Processing parameters involved in the development of texture and tyrosine precipitates in dry-cured ham: Modelisation of texture development.

The aim of this study was to quantify the effects of different processing parameters on texture development and the incidence of white film and tyrosine crystals in dry-cured ham. Hams were dry-salted for 0.65, 0.8 or 1.0 days/kg. After drying for 45 days at 5 °C, they were dried at 10, 15 or 20 °C until reaching 33% weight loss and, thereafter, dried at 25 °C until reaching 36 or 40% weight loss. The salting time, drying temperature and target weight loss significantly affected the texture and incidence of white film and tyrosine crystals. A beneficial effect of drying at 20 °C on texture was found, which was especially important for low target weight loss (33%). Besides, hams dried at 20 °C and those with 40% weight loss showed higher incidence of tyrosine crystals. Contour plots and predictive models for texture can be used to define optimal processing parameters.

Instrumental texture analysis on the surface of dry-cured ham to define the end of the process.

The end of the elaboration process of dry-cured ham is currently decided by product weight loss and/or by an expert who carries out an evaluation of the tactile texture on the surface. The objective of this study was to define the optimal measurement conditions of an instrumental texture analysis on the surface of the dry-cured ham (ITAS), to define the end of process. 120 dry-cured hams were classified by experts into Hard (appropriate) or Soft (non-appropriate) texture groups and used to perform compression tests using different probes on three anatomical positions. Results showed that the small probe in position 2 gave the most discriminant conditions, providing representative information of the internal texture. Although classification using only weight loss was possible with an accuracy rate of 80.4% or 66.7% depending on the weight loss, the maximum classification accuracy was obtained when using ITAS in combination with weight loss. Further studies at industrial level are needed.

Effect of high pressure processing temperature on dry-cured hams with different textural characteristics.

High pressure processing is mainly used to eliminate pathogenic microorganisms and extend the shelf-life of dry-cured hams, but it also modifies its texture. These changes might be different depending on the initial textural characteristics. In this study, texture, colour and colour stability were evaluated after pressurization at 600 MPa during 6 min at 7 °C, 20 °C and 35 °C in samples with different textural characteristics (no pastiness, medium and high pastiness groups). HP treatments produced an increase of hardness (F0) and lightness (L*) values and a decrease of softness/pastiness (Y2 and Y90) and redness (a*) values at any processing temperatures. However, the increase of F0 and L* values was more pronounced in non-pasty samples. In samples with high pastiness and softness, HP processing at high temperature (35 °C) reduced the intensity of pastiness. However, texture of hams with non-pasty texture might be negatively affected. Therefore, the optimal temperature of HP processing depends on the textural characteristics of dry-cured hams.