Study the behavior of heat-treated soy protein isolate.

The potential of using soybeans for direct feeding or as a source of functional ingredients has increased considerably throughout the last decade. Hydrolysates play an important role in determining the composition of formulations that nutritionally enrich foods.

The objective of work in Brazil was to evaluate the behavior of soy protein isolate (SPI) when submitted to heat or to a chemical treatment with maleic anhydride (MA). Investigators also wanted to study the effects of these treatments on hydrolysis by a-chymotrypsin.

The native soy protein isolate (SPIn), produced in the laboratory, was submitted to heat treatments at 70 C (IPS70) and 80 C (IPS80) and to chemical treatment with 0.1535M MA (IPSM). Hydrolysis was monitored, and the trypsin inhibitors in the isolates were quantified.

The electrophoretic profiles of the SPIn and the heat-treated isolates showed no differences in the relative proportions of the 7S and 11S fractions, although when compared to IPSM, researchers found differences in the sub-units. The chromatographic profiles of the isolates revealed great differences in the hydrophobic nature of the isolates.

The susceptibility of the 7S and 11S fractions to hydrolysis was greater in the hydrolysates treated at 80 C and with MA. The characteristics of the hydrolysates appear to be dependent on the treatment previously suffered by the protein. The hydrolysates could show differentiated functional characteristics. They can show emulsification and formation properties. They can be used in a range of food systems as products for infants, for those with special medical needs and others. Researchers intend to continue their efforts and work with more complex model systems, for instance protein hydrolysates and lipids or carbohydrates.

On another front, an upgraded tool for analyzing the performance of soybean varieties is available on the Worldwide Web at http://web.aces.uiuc.edu/vips. The Varietal Information Program for Soybeans (VIPS) contains detailed information on more than 2000 different soybean varieties grown in Illinois and Iowa. In most cases, more than 30 different compositional attributes are listed for each variety.

This program offers information on the production attributes of numerous soybean varieties. It integrates information on yield, protein and oil content with new data on disease susceptibility. VIPS also provides specific information on the environmental and agronomic conditions for all trial locations. Data on disease resistance for white mold, soybean sudden death syndrome (SDS), soybean cyst nematode (SCN), rhizoctonia root rot and seed mottling are available for many varieties. The recent upgrade has also added soybean varietal data from the 2000 Iowa Crop Performance Tests.

An additional component of VIPS is designed for users interested in an in-depth analysis of soybean composition. Data from VIPS composition provide information on 31 end-use attributes of soybean composition. The database covers more than 2000 different varieties. VIPS composition includes data for protein, fatty acids, amino acids and isoflavones.

Further information. In Brazil: Flavia Maria Netto, Faculdade de Engenharia de Alimentos-UNICAMP, CP 6121, Campinas, SP, Brasil, CEP 13083-970; phone: [phone]; fax: [phone]; email: [e-mail]. VIPS: Phil Orwick, University of Illinois Urbana-Champaign, 170 National Soybean Research Center, 1101 W. Peabody Dr., Urbana, IL 61801; phone: [phone]; fax: [phone]; URL: www.nsrl.uiuc.edu.