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

Abstract

The protein particles in soymilk were fractionated in size by differential centrifugation. Particles of more than 100nmin diameter (LSP) constituted 40%of the total protein in raw soymilk, 70% of the protein components being IIS globulin. LSPwas not formed in the presence of2-mercaptoethanol and sodium ascorbate. LSP was decreased by heating, and particles of 100-40 nmin diameter (MSP) were increased. The formation of MSPwasnot due to any degradation of LSPbut to the combination of supernatant proteins of less than 40nm in diameter with each other. MSP formed by heating contained the ft subunit of 7S and the basic subunit of USas main components. The particles of more than 40nm in diameter (LSP+MSP)constituted 50%of the total protein in both raw soymilk and soymilk. Tofu (bean-curd) is made by coagulating the proteins from soymilk with calcium or magnesium salt, which itself is made by grinding and heating soaked soybeans. were stored at 5°C until being used. All chemicals were of the highest purity available and were used without further purification.Preparation of soymilk. The beans were soaked in de-ionized water with or without 1% 2-mercaptoethanol for 20hr at 4°C. The swollen beans were then ground to a homogenate containing 10% of solids with the soaking water by an Oster blender. The homogenate was next filtered through a de-fatted cotton sheet, the filtrate being designated as raw soymilk. The homogenate was heated in boiling water for 5min and then filtered through a de-fatted cotton sheet, this filtrate being designated as soymilk. The raw soymilk heated in this way is designated as heated raw soymilk. When the swollen beans were ground to prepare the raw soymilk, it was treated by the following methods: replacement of the air by nitrogen gas and the addition of mercaptoethanol, 2% hydrogen peroxide or 0.2 m ascorbate, respectively, before grinding;and aeration for 20min and sonication for 5min after grinding. These treatments are expressed in Table II as substitution with N2, mercaptoethanol, 2% H2O2, 0.2m Na-ascorbate, aeration and sonication, respectively.Preparation of protein particles. Protein particles of a definite size were prepared from the soymilks by the method of differential centrifugation.6) The average size of the fractionated particles was calculated by using 1.2 f Present address:

Influences of Calcium and pH on Protein Solubility in Soybean Milk

“…It supports the idea that the particles in RSM was not assembled from soluble proteins but produced by disassembling protein bodies. 1 ) After the particles were formed, the phytate would bind to the surface of the particles. It means that calcium binding sites of particulate protein are not the same as those of soluble protein in RSM.…”

“…The proteins. of soybean milk exist in complexes called 7S and lIS, and in protein particles 40-200 nm in diameter.l) It is reported that the particles comprise 50% of the total protein in raw soybean milk and soybean milk 1 ) (water and hot-water extracts, respectively). The main particles of raw soybean milk are in the range of 100-200 nm in diameter.…”

Optimization of soymilk, mango nectar and sucrose solution mixes for better quality of soymilk based beverage

“…As expected, protein content increased with an increase in SM% and decreased with an increase in proportions of MN and SS. This trend might be correlated with the relatively high protein in SM (Ono et al, 1991). The protein component in soy milk has been reported to be high in comparison to mango (0.44-0.58%; Naz et al, 2014), and protein content would be zero in SS.…”

Characterization of Soymilk Prepared from Non-imbibed Soybean Seeds

“…Estimation of soymilk particle size Soymilk reportedly includes protein suspension and emulsion consisting of protein and lipid (Ono et al, 1991;Ono, 2008). We therefore measured the particles derived from the emulsion using a laCharacterization of Soymilk Prepared from Non-imbibed Soybean Seeds …”

“…Soymilk consists of soluble protein, protein particles (i.e., protein suspension) and emulsion derived from lipid and protein (Ono et al, 1991;Ono, 2008). Research on soymilk has been extensive, especially with regard to the effect of heat treatment (Ono et al, 1991;Guo et al, 1997;Shimoyamada et al, 2008), tofu processing (Tezuka et al, 2004;Onodera et al, 2009), yuba processing (Chen et al, 2009), and novel soymilk-derived gel formation (Shimoyamada et al, 1999a(Shimoyamada et al, , 1999bKamata et al, 2004).…”