A combined high pressure carbon dioxide and high power ultrasound treatment for the microbial stabilization of cooked ham
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The feasibility of a combined treatment based on high pressure carbon dioxide and high power ultrasound (HPCD þ HPU) technologies was investigated for the microbial stabilization of cooked ham and compared with the one of HPCD alone. Inactivation kinetics of the natural microbiota (mesophilic microorganisms, lactic acid bacteria, yeasts and molds) were determined at 12 MPa, 40 and 45 C, 10 and 20 W (delivered continuously or every 2 min during the combined treatment) from 2 up to 15 min. Additionally, a shelf life study of the product treated at the optimal process conditions was performed for 4 weeks at 4 C to evaluate the effects of the combined process on its quality (pH, acidity, color and texture) and long term stability. At 12 MPa, 45 C and 10 W delivered every 2 min of treatment, inactivation to undetectable levels of lactic acid bacteria, yeasts and molds was achieved after 15 and 4 min while 4 log reductions of mesophilic microorganisms was obtained after 15 min of the combined treatment. On the contrary, HPCD performed alone induced the same inactivation degree of mesophilic and lactic acid bacteria increasing the treatment time to 60 and 45 min, respectively. The microbial stability of the product was assured up to 3 weeks of storage. The analysis of the quality attributes revealed that the pH, acidity and texture remained stable for the entire storage time while color changes were perceivable after the second week. Overall, the results showed the feasibility and potential of HPCD þ HPU as an innovative non-thermal tool for the microbial stabilization of ready-to-eat meat.