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Isoflavone Aglycone Content and the Thermal, Functional, and Structural Properties of Soy Protein Isolates Prepared from Hydrothermally Treated Soybeans

Wally‐Vallim, Ana Paula, Vanier, Nathan Levien, Zavareze, Elessandra da Rosa, Zambiazi, Rui Carlos, de Castro, Luis Antônio Suita, Schirmer, Manoel Artigas, Elias, Moacir Cardoso
Journal of food science 2014 v.79 no.7 pp. E1351
absorption, beta-glucosidase, differential scanning calorimetry, digestible protein, foaming, foaming capacity, hot water treatment, hydrophobicity, scanning electron microscopy, soy protein isolate, soybeans, temperature
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.