Changes in the Composition and Size Distribution of Soymilk Protein Particles by Heating

Effect of concentration and incubation temperature on the acid induced aggregation of soymilk

“…The selective precipitation at pH 5.9e5.8 can be explained by the difference in the isoelectric point between the polypeptides (Lakemond et al, 2000;Renkema et al, 2002). It has been previously established that during acid gelation of soymilk, protein particles destabilize and form a network which is followed by incorporation of soluble proteins consisting mainly of the a and a 0 subunits of b-conglycinin and the acidic polypeptide of glycinin (Guo, Ono, & Mikami, 1997;Ono et al, 1991). Protein incorporation occurs as the pH continues to drop and charges are further neutralized (Guo & Ono, 2005;Ono, Katho, & Mothizuki, 1993).…”

“…Together with the A3 and the basic glycinin polypeptide, the b subunit of b-conglycinin also was no longer present in the supernatant at pH <5.9. It has been previously suggested that the bsubunits of b-conglycinin interact with the basic polypeptides of glycinin predominantly through electrostatic interaction (German, Damodaran, & Kinsella, 1982;Ono et al, 1991;Ren et al, 2009). These polypeptides are the first fractions to destabilize in heated soymilk, during acidification.…”

“…After heating, over half of the particles are larger than 40 nm (Ono, Choi, Ikeda, & Odagiri, 1991). The majority of the protein particles in heated soymilk are soluble (Malaki Nik, Tosh, Poysa, Woodrow, & Corredig, 2008b), and contain the major soy protein subunits (Malaki Nik et al, 2008a).…”

Physicochemical characterization of soymilk after step-wise centrifugation

“…A portion of soymilk was then divided in test tubes (10 ml each tube) and placed in boiling water (95-100°C) for 7 min, following a previously published procedure (Ono et al, 1991) and then cooled to room temperature in an ice-waterbath (heated soymilk). A portion of the heated soymilk was passed through a valve homogenizer (Emulsiflex C5, Avestin, Ottawa, Canada) at 69 MPa at room temperature for four passes (heated-homogenized soymilk).…”

“…It has been previously reported that large particles are present in unheated soymilk and that they are disrupted during heat treatment (Ono, Choi, Ikeda, & Odagiri, 1991) as well as after high pressure homogenization (Cruz et al, 2007), however, a detailed study on the characterization of the soymilk dispersions has never been reported.…”