Maurício de Oliveira Leite

Blue discoloration caused by Pseudomonas spp. remains a recurring issue in fresh cheeses. This study evaluated gaseous ozone and ozonated mist as two distinct disinfection strategies for reducing populations of Pseudomonas paracarnis A006 on a fresh-cheese model matrix (FCMM) and assessed their effects on lipid integrity. Gaseous ozone and ozonated mist were applied at different concentrations for up to 90 min at 25 °C. Ozone treatments reduced Pseudomonas populations by up to 1.20 log CFU/g (gaseous ozone) and 1.67 log CFU/g (ozonated mist), without affecting aerobic mesophilic counts. Ozonation significantly improved color parameters associated with blue discoloration, while only minor changes in water activity were observed. Fatty acid profiles remained largely unaffected under the most intense treatments. This study provides novel evidence on the application of ozonated mist to mitigate P. paracarnis -associated blue discoloration in a high-moisture FCMM while preserving lipid integrity, highlighting ozone as a promising and sustainable intervention for fresh-cheese decontamination.

The high protein content of several microalgal species makes them attractive and unconventional candidates for use in the food and pharmaceutical industries. Due to the robust cell walls of microalgae, cell rupture is necessary to improve the extraction of intracellular proteins. Thus, choosing a suitable cell-breaking treatment before protein extraction is a vital downstream processing step. Additionally, it is necessary to use an effective technique for monitoring and measuring the impact of rupture treatments on microalgal cell walls. In our study, Tetradesmus obliquus cells were disrupted using three different mechanical rupture methods: high-pressure homogenization (HPH), ultrasound (US), and ball milling (BM). The ruptured biomass cells were counted, and soluble proteins were extracted and quantified. The cell-counting technique did not detect any differences between intact and damaged cells after BM treatment because the dye (erythrosine B) did not permeate the microalgal biomass accurately. The US treatment promoted the highest yield of total protein extraction (19.95%), while the highest yields in the HPH and BM treatments were 15.68% and 14.11%, respectively. Since the cell breakage method affects protein extraction from microalgal biomass, protein release can be used as a central indicator of the degree of cell disruption.

The high protein content of several microalgal species makes them attractive and unconventional for applications in the food and pharmaceutical industries. Due to microalgae's robust cell wall, cell rupture is necessary to improve the extraction of their intracellular proteins. Thus, choosing a suitable cell-breaking treatment before protein extraction is a vital downstream processing step. Additionally, it is necessary to use an effective technique for monitoring and measuring the impact of rupture treatments on microalgal cell walls. In our study, Tetradesmus obliquus cells were disrupted by three different mechanical rupture methods: high-pressure homogenization (HPH), ultrasound (US), and ball milling (BM). The ruptured biomass cells were counted, and soluble proteins were extracted and quantified. The cell counting technique did not detect differences between intact and damaged cells after BM treatment because the dye (erythrosine B) did not permeate the microalgae biomass accurately. The US treatment promoted the highest yield of total protein extraction (19.95%). The yields of protein extraction of T. obliquus with HPH (15.68%) and BM (14.11%) were significantly (p value ≤ 0.05) lower than that achieved in the US treatment. The increase in the number of extraction steps increased the protein recovery. Thus, the content of extracted soluble protein was a reliable indirect index for a quantitative comparison of the cell disruption level.