Modeling salt diffusion in Iberian ham by applying MRI and data mining Daniel Caballero a, * , Andr  es Caro b , Pablo G. Rodríguez b , María Luisa Dur  an b , María del Mar  Avila b , Ram  on Palacios c , Teresa Antequera a , Trinidad P  erez-Palacios a a Food Technology Department, Research Institute of Meat & Meat Product (IproCar), University of Extremadura, Av. Universidad s/n,10003, C aceres, Spain b Computer Science Department, Research Institute of Meat & Meat Product (IproCar), University of Extremadura, Av. Universidad s/n, 10003, C aceres, Spain c “Infanta Cristina” University Hospital, Radiology Service, Crta. De Portugal s/n, 06800, Badajoz, Spain article info Article history: Received 25 January 2016 Received in revised form 2 June 2016 Accepted 6 June 2016 Available online 8 June 2016 Keywords: MRI Computer vision Classification Prediction Iberian ham Salt uptake abstract Salt content analysis is needed to ensure a healthy level of sodium in foods. In Iberian hams, this is laborious, time consuming and destructive analysis. This study proposes the use of an active contour algorithm combined with computational textures on Magnetic Resonance Imaging (MRI) to analyze salt diffusion in Iberian hams in a non-destructive way. Data mining techniques (OneR, J48 decision tree, and multiple linear regression) were tested for i) classifying ham muscles and processing stages as a function of salt diffusion and ii) predicting salt content. The proposed methods are useful to differentiate the images of different muscles and stages of processing. For classification purposes, the best procedure is applying the J48 decision tree on the Gray Level Co-Occurrence Matrix (GLCM) method (77.88e79.21% of correct classification). For predicting salt content, the application of multiple linear regression on GLCM methods is accurate (R 2 ¼ 0.972e0.994 and MAE ¼ 0.007e0.044). Then, MRI, computational algorithms and data mining allow determining salt diffusion in Iberian hams in a non-destructive way. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Salt content influences the sensory characteristics of ham, mainly texture and taste attributes (P erez-Palacios et al., 2011a). The salt also influences on the activity of muscle enzymes and the protein solubilisation, and, consequently, on the texture and flavour of the final product (Toldr a et al., 1997). When the salt content is lacking, values of water activity does not decreased and microbial growth occur, leading to putrefactions in the ham, with the consequent economic loss (C ordoba et al., 2001). The Iberian ham processing is based on salt deposition and its further distribution into the piece at low temperatures (3e4  C) and high relative hu- midity (around 90%), followed by partial dehydration. The salting stage aims to bring into the ham an adequate salt quantity. This step takes about 1 day per kilogram of ham. After salting, the temper- ature increases from 4 to 8  C and the relative humidity decreases around 75% (P erez-Palacios et al., 2011b): this is the post-salting stage. It takes around 90 days in Iberian hams. During this step, salt should be distributed in the whole piece, reaching outer and inner muscles (Andr es and Ruiz, 2001). Once the post-salting is finished, and thus, the ham is stabilized microbiologically, at the following stages (drying and cellar) the temperature increases to allow the development of the quality characteristics of the Iberian ham. Most studies in the literature analyzed the salt content at the end of the processing of hams, however it is necessary to guarantee an adequate quantity of salt in the whole ham at the end of the post-salting step in order to get the microbial stabilization of the thigh. In the ham industry, the analysis of salt content is usually carried out by the official method for meat and meat products (AOAC, 2000; reference 971.19). It consists of mixing the sample with water and ethyl alcohol. After successive centrifugations the final extract is obtained and further measured with a volumetric analysis by precipitation. This technique is laborious and time consuming and requires destroying the piece. At this respect, some researchers have studied the salt diffusion in different pork muscles by using Magnetic Resonance Imaging (MRI), a non-destructive, non-invasive, non-intrusive and innocuous technique. Most of * Corresponding author. E-mail addresses: dcaballero@unex.es (D. Caballero), andresc@unex.es (A. Caro), pablogr@unex.es (P.G. Rodríguez), mlduran@unex.es (M.L. Dur an), mmavila@unex. es (M.M.  Avila), raigpalacios@telefonica.net (R. Palacios), tantero@unex.es (T. Antequera), triny@unex.es (T. P erez-Palacios). Contents lists available at ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng http://dx.doi.org/10.1016/j.jfoodeng.2016.06.003 0260-8774/© 2016 Elsevier Ltd. All rights reserved. Journal of Food Engineering 189 (2016) 115e122