Characterization of Soymilk Prepared by Milling and Pressing at High Temperature

Abstract

The effect of milling and pressing soybeans at high temperatures (50–90C) was examined for laboratory‐scale soymilk preparation. Soymilk that was milled and pressed at high temperatures showed more precipitate and a slightly lower protein content. The surface sulfhydryl content and surface hydrophobicity of the soymilk protein increased with milling temperature, which indicates some acceleration of the thermal denaturation of proteins. Ultracentrifugation and laser diffraction particle size analysis of the soymilk showed that milling at 90C resulted in highly dispersed protein aggregates and emulsions. Practical Applications Processing method for soymilk was improved to decrease beany flavor derived from lipoxygenase. Now soybean is milled at high temperatures to inactivate lipoxygenase activity, but there are no useful data on the quality of the resulting soymilk. In this study, milling at 90C showed more disperse soymilk than at 80C by considering droplet size distribution and protein denaturation behavior. These data are useful for estimation of the quality of soymilk beverage and for improvement of soymilk processing for more palatable beverages.

Effects of pH and salt concentration on freeze–thaw fractionation of soymilk protein

“…Previous studies have suggested that a peak of around 0.3 μm indicates a dispersion of non-aggregated oil droplets. 19,26 Additionally, peaks larger than 1 μm are considered to represent aggregates of oil droplets. 18 In the sample with a pH of 11.6, a unimodal size distribution with a maximum of around 0.26 μm was observed.…”

“…Two peaks were observed within the pH range of 4.3–6.7, and the peak shifted towards smaller particle sizes as the pH increased. Previous studies have suggested that a peak of around 0.3 μm indicates a dispersion of non‐aggregated oil droplets 19,26 . Additionally, peaks larger than 1 μm are considered to represent aggregates of oil droplets 18 .…”

An Updated Review of Soy-Derived Beverages: Nutrition, Processing, and Bioactivity

“…To avoid the enzymatic oxidation of unsaturated fatty acids by LOX, responsible for the beany flavor of traditional soy milk, soybean is milled at high temperatures to inactivate the enzymatic activity. Milling at high temperatures (>70 • C) leads to an increase in the amounts of precipitate [42]. This has been mainly attributed to the denaturation of β-conglycinin at temperatures above 70 • C [43].…”

“…This has been mainly attributed to the denaturation of β-conglycinin at temperatures above 70 • C [43]. Although protein composition does not change at different milling temperatures, the protein content gradually decreases at temperatures above 80 • C, indicating a partial insolubilization or incomplete solubilization of proteins [42]. Many Western manufacturers apply a blanching process to inactivate LOX activity.…”

In vitro bioaccessibility of isoflavones from a soymilk-based beverage as affected by thermal and non-thermal processing

“…Beverages have traditionally been preserved by thermal J o u r n a l P r e -p r o o f Journal Pre-proof treatment (TT) mainly to avoid microorganism spoilage or contamination with pathogens (Odriozola-Serrano, Aguiló-Aguayo, Soliva-Fortuny, & Martín-Belloso, 2013). Nevertheless, heat processing can yield unfavorable soymilk features by reducing the protein solubility, changing the stability, increasing the droplet particle size and decreasing their nutritional and sensorial properties (Shimoyamada, Mogami, Tsuzuki, & Honda, 2014).…”