A time-resolved investigation at multiple-length scales of the structure of liquid foam stabilized by albumins from pea.

ABSTRACT

HYPOTHESIS: The structural details of foams made with pea albumins are affected by the pH of the initial solution and followed heat treatment. EXPERIMENTS An in situ, time-resolved investigation of foams prepared with pea albumins was conducted using small-angle neutron scattering (SANS) in combination with imaging and conductance measurements. Solutions were tested at pH three pH values (3, 4.5, and 8) before and after heating (90 °C for 1 and 5 min). FINDINGS: The characteristic structures present in the foam from the nano to the meso-scale differed during drainage depending on solution pH. Foams obtained at pH 3, had the largest bubble radius and thinnest plateau border, as well as the highest extent of liquid drainage. At pH 4.5, close to the isoelectric point of the proteins, foams displayed similar bubbles' behavior to those at pH 8, but with the largest film thickness. In this case, the proteins were extensively aggregated. Heating of the solutions prior to foaming did not significantly affect the foam aging regardless of pH. The quantification of specific surface areas and film thickness over time without sample disruption shows to be a powerful approach to designing foam structures.