title: Influence of the presence of monoglyceride on the interfacial properties of soy protein isolate.
abstract: BACKGROUND
  This study focused on the contribution of soy protein isolate (SPI), in the absence or presence of monostearin (ME), to surface and interfacial properties as a function of protein concentration and pH, which is relevant to the physical stability of a variety of food systems.
  
  
  RESULTS
  An increase in protein content always yielded a rapid decrease in surface tension followed by an evolution towards an asymptotic value. Addition of ME gave rise to mixed SPI/ME films, although the interface became dominated by SPI above the concentration for interfacial saturation. The relative interfacial shear viscosity of SPI films showed a marked dependence on: aging time, which may be attributed to a reorganisation of protein species at the interface with some penetration of hydrophobic parts into the oil phase; shear forces, which may partially reverse this reorganisation, leading to shear-thickening behaviour; and pH, which is the key factor controlling which SPI species is predominant at the interface. The effect of adding ME also depends on pH, favouring a reinforcement of SPI/ME films only at low pH, at which 3S and 7S fractions are dominant.
  
  
  CONCLUSIONS
  The results obtained indicate that SPI shows excellent potential to favour stabilisation of air/water and oil/water interfaces in food systems.
authors.affiliation: Departamento de Ingeniería Química, Universidad de Sevilla, Sevilla, Spain.
authors.forename: M Luisa
authors.initials: ML
authors.lastname: López-Castejón
authors.forename: Julia
authors.initials: J
authors.lastname: de la Fuente
authors.forename: Manuela
authors.initials: M
authors.lastname: Ruiz
authors.forename: Antonio
authors.initials: A
authors.lastname: Guerrero
mesh_terms: D005524:Food Technology; D005989:Glycerides / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D050178:Monoglycerides / Q000737:chemistry*; D030262:Soybean Proteins / Q000737:chemistry*; D013314:Stress, Mechanical; D013500:Surface Tension; D014783:Viscosity
chemical_list: D005989:Glycerides; D050178:Monoglycerides; D030262:Soybean Proteins; C048159:glyceryl monostearate