High power ultrasound assisted high pressure carbon dioxide pasteurization of fresh cut coconut
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The feasibility of a combined high pressure carbon dioxide and high power ultrasound (HPCD+HPU) treatment was tested for the pasteurization of fresh cut coconut. Inactivation kinetics of the natural microbial flora were determined at 12 MPa and 10 W delivered every 2 min of treatment as a function of temperature (24 and 35 degrees C) and time (from 5 up to 30 min). Salmonella enterica was also spiked on fresh cut coconut and inactivation kinetics were obtained at the same process conditions as a function of temperatures (40 and 50 degrees C) and times (from 3 up to 30 min). Additionally, the quality attributes of the product were measured after HPCD+HPU and during a refrigerated shelf-life of 4 weeks. The results revealed that the combined treatment increased microbial inactivation rates: S. enterica was reduced to undetectable levels at 12 MPa, 40 degrees C, 20 min while just 4 Log reductions were achieved when HPCD was performed alone. Inactivation of the natural microbial flora was obtained at milder conditions compared to the optimal ones identified for HPCD alone: 35 degrees C, 12 MPa for 30 min assured inactivation to undetectable level even of mesophilic microorganisms, the most resistant strain. Total acidity, and pH attributes were stable while slight differences were observed for color and texture. The results showed the feasibility and the potential of HPCD+HPU as an innovative non-thermal pasteurization technology of fresh cut fruits.