [20], after the extraction of the fat with nonhalogenated organic solvents, followed by methylation with 0.5 M potassium hydroxide and boron trifluoride in methanol, and separation in a CP-Select FAME chromatographic column (100 m, Agilent, Santa Clara, CA, USA), with adequate calibration standards.

Statistical Analysis
An analysis of variance was performed on meat quality data using the IBM SPSS Statistics Base 22.0 for Windows. Descriptive statistics were generated for all the variables in the dataset. The analysis was carried out using a t-test of independent samples with variable grouping of breast and drumstick portions.

Carcass Traits Evaluation
The carcass characteristics of the "Barcelos" and "Amarela" roosters are shown in Table 1. The BW and CW showed higher values (p ≤ 0.001) in the roosters of the Sasso line than those of the "Amarela" breed, at the same age. Table 1. The carcass characteristics of the "Barcelos" and "Amarela" roosters (average ± SD, Min and Max).  364.00 *** SD-standard deviation; Min-minimum; and Max-maximum. LW, live weight at slaughter; CW1, bled and plucked carcass weight; CW2, eviscerated carcass, with head, feet, and edible viscera weight; CW3, eviscerated carcass, without head, feet, and edible viscera weight; and EW, edible viscera weight (head, feet, gizzard, heart, liver, and kidneys). B*A column indicates significant differences for the same parameters between the "Barcelos" and "Amarela" genotypes. *** (p ≤ 0.001).

Chemical Composition of the Roosters Raw Meat
The chemical composition of the "Barcelos" and "Amarela" roosters, expressed in fresh meat weight percentage, is shown in Table 2. Table 2. Effect of breed and rooster pieces, breast, and drumstick in the chemical composition of "Barcelos" and "Amarela" roosters (expressed in % weight of fresh meat) (mean ± SD, Min and Max).

Drumstick and Breast Chemical Composition
Results regarding the proximate composition analysis showed that, in both groups of rooster origin, drumstick meat had higher values for total fat (p ≤ 0.001), as well as pH (p ≤ 0.001) and protein (p ≤ 0.001) contents, when compared to the breast meat (Table 2). "Amarela" roosters presented lower breast moisture (p ≤ 0.01) content in comparison with drumstick meat.

Discussion
The genotype and production system, particularly outdoor production, affect many aspects of the overall quality of poultry products, including nutrient content and functional properties [21,22]. Our results were in accordance with different studies presenting similar genotypes and production systems, such as Sasso line roosters and autochthonous breeds capons and roosters, produced in a traditional system [8,[21][22][23][24].
The pH values were similar to those observed in roosters, capons, or other native breeds of chickens, by different authors [25,26]. Values may be affected by different intrinsic Animals 2022, 12, 1556 7 of 11 factors, such as age (at slaughter), genotype (breed), and sex, with particular influence in the sensorial and technological characteristics of meat [25][26][27].
Lower pH values are related to the production system, extensive or organic, due to better welfare conditions that reduced pre-slaughter stress and, therefore, glycogen consumption. Stress plays a key role in pH rate decline: short-term stress before slaughter increases the in vivo metabolic rate and influences the perimortem metabolism of the animal [21,28].
Differences (p ≤ 0.001) in the pH values found in the drumstick and breast could be explained by the unequal activity of each muscle, with a higher concentration of glycogen and less activity in the muscle with lower pH values [29,30]. Animal physical activity can change the metabolic characteristics of the muscles, increasing the muscle oxidative capacity, with the pyruvate aerobic enhancement causing a sparing of glycogen. The hypothetically greater availability of glycogen, and the predominance of oxidative muscles in the drumstick and glycolytic muscles in the breast, could explain the pH values observed [23,29,31].
Moisture is also affected by genotype and slaughtering age [25,32,33]. More moisture could indicate a less physiologically mature state, and concerning the age effect, in general, with increasing age, the level of moisture decreased in meat. A lower moisture percentage observed in our study, compared to broilers or indigenous breeds, may be due to rooster slaughter age (more than 120 days old) and genotype [24,29,34]. Statistically significant differences (p ≤ 0.05) in moisture content between drumstick and breast were verified, inside the range of values reported by other authors [24,34,35]. Similar mean values of moisture content in pectoralis major muscle (74%) were obtained, within the range of values described by [29,[31][32][33], in autochthonous breeds and improved hybrids commercial breeds for meat production.
The ash content was similar to the ash contents observed in previous studies for Portuguese autochthonous breeds or other indigenous breeds. Other authors present slightly higher ash contents, including in native breeds, and the differences could be due to the lack of standardization in the productive performances and meat quality traits of the animals [23,25,30,33].
Concerning protein, our results were very similar to those described in the literature for autochthonous breeds and broilers [30,33,35,36]. The effect of the genotype was observed, in accordance with different studies with indigenous breeds, not submitted to genetic selection for productive performance and meat quality characteristics, presenting greater variability when compared to commercially used hybrids [33,[35][36][37].
Age (tissue protein deposition persisting after 150 days old [31]), genotype, rearing system, and feeding system had a significant effect on muscle development (protein content of drumstick and breast) [25,29,33,38]. Protein content in autochthonous breeds [24,29,32,37,39] or in commercial settings [38,40] reaches, within the range obtained by both cuts, the highest values in the breast, in accordance with our results.
Poultry meat is known for its low fat because, unlike other meat animals, fat is mainly deposited subcutaneously or in the abdomen, rather than in the meat. In the present study, fat content differences were observed between genotypes, with similar values to those in autochthonous breeds [24,33,37,40] or a free-range system [28,41].
According to different authors, lipid content in the muscle is influenced by age and genotype, diet composition, and environment [42,43]. Drumstick meat had significantly more fat than breast meat, which is leaner (typically < 2 g fat/100 g) than other meats and supplies high-quality protein. Breast meat has low-fat content due to the reduced need to store energy [39,43], as observed in our study.
In the second week of life, approximately 36 and 35% of lean meat is located in the breast and legs, respectively, and as chickens grow, the percentage of lean tissue increases to 44% in breast and reduces to 32% in drumsticks, relative to total carcass lean tissue [43,44]. A greater motion reduced the abdominal fat yield of chickens, in the free-range system, and favored muscle mass development [32,45].
Lipids are important constituents of the diet because, in addition to their high energy values, they provide fat-soluble vitamins and essential fatty acids [46]. In an intensive system of mass production, stress increase, and deterioration of broiler carcass quality and meat characteristics. Under a high rearing density, high levels of heat and ammonia are produced and are associated with excessive production of reactive oxygen species, which reduce the immune function and antioxidant activities [47]. Poultry meat has been considered one of the main sources of PUFA, particularly n-3 PUFA, for human diets [47,48].
According to different authors [24,41,49], high levels of polyunsaturated, n-3 PUFA, and SFA total contents are obtained in the breast meat of organically produced animals, slightly higher than those obtained in the present study.
Similar results were observed by [50], concerning saturated, monounsaturated, and PUFA contents of chicken breast meat from conventional and organic farms. Breast meat from birds with free access to pasture presents lower levels of the n-6 and n-3 fatty acid precursors linoleic acid (18:2n-6) and alpha-linolenic acid (18:3n-3), respectively. Fatty acid profile is related to rearing methods [50,51], diet composition, and dietary changes, so farm fodder in organic systems can be used to modify the proportion of PUFA.
"Barcelos" and "Amarela" roosters were characterized by high proportions of individual and total n-3 fatty acids and a favorable n-6/n-3 fatty acid ratio. In autochthonous populations, breed and feeding significantly affect fatty acid content (lower SFA, n-6/n-3 ratio, and higher PUFA and P/S ratio), presenting a favorable fatty acid profile [25,29], as observed in our study. In native breeds, the mechanism implicated in the incorporation of long PUFA in the muscles is more efficient, and the PUFA content depends on its process of elongation/desaturation [24].

Conclusions
Poultry meat contributes to human nutrition by providing high-quality protein and low levels of fat, with a desirable fatty acid profile, and consumers are increasingly demanding poultry meat products.
To guarantee authenticity, and to protect, qualify, and promote the traditional "Barcelos rooster" dish, chemical and sensorial characterization is mandatory. The influence of the genotype must be considered as a relevant factor in the "Barcelos Rooster" qualification, in particular due to the significantly higher total fat and protein contents, and the favorable n-6/n-3 fatty acid ratio of Sasso line, in comparison with "Amarela" authoctonous rooster bred in some traditional production systems.
After characterizing the production system and obtaining a product similar to that of native animal genotypes, further studies are needed in the sensorial and in the the confection process characterization, with a view to their qualification.