The influence of ultrasonic treatment on the growth of the strains of Salmonella enterica subs. typhimurium.

Abstract

This study proposes the destruction of pathogenic bacteria with the use of ultrasound waves because the more commonly used thermal processing methods often result in lowering the nutritional value of food. The study presents the impact of ultrasound of 20, 40 and 100kHz frequencies and the power of 10.5W/cm2 on the growth of the strain of Salmonella enterica subs. typhimurium. The tests were carried out both in chilled and non-chilled treatment mediums, with an average bacterial population >105 and >108CFU/cm3. The total inactivation of Salmonella spp. was observed in the tests in the low-population non-chilled treatment medium after sonication at 20 and 40kHz for 30min, and in high bacterial population at 20kHz for 30min. A reduction in the average number of bacteria was reported in the low-population non-chilled medium after 15min of sonication at 20, 40 and 100kHz; after 15min of sonication at 20 and 100kHz of the material of high bacterial population; and in the low-population chilled treatment mediums after 15 and 30min at 20kHz. The samples with inactivated bacteria and those with reduced bacterial counts maintained the same levels when stored at 4°C for 24 and 48h. Bacteria inactivation obtained after sonication lasted for up to 48h in storage at 21°C. For the samples with reduced bacterial counts stored at 21°C, a rise in the average number of bacteria was recorded.