Effect of pH on heat-induced gelation of duck blood plasma protein

Duck blood plasma, a by-product of the meat industry, is enriched in proteins and has novel food applications such as gelling agents and stabilizers. The effects of pH in the range of 5.5–7.5 on the gelation behavior and gel properties of duck plasma protein (DPP) were studied via rheology, textural analysis, nuclear magnetic resonance (NMR), and scanning electron microscopy. The results were compared with those of porcine plasma protein (PPP). The rheological test showed that the gelation of PPP was more pH-dependent than that of DPP. Textural properties and water-holding capacity improved with increasing pH for both DPP and PPP. However, higher values were obtained for the latter. NMR showed reduced mobility of water protons in both the DPP and PPP systems at high pH values. The DPP gel network microstructure was homogeneous and ordered when the pH level was higher than 6.0, compared pH 5.5 for PPP gel. These findings show that the gelation behavior and gel properties of DPP can be finely adjusted by pH.