Physicochemical characteristics of three muscles from free-range reared Iberian pigs slaughtered at 90 kg live weight Ramo´n Cava*, Mario Este´vez, Jorge Ruiz, David Morcuende Tecnologı´a de los Alimentos. Facultad de Veterinaria, Universidad de Extremadura, Campus Universitario, Ca ´ceres 10071, Spain Received 31 January 2002; received in revised form 28 June 2002; accepted 29 June 2002 Abstract Three muscles from free-range reared pigs with different metabolic pattern were studied. m. Masseter (M), m. Longissimus dorsi (LD) and m. Serratus ventralis (SV) the first having an oxidative metabolism and the other two an intermediate and glycolytic metabolism. m. Masseter contained the highest content of myoglobin (M: 6.65 mg/g, LD: 3.00 mg/g and SV: 3.64 mg/g; P < 0.001) and exhibited the highest CIE a* (M:17.10, LD: 14.83, SV:15.34, P < 0.001) and C* (M: 17.95, LD: 15.61, SV: 15.54, P < 0.001) values. m. L. dorsi and S. ventralis contained a higher intramuscular fat content than m. Masseter (M: 2.26 g/100 g muscle, LD: 4.79 g/100 g muscle, SV: 3.52 g/100 g muscle, P=0.001) and lower amounts of phospholipids (M: 0.33 g/g imf, LD: 0.12 g/g imf, SV: 0.19 g/g imf; P < 0.001). Fatty acid profiles from total intramuscular fat and lipid fractions, neutral lipids and polar lipids, sig- nificantly differed among muscles, there being a higher content of unsaturated fats (especially in the C18:2 and C20:4 percentages) in the m. Masseter than in the other two muscles analysed. Comparatively, muscles from 90 kg live weight Iberian pigs contained more fat and heme pigments and were redder than those from the commercial pig crosses usually produced. # 2002 Elsevier Science Ltd. All rights reserved. Keywords: Iberian pig; Muscle; Lipid content; Meat colour; Free-range rearing 1. Introduction The Iberian pig is a rustic pig breed reared in the south west of the Iberian Peninsula. In contrast with industrial pig breeds and their crosses, the Iberian pig production system involves a long period of time. Iber- ian pigs are slaughtered at greater ages (12–14 months) and live weights (150–160 kg live weight), the last 40–60 days previous to slaughter being the most important phase in the productive system due to characteristics of feed (acorn, grass or concentrate feeds) consumed by the pigs. Traditionally, meat from Iberian pigs has been trans- formed into dry-cured meat products: dry-sausages, shoulders, loins and hams. Literature concerning the effect of fattening phase characteristics on lipid content and fatty acid composition of muscle, liver and sub- cutaneous adipose tissue lipids and the characteristics of dry cured products obtained is very abundant (Cava et al., 1997; Cava, Ruiz, Tejeda, Ventanas, & Antequera, 2000; Cava, Ruiz, Ventanas, & Antequera, 1999; Ruiz et al., 1998). However, there is no information about character- istics of meat from free-range reared Iberian pig to fresh consumption. In recent years, interest by consumers in the so-called ‘natural’, ‘bio’ or ‘organic’ meats has been increasing. Therefore meat from pig production systems in which pigs are free-range reared, and fed on natural feeds with no growth promoters and antibiotics, begins to be an important field of interest. In some European countries like Denmark (Norgaard & Bennet, 1995), France (Coutron-Gambotti, Gandemer, & Casabianca, 1998; Dargon, Badouard, & Boulot, 1996), Germany (Hoges, 1988); Hungary (Dworscha´k et al., 1995), Swe- den (Jonsa¨ ll, Johansson, & Lundstro¨ m, 2001) and Netherlands (de Kleijn et al., 1991) free-range rearing pig production is beginning to have a sounder base from which to expand, and sales levels look likely to strongly increase (McIntyre, 1999). Muscles are comprised of different type of fibres (aW, aR and bR) with different contractile and metabolic properties. The relative proportion of the three types of 0309-1740/03/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved. PII: S0309-1740(02)00180-8 Meat Science 63 (2003) 533–541 www.elsevier.com/locate/meatsci * Corresponding author. Tel.: +34-927-257-169; fax: +34-927- 257-110. E-mail address: rcava@unex.es (R. Cava).