Effect of pH on the Gel Properties of Lamb Plasma Protein during Heat-induced Gelation

Abstract:

The effect of pH on the heat-induced gel properties of lamb plasma proteins under various pH conditions was investigated by texture and rheology analysis. The pH had a significant impact on each of the properties tested. The lowest water-holding capacity and hardness were observed at pH 5.0, which resulted in a typical particulate gel with a coarse and disordered microstructureas well as large holes (based on diameter) in the network. The highest water-holding capacity and hardness of the lamb plasma proteins were both detected at pH 8.6, which resulted in a typical fine-stranded gel with a compact and ordered microstructure. The storage modulus vs temperature curve of the heat-induced gelation included two segments, stabilizing at 0 Pa and then increasing. The denaturation temperatures of the lamb plasma protein were 71.5 ℃ at pH 5.0 and 80.9 ℃ at pH 8.6. The temperature corresponded to that of the gelation point obtained from rheology analysis for the respective pH value. Based on SDS-PAGEpatterns, globins and albumin aggregates are the main structural blocks of the gels, for gels, and part of proteins with MW of 51 kU aggregated to form dimers, aggregates, finally 3-dimentional network of gels at pH 5.0. This work indicated that the performance of Lamb Plasma Protein gels can be improved via the modulation of pH values.