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Changes of isoflavones during processing of soy protein isolates

Abstract

Soy protein isolate (SPI) is a widely used food ingredient and is made by extracting soy flour (SF) under slightly alkaline pH, followed by precipitation, washing, and drying. Soy foods and foods containing soy protein ingredients have great potential in the prevention of cardiovascular diseases and cancers. These health benefits have been attributed to isoflavones in soy protein ingredients. However, the current processing techniques were developed many years ago without this knowledge. The objective of this study was to investigate the mass balance of different isoflavones during manufacturing of SPI and to provide basic information to assist further development efforts leading to preservation of soy isoflavones in soy protein ingredients. The study revealed that only about 26% of the total isoflavones in SF remained in SPI. The percentages of total isoflavones lost during extraction, precipitation, and washing were 19, 14, and 22%, respectively. Washing was the step where most isoflavones were lost. The isoflavone profile of the SPI was different from that of SF. The former contained much more aglucones (genistein and daidzein), while the latter had almost none. The high content of aglucones in SPI was probably due to the hydrolysis of glycosides.

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References

  1. Carrol, K.K., Review of Clinical Studies on Cholesterol-Lowering Response to Soy Protein, J. Am. Diet. Assoc. 91:820–827 (1991).

    Google Scholar 

  2. Slavin, J., Nutritional Benefits of Soy Fiber, Ibid.:816–819 (1991).

    PubMed  CAS  Google Scholar 

  3. Jacues, H., D. Laurin, S. Moorjani, F.H. Steinke, C. Gagne, D. Brun, and P.J. Lupien, Influence of Diets Containing Cow’s or Soy Protein Beverage on Plasma Lipid in Children with Familial Hypercholesterolemia, J. Am. Coll. Nutr. 11:69S-73S (1992).

    Google Scholar 

  4. Adlercreutz, H., H. Honjo, A. Higashi, T. Fotsis, E. Hamalainen, T. Hasegawa, and H. Okada, Urinary Excretion of Lignans and Isoflavonoid Phytoestrogens in Japanese Men and Women Consuming a Traditional Japanese Diet, Am. J. Clin. Nutr. 54:1093–1100 (1991).

    PubMed  CAS  Google Scholar 

  5. Lee, H.P., L. Gourley, S.W. Duffy, J. Esteve, J. Lee, and N.E. Day, Dietary Effects on Breast-Cancer Risk in Singapore, Lancet 337:1197–1200 (1991).

    PubMed  Article  CAS  Google Scholar 

  6. Wang, H.J., and P.A. Murphy, Isoflavone Content of Commercial Soybean Foods, J. Agric. Food Chem 42:1666–1673 (1994).

    Article  CAS  Google Scholar 

  7. Messina, M.J., V. Persky, K.D.R. Setchell, and S. Barnes, Soy Intake and Cancer Risk: A Review of the In Vitro and In Vivo Data, Nutr. Cancer 21:113 (1994).

    PubMed  CAS  Article  Google Scholar 

  8. Eldridge, A.C., and W.F. Kwolek, Soybeans Isoflavones: Effect of Environment and Variety on Composition, J. Agric. Food Chem. 31:394–396 (1983).

    PubMed  Article  CAS  Google Scholar 

  9. Anderson, R.L., and W. Wolf, Compositional Changes in Trypsin Inhibitors, Phytic Acid, Saponins and Isoflavones Related to Soybean Processing, J. Nutr. 125:581S-588S (1995).

    PubMed  CAS  Google Scholar 

  10. Barnes, S., and M. Messina, Soy and Its Role in Cancer Prevention, The Soy Connection. 1:1–3 (1993).

    Google Scholar 

  11. Smith, A.K., and S.J. Circle, in Soybeans: Chemistry and Technology, edited by A.K. Smith and S.J. Circle, AVI Publishing Co., Westport, 1976, p. 339.

    Google Scholar 

  12. Eldridge, A.C., Determination of Isoflavones in Soybean Flours, Protein Concentrates, and Isolates, J. Agric. Food Chem. 30:353 (1982).

    Article  CAS  Google Scholar 

  13. Wang, H.J., and P.A. Murphy, Isoflavone Composition of American and Japanese Soybeans in Iowa: Effects of Variety, Crop Year, and Location, J. Agric. Food Chem 42:1674–1677 (1994).

    Article  CAS  Google Scholar 

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Correspondence to C. Wang.

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Wang, C., Ma, Q., Pagadala, S. et al. Changes of isoflavones during processing of soy protein isolates. J Amer Oil Chem Soc 75, 337 (1998). https://doi.org/10.1007/s11746-998-0050-7

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  • DOI: https://doi.org/10.1007/s11746-998-0050-7

Key Words

  • Daidzein
  • genistein
  • isoflavones
  • processing
  • soy protein isolate