Effect of pH and Ca2+-induced associations of soybean proteins

Yong J. Yuan; Orlin D. Velev; Ken Chen; Bruce E. Campbell; Eric W. Kaler; Abraham M. Lenhoff

doi:10.1021/jf025582d

Effect of pH and Ca²⁺-induced associations of soybean proteins

Yong J. Yuan, Orlin D. Velev, Ken Chen, Bruce E. Campbell, Eric W. Kaler, Abraham M. Lenhoff

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Abstract

An experimental procedure was developed to characterize the solubility of the soybean protein fractions close to the isoelectric point. The results show that the 7S fraction is precipitated in a much narrower range of pH values than the 11S fraction. Surprisingly, the addition of salt to the solutions leads to increased solubility of proteins, unlike the common "salting out" effect generally expected for proteins in solution in this range of salt concentrations. The precipitation equilibria of both soybean fractions in the presence of calcium ions and electrolyte were characterized. The amount of calcium ions required to precipitate a mole of the 7S fraction is much larger than that required for the 11S fractions. The precipitation pattern can be correlated to the charge density per surface area of the proteins.

Original language	English (US)
Pages (from-to)	4953-4958
Number of pages	6
Journal	Journal of agricultural and food chemistry
Volume	50
Issue number	17
DOIs	https://doi.org/10.1021/jf025582d
State	Published - Aug 14 2002

Keywords

Calcium
Electric charge
Equilibrium
Precipitation
Soybean proteins
pH

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AU - Lenhoff, Abraham M.

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