Evaluation by NIRS technology of curing process of ham with low sodium content

Highlights

• Evaluation of curing process of ham with low sodium content by NIR spectroscopy

• Development of prediction models of the influential parameters in ham curing process

• NIRS shows viability for control and monitoring of the stages in ham curing process.

Abstract

NIR spectroscopy combined with chemometric methods has been used to develop a prediction models of the most influential parameters in curing process of two types of hams (140 hams) using different salting techniques, lean hams salted on a tray and fatty hams in a tub, in which sodium is partially replaced. Spectral data were examined by principal component analysis and cross-validated calibration equations were developed using partial-least squares regression. Calibration errors for each parameter, obtained from cross validation (RMSECV), were similar to those obtained by reference method. For lean and fatty hams the RMSECV values were: Moisture 0.78% and 0.80; Fat 2.5 and 1.2%; Protein 0.7 and 1.7%; water activity 0.008 and 0.006; Proteolysis Index 1.6 and 1.7%; Sodium 0.11 and 0.10%; and Potassium 0.04 and 0.10. Results allow the prediction of the parameters involved in ham curing process, demonstrating the viability of the proposed method for the control and monitoring of the different stages until obtaining the final product.

Introduction

Currently, there is clear evidence that the consumption of foods high in salt has a significant cardiovascular risk associated, since the excess in sodium intake directly influences blood pressure. Therefore, sodium intake should be controlled in order to reduce the risk of coronary heart diseases and strokes, so common in our society (World Health Organization/Food and Agriculture Organization [WHO/FAO], 2003; McCarty, 2004; Ruusunen & Puolanne, 2005).

Common salt (NaCl) is an essential ingredient in processed meat products, especially those subjected to a curing process. This ingredient significantly improves the binding properties of fat and water in meat products (Ventanas & Andrés, 2001), color, flavor and texture. Additionally, it contributes to microbial stability, by reducing the activity of water (aw) that significantly affects the shelf life of food (Wirth, 1989, cited by Ellekjær, Hildrum, Næs, & Isaksson, 1993; Martin, 2001, cited by Ripollés, Campagnol, Armenteros, Aristoy, & Toldrá, 2011).

Cured ham is one of the most traditional cured meat products in the Mediterranean area, with enormous economic impact in its sector. However, it is not recommended in hypertensive population due to its high sodium content. The objective of this work is to assess the use of the Near Infrared Spectroscopy technique (NIRS) to facilitate the monitoring of the curing process to obtain a healthier product, reducing its sodium content without altering neither its own organoleptic characteristics nor the conditions related to microbial growth and control (Desmond, 2006). This technique, in addition to an easy preparation of the samples (Pojić, Mastilović, & Majcen, 2012), allows a simultaneous evaluation of different properties through the development of calibrations that relates spectral measurement of samples with the analytical data of the parameter in study, which are determined by wet chemistry reference methods (Collell, Gou, Arnau, & Comaposada, 2011). Multivariate data analysis tools are needed to carry out the linear adjustment of the available information due to complexity of NIR spectral information (Pérez-Marín, Garrido-Varo, & Guerrero, 2007).

In this work, NIR calibrations of the most influential parameters (moisture, fat, protein, water activity, proteolytic activity, sodium and potassium) have been developed in the curing process of two types of hams elaborated using different salting techniques. On one hand, lean hams individually salted on salting trays and on the other hand, fatty hams in a tub, salted and piled up in a tub. The purpose is to demonstrate the feasibility of the NIRS technology to carry out the control and monitoring of all stages of the process until obtaining the final product.