EN
The influence of low frequency (40 kHz) and medium intensity (2 W·cm⁻²) ultrasound on the total number of bacteria and Salmonella on the skin of chicken broilers before chilling was investigated. Chicken wings were used for the study. The first part of raw wings was used for total number of bacteria investigation. The second part was contaminated with Salmonella. The changes of total number of bacteria (OLD) and number of Salmonella (SALM) after sonication were determined. Ultrasound treatment was conducted in distilled water (AQ) or 1% lactic acid aqueous solution (LA) at 20°C. The sonication time of a sample was 1, 3 or 6 minutes. The sonicated samples were compared with parallel, untreated samples. The obtained results show that OLD on wings’ skin decreased more than 1.8 log after 6 min of sonication in AQ and SALM decreased 3.6 log in LA. The effect was caused by the ultrasonic cavitation and microflows in the ultrasonic field. The phenomena removed the bacteria from the skin and passed it to the solution and become inactivated. It was concluded that the sonication effect was amplified by the LA. It was supposed that LA stimulates sonobiological phenomena in cell membranes and, in effect, decreases its vital functions and causes the death of bacteria. The cleanness of chicken carcass’ (wing) skin was increasing with the longer duration of sonication. But it was supposed at the same time that the temperature of the liquid (AQ, LA) in the ultrasonic field increases directly in proportion to the time of exposure, 4.5°C in 6 min. The low frequency and medium intensity ultrasound decreases the microbial load on carcass skin, especially the Salmonella, while treated in aqueous lactic acid solution. Sonication should be conducted before the chilling of the carcass. The utilization possibility of chicken carcass decontamination ultrasonic method is confirmed.