CONICET | Buscador de Institutos y Recursos Humanos

Amaranth is an American pseudocereal whose storage proteins and polypeptides presentdifferent biological activities as in-vitro antitumoral, antioxidant and antithrombotic activities,and in-vitro and in-vivo antihypertensive one. It could be interesting the application of theseproteins as functional ingredients in food formulation. The aim of this work was to study theadsorption kinetics of A. hypochondriacus soluble proteins (pH2 and 8; ionic strength 0.06 and0.5) at the air/water interface and its relationship with foaming capacity.Solubility, particle size distribution and polypeptides composition were studied for allsamples. Protein adsorption to the surface was studied by drop tensiometry through its ability tolower the surface tension. We used a low concentration of protein where surface adsorption waslimited by diffusion. A greater concentration was used to model the protein adsorption andrearrangement at surface, and to study foaming capacity.At pH2 the protein is dissociated, while at pH8 maintain the native conformation. At bothpHs two populations of particle size were detected. The proportion of the second populationdecreases with the increase of ionic strength, according with solubility decrease. The decrease insurface tension at short times of bubble formation (3s) is linearly related to the rate of liquidincorporation to the foam, being the last one higher at pH2 than pH8, and even higher at highionic strength at both pHs.At pH2 is not only interesting the protein surface adsorption rate, but also the viscoelasticproperties of the film which has a dilatational modulus higher than 100mN/m whereas at pH8 islower than 30mN/m.These results encourage us using these biologically active proteins and peptides infoamed foods.