Low-frequency focused thermosonication for Salmonella typhimurium inactivation: an in vitro study

• Published in: Italian journal of food safety Vol. 13; no. 3; p. 12217
• Main Authors: Lauteri, Carlotta, Pennisi, Luca, Di Clerico, Daniele, Pennisi, Viola, Vergara, Alberto
• Format: Journal Article
• Language: English
• Published: Italy PAGEPress Publications, Pavia, Italy 05-08-2024; PAGEPress Publications
• Subjects: low frequency focused ultrasound; Salmonella inactivation in food matrix; Salmonella typhimurium; thermosonication; low frequency focused ultrasound; Salmonella inactivation in food matrix; thermosonication; Salmonella typhimurium
• ISSN: 2239-7132; 2239-7132
• DOI: 10.4081/ijfs.2024.12217

Customer requests are addressed to safe products that best express their characteristics of "naturalness" and "freshness" for their entire shelf life; therefore, scientific research has been exploring the use of "non-thermal technologies". Thermosonication using low-frequency focused ultrasound determines bacterial inactivation through the phenomenon of "cavitation", guaranteeing high-quality standards of safety, nutrition, and freshness of the products. The present work aims to evaluate the effectiveness of the inactivation of
in culture broth by low-frequency focused thermosonication with two different operational parameters: sublethal temperature (40°C, 50°C) and treatment time (5, 10, and 15 minutes). Treatment determined a bacterial load reduction compared to the negative control (untreated inoculum), which was statistically significant at the
-test (p<0.05). Average decreases of 1.5 log and 3.5 CFU/mL were observed, respectively, after treatment and after 24 hours of storage at +4°C. Treatment at 50°C for 15 minutes was the most effective (average value: 3.06 log CFU/mL; minimum value: 2.13 log CFU/mL; maximum value: 4.59 log CFU/mL). However, strains have shown markable variability: one of them even showed an increase in the microbial load 24 hours after treatment at 40°C for 5 minutes (-0.20 log CFU/mL); however, the same treatment showed a reduction of bacterial charge in all the other strains (average value: 1.05 log CFU/mL; minimum value: -0.20 log CFU/mL; maximum value: 2.28 log CFU/mL). This study poses numerous perspectives on the use of low-frequency focused thermosonication treatment in the food industry as a sustainable and safe alternative to classic thermal treatments.