Sensory traits prediction in dry-cured hams from fresh product via MRI and lipid composition Trinidad Pérez-Palacios a, * , Teresa Antequera a , Rubén Molano b , Pablo G. Rodríguez c , Ramón Palacios d a Tecnología de los Alimentos, Facultad Veterinaria, Universidad de Extremadura, Av. Universidad s/n, 10071 Cáceres, Spain b Departamento de Matemáticas, Escuela Politécnica, Universidad de Extremadura, Av. Universidad s/n, 10071 Cáceres, Spain c Departamento de Ingeniería de Sistemas Informáticos y Telemáticos, Escuela Politécnica, Universidad de Extremadura, Av. Universidad s/n, 10071 Cáceres, Spain d Servicio de Radiología, Hospital Universitario Infanta Cristina, Ctra. de Portugal s/n, 06800 Badajoz, Spain article info Article history: Received 18 February 2010 Received in revised form 16 June 2010 Accepted 20 June 2010 Available online 7 July 2010 Keywords: Sensory traits Iberian ham MRI Computational texture features Lipid composition Multiple Linear Regression abstract The aim of this paper is to describe a methodology that can predict Iberian dry-cured ham sensory traits from raw material characteristics, lipid composition and Magnetic Resonance Imaging-based analysis, by using Multiple Linear Regression statistics. Thus, 18 sensory traits are tried to be defined from 10 fatty acids and 17 computational texture features. Dependence linearity within each group of independent variables is determined. Then, Multiple Linear Regression (MLR) is applied, obtaining allowable statistical coefficients (adjusted coefficient of determination, R 2 > 0.750 and p-value < 0.05) for five sensory traits defined from fatty acids (fat hardness, lean hardness, flavour intensity, brightness and juiciness), and four traits from computational texture features (marbling, odour intensity, flavour intensity and redness). Finally, prediction analysis is validated with a display of statistical data ( R 2 LOO and p-value LOO ). Therefore, some sensory traits in Iberian dry-cured hams can be predicted from fatty acids and computational tex- ture characteristics in fresh products. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction The Iberian pig is an autochthonous porcine breed developed traditionally in the south-west of Spain. Hams from Iberian pigs fattened on acorn and grass in an extensive rearing system are more highly appreciate by consumers, in Spain as well as in many other countries (M.A.R.M., 2009), because of their exceptional sen- sory attributes (García et al., 1996). Juiciness and flavour intensity are two sensory traits that better explained the acceptability of dry-cured ham (Ruiz et al., 2002). The curing process for Iberian ham includes three major phases: a first period (salting/post-salt- ing) in which low temperature is combined with high relative humidity to allow for salt diffusion within the hams. A second stage at moderately raised temperatures (26–28 °C) and progres- sively lowered relative humidity (to 40%) in order to achieve adequate drying of the hams. Finally, hams are left to mature for 12–15 months in a cellar (temperatures ranging between 10 and 22 °C with relative humidity of about 70%). The composition of the fresh Iberian hams, especially lipid-re- lated ones, which are characterized by high levels of intramuscular fat and monounsaturated fatty acids (MUFA) (Cava et al., 2000), has a great influence on dry-cured sensory characteristics (Andrés et al., 1999, 2004). Several factors, including genetics, crossbreeding and rearing system influence the fatty acid profile of Iberian hams (Tejeda et al., 2002; Andrés et al., 2007), having an effect on sensory char- acteristics (Carrapiso et al., 2003). In fact, some studies have shown the relationship between some fatty acids of raw material and a number of sensory traits in dry-cured hams (Carrapiso et al., 2003; Ruiz-Carrascal et al., 2000). In addition, the proportions of major fatty acids (FA) (palmitic (C16:0), stearic (C18:0), oleic (C18:1 n  9) and linoleic (C18:2 n  6) acids) from subcutaneous fat have been used to classify Iberian pigs as a function of their feeding background during the fattening period (Pérez-Palacios et al., 2009). There is an increased interest in non-destructive methods for analysing meat products, a scope where Magnetic Resonance Imaging (MRI) can be integrated as a non-destructive, non-inva- sive, non-radiant and innocuous technique. The combination of MRI and image analysis can present decisive capabilities for the characterisation of muscle structures. Different MRI applications have demonstrated the feasibility of this technique for studying meat and meat products. The calculation of intramuscular fat lev- els in the Iberian ham Biceps femoris and Semimembranosus mus- cles can also result from MRI applications (Ávila et al., 2005). The implementation of active contours in MRI can be used to explore 0260-8774/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2010.06.015 * Corresponding author. Fax: +34 927 257110. E-mail address: triny@unex.es (T. Pérez-Palacios). Journal of Food Engineering 101 (2010) 152–157 Contents lists available at ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng