Ultra-High Pressure Homogenization enhances physicochemical properties of soy protein isolate-stabilized emulsions.

The effect of Ultra-High Pressure Homogenization (UHPH, 100-300MPa) on the physicochemical properties of oil-in-water emulsions prepared with 4.0% (w/v) of soy protein isolate (SPI) and soybean oil (10 and 20%, v/v) was studied and compared to emulsions treated by conventional homogenization (CH, 15MPa). CH emulsions were prepared with non-heated and heated (95°C for 15min) SPI dispersions. Emulsions were characterized by particle size determination with laser diffraction, rheological properties using a rotational rheometer by applying measurements of flow curve and by transmission electron microscopy. The variation on particle size and creaming was assessed by Turbiscan® analysis, and visual observation of the emulsions was also carried out. UHPH emulsions showed much smaller d3.2 values and greater physical stability than CH emulsions. The thermal treatment of SPI prior CH process did not improve physical stability properties. In addition, emulsions containing 20% of oil exhibited greater physical stability compared to emulsions containing 10% of oil. Particularly, UHPH emulsions treated at 100 and 200MPa with 20% of oil were the most stable due to low particle size values (d3.2 and Span), greater viscosity and partial protein denaturation. These results address the physical stability improvement of protein isolate-stabilized emulsions by using the emerging UHPH technology.

Role of quantity and quality of fat in meat models inoculated with Listeria innocua or Salmonella Typhimurium treated by high pressure and refrigerated stored.

Several variables can influence the effects of high hydrostatic pressure processing (HPP), but the role of fat in the treated sample is still uncertain. We designed a model by which controlling the known variables we could elucidate that role. We applied 400 MPa for 2 min to minced chicken samples inoculated with Listeria innocua and Salmonella Typhimurium mixed with 10% and 20% of three fat types with different fatty acid composition. Microbial counts were performed during 60 days of refrigerated storage either at 2 degrees C or 8 degrees C. Immediately after HPP bacterial growth was independent of the type and percentage of fat content, but a possible effect of type of fat could be observed after 60 days of cold storage.