Amaranth proteins foaming properties: Film rheology and foam stability – Part 2

Abstract

In this work the influence of pH and ionic strength on the stability of foams prepared with amaranth protein isolate was analyzed. The behaviour observed was related to the physico-chemical and structural changes undergone by amaranth protein as a result of those treatments. The results obtained show that foams prepared at acidic pH were more stable than the corresponding to alkaline pH. At pH 2.0 the foams presented higher times and more volumes of drainage. This behaviour is consistent with the characteristics of the interfacial film, which showed a higher viscoelasticity and a greater flexibility at acidic pH than alkaline pH value, which in turn increased by increasing the concentration of proteins in the foaming solution. It is also important to note that the presence of insoluble protein is not necessarily detrimental to the properties of the foam. Detected changes in the characteristics of the interfacial film as in the foam stability have been attributed to the increased unfolding, greater flexibility and net charge of amaranth proteins at acidic conditions.

Proteins of Amaranth (Amaranthus spp.), Buckwheat (Fagopyrum spp.), and Quinoa (Chenopodium spp.): A Food Science and Technology Perspective

“…High ionic strength favors amaranth protein foam formation at pH 2.0 and pH 8.0 (Bolontrade and others ). However, the obtained foams are less stable than those produced at low ionic strength (Bolontrade and others ). At low ionic strength, the protein film at the interface is thicker.…”

“…(Partial) hydrolysis of amaranth proteins into smaller fragments improves their diffusion to the air/water interface. Amaranth protein foams are more stable at pH 2.0 than at pH 8.0, due to their interfacial protein films being more viscoelastic and flexible at the former pH (Bolontrade and others ). However, the pH at which foaming is optimal seems to be cultivar‐dependent (Shevkani and others ; Steffolani and others ).…”

“…This retards gas diffusion and, hence, bubble disproportionation and coalescence. Furthermore, there is more electrostatic repulsion at low than at high ionic strength (Bolontrade and others ). Amaranth proteins foam better than soy protein isolates obtained under similar conditions, due to a faster reduction in interfacial tension in the former case (Bejosano and Corke ; Ventureira and others ).…”

The effects of different gluten-free flours on the physical, chemical, functional and sensorial properties of tarhana

“…In a previous study of İbanoğlu and İbanoğlu (1999), foaming stability and foaming capacity of tarhana were affected by the tarhana concentration, whipping time and processing methods. Bolontrade et al (2016) reported that the foams prepared at acidic pH were stable than the alkaline pH and also reported that soluble fractions of protein showed grater stability than the total protein. In the present study, the foaming capacity of CRT, LPT and CBT were found significantly higher than control sample (WHT).…”

Effects of dynamic ultra-high pressure homogenization on the structure and functional properties of casein

“…It was reported that the dynamic UHPH could improve the solubility and molecular flexibility of proteins, and reduce their interfacial tension. Therefore, casein molecules were more likely to be unfolded and adsorbed at the gas-water interface and to form a hard film at the gas-water interface, thus improving the foaming properties of casein [29] . However, when the pressure level further increased, the dynamic UHPH destroyed the equilibrium between hydrophobic/hydrophilic groups.…”