Prospects of cowpea protein as an alternative and natural emulsifier for food applications: Effect of pH and oil concentration

Maria Mariana Garcia de Oliveira; Ana Gabriela Baroni Wicher Fessori; Víctor Justiniano Huamaní-Meléndez; Sérgio Luís Ferreira Júnior; Ícaro Putinhon Caruso; Maria Aparecida Mauro

doi:10.1016/j.ijbiomac.2025.139727

Prospects of cowpea protein as an alternative and natural emulsifier for food applications: Effect of pH and oil concentration

Int J Biol Macromol. 2025 Jan 9:139727. doi: 10.1016/j.ijbiomac.2025.139727. Online ahead of print.

Authors

Maria Mariana Garcia de Oliveira¹, Ana Gabriela Baroni Wicher Fessori², Víctor Justiniano Huamaní-Meléndez³, Sérgio Luís Ferreira Júnior⁴, Ícaro Putinhon Caruso⁵, Maria Aparecida Mauro⁶

Affiliations

¹ Department of Food Engineering and Technology, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), Street Cristóvão Colombo, 2265, São José do Rio Preto 15054-000, Brazil. Electronic address: [email protected].
² Department of Food Engineering and Technology, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), Street Cristóvão Colombo, 2265, São José do Rio Preto 15054-000, Brazil. Electronic address: [email protected].
³ Department of Food Engineering and Technology, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), Street Cristóvão Colombo, 2265, São José do Rio Preto 15054-000, Brazil. Electronic address: [email protected].
⁴ Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), Street Cristóvão Colombo, 2265, São José do Rio Preto 15054-000, Brazil. Electronic address: [email protected].
⁵ Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), Street Cristóvão Colombo, 2265, São José do Rio Preto 15054-000, Brazil. Electronic address: [email protected].
⁶ Department of Food Engineering and Technology, Institute of Biosciences, Humanities and Exact Sciences, São Paulo State University (UNESP), Street Cristóvão Colombo, 2265, São José do Rio Preto 15054-000, Brazil. Electronic address: [email protected].

PMID: 39798728
DOI: 10.1016/j.ijbiomac.2025.139727

Abstract

In response to the growing need to expand the knowledge base on novel, more sustainable protein sources, this study investigated the effectiveness of cowpea protein concentrate (CPC) as a natural emulsifying agent, examining the relationships between pH (3-11), oil concentration (2-10 %), and emulsion stability. pH and oil concentration significantly impacted droplet size distribution, with uniformity decreasing in the order of pH 9 > pH 11 > pH 7, which was attributed to droplet coalescence and flocculation. As evidenced by circular dichroism, alkalinity induced a slight increase in the beta-sheet content of CPC, while simultaneously reducing the alpha-helix content. Rheological analysis of CPC-stabilized emulsions revealed a transition from shear-thinning to thickening flow behavior at higher shear rates. At pH 7, viscosity decreased with increasing oil concentration, whereas this effect was less pronounced in alkaline media. Alkalinity also prevented aggregation of oil droplets when emulsions were heated. At pH 3 and 5, phase separation occurred within 24 h. Emulsions at pH 9 and 11 exhibited the highest stability over a 30-day storage period, while the lowest stability (pH 7) was correlated with increased particle mobility. In most cases, at neutral and alkaline pH, CPC proved to be an effective emulsifying agent, demonstrating its ability to enhance stability by preventing coalescence and sedimentation.

Keywords: Cowpea protein; Emulsifying agent; Particle size distribution; Plant protein; Rheological behavior; Thermal effects.