Influence of energy density and viscosity on foam stability – A study with pea protein (Pisum Sativum L.)

Abstract

A high foam stability (FS) is important for manufacturers and is mainly achieved through high protein concentrations. Consequently, the increase of FS at lower protein concentrations is desirable from an economic point of view, especially for proteins that show a lower foamability and FS, such as pea protein isolate (PPI). The hypothesis of this study was that if the viscosity of a PPI dispersion is adjusted to a higher protein concentration (i.e. 5 wt% PPI adjusted to the viscosity of 7.5 wt% PPI), a similar FS can be obtained, while reducing the needed protein concentration. Therefore, the influence of energy density (E_vol) and viscosity on FS was examined. For this, foams were prepared (E_vol = 3.6 × 10⁸ J m⁻³ to 14.4 × 10⁸ J m⁻³) with PPI (c = 5, 7.5, 10 wt%), as well as with mixtures of PPI and non-surface-active maltodextrin (MD) to modulate the viscosity of the continuous phase. Overall, it was shown that MD was able to considerably improve FS of PPI. Mixtures of PPI and MD with the same viscosity as the pure PPI dispersions exhibited a similar FS. For example, the addition of MD to 5 wt% PPI for adjustment of the viscosity to that of the pure 7.5 wt% PPI facilitated a FS of 1664 s ± 2 s compared to 1354 s ± 122 s. Generally, the addition of MD led to a higher viscosity of the continuous phase and an increase in protein surface load, which both attributed positively to FS.

Graphical Abstract

Keywords:

• Whipping
• Foam capacity
• Mean bubble diameter
• Interfacial area
• Alternative proteins

Acknowledgments

We would like to thank Dario Beljo for carrying out the molecular weight distribution measurements.