Nutritional Values, Physicochemical and Microbiological Properties of Turkey Thigh Muscle—Effect of Wild Garlic (Allinum ursinum L.) Supplementation

Abstract

The current study assessed the impact of adding wild garlic (Allinum ursinum L.) to the diets of turkeys on the physicochemical and microbiological properties as well as the fatty acid profile and antioxidant potential of thigh muscle. The tested materials were thigh muscle from 40 turkeys (Big-6 type) divided into two groups (P1—control group and P2—sample supplemented with wild garlic at a level of 0.2% in the feed mixture). Measurements of chemical composition, pH, water activity, color, total heme pigments, lipid oxidation, and microbiological analysis (Enterobacteriaceae, E. coli, Salmonella spp., L. monocytogenes) showed that the addition of wild garlic to a turkey diet did not affect thigh meat quality. The effect of adding wild garlic (Allinum ursinum L.) to the diets of turkeys on the antioxidant potential (against the DPPH radical) and fatty acid profile of the thigh muscle was noted. Thigh muscles obtained from turkeys reared in group P2 were characterized by a significantly higher PUFA content compared to meat from the control group. Further studies should consider turkey diet supplementation with a higher level of wild garlic and an in-depth analysis of meat quality.

1. Introduction

In recent decades, there has been a significant increase in global poultry meat consumption, which is associated with, among other things, changes in consumer eating habits and lower prices of poultry meat compared to red meat. Therefore, the poultry market has been growing steadily in recent years. Turkey is the second most popular poultry. In order to meet the growing demand and expectations of the market, poultry production is developing, which results in a constant expansion of the range of poultry meat and processed products [1,2]. Adjusting production conditions to market expectations is facilitated by the modification of poultry breeding programs, leading to shorter breeding times, improved performance of birds, and increased meat quality. In this context, environmentally friendly feed additives are sought as an alternative to withdrawn antibiotics [3,4,5]. The most important of such additives include herbs and plant extracts, probiotics, prebiotics, synbiotics, and organic acids [6,7,8,9].

Feed components have a great effect on animal health and meat quality [10]. Supplementing the diet with herbs and herbal extracts is a simple method to improve both productivity and maintain animal health, but it is also a valuable and natural method to increase the nutritional value of meat. This is because herbs are a natural and valuable source of bioactive ingredients, which, when taken with feed, increase, among others, the antioxidant potential of animal raw materials [11]. Several studies have suggested that garlic and its products are valuable ingredients in animal feeding, either in the feed or in the drinking water in different forms [12,13,14,15]. The aim of most research is to assess the impact of dietary garlic on the production performance parameters of poultry [14,15], the effect on the immune response [12,16,17], and the effect on the antioxidant status and blood parameters of birds [12,13,14]. Few studies are concerned with the impact of dietary supplementation of poultry with garlic on the quality of meat. Moreover, no studies were found regarding the effect of dietary supplementation of turkeys with wild garlic on the quality of meat.

The key bioactive component in both wild garlic (Allium ursinum L.) and garlic (Allium sativum L.) is allicin (diallylthiosulfinate), which has antimicrobial, nematocidal, and anthelmintic properties [18]. As indicated by Stupar et al. [19], wild garlic exhibits antibacterial activity against many Gram-positive and Gram-negative bacteria and also exhibits antifungal, antiviral, and antiparasitic properties [18,20]. According to some authors [21], its covalent interaction with thiol groups of metalloproteins is responsible for the mechanism of the antibacterial action of allicin. The properties of wild garlic are used in the production of food and dishes as a flavor additive and to increase the nutritional value of food [22,23,24,25,26]. As stated by Markham [27], wild garlic (Allium ursinum) tastes like garlic, but it is grassier. The aroma and pharmacological properties of wild garlic are mainly attributed to the phytochemicals containing sulfur atoms, primarily cysteine sulfoxides (CSOs) [28]. Moreover, wild garlic is a very valuable raw material due to its vitamins (C, E, A), minerals (P, Mg, K, Fe, Mn, Zn, S, Se), and glutamyl peptide content [29]. As previously reported, the leaves of wild garlic are a rich source of compounds with antioxidant properties, mainly kaempferol derivatives, carotenoids, and glutathione, as well as the antioxidant enzymes catalase and glutathione peroxidase [23]. According to Preuss et al. [30], wild garlic (Allium ursinum) has a greater effect on blood pressure and blood chemistries of rats compared to regular garlic (Allium sativum). As for other interactions, wild garlic decreased total cholesterol significantly and tended to increase HDL compared to regular garlic.

In this context, wild garlic has been associated with the prevention and treatment of several diseases in humans [18]. In the case of animals, the addition of garlic to livestock feed has been associated with reduced disease incidence in pigs [31] and lower enteric methane production in cattle [32]. The lack of research in the available literature on the use of wild garlic in turkey feeding was the inspiration for conducting this experiment. Its aim was to determine the impact of adding wild garlic to the diet of turkeys on the nutritional value and the physicochemical and microbiological properties of thigh muscle. We hypothesized that the introduction of dried wild garlic supplementation in turkey diets would improve meat quality, in particular, antioxidant potential and microbiological quality.

2. Materials and Methods

2.1. Tissue Samples Collection

The experiment was conducted on thigh muscle from 40 female turkeys (Big-6 type) divided into two equinumerous groups (P1 and P2). Each group consisted of 20 turkeys. The birds were kept on a farm located in Hadynów in the Olszanka commune in extensive rearing with free access to grass.

The birds were fed in accordance with the nutritional recommendations [33]. The rearing comprised six feeding periods: 1–3 weeks, 4–9 weeks, 10–13 weeks, 14–15 weeks, 16–19 weeks, and 20–25 weeks. Both groups of birds, P1 and P2, received complete feed rations based on wheat, wheat bran, sunflower meal, rapeseed meal, soybean meal, barley, and soybean oil, together with mineral and vitamin supplements (Table S1).

Turkeys from group P2 received feed supplemented with dried wild garlic at a level of 0.2% in the feed mixture. Wild garlic was added to the feed mixture from the 3rd to the 20th week of breeding. The birds were slaughtered after the 25th week of rearing using a standard procedure at a slaughterhouse in Stasin, located in the Masovian Voivodeship. The slaughter weight of the turkeys was about 6.5 kg. The time and temperature of carcass cooling were 24 h at 4 °C, respectively. After cooling, the carcasses were divided into basic parts. The thighs were selected for testing. Thigh muscles were obtained by separating them from the bones.

2.2. Sample Preparation for Analysis

The thigh muscles were vacuum-packed in PA/PE bags (Edesa VAC-6 T, Edesa HoReCa, Sp. z o.o., Czosnów, Poland) and then were transported at a temperature of 4 °C to the laboratory. At 2 days postmortem, the samples were analyzed, taking into account chemical composition, pH, aw, color parameters, TBARS, total heme pigments, antioxidant potential, and fatty acid profiles, as well as microbial analysis. Analyses were also carried out on vacuum-packed thigh muscle samples stored for 10 days at a temperature of 4 °C. The experimental design is shown in Figure 1.

2.3. Chemical Composition Analysis

The composition analysis of turkey meat (collagen, moisture, protein, and fat) was determined using a Food Scan Lab 78,810 (Foss Tecator Co., Ltd., Hillerod, Denmark).

2.4. Microbiological Analyses

The original TEMPO^® tests and the TEMPO^® LAB automated microbial counting system (Biomerieux, TEMPO^® System, Marcyl’Etoile, France) were used to determine the number of Enterobacteriaceae and E. coli in turkey thigh muscles. The following incubation parameters were used: time—22–27 h, temperature—35 °C. The number of Enterobacteriaceae, E. coli, was presented in a log CFU g⁻¹. The presence of L. monocytogenes and Salmonella spp. in 25 g of the sample was analyzed at Agrolab Polska Sp. z o. o. (Dęblin, Poland) [34,35].

2.5. Physicochemical Parameters—Substances Reactive to 2-Thiobarbituric Acid (TBARS), Total Heme Pigments, Water Activity (a_w), pH, Color Parameters

The quantification of compounds reacting with thiobarbituric acid (TBARS) was conducted following the procedure described by Pikul et al. [36], with perchloric acid used as the solvent. Absorbance was measured at 532 nm using a UV spectrophotometer (Nicolet Evolution 300, Thermo Electron Corp., Waltham, MA, USA). The results were presented as mg of malondialdehyde (MDA) per kilogram of sample. The total heme pigments in meat were determined following the analytical conditions described by Hornsey [37] with a slight modification described in a previous study [38]. The results were calculated according to the procedure by Lee et al. [39] and expressed in mg kg⁻¹. The water activity (a_w) was measured using a water activity analyzer (Novasina AG, Lachen, Switzerland). The analyzer had been calibrated with Novasina SAL-T humidity standards (33%, 75%, 84%, and 90% relative humidity). For pH measurement, a digital pH meter CPC-501 (Elmetron, Zabrze, Poland) equipped with a temperature sensor and pH electrode (ERH-111, Hydromet, Gliwice, Poland) was used. The pH measurement was performed on a homogenate of minced meat and distilled water (1:5 ratio) prepared just before the measurement. An X-Rite 8200 colorimeter (X-Rite, Inc., Grand Rapids, MI, USA) calibrated using the black glasses and white tiles was used for color parameter measurements. The measurement was made on the cross-section of the meat sample (10 mm thick) immediately after cutting. The instrumental conditions were a 12 mm diameter area aperture. The measurement was carried out in the range of 360 to 740 nm. The illuminant D65 and a 10° standard colorimetric observer were used as a source of light. The results were expressed in units of the CIE LAB [40] system.

2.6. Determination of Antioxidant Potential

The antioxidant capacity of the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,20-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt was carried out according to a previous method [41]. The samples’ ability to scavenge ABTS*+ and DPPH free radicals was assessed by comparing the results to a Trolox standard curve. The results were expressed in mg g⁻¹ of product.

2.7. Fatty Acid Profile Measurements and Lipid Quality Indicators Calculation

Fatty acid analyses were carried out using a gas chromatograph (Varian 450-GC, Walnut Creek, CA, USA) following the conditions reported by Kononiuk and Karwowska [42]. Among the identified fatty acids, the following fatty acids groups were distinguished: ΣSFA (Saturated fatty acids), ΣMUFA (Monounsaturated fatty acids), ΣPUFA (Polyunsaturated fatty acids), ΣPUFA n-3 (Polyunsaturated fatty acids n-3), ΣPUFA n-6 (Polyunsaturated fatty acids n-6), ΣPUFA n-3/ΣPUFA, ΣUFA/ΣSFA, and ΣPUFA/ΣSFA. Lipid quality indicators (AI—atherogenic index; TI—thrombogenic index) were calculated according to Goluch et al. [43].

2.8. Statistical Analysis

The data obtained were subjected to statistical analysis using Statistica software version 9.1 (StatSoft, Krakow, Poland). The Shapiro–Wilk test was carried out to verify the normality of the variable distributions in the groups. The experimental groups were compared using ANOVA and post-hoc Tukey’s test (at p ≤ 0.05). The results were presented as mean ± standard deviation.

3. Results

3.1. Chemical Composition

Analysis of the basic chemical composition of turkey thigh muscles did not show a statistically significant effect of nutrition on fat, protein, moisture, and collagen content (

Table 1. Chemical composition of turkey thigh muscles.

Compound [%]	P1	P2	F-Value	p-Value
Fat	4.71 ± 0.68	5.30 ± 0.75	1.36	0.28
Protein	22.12 ± 0.28	21.57 ± 0.51	3.54	0.11
Moisture	73.31 ± 0.52	72.94 ± 0.27	1.58	0.26
Collagen	1.10 ± 0.13	1.11 ± 0.07	0.04	0.08

P1—control sample; P2—sample supplemented with wild garlic. No statistically significant differences were found between the samples.

). The average content of analyzed chemical components in the muscles from the control group (P1) and supplemented with wild garlic (P2) was 4.71 and 5.30% fat, 21.57 and 22.12% protein, and 72.94 and 73.31% moisture, respectively.

3.2. Results of Microbiological Analysis

Statistical analysis of the microbiological test results did not show any effect of wild garlic supplementation in turkeys on the number of Enterobacteriaceae, E. coli, Salmonella, and L. monocytogenes in thigh muscles (

Table 2. Results of the microbiological analysis of turkey thigh muscles.

	Day	P1	P2	P1 vs. P2		Day 1 vs. Day 10		Interaction
				F-Value	p-Value	F-Value	p-Value	F-Value	p-Value
Enterobacteriaceae [log CFU g−1]	1	3.22 ± 0.23 a	3.20 ± 0.38 a	0.02	0.887	722.0	<0.001	0.03	0.862
	10	6.19 ± 0.36 b	6.18 ± 0.39 b
E. coli [log CFU g−1]	1	2.75 ± 0.21 a	2.61 ± 0.35 a	0.29	0.594	16.7	<0.001	0.36	0.552
	10	2.71 ± 0.68 a	2.65 ± 0.52 a
Salmonella [CFU g−1]	1	<10	<10	_	_	_	_	_	_
	10	<10	<10
Listeria monocytogenes [CFU g−1]	1	<10	<10	_	_	_	_	_	_
	10	<10	<10

P1—control sample; P2—sample supplemented with wild garlic. ^a,b Values in rows with different letters are significantly different at p ≤ 0.05.

). The number of analyzed microorganisms did not change significantly during the 10-day storage, except for Enterobacteriaceae. In the case of Enterobacteriaceae, a significant increase in the number of this group of microorganisms was observed from ≈3.20 log CFU g⁻¹ to ≈6.20 log CFU g⁻¹. Analysis for the presence of Listeria monocytogenes and Salmonella spp. did not reveal the presence of these pathogens in the turkey thigh muscles at the beginning (Day 1) and at the end of the experiment (Day 10).

3.3. Basic Technological Parameters

Based on the findings of the physicochemical analysis, it was observed that wild garlic added to the diet of turkey did not cause statistically significant differences in the evaluated parameters (

Table 3. Basic technological parameters of turkey thigh muscles.

	Day	P1	P2	P1 vs. P2		Day 1 vs. Day 10		Interaction
				F-Value	p-Value	F-Value	p-Value	F-Value	p-Value
TBARS [mg MDA kg−1]	1	0.57 ± 0.05 a	0.51 ± 0.02 a	1.22	0.274	147.8	<0.001	0.98	0.326
	10	0.91 ± 0.13 b	0.76 ± 0.07 b
Total heme pigments [mg kg−1]	1	84.25 ± 6.43 a	82.82 ± 8.85 a	0.45	0.506	2.13	0.149	1.67	0.201
	10	83.84 ± 9.69 a	86.43 ± 10.55 a
pH	1	6.14 ± 0.11 a	5.95 ± 0.12 a	9.85	0.003	0.77	0.384	1.22	0.274
	10	6.23 ± 0.09 a	6.14 ± 0.17 a
aw	1	0.979 ± 0.004 a	0.987 ± 0.007 a	0.11	0.741	89.4	<0.001	0.03	0.857
	10	0.992 ± 0.005 a	0.998 ± 0.005 a
L*	1	48.97 ± 3.55 a	46.95 ± 4.83 a	0.87	0.356	4.95	0.031	1.23	0.273
	10	46.21 ± 3.88 a	48.05 ± 3.68 a
a*	1	7.89 ± 1.09 a	7.79 ± 2.43 a	7.32	0.009	12.4	<0.001	3.89	0.049
	10	7.41 ± 2.82 a	6.56 ± 2.87 a
b*	1	11.13 ± 1.49 a	9.92 ± 1.77 a	1.05	0.310	8.76	0.005	0.45	0.505
	10	10.05 ± 1.48 a	10.42 ± 3.00 a
h*	1	13.69 ± 1.37 a	12.74 ± 2.38 a	0.33	0.567	6.44	0.014	1.98	0.165
	10	12.59 ± 2.70 a	12.41 ± 3.82 a
C*	1	54.51 ± 5.19 a	52.25 ± 8.30 a	5.12	0.028	10.2	<0.001	2.01	0.163
	10	54.72 ± 7.20 a	58.12 ± 7.71 a

P1—control sample; P2—sample supplemented with wild garlic. ^a,b Values with different letters are significantly different at p ≤ 0.05.

). For most of the parameters assessed, no significant effect of storage time was found. The exception was the TBARS index, the value of which increased significantly on day 10 compared to day 1 for both samples P1 and P2. Despite the changes observed during storage, TBARS values were relatively low and did not exceed 1 mg MDA/kg on day 10. Turkey thigh muscles were characterized by a total heme pigments ranged from 82.82 mg kg⁻¹ for P2 on day 1 to 86.42 mg kg⁻¹ for the same sample on day 10. The pH value of the thigh muscles ranged from 5.95 for the P2 sample on day 1 to 6.23 for the P1 sample on day 10. The pH value was not significantly influenced by the storage time. The water activity and color parameters of the thigh muscles did not differ significantly between samples and with storage time. Although ANOVA initially shows significant differences, the more restrictive post hoc test does not confirm differences between group pairs. For most of the parameters assessed, no significant effect of storage time was found.

3.4. Antioxidants Potential

The results of measuring the antioxidant activity of turkey meat showed statistically significant differences (p ≤ 0.05) between the control meat sample and the sample supplemented with wild garlic (

Table 4. Antioxidants potential of turkey thigh muscles.

	Day	P1	P2	P1 vs. P2		Day 1 vs. Day 10		Interaction
				F-Value	p-Value	F-Value	p-Value	F-Value	p-Value
ABTS [mg Trolox eqv. g−1]	1	0.13 ± 0.01 b	0.06 ± 0.01 a	48.7	<0.001	0.92	0.343	25.3	<0.001
	10	0.12 ± 0.01 b	0.07 ± 0.01 a
DPPH [mg Trolox eqv. g−1]	1	0.13 ± 0.01 a	0.14 ± 0.01 a	12.5	0.001	890.2	<0.001	15.8	<0.001
	10	0.02 ± 0.02 b	0.06 ± 0.03 b

P1—control sample; P2—sample supplemented with wild garlic. ^a,b Values with different letters are significantly different at p ≤ 0.05.

). Turkey thigh muscles from the control group were characterized by significantly higher antioxidant potential against ABTS radical on both days 1 and 10, while the analysis of antioxidant properties against the DPPH radical did not show any significant differences between samples P1 and P2. Moreover, the antioxidant potential against the ABTS radical did not change during the 10-day storage for both samples; the potential measured against the DPPH radical decreased significantly on the 10th day for samples P1 and P2.

3.5. Fatty Acid Profile and Lipid Quality Indicators

The fatty acid profile (%) of turkey thigh muscles is presented in

Table 5. Fatty acid profile [%] and lipid quality indicators of turkey thigh muscles.

	P1	P2
C6:0	0.100 ± 0.025 a	0.088 ± 0.033 a
C8:0	0.153 ± 0.042 a	0.135 ± 0.054 a
C10:0	0.050 ± 0.008 a	0.063 ± 0.015 a
C11:0	0.020 ± 0.001 a	0.020 ± 0.001 a
C12:0	0.223 ± 0.024 a	0.883 ± 0.078 b
C14:0	1.195 ± 0.111 a	1.495 ± 0.119 b
C14:1n5	0.173 ± 0.036 a	0.198 ± 0.010 a
C15:0	0.195 ± 0.021 a	0.193 ± 0.025 a
C15:1n5	0.093 ± 0.028 a	0.063 ± 0.021 a
C16:0	22.700 ± 1.786 a	20.988 ± 2.911 a
C16:1n7	5.853 ± 0.611 b	4.765 ± 0.374 a
C17:0	0.213 ± 0.035 a	0.238 ± 0.028 a
C18:0	10.105 ± 0.844 a	9.418 ± 0.835 a
C18:1n9c + C18:1n9t	29.848 ± 1.795 a	29.735 ± 0.670 a
C18:2n6c + C18:2n6t	23.160 ± 1.858 a	28.478 ± 3.111 b
C18:3n3 (alpha)	1.040 ±0.028 a	1.540 ± 0.530 a
C20:0	0.143 ± 0.015 a	0.133± 0.030 a
C20:1n9	0.078 ± 0.056 a	0.110 ± 0.038 a
C21:0	0.030 ± 0.009 a	0.077 ±0.090 a
C20:5n3	0.113 ± 0.005 a	0.130 ±0.018 a
C22:0	0.113 ± 0.032 a	0.295 ±0.239 a
C22:1n9	0.123 ± 0.090 a	0.068 ±0.022 a
C22:2n6	0.235 ± 0.057 b	0.140 ±0.010 a
C23:0	0.035 ± 0.007 a	0.037 ±0.015 a
C23:0	0.058 ± 0.015 a	0.050 ±0.018 a
C22:6n3	0.183 ± 0.060 a	0.115 ±0.44 a
Σ SFA	36.835 a	34.065 a
Σ MUFA	36.185 a	34.318 a
Σ PUFA	23.710 a	28.358 b
Σ n-3	1.515 a	1.785 a
Σ n-6	16.395 a	28.603 b
Σ n-6/Σ n-3	10.233 b	15.756 a
Σ UFA/Σ SFA	1.691 a	1.897 b
Σ PUFA/Σ SFA	0.670 a	0.847 b
AI	0.700 b	0.579 a
TI	1.101 b	0.897 a

P1—control sample; P2—sample supplemented with wild garlic. ^a,b Values in rows with different letters are significantly different at p ≤ 0.05.

. Both the control sample (P1) and the one supplemented with wild garlic (P2) contained the highest proportion of MUFA, followed by SFA, and then PUFA. Based on statistical analysis, it can be noted that there was no statistically significant effect of turkey feeding on the total MUFA and SFA. The analyzed thigh muscles from the two feeding groups (P1 and P2) differed significantly in the case of PUFA. Thigh muscles from turkeys supplemented with wild garlic (P2) were determined by a significantly higher sum of PUFAs than muscles from P1. As far as PUFA is concerned, the highest proportion was recorded for C18:2 n−6 (average 23.160–28.479%), C22:2 n−6 (average 0.235–0.140%), and C22:6 n−3 (average 0.163–0.085%). Thigh muscles obtained from birds supplemented with wild garlic were characterized by a significantly higher proportion of C18:2 n-6 compared to the muscles from the control group. Considering the value of lipid indicators in the turkey thigh muscle, there was a significant effect of feeding on n−6/n−3, UFA/SFA, PUFA/SFA, atherogenicity index (AI), and thrombogenicity index (TI). The samples from group P2 were characterized by significantly higher values of n−6/n−3, UFA/SFA, and PUFA/SFA, as well as lower AI and TI lipid quality indicators compared to samples from group P1.

4. Discussion

Turkey meat is the second most commonly consumed poultry meat in the world and is an economical source of high-quality protein for human consumption [44]. In order to meet the growing expectations of consumers regarding the quality and nutritional value of meat, natural feed additives are sought that would improve animal welfare and increase the nutritional value of meat. Herbs can be a valuable component of feed mixtures used in poultry nutrition, whose scientifically proven healing effects allow for the lowering of the use of pharmaceuticals such as antibiotics and thus return to a natural diet [9].

The available scientific literature shows that Allium sativum L. in various forms (mainly powder form) is a commonly used natural supplement in poultry feed or drink. This is because of its benefits for digestive function and lipid metabolism by affecting the activity of enzymes involved in lipid hydrolysis and absorption [45]. Due to the lack of studies on the use of wild garlic in poultry feeding on meat quality characteristics in the available literature, the results obtained were related in this discussion to those concerning the effect of supplementation with Allium sativum L. garlic preparations.

For consumers of turkey meat, its chemical composition and technological properties play an important role, as they determine the sensory characteristics and nutritional value of products and dishes obtained from it. The main ingredients of turkey meat are protein and fat. High protein content and low fat content are the most important criteria for the consumer to choose this type of meat. Results of chemical composition presented in the current study showed a high protein content in the turkey thigh muscle, an average of 21.57–22.12%, and fat content in the range of 4.71–5.30%. Moreover, the chemical composition of turkey thigh muscle was not significantly affected by wild garlic supplementation (p ≥ 0.05). Lower protein content (19.69–20.24%) in the turkey thigh muscles compared to our results was reported by Czech et al. [46]. As stated by the research, the differences in the chemical composition of turkey meat could be related to the feeding or housing system of turkeys.

Another important attribute of meat quality is color [47], which was assessed instrumentally in this study. When it comes to breeding aspects, the color of meat is determined by a number of factors related to both the origin of the birds and the feeding or housing system [48]. The results of the current study indicated that wild garlic added to the diet of turkey did not cause statistically significant differences in color parameters. It is shown that the thigh muscle of the Big-6 type turkey was lighter (mean L* = 48.05–48.97) and more yellow (mean b* = 9.92–11.13) compared to broad-breasted Bronze turkey (mean L* = 43.42; b* = 7.95) [46]. The more yellow color of the meat is the result of the birds consuming large amounts of plant material rich in carotenoids. The poultry meat characterized by higher lightness (L* color parameter) seems to be more preferred by a modern consumer, as noted by Wideman et al. [48]. Moreover, as stated by Wideman et al. [48], other factors affect the color of meat, such as pH and the content of heme pigments, mainly myoglobin. The present study did not show a statistically significant effect of wild garlic supplementation of turkeys on meat acidity and heme pigment content.

The microbiological quality of meat, especially poultry, is crucial for health safety for the consumer, particularly in the context of the presence of Salmonella [49]. Contaminated poultry meat and eggs are the major sources of human Salmonella infection [50]. The microbiological analysis conducted in this study did not reveal the presence of Salmonella spp. in the thigh muscles of turkeys from the control group and the group supplemented with wild garlic. The effect of wild garlic supplementation was also not observed in the number of Enterobacteriaceae and E. coli. Research conducted by Hossain et al. [51] showed that with dietary supplementation of aged garlic extract at the level of 0.1 and/or 0.2%, increasing body weight gain and decreasing liver weight and cecal E. coli count in broilers were observed.

It seems that wild garlic is a valuable component of poultry feed. Its potential beneficial effect on birds may result from the presence of various phytochemicals with high therapeutic potential and biological activities [52]. It contains not only sulfur compounds, which are responsible for many physiological functions, including lowering insulin levels and total cholesterol, but also polyphenol compounds. As indicated by some authors [53], wild garlic leaves are a rich source of ferulic and vanillic acid, p-coumaric acid, and kaempferol derivatives. Moreover, wild garlic contains other valuable ingredients such as triterpenoids, chlorophylls and carotenoids, vitamin C, and macro- and microelements [54]. The health benefits of phenolic compounds as well as chlorophylls and carotenoids derive from their, among others, antioxidant properties. Voca et al. [52] conducted studies on the content of bioactive compounds in wild garlic leaves, taking into account various factors (location and phenophase). The studies showed a significant content of vitamin C (63.31 mg/100 g fw) and total phenol content (186.18 mg GAE/100 g fw) in the analyzed raw material. Additionally, a high value of antioxidant capacity of wild garlic leaves was noted, amounting to 2230.66 mol TE/l (according to Trolox). According to Nencini et al. [55], the level of antioxidant capacity analyzed by FRAP assay in leaves of garlic (Allium sativum) was 2.1 folds lower than that of leaves of wild garlic. In this context, this study investigated whether the supplementation of turkey diet with wild garlic affected the antioxidant potential of meat. The results of the conducted research on the antioxidant potential of turkey thigh muscle against ABTS and DPPH radicals did not show a positive effect of wild garlic supplementation.

The presence of antioxidant compounds in meat determines its oxidative stability, which is very important for turkey meat, as turkey meat is very susceptible to oxidation due to its high polyunsaturated fatty acids content. The presence of PUFA can affect the lowering of oxidative stability of meat [56]. This is because PUFA fatty acids are more susceptible to oxidative processes that lead to the formation of primary and later secondary fat oxidation products. Fat oxidation products can additionally react with other meat components, leading to, for example, reduced protein digestibility. In the context of nutritional value, a higher PUFA content has a beneficial effect on human health as it may have beneficial actions on some diseases (m.in. neurological, allergic, cardiovascular) [57]. An analysis of the main fractions of the fatty acid profile of turkey thigh muscle indicated that PUFA fatty acid accounted for the lowest proportion and MUFA represented the highest proportion, followed by SFA fatty acid. The results of this study differed from those obtained by Czech et al. [46], who studied the fatty acid profile of broad-breasted Bronze turkey muscles. They showed that the muscles of turkeys (broad-breasted Bronze) were characterized by the highest proportion of PUFAs, followed by MUFAs and SFAs. The differences may result from genotype and feeding method. The results of the present study showed that dietary supplementation of turkey diet with wild garlic did not change the lipid stability of thigh muscles, as indicated by TBARS values, despite a significantly higher content of PUFA fatty acid. The TBARS index indicates the presence of products reacting with thiobarbituric acid, which mainly includes malondialdehyde, the main secondary product of fat oxidation. In this study, low TBARS values were obtained for meat from both the control and wild garlic supplemented groups, which means that the samples, despite differences in the fatty acid profile, show similar susceptibility to oxidation during storage and processing. Previous studies on the effects of supplementing diets of chicken with garlic powder and alpha-tocopherol indicated that the TBA reactive substances values of meat were significantly reduced, which may indicate the advisability of conducting future studies using wild garlic in combination with antioxidants such as tocopherols [58].

Considering the value of lipid quality indicators of thigh muscles, the turkey diet supplementation with wild garlic had a significant impact on the assessed indicators. The muscles obtained from birds of group supplemented with wild garlic were characterized by significantly higher values of n-6/n-3, UFA/SFA, and PUFA/SFA, as well as lower AI and TI lipid quality indicators compared to muscles from group P1. Similar to our study, Choi et al. [58] showed that dietary garlic powder or garlic powder plus alpha-tocopherol supplementation increased the sum of UFA fatty acid and UFA/SFA ratios.

The PUFA/SFA ratio obtained in this experiment for turkey thigh muscle was 0.670 for samples from group P1 and 0.847 for samples from group P2. The obtained values exceed the values recommended for preventing ischemic heart disease (0.45) [43]. The n-6/n-3 ratio obtained in our study was higher than the dietary recommendations (<4). As stated by Prado et al. [59], this is related to the high content of C18:2n-6 in poultry meat. The addition of wild garlic to the diet of turkey resulted in a significant growth in the n-6/n-3 ratio of meat. When it comes to nutritional aspects, the lower n6/n3 ratio is more beneficial for consumers’ health. The results obtained in the current study for meat from the control group were comparable to those reported by Czech et al. [46] and Batkowska et al. [60] but higher than those obtained by Drażbo et al. [61]. The atherogenicity index (AI) was lower in the case of thigh muscle from birds supplemented with wild garlic (< 0.6) compared to muscles from the control group. Ouraji et al. [62] reported that an AI index above 1.0 is harmful to humans. In the current study, all samples obtained an AI index below 1.0. Thrombogenicity index (TI), whose value <1.0 is also recommended, had values lower than 1.0 in the case of thigh muscle from turkey supplemented with wild garlic. The AI and TI index results obtained in this study are higher compared to those obtained for broad-breasted bronze turkeys [46].

5. Conclusions

In conclusion, the addition of wild garlic (Allinum ursinum L.) to turkey diets had an impact on some of the assessed meat characteristics (antioxidant properties and fatty acid profile). Measurements of chemical composition, pH, water activity, color, total heme pigments, and lipid oxidation showed that the addition of wild garlic to a turkey diet did not affect thigh meat quality. Although wild garlic contains valuable antimicrobial compounds, microbiological analyses did not show any effect of its addition to turkey feed (at a level of 0.2% in the feed mixture) on the number of Enterobacteriaceae, E. coli, Salmonella spp., L. monocytogenes). Observations of changes in TBARS and antioxidants potential values did not suggest that the addition of wild garlic to turkey diet plays an antioxidant role in raw meat. The lack of an antioxidant effect as a result of the supplementation of turkey diets with wild garlic may be attributed to the level of inclusion in animal diets used in the present study. Therefore, further research is necessary to ascertain whether feeding with wild garlic at higher levels or in combination with antioxidants such as tocopherols could have a significant effect on enhancing the nutritional values, antioxidant potential, and oxidation stability of turkey meat.