Particle formation during soy protein precipitation

Lui, D. Y., Litster, J. D. and White, E. T. (2005). Particle formation during soy protein precipitation. In: Dr Matt Hardin, 33rd Australasian Chemical Engineering. CHEMECA 2005, Brisbane, Australia, (1-7). 25-28 September 2005.

Author Lui, D. Y.
Litster, J. D.
White, E. T.
Title of paper Particle formation during soy protein precipitation
Conference name CHEMECA 2005
Conference location Brisbane, Australia
Conference dates 25-28 September 2005
Proceedings title 33rd Australasian Chemical Engineering
Place of Publication Brisbane, Australia
Publisher Institute of Engineers, Australia
Publication Year 2005
Sub-type Fully published paper
ISBN 1864998326
Editor Dr Matt Hardin
Volume 2005
Issue 301
Start page 1
End page 7
Total pages 7
Collection year 2005
Abstract/Summary The current success of soy foods is driving soy ingredient manufacturers to develop innovative products for food manufacturers. One such innovation is separating the soy proteins glycinin and beta-conglycinin to take advantage of their individual functional and nutritional properties. Precipitation by acidification is a low-cost method for separating these two proteins. Separation is achieved by preferentially precipitating glycinin at pH ~ 6 while beta-conglycinin remains in solution. Understanding the particle formation during protein precipitation is important as it can influence the efficiency of the precipitation process as well as subsequent downstream processes such as the particle-liquid separation step, usually achieved by centrifugation. Most of the previous soy protein precipitation studies are limited to precipitation at pH 4 as this is the pH range most commonly used in the commercial manufacturing of soy protein isolates. To date, there have been no studies on the particle formation during precipitation at pH > 5.Precipitation of soy protein is generally thought to occur by the rapid formation of primary particles in the size range of 0.1 - 0.3 microns followed by aggregation of these particles via collision to aggregates of size about 1 - 50 microns. The formation of the primary particles occurs on a time scale much shorter than that of the overall precipitation process (Nelson and Glatz, 1985). This study shows that precipitation of soy protein is indeed rapid. At high pH levels, binary liquid-liquid separation occurs forming a protein-rich heavy phase. The protein-rich phase appears as droplets which can be coalesced to form a uniform bulk layer under centrifugation forces. Upon lowering the pH level by the addition of acid, further protein is precipitated as amorphous material which binds the droplets together to form aggregates of amorphous precipitates. Liquid-liquid separation has been observed in many protein solutions but this phenomenon has only scarcely been reported in the literature for soy proteins. It presents an exciting opportunity for an innovative product. Features of the liquid-phase protein such as protein yield and purity will be characterized.
Subjects E1
290603 Membrane and Separation Technologies
670199 Processed food products and beverages not elsewhere classified
Q-Index Code E1

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Created: Thu, 23 Aug 2007, 20:24:56 EST