title: Isoflavone aglycone content and the thermal, functional, and structural properties of soy protein isolates prepared from hydrothermally treated soybeans.
abstract: Soybeans were hydrothermally treated at 2 different temperatures (40 °C and 60 °C) and for 4 different hydration times (4, 8, 12, and 16 h) to (i) increase the isoflavone aglycone content in a soy protein isolate and (ii) evaluate the changes in thermal, functional, and structural properties of a soy protein isolate as a function of hydrothermal treatment conditions. Our study is the first to evaluate aglycone content, extraction yield, β-glucosidase activity, differential scanning calorimetry, protein digestibility, scanning electron microscopy, water absorption capacity (WAC), foaming capacity (FC), and foaming stability of soy protein isolates prepared from hydrothermally treated soybeans. For aglycone enhancement and the extraction yield maintenance of soy protein isolates, the condition of 40 °C for 12 h was the best soybean hydrothermal treatment. The structural rearrangement of proteins that occurred with the hydrothermal treatment most likely promoted the capacity of proteins to bind to aglycone. Moreover, the structure shape and size of soy protein isolates verified by scanning electron microscopy appears to be related to the formation of hydrophobic surfaces and hydrophobic zones at 40 °C and 60 °C, respectively, affecting the protein digestibility, WAC, and FC of soy protein isolates.
  
  
  CONCLUSIONS
  The aglycone content in the soy protein isolate can be improved with the hydrothermal treatment of soybeans. The temperature and time used for hydrothermal treatment must be selected in order to achieve a soy protein isolate with high aglycone content, extraction yield, and functionality. This technology is suitable for providing healthier soy protein isolates for food industry with improved functional and structural properties.
authors.affiliation: Depto. de Ciência e Tecnologia Agroindustrial, Univ. Federal de Pelotas, 96010-900, Capão do Leão, Brazil; Inst. Federal Sul-Riograndense, Campus Pelotas - Visconde da Graça, 96060-290, Pelotas, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Wally-Vallim
authors.forename: Nathan Levien
authors.initials: NL
authors.lastname: Vanier
authors.forename: Elessandra da Rosa
authors.initials: Eda R
authors.lastname: Zavareze
authors.forename: Rui Carlos
authors.initials: RC
authors.lastname: Zambiazi
authors.forename: Luis Antônio Suita
authors.initials: LA
authors.lastname: de Castro
authors.forename: Manoel Artigas
authors.initials: MA
authors.lastname: Schirmer
authors.forename: Moacir Cardoso
authors.initials: MC
authors.lastname: Elias
mesh_terms: D007529:Isoflavones / Q000032:analysis*; D030262:Soybean Proteins / Q000737:chemistry*; D013025:Glycine max / Q000737:chemistry*; D013696:Temperature; D014867:Water
chemical_list: D007529:Isoflavones; D030262:Soybean Proteins; D014867:Water
keywords: aglycone; functional properties; isoflavone; soy protein