Ultrasound-assisted post-packaging pasteurization of sausages

• Pasteurization with ultrasound is an alternative for packaged products.
• Ultrasound allowed the reduction of time and temperature of pasteurization.
• More uniform distribution of heating within product was found using ultrasound.
• Physicochemical properties of sausages were not modified by the use of ultrasound.
• Shelf life was extended by the use of ultrasound for pasteurization.

Ultrasound (US) is proposed to reduce temperature and accelerate the process of pasteurization of packaged hot dog sausages. They were pasteurized in an ultrasonic bath (25 kHz, 200 W) for 10.53 min at 74 °C with (US) and without ultrasound (WUS) and also with conventional pasteurization (CT, water bath at 82 °C, 16 min to reach 73 °C inside of sausages). The temperature was 3.9 °C higher inside of pasteurized sausages using US in comparison to WUS. Sausages were stored by 60 days and physico-chemical and microbiological parameters were evaluated. US treatment inhibited the growth of psychrotrophic and lactic bacteria, reduced the lipid oxidation and promoted little pH and texture modifications during storage, improving the pasteurization. However, no information are available about the possible generation of toxic substances after US processing and further investigations must be carried out before the industrial scale-up of the process.Industrial relevanceAn improvement on the effect of pasteurization of packaged sausages could be obtained by the use of ultrasound, reducing the time and the temperature used in conventional process and improving the shelf life of product without changes in its physical and chemical characteristics. The adaptation of the proposed process is relatively simple to be performed in conventional equipment used in industry and has potential for continuous processing and scale up. Because no information are available about the possible generation of toxic substances after the US processing, further investigations must be carried out before the industrial scale-up of the process.