Study of variability in antioxidant composition and fatty acids profile of Longissimus dorsi and Serratus ventralis muscles from Iberian pigs reared in two different Montanera seasons

Meat Science 90 (2012) 414–419

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Study of variability in antioxidant composition and fatty acids profile of Longissimus dorsi and Serratus ventralis muscles from Iberian pigs reared in two different Montanera seasons D. Tejerina a,⁎, S. García-Torres a, M. Cabeza de Vaca a, F.M. Vázquez a, R. Cava b a b

Centro de Investigación Agraria Finca La Orden, Valdesequera, Finca La Orden, Junta de Extremadura, Ctra. N-V. Km. 372. 06187 Guadajira, Badajoz, Spain Food Science and Technology, Tradinnoval Research Group, Faculty of Veterinary Science, University of Extremadura, Cáceres 10071, Spain

a r t i c l e

i n f o

Article history: Received 12 October 2010 Received in revised form 9 August 2011 Accepted 18 August 2011 Keywords: Iberian pigs Montanera Meat Acorns Grass Diet composition

a b s t r a c t This investigation was designed to evaluate the effects of variations in antioxidant and fatty acids composition of acorns and grass from two Montanera (free-range system and feeding based on acorns and grass) seasons (2006/07 and 2007/08) on the antioxidant composition and fatty acids profile of m. Longissimus dorsi (LD) and m. Serratus ventralis (SV) from Iberian pigs reared under these Montanera seasons. Acorn and grass composition was affected by Montanera season and consequently, LD and SV muscles showed different contents of α-tocopherol, total phenols, hydrophilic and lipophilic antioxidant activity and fatty acid profile, according with the composition of acorns and grass ingested. Results suggest a lack of uniformity in meat quality between different seasons. This could be due to the variable nature of extensive pig production as reflected in the variability in the composition of the diet (acorns and grass). © 2011 Elsevier Ltd. All rights reserved.

1. Introduction An increased demand for traditional products of high quality has occurred in the last years (Kernmeyer, 1993). Meat products from Iberian pigs reared under Montanera (typical free-range system from SW of Spain and feeding based on acorns and grass) are highly appreciated by consumers, mainly due to their sensory characteristics (Ventanas, Tejeda, & Petrón, 2001) and reaching higher prices in markets than those from pigs fed with mixed diets (Rey, Daza, López-Carrasco, & López-Bote, 2006). Several authors had reported relevant information about the quality of meat and meat products from Iberian pigs (Carrapiso & García, 2005; Cava, Ventanas, Tejeda, Ruiz, & Antequera, 2000; Daza, Olivares, Rey, Ruiz, & López-Bote, 2008; López-Bote et al., 2008; Morcuende, Estévez, Ruiz, & Cava, 2003; Rey et al., 2006). Results suggest a lack of uniformity of meat quality, which makes it difficult standardise production. This could be due to the variable nature of extensive pig production (production and composition of acorns and grass within and between seasons, density of animals, animal crossbreeding and

⁎ Corresponding author at: Research Centre Finca “La Orden-Valdesequera”, Finca "La Orden", Ctra N-V km 372, 06187 Guadajira, Badajoz, Spain. Tel.: +34 924 01 40 00; fax: +34 924 01 40 01. E-mail address: [email protected] (D. Tejerina). 0309-1740/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2011.08.010

weather conditions), which affect the intramuscular and subcutaneous lipid contents, fatty acid profiles and antioxidants in Iberian pig tissues. Additionally, the carcass from Iberian pigs is valued in the market according to major fatty acids proportion of its lipid depots – intramuscular and subcutaneous fat – especially subcutaneous fat. In fact, in the Iberian pig sector, a high proportion of oleic acid (C18:1 n-9) and lower proportions of palmitic (C16:0) stearic (C18:0) and linoleic (C18:2 n-6) acids in the carcass are used as quality indicators (De Pedro, 2001). The digestive characteristics of the gastrointestinal tract of pigs allow modification of the fatty acid composition of fat depots by modifications of the diet. In this sense, numerous experiments have been carried out using different dietary fats to modify pig lipid depots, and attempting to increase the proportion of oleic acid (Cava et al., 1997; Larick, Turner, Schoenherr, Coffey, & Pilkington, 1992). Previous studies (Cava et al., 2000; Echenique, 2007; Rey et al., 2006 or Daza et al., 2008) reported that the feeding of Iberian pigs during the fattening phase is the most important phase of the production of Iberian pig and have a great influence on carcass quality and muscle and adipose tissue composition (intramuscular fat content, fatty acid composition of total lipids and lipid fractions, antioxidant content…). However, the effect of other factors such as genetic, age, sex and slaughter weight on carcass and meat composition have also been described previously (Daza et al., 2008; Ramírez & Cava, 2007).

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On the other hand, previous works (Afzal-Rafii, Dodd, & Pelleau, 1992; López-Carrasco, Daza, Rey, & López-Bote, 2004; Tejerina, García-Torres, Cabeza de Vaca, Cava, & Vázquez, 2010, 2011, Tejerina, García-Torres, Cabeza de Vaca, Vázquez, & Cava, 2011; Vázquez et al., 2001) have shown a great variability in the morphological, proximate composition, phytosanitary status, and digestibility of acorn and grass between different Montanera seasons and in the same season. Although, most of the studies have considered both, acorns and grass, have a homogeneous and static physico-chemical composition in time (Andrés et al., 2001; Cava et al., 1999 or Rey et al., 2006), previous studies (Tejerina et al., 2010) have shown a dynamic composition of acorn and grass within a Montanera season and among different Montanera seasons. Thus, variations in acorn and grass composition (antioxidants, fatty acids, etc. ) result in variations in Iberian pig tissue composition and therefore in meat product quality (Echenique, 2007). Although the lack of uniformity is a common problem in the meat industry, to our knowledge, there are few scientific studies on the influence of different Montanera seasons on antioxidant composition and fatty acid profile of muscles from Iberian pig. Therefore, to ensure the homogeneity of batches, for each Montanera season animals were selected with the same genetic base (“Line Valdesequera”), with similar age at the beginning of the fattening and similar age and weight of slaughter. Thus, the aim of this work was to study the antioxidant composition, oxidative status and fatty acids profile of m. L. dorsi and m. S. ventralis from Iberian pigs reared on two consecutive Montanera seasons, as a possible reason of the lack of uniformity in the products obtained during the Montanera system.

2. Material and methods 2.1. Acorn and grass samples The study covered two consecutive Montanera seasons (2006/07 – between 15th November 2006 and 31th of January 2007 – and 2007– 08 — between 15th November 2007 and 31th of January 2008) in an farm with the characteristics typical of a dehesa ecosystem. This farm, known as “Valdesequera”, is located in the southwest of the Iberian Peninsula (39° 3′39.25″N; 6°50′45.24″W). The study area was devoted to the traditional free-range rearing of Iberian pigs. Valdesequera's trees are Holm oak (100%), with a 0.3–0.5 cover fraction, i.e., the fraction of ground area shaded by the vertical projection of the trees' outermost perimeters (measured as per one, units). The soil is a vertisol with a sandy texture and a pH of 5.6–6.7. Sampling of acorns and grass was carried out following the procedures described in Tejerina et al. (2011).

2.2. Animal and meat samples In each Montanera season, thirty males castrated Retinto Iberian pigs (Line Valdesequera, Junta de Extremadura, Badajoz, Spain), being the progeny in successive years of the same outdoor breeding herd, were selected at 90 ± 5 kg live weight. During each last fattening phase, pigs were raised extensively, in the same plots, and fed on natural feed resources, mainly acorns and grass, available in the dehesa ecosystem. Each pig had an approximately space of ~ 2.5 ha in the Valdesequera farm (39°03′N, 6°50′W). Each year, pigs were slaughtered at the same time and similar live weight (150 ± 10 kg), by electrical stunning and exsanguinations in a local slaughterhouse. A portion of m. Longissimus dorsi from the last lumbar to the first thoracic vertebra and the whole m. Serratus ventralis were removed and vacuum-packed in nylon/polyethylene vacuum bags (O2 permeability, 9.3 mL O2/m2/24 h at 0 °C) and kept frozen at −20 °C until analysis.

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2.3. Proximate composition Intramuscular fat (IMF) was measured according to Folch et al. (1957). Moisture content was assayed following the official AOAC method (AOAC, 2003). 2.4. Antioxidant composition 2.4.1. Determination of α-tocopherol and γ-tocopherol Prior to analysis, muscle samples were thawed at + 4 °C during 24 h and homogenised in kitchen blender. α- and γ-tocopherol contents were assayed by the method described by Liu et al. (1996) with some modifications proposed by Cayuela et al. (2003). Tocopherol extract was obtained by homogenising of 1 g of sample, 250 mg of ascorbic acid, 7.5 ml of saponifying solution (KOH 11.5% in CH3CH2OH /H2O 55:45) and 4 ml of 0.01% BHA in iso-octane. Samples were heated at 80 °C for 15 min. After cooling, samples were centrifuged at 1500 rpm for 5 min and the upper layer was collected for HPLC analysis. Tocopherol determination was performed on an Agilent Technologies HPLC Series 1100 instrument (Agilent Technologies, Santa Clara, CA, USA) equipped with a Kromasil Silica column (5 μm particle size, 150 × 4.6 cm) (Symta, Madrid, Spain) and a Kromasil Silica Guard Column (10 μm) (Symta, Madrid, Spain). The mobile phase was isooctane/tetrahydrofurane (97:3 v/v), at a flow rate of 1 ml/min and the fluorescence detector (Agilent Technologies Series 1200) was fixed at λ-excitation- 295 nm and λ-emission- 330 nmn. Identification and quantification of the peaks were done by comparison with αtocopherol and γ-tocopherol standards (0.2–14 μg/ml). Results were expressed as μg of α- or γ-tocopherol/g fresh matter. 2.4.2. Determination of total phenolic compounds Phenolic compounds were quantified according to the method proposed by Singleton and Rossi (1965). To obtain the muscle extract, muscle samples were homogenised using a kitchen blender (Moulinex®), and extracted in CH3OH:H2O (80:20 v/v) for 24 h, and finally filtering the extract through 0.45 μm pore filters. Total phenolic compounds were determined colorimetrically using a Thermo® Helγos UV–Visible spectrophotometer (Thermo Scientific, Waltham, MA, USA). Total phenolic compounds were quantified using a gallic acid standard curve ranging 2.5–50 μg/mL. Results are expressed as μg gallic acid (GAE)/g raw matter. 2.4.3. Determination of total antioxidant activity (TAA) in muscle samples The total antioxidant activity (TAA) was determined according to Cano et al. (1998). TAA was determined as the sum of lipophilic antioxidant activity (LAA) and hydrophilic antioxidant activity (HAA). In both, a standard curve of Trolox (0.2–2 mg/mL) was used for the quantification of the antioxidant activity. Lipohilic and hydrophilic extracts were obtained following the method described by Folch et al. (1957). The organic phase was used for the LAA assay, while the aqueous phase was used for the HAA assay. To an aliquot of the organic phase (LAA assay) or aqueous phase (HAA assay), 1 mL of ABTS in ethanol or phosphate buffer solution, respectively, was added to launch the reaction. The kinetics were followed by absorption spectroscopy at 730 nm of the reduction of the ABTS solution. The difference between the initial and final absorbance gave the resulting LAA or HAA by comparison with the Trolox standard. Results are expressed as μg Trolox/g fresh matter. 2.5. Determination of fatty acid profiles The fatty acid composition of muscles was determined by preparing fatty acid methyl esters (FAME) in acidic conditions (H2SO4:CH3OH). The FAMEs were assayed using a Varian® model 3900 gas chromatograph (Varian, Palo Alto, CA, USA), equipped with a flame ionisation

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Table 1 Average composition of acorn and grass in two different Montanera seasons (Data from Tejerina et al., 2011). Data are presented as mean ± standard deviation. Acorn

Grass

Parameters

2006/07

2007/08

Significance

2006/07

2007/08

Significance

Dry-matter (g/kg)

588.2 ± 3.55

637.8 ± 3.21

***

160.9 ± 5.21

129.9 ± 3.14

**

15.3 ± 1.01 60.3 ± 2.62 13.6 ± 0.82

10.9 ± 0.92 84.4 ± 2.98 9.8 ± 0.78

* *** **

33.9 ± 2.30 3.8 ± 0.62 5.9 ± 0.11

26.3 ± 1.12 5.1 ± 0.63 5.1 ± 0.09

*** *** ***

0.7 ± 0.06 5.4 ± 0.61

1.4 ± 0.04 6.9 ± 0.43

*** **

0.5 ± 0.04 11.4 ± 0.66

0.4 ± 0.02 15.9 ± 0.51

*** ***

Antioxidant composition α-tocopherol (mg/kg d.m.) γ-tocopherol (mg/kg d.m.) Total phenolics (g GAE/kg d.m.) Antioxidant activity LAA (g Trolox/kg d.m.) HAA (g Trolox/kg d.m.)

d.m., dry matter; GAE, gallic acid equivalents; LAA, lipophilic antioxidant activity; HAA, hydrophilic antioxidant activity. ns: not significant (p N 0.05); *** (p ≤ 0.001); ** (p ≤ 0.01); * (p ≤ 0.05).

detector (FID). They were separated on a 60 m DB-23 fused-silica column (Agilent Technologies, Santa Clara, CA, USA) with an i.d. of 0.25 mm and a 0.25 μm film thickness. The injector and detector were maintained at 250 °C. The oven temperature was maintained constant at 220 °C. The carrier gas was nitrogen at a flow rate of 10 mL/min. FAMEs were quantified using tridecanoic acid as internal standard. Response factors were determined for all fatty acids by injecting samples containing a known amount of FAME standard and tridecanoate methyl ester. Identification of FAMEs was performed by comparison of the retention times with FAME reference compounds (Sigma Aldrich, St. Louis, MO, USA). Results are expressed as g/100 g of FAMEs identified. 2.6. Statistical analysis Statistical analysis was carried out by means of one-way analysis of variance (1-way ANOVA) using the general linear models procedure of SPSS.PC+ (2005). Data are presented as the mean and standard deviation. 3. Results and discussion 3.1. Antioxidant composition in acorns and grass samples Table 1 shows antioxidants composition and lipophilic and hydrophilic antioxidant activities of acorns and grass in 2006/07 and 2007/08 Montanera seasons. This composition was variable within a Montanera season and the two years of study as previously reported Tejerina et al. (2011), but data are presented as average values of each parameter within each Montanera season. In both, acorn and grass, antioxidant content, lipophilic and hydrophilic antioxidant activities significantly changed between the two Montanera seasons. In acorns, those sampled in the 2006/07 Montanera season showed higher α-tocopherol and total phenolic compounds

than 2007/08 Montanera season. Concerning antioxidant activities, LAA and HAA were significantly lower in 2006/07 Montanera season than in 2007/08 Montanera season. Grass samples showed a similar trend, except for LAA. So, in 2006/07 Montanera season, grass had a higher content of α-tocopherol, total phenolic compounds and LAA than in 2007/08 Montanera season, but lower content of γ-tocopherol and HAA. 3.2. Antioxidant composition and antioxidant activities of m. Longissimus dorsi and m. Serratus ventralis Table 2 shows data of antioxidant composition of m. L. dorsi and m. S. ventralis during 2006/07 and 2007/08 Montanera season. Significant differences were found in the antioxidant contents, both in m. L. dorsi and m. S. ventralis, between different Montanera seasons. In general, concentrations in muscles in the two Montanera seasons studied were related with the amounts of the different antioxidant compounds detected in acorn and grass in each Montanera season Thereby, the higher content of certain antioxidants in acorn and grass in a Montanera season, will be related with the higher content of these antioxidants in the muscles. In a previous study, López-Bote et al. (2000) reported a daily raw matter intake of 5–8 kg of acorn and 1–2 kg of grass. In the same way, Rodríguez-Estévez et al. (2009) described a daily DM intake of 3.1– 3.6 kg of acorn kernel and 0.38–0.49 ± 0.04 kg of grass. These acorn and grass intake implies an daily intake of 232.6–372.4 g lipids/kg DM and 0.71–1.41 g lipids/kg DM from acorn and grass, respectively. So, although both acorns and grass are a good source of lipophilic antioxidants, increased deposition in tissues could be due mainly to the intake of acorns. Both muscles, m. L. dorsi and m. S. ventralis, showed higher αtocopherol content in 2006/07 Montanera season than in 2007/08 one, according with the higher contents of these compounds found

Table 2 Antioxidant composition and antioxidant activity of m. Longissimus dorsi and m. Serratus ventralis from Iberian pigs raised extensively in two different Montanera seasons. Data are presented as mean ± standard deviation. Longissimus dorsi

Antioxidant composition α-Tocopherol (μg/g) γ-Tocopherol (μg/g) Total Phenolics (μg GAE/g) Antioxidant activity LAA (μg trolox/g) HAA (μg trolox/g)

Serratus ventralis

2006/07

2007/08

Significance

2006/07

2007/08

Significance

3.1 ± 0.05 1.0 ± 0.06 173.5 ± 5.24

2.7 ± 0.03 1.9 ± 0.04 126.4 ± 4.75

* *** ***

6.4 ± 0.06 1.4 ± 0.01 241.8 ± 5.87

5.2 ± 0.04 1.6 ± 0.01 217.3 ± 5.12

* * ***

38.6 ± 2.16 20.5 ± 1.92

23.51 ± 1.95 15.7 ± 1.62

*** **

33.7 ± 2.45 18.7 ± 1.84

23.7 ± 1.96 14.9 ± 1.54

*** *

GAE, gallic acid equivalents; LAA, lipophilic antioxidant activity; HAA, hydrophilic antioxidant activity. ns: not significant (p N 0.05). *** (p ≤ 0.001); ** (p ≤ 0.01); * (p ≤ 0.05).

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in acorns and grass in the same season. Results are in accordance with those reported previously by Cava et al. (2000) in studies with Iberian pigs fed under free-range system (acorn and grass) and diet enriched with α-tocopherol and with findings reported by Rey et al. (2006) in studies of free-range system and fed on acorns and grass. These authors affirmed that the free-range rearing system could be a natural way to increase the content of antioxidants in pigs. Echenique (2007) and Gonzalez and Tejeda (2007) also reported the αtocopherol content in muscle is affected by diet. Inversely, m. L. dorsi and m. S. ventralis showed lower γ-tocopherol content in 2006/07 Montanera season than in 2007/08 one, reflecting the higher content of this compound in acorns and grass in the 2007/08 Montanera season. This supports the affirmed by Daza et al. (2005), Rey et al. (2006) and Gonzalez and Tejeda (2007) that γ-tocopherol in muscle reflected the concentration of this compound in the diets, and due to the high content of γ-tocopherol in acorns. Reported contents of α-and γ-tocopherol in m. L. dorsi were similar to those found by Rey et al. (2006) and Gonzalez and Tejeda (2007) in the same muscle, although we found higher values of both compounds in m. S. ventralis than in m. L. dorsi. Several studies have demonstrated the role of tocopherols (α- and γ-isomers) on the modulation of the susceptibility to lipid oxidation of different tissues in vivo, in vitro and postmortem (Cava et al., 1999, Cava et al., 2000; Daza et al., 2005; Rey et al., 2006). Total phenolics content were significantly higher in 2006/07 than in 2007/08 Montanera season in both m. L. dorsi and m. S. ventralis, in contrast with the finding by Gonzalez and Tejeda (2007), who affirmed that phenol content in m. L. dorsi was not affected by the type of feeding, although Estévez et al. (2006) found higher amounts of total phenolic compounds in meat from free-range reared Iberian pigs. As expected, muscles from pigs fattened in the Montanera season with higher contents of antioxidant compounds also showed the higher LAA and HAA. So, LAA and HAA were higher in 2006/07 than 2007/08 Montanera season in both, m. L. dorsi and m. S. ventralis. 3.3. Fatty acids composition in acorn and grass samples Fatty acids composition of acorn and grass in 2006/07 and 2007/08 Montanera seasons is presented in Table 3 (Data from Tejerina et al., 2011). Both, acorns and grass, showed different fatty acids profile depending of Montanera season. Thus, in acorns samples C18:1 n-9 was higher in 2007/08 than in 2006/07 season. Differences were not found in SFA and PUFA content. Tejerina et al. (2011) reported changes in major fatty acids in acorns, being in accordance with Vázquez (2000) who described the variability in the composition of acorns.

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In other hand, grass samples shown higher C18:0 content in 2006/07 than 2007/08 and therefore higher SFA content. On the contrary, the C18:1 n-9 and MUFA content was higher in 2007/08 than 2006/07 season and lower SFA. Tejerina et al. (2011) reported that it could be due the different meteorological conditions of the two study years and the soil characteristics of the study area. Results are in accordance with those reported by Cava et al. (1999 and 2000), Rey et al. (2006) and Daza et al. (2007).

3.4. Fatty acid composition m. Longissimus dorsi and m. Serratus ventralis Fatty acid composition in m. L. dorsi and m. S. ventralis during 2006/07 and 2007/08 Montanera season is presented in Table 4. Similar to previously described for antioxidant compounds, significant differences were found in the certain fatty acids of intramuscular fat of m. L. dorsi and m. S. ventralis due to Montanera seasons. In general, majority fatty acids, especially C18:1 n-9, in muscles in the two Montanera seasons were related with the amounts detected in acorn in each Montanera season. Thereby, the higher content of C18:1 n-9 in acorn in a Montanera season, the higher C18:1 n-9 content in the muscles. So, m. L. dorsi showed higher C18:1 n-9 and MUFA content in 2007/08 than 2006/07 Montanera season and lower C18:2 (n-6), C18:3 (n-3) and PUFA content. On other hand, m. S. ventralis showed a similar trend than m. L. dorsi. C18:1 n-9 and MUFA content were higher in 2007/08 Montanera season. In contrast, C18:2 n-6, C18:3 n3 and PUFA contents were lower in this season. Previous works related to the feeding of Iberian pigs (Cava et al., 2000; Gonzalez & Tejeda, 2007; Rey et al., 2006) have reported differences on fatty acids profiles as affected by composition of diets. In this sense, Rey et al. (2006) found similar differences to our results, in C18:1 (n-9), C18:2 (n-6) and C18:3 (n-3), mainly to due to fatty acids composition of the diet. Cava et al. (2000) observed that diets composition affected to MUFA content, but not affected to PUFA content. Information concerning the influence of variations in the acorns and grass composition in different Montanera seasons is extremely scarce or non-existent. Our results confirm the well known reality that changes in the content of antioxidants compounds and fatty acids of natural resources among Montanera seasons, specially acorn composition, are responsible of changes in the muscle composition of Iberian pig. It is generally accepted that fatty acid profiles of acorns and grass are the main factors that affect the quality of meat and meat products of Iberian pigs raised under extensive conditions due to the tissues of pigs reflect the fatty acid composition of the feeds consumed during fattening period (Cava et al., 1997, 1999; Daza et al., 2008, 2005; Echenique, 2007; Rey et al., 2006).

Table 3 Average composition of majority fatty acids (g/100 g FAMEs ) of acorn and grass in two different Montanera seasons (Data from Tejerina et al., 2011). Data are presented as mean ± standard deviation. Fatty acid

C16:0 C16:1 n-7 C18:0 C18:1 n-9 C18:2 n-6 C18:3 n-3 C20:0 C20:1 n-9 C20:4 n-3 SFA MUFA PUFA

Acorn

Grass

2006/07

2007/08

Significance

2006/07

2007/08

Significance

13.2 ± 0.06 0.2 ± 0.02 3.1 ± 0.08 61.8 ± 0.46 17.8 ± 0.16 0.9 ± 0.02 0.4 ± 0.01 0.5 ± 0.01 0.3 ± 0.01 16.9 ± 0.03 62.6 ± 0.10 18.9 ± 0.05

13.4 ± 0.05 0.3 ± 0.02 3.5 ± 0.09 62.9 ± 0.32 17.7 ± 0.14 0.9 ± 0.03 0.5 ± 0.01 0.6 ± 0.01 0.2 ± 0.01 17.4 ± 0.03 63.7 ± 0.12 18.7 ± 0.06

* ns ns *** ns ns *** ns ** ns ** ns

14.3 ± 0.21 1.6 ± 0.05 6.4 ± 0.21 3.8 ± 0.14 9.8 ± 0.26 56.6 ± 0.95 0.7 ± 0.03 0.4 ± 0.02 0.7 ± 0.03 22.7 ± 0.46 10.2 ± 0.69 67.1 ± 1.01

14.1 ± 0.14 1.5 ± 0.03 3.4 ± 0.12 8.8 ± 0.23 9.4 ± 0.31 54.2 ± 0.54 0.7 ± 0.03 0.5 ± 0.03 0.7 ± 0.03 19.3 ± 0.34 14.9 ± 0.48 64.4 ± 0.77

ns ns *** *** ns ns ns ns ns *** ** ns

SFA, saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids. ns: not significant (p N 0.05); *** (p ≤ 0.001); ** (p ≤ 0.01); * (p ≤ 0.05).

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Table 4 Fatty acid contents (g/100 g FAMEs) of m. Longissimus dorsi and m. Serratus ventralis from Iberian pigs raised extensively in two consecutive Montanera seasons. Data are presented as mean ± standard deviation. Fatty acid

C 16:0 C16:1 n-7 C18:0 C18:1 n-9 C18:2 n-6 C18:3 n-3 C20:0 C20:1 n-9 C20:4 n-3 SFA MUFA PUFA

Longissimus dorsi

Serratus ventralis

2006/07

2007/08

Significance

2006/07

2007/08

Significance

23.6 ± 0.29 4.5 ± 0.11 9.6 ± 0.43 49.7 ± 0.53 5.8 ± 0.14 0.5 ± 0.02 0.2 ± 0.01 0.7 ± 0.01 0.7 ± 0.02 35.1 ± 0.27 54.9 ± 0.62 6.9 ± 0.16

23.7 ± 0.32 4.9 ± 0.16 8.5 ± 0.31 52.4 ± 0.61 5.1 ± 0.11 0.3 ± 0.01 0.2 ± 0.01 0.7 ± 0.01 0.6 ± 0.01 34.1 ± 0.29 58.1 ± 0.51 6.1 ± 0.11

ns ns ns ** * *** ns ns ns ns ** **

23.9 ± 0.18 3.5 ± 0.09 9.9 ± 0.19 48.4 ± 0.33 7.9 ± 0.14 0.7 ± 0.02 0.2 ± 0.01 0.7 ± 0.01 0.7 ± 0.01 35.8 ± 0.31 52.8 ± 0.37 9.2 ± 0.15

23.4 ± 0.18 3.5 ± 0.1 9.6 ± 0.22 51.4 ± 0.41 7.1 ± 0.15 0.5 ± 0.02 0.2 ± 0.01 0.8 ± 0.02 0.7 ± 0.01 35.3 ± 0.24 55.9 ± 0.29 8.2 ± 0.11

ns ns ns *** *** *** ns ns ns ns *** ***

SFA, saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids. ns: not significant (p N 0.05); *** (p ≤ 0.001); ** (p ≤ 0.01); * (p ≤ 0.05).

Changes in the composition of acorn and grass between different years can be, in part, responsible of a different accumulation of those compounds in the tissues of Iberian pigs affecting the oxidative stability, composition and therefore the quality of the meat and meat products. 4. Conclusions To our knowledge, there is not any published information concerning the variations in antioxidant contents and fatty acid profiles of muscles from Iberian pigs in two different Montanera seasons. Variations in acorn and grass composition modify the antioxidants contents and fatty acids profile of muscles from Iberian pigs reared under Montanera systems. Thus, this could be a reason for the lack of uniformity in meat and meat products from Iberian pigs reared in free-range system in the same farm in different years. Acknowledgements The authors acknowledge the helpful advice of Dra. Mercedes Izquierdo Cebrián and the technical assistance of M.D. Ayuso and J. Bazán. Dra. S. García-Torres thanks the “Fondo Social Europeo” for the contract support and D. Tejerina thanks the INIA for his PhD-grant and M. Cabeza de Vaca for her grant from the regional government of Extremadura (Junta de Extremadura). This study was supported in part by the Jun-07-564 of the Spanish National Institute for Agricultural and Food Research and Technology (INIA). References Afzal-Rafii, Z., Dodd, R. S., & Pelleau, Y. (1992). Mediterranean evergreen oak diversity: Morphological and chemical variation of acorns. Canadian Journal of Botany, 70, 1459–1466. Andrés, A. I., Cava, R., Mayoral, A. I., Tejeda, J. F., Morcuende, D., & Ruíz, J. (2001). Oxidative stability and fatty acid composition of pig muscles as affected by rearing system, crossbreeding and metabolic type of muscle fibre. Meat Science, 59, 39–47. AOAC (2003). Official methods of analysis of the Association of Official Analytical Chemists (17th ed.). Gaithersburg, MD: AOAC International. Cano, A., Hernández-Ruiz, J., García- Canovas, F., Acosta, M., & Arnao, M. B. (1998). An end-point meted for estimation of the total antioxidant activity in plant material. Phytochemical Analysis, 9, 196–202. Carrapiso, A. I., & García, C. (2005). Instrumental colour of Iberian ham subcutaneous fat and lean (bíceps femoris): Influence of crossbreeding and rearing system. Meat Science, 71, 284–290. Cava, R., Ruiz, J., López-Bote, C., Martín, L., García, C., Ventanas, J., et al. (1997). Influence of fininishing diet on fatty acid profiles of intramuscular lipids, triglycerides and phospholipids in muscles of the Iberian pig. Meat Science, 45, 263–270. Cava, R., Ruíz, J., Ventanas, J., & Antequera, T. (1999). Oxidative and lipolytic changes during ripening of Iberian hams as affected by feeding regime: Extensive feeding and alpha-tocopheryl acetate supplementation. Meat Science, 52, 165–172. Cava, R., Ventanas, J., Tejeda, J. F., Ruiz, J., & Antequera, T. (2000). Effect of free-range reaing and α-tocopherol and copper supplementation on fatty acid profiles and

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