Group B saponins in soy products in the U.S. Department of Agriculture--Iowa State University isoflavone database and their comparison with isoflavone contents.

Isoflavones in soy protein foods are thought to contribute to the cholesterol-lowering effect observed when these products are fed to humans. The group B saponins are another ethanol-soluble phytochemical fraction associated with soy proteins and isoflavones and have also been associated with cholesterol-lowering abilities. We measured the group B soyasaponin concentrations in a variety of soy foods and ingredients in the U.S. Department of AgricultureIowa State University Isoflavone Database. We compared the isoflavone and soy saponin concentrations and distributions in intact soybeans, soy ingredients, and retail soy foods. Group B saponins occur in six predominant forms. There appears to be no correlation between saponin and isoflavone concentrations in intact soybeans ranging from 5 to 11 mumol isoflavones/g soybean and from 2 to 6 mumol saponin/g soybean. Depending upon the type of processing, soy ingredients have quite different saponins/isoflavones as compared to mature soybeans. In soy foods, the saponin:isoflavone ration ranges from 1:1 to 2:5, whereas in soy protein isolates, the ratio is approximately 5:3. Ethanol-washed ingredients have very low saponins and isoflavones. These very different distributions of saponins and isoflavones in soy products may affect how we view the outcome of feeding trials examining a variety of protective effects associated with soy consumption.

Effect of processing on fumonisin content of corn.

Fumonisins (FBs) are a family of mycotoxins produced by Fusarium moniliforme and F. proliferatum, predominant corn pathogens, and are found in most corn-containing foods. The FBs are heat stable, resistant to ammoniation, and unlike most mycotoxins, are water-soluble. The levels in corn and corn-containing foods will be presented ranging from < 20 ppb to > 2 ppm. Washing of contaminated FB-corn with water did not reduce the measured FB levels of significantly. The traditional processing step to make tortilla flour, nixtamalization [Ca(OH)2 cooking] to produce masa, reduced FB levels but produced hydrolyzed FB which was almost as toxic as FB. Retorting sweet corn in brine apparently produced hydrolyzed FB. Fermentation of corn to ethanol did not alter FB levels but distillation yielded FB-free ethanol. Attempts to enzymatically modify FB with several enzymes were unsuccessful. Reactions between FB and reducing sugars (glucose or fructose) to produce Schiff's bases yielded products that were not toxic. The effects of these processing treatments must be evaluated both chemically and biologically.