Steam-ultrasound combined treatment: A promising technology to significantly control mozzarella cheese quality

The adoption of new techniques for food preservation becomes an alternative strategy to the traditional treatments mainly based on the exclusive use of heat. In this study, the potential application of steam (94-95 °C) and ultrasound (25-40 kHz) used simultaneously for a short time was investigated on mozzarella cheese. First, the effect of the technique was evaluated on reduction of Pseudomonas fluorescens and Enterobacteriaceae, inoculated on cheese surface at two different concentrations. Then, both untreated and combined steam ultrasound (SonoSteam) treated samples were packaged in plastic trays with brine and stored at 8 °C. Enterobacteriaceae, Pseudomonas spp., pH and sensory properties were monitored. All data highlighted that SonoSteam was effective to reduce the microbial contamination with a reduction ranged between 0.8 and more than 2 log cycles, thus preserving the product quality. From a sensory point of view, no modifications occurred in treated samples, thus suggesting the potential of SonoSteam for food applications. As a fact, these preliminary results are relevant because the treatment is very rapid (few seconds) and could gain great interest for future industrial scale-up.