Protein isolates made in the laboratory versus the factory: A case study with mung bean and chickpea

Abstract

AbstractProtein isolates deliver functionalities such as gelling, emulsifying, and foaming, and many recent publications are reporting the functionality of new protein isolates produced in the laboratory. Laboratory protein isolation processes are quite different to industrial processes, and therefore isolate functionalities are likely to be different. We examined some of the differences between laboratory isolates and commercial isolates of mung bean and chickpea protein (MPBI and CPPI). We tested solubility as a function of pH, dispersibility by static light scattering, and viscosity enhancement in a rapid visco analyzer (RVA). Thermal transitions were evaluated with differential scanning calorimetry (DSC), and powder morphology was examined by scanning electron microscopy (SEM). Laboratory isolates were more soluble (e.g. 54%–57% vs. 5%–45% at pH 8) and dispersible than commercial isolates, with the largest DSC endotherms, indicating the least denaturation. Among commercial isolates, we found large differences in solubility, thermal properties, and viscosity enhancement, and minor differences in dispersibility and powder morphology. The hydration protocol had a strong effect on solubility and DSC results, and a moderate effect on RVA results. Comparisons between isolates produced in different laboratories are currently hampered by the use of nonstandard empirical methods for certain functionalities, and we highlight standardized methods for measuring dispersibility and viscosity enhancement. Protein isolation processes affect isolate functionality via effects on protein denaturation and aggregation, and via the morphology and surface chemistry of isolate powders. This means that findings with laboratory isolates cannot necessarily be extrapolated to commercial counterparts but also indicates the power of process design to modulate isolate functionality.