Gelation of Soybean Protein Isolates in Acidic Conditions. Effect of pH and Protein Concentration

Whey protein concentrate gels with honey and wheat flour

“…The high solubility in BSU of protein components in the acidic gels indicates that noncovalent bonds are the responsible of the maintenance of the structure in these gels, in agreement with previous results obtained in gels without wheat flour (Lupano et al, 1992(Lupano et al, , 1996Puppo, Lupano, & Añó n, 1995). This fact was expected because sulphydryl-disulphide interchange reactions practically do not take place at acid pH.…”

Characterization of Soybean Proteins–Fatty Acid Systems

“…As analyzed in a previous work [3], the solubility of alkaline soybean protein isolate (P8) was higher than values obtained for the acid protein (P2.5), at both temperatures. In addition, we observed that P8 did not change its solubility with heating at 60°C, while for P2.5 solubility decreased due to partial denaturation and aggregation of these proteins under acid conditions [3,17]. Treatment of proteins with fatty acid at 40°C produced an alkaline complex of lower solubility (P8 ?…”

“…An alkaline extraction from the flour (pH 8.0), followed by precipitation at the isoelectric point (pI = 4.5) was carried out according to Puppo et al [3]. The isoelectric precipitate was dispersed in distilled water and adjusted to pH 8.0 with 2N NaOH to obtain alkaline isolate (P8) or to pH 2.5 with 2N HCl to obtain acid isolate (P2.5).…”

“…Soybean proteins are utilized in numerous food products, such as drinks, desserts and mayonnaise. Functional properties of these proteins, such as gelation [3,4], emulsification [5] and foaming [6] have been widely studied by our group and around the world by several authors. Those functional properties were improved by changes in pH, protein concentration, salt addition, thermal and high pressure treatments.…”

Physicochemical and functional properties of soy protein isolate as a function of water activity and storage

“…Gels were prepared according to Puppo, Lupano, and Añ ó n (1995) with some modifications: protein suspensions (13%) with the pH value adjusted to 7.0 were stirred for 10 min and then centrifuged at 1200g for 10 min at 20°C to de-aerate the solution, before being transferred to glass tubes (6 cm high and 2 cm internal diameter). The tubes were sealed, heated at 90°C for 30 min in a water bath and then cooled to 15°C.…”