Emulsifying and gelling properties of porcine blood plasma as influenced by high-pressure processing

The emulsifying properties and the characteristics of heat-induced gels (te xture and water-holding capacity) prepared from pressurised blood plasma so lutions of different pH (5.5-7.5) were investigated. Changes in the plasma, that affected its behaviour as an emulsifier, occurred after pressurisatio n. The highest emulsifying activity was found for samples treated at 400 MP a. At pressures above 400 MPa, the emulsifying activity and stability, at a ll pHs, decreased with increasing pressure. The hardness of heat-induced ge ls decreased significantly as the pressure increased above 400 MPa, this ef fect being more noticeable with decreasing pH. However, although a 600 MPa pressurisation induced a further decrease in the firmness of gels from solu tions at pH 6.5 and 7.5, it increased the hardness of gels at pH 5.5. For t reatments up to 500 MPa, the highest elasticity was found in gels from solu tions at pH 7.5. Pressure treatments above 400 MPa improve the water-holdin g capacity of heat-induced gels prepared from plasma solutions at pH greate r than or equal to6.5. (C) 2001 Elsevier Science Ltd. All rights reserved.