Effect of bacterial cellulose on the foaming properties of egg white and soy proteins

Abstract

Food foams are highly industrially relevant systems, responsible for the visual appearance and organoleptic properties of many processed foods. Foam characteristics can be further improved by food-grade additives. This study investigates the influence of bacterial cellulose (BC) on the foaming capacity (FC) and foam stability (FS) of egg white protein (EWP) and soy protein isolate (SPI), important food foaming agents. The effects of pH, BC concentration and particle size on the FS and FC were analyzed. Compared to SPI, EWP demonstrated higher FC, an effect that is tentatively assigned to its lower molecular weight, hence faster diffusion to the interface. Adding 0.1% BC to EWP (4%, at pH 7.0) and to SPI (4%, at pH 3.0) increased the FC by 1.6 and 1.5 times, respectively. The addition of BC also reduced the foam's liquid drainage, although not impacting the FS. Surprisingly, large flakes of BC (Dv(50) of 1104 µm) yielded higher FC values than smaller ones. We hypothesize that larger BC flakes may act as anchoring sites, stabilizing the air bubbles during whipping. BC flakes were observed in the plateau borders and nodes of EWP foams, clogging the water channels and preventing drainage. This work demonstrates the potential of BC as a food-grade foam enhancer, providing a new tool for the food engineer´s arsenal.