Biophysical Evaluation of SonoSteam®: Effects on Chicken Broiler Skin, Escherichia coli and Campylobacter jejuni

In this study we employ a biophysical and molecular approach for the investigation of qualitative and quantitative changes in both food surface and bacteria upon surface decontamination by SonoSteam®. SonoSteam® is a recently developed method of food surface decontamination, which employs steam and ultrasound for effective heat transfer and short treatment times, resulting in significant reduction in surface bacteria.
An efficient decontamination method should be cheap and fast, while eliminating harmful microorganism without decreasing the quality of the food. However, all known methods represent compromises between the abovementioned facts. Therefore it is important to develop new tools of analysis, which allow for an optimization of food decontamination.
In this study we developed biophysical evaluation methods employing differential scanning calorimetry, second harmonic generation microscopy, two photon fluorescence microscopy and green fluorescence protein expressing Escherichia coli and Campylobacter jejuni. We employ these methods in the investigation of the effects of SonoSteam on both bacteria and broiler skin and compare our results with those obtained by traditional methods of food quality and safety evaluations. Our results show that there are no contradictions between data obtained by either approach. However, the biophysical methods draw a much more nuanced picture of the effects and efficiency of the investigated decontamination method, revealing e.g. an exponential dose/response relationship between SonoSteam treatment time and changes in collagen I, and a depth dependency in bacterial reduction, which points toward CFU counts overestimating total bacterial reduction. In conclusion the biophysical methods provide a less biased, reproducible and highly detailed system description, allowing for focused optimization and method validation.