High-pressure homogenization and pulsed electric fields for favoring the release of β-glucans and mannoproteins from yeast cell walls

Background: The food packaging industry is increasingly addressing the issue of plastic packaging by developing biodegradable alternatives to petroleum-based polymers. β-glucans and mannoproteins, derived from yeast cell walls, are gaining great importance among alternative biopolymers due to their unique properties, such as high apparent vis-cosity and stabilization of emulsions. However, their extraction from yeast biomass, con-taining 30–60% β-glucans and 10–20% mannoproteins, is challenging due to the compact cell wall. This study evaluates the potential of high-pressure homogenization (HPH) and pulsed electric fields (PEF) treatments for breaking yeast cell walls and recovering β-glu-cans and mannoproteins from baker's commercial yeast (BCY) and brewer's spent yeast (BSY) biomasses. Methods: Several treatments were applied, including HPH (125 MPa for 3 passes), PEF (1.5 kV/cm for 45 μs) and additional thermal treatments (TT: 90 °C for 20 minutes). The dispersions and supernatants (obtained after centrifugation) were characterised for their β-glucans and mannoproteins content; microscopic analysis was also performed to assess the effectiveness of cell wall rupture. Results: The results obtained have demonstrated how the application of HPH treat-ments, whether in combination or not with heat treatment or with PEF, led to an increase in the release of intracellular components compared to native yeast and heat treatment alone. The combination of HPH+PEF and PEF+HPH allowed for the highest release of intracellular components (carbohydrates, proteins, β-glucans and mannoproteins). Fur-thermore, these two combinations of treatments enabled complete yeast cell disruption with the release of intracellular material and some reaggregation of the same. Conclusions: These results underline the promise of HPH and PEF in advancing the extraction and recovery of β-glucans and mannoproteins from yeast biomass for various applications, including obtaining innovative biopolymers for food packaging.