Use of high-power ultrasound combined with supercritical fluids for microbial inactivation in dry-cured ham

Abstract

The aim of this study was to analyze the application of supercritical carbon dioxide combined with high-power ultrasound (SC-CO2 + HPU) and the use of a saline solution (SS; 0.85% NaCl) on the microbial inactivation and the quality of dry-cured ham. The effect of temperature, pressure and treatment time was studied using RSM. Physicochemical analyses were carried out after the treatments and during refrigerated storage (30 days / 4 °C). The most significant inactivation of Escherichia coli (3.62 ± 0.20-log CFU/g) was obtained using the SC-CO2 + HPU + SS (25 MPa, 46-°C and 10-min), with temperature being the most important process variable. Fat content showed a significant (p < 0.05) reduction (46%) after the SC-CO2 + HPU treatment. The breakage of the muscle fibers, the disorganization in the myofibrils, as well as the enlargement of the interfibrillar spaces led to the ham softening (avg 26.5%). No significant (p > 0.05) changes in color, texture or pH were found during storage. Thus, ultrasonic-assisted SC-CO2 could be used, in combination or not with SS, to improve the shelf of dry-cured ham. Industrial relevanceSupercritical carbon dioxide (SC-CO2) inactivation technology has been shown to be highly efficient at reducing different bacteria in liquid media with minimum effect on food quality. This technology is barely applied to solid products and its use is limited by the long processing times and reduced inactivation capacity. The application of high-power ultrasound (HPU) leads to a shorter process time. This technology is useful for the inactivation of ham microbiota and inoculated E.coli. A liquid medium surrounding the treated solid can enhance microbial inactivation for the purposes of improving the effect of ultrasound cavitation, while only minimally affecting the quality of the samples (color, texture, fat and moisture contents).