Soy isoflavone analysis: quality control and a new internal standard

Area of Science:

• Food Science
• Analytical Chemistry
• Nutritional Science

Background:

• Accurate quantification of soy isoflavones is crucial for food databases.
• Existing methods require validation for diverse food matrices.

Purpose of the Study:

• To develop and validate accurate and precise analytical methods for soy isoflavone determination.
• To establish a comprehensive database of soy isoflavone content in various soy products.

Main Methods:

• Validated internal and external standards for accuracy and precision assessment.
• Utilized High-Performance Liquid Chromatography (HPLC) for isoflavone isomer separation and quantification.
• Developed extraction methods tailored to different soyfood matrices.

Main Results:

• Achieved high precision with coefficients of variation (CVs) < or = 8%.
• Quantified 12 isoflavone isomers, including 3 aglycones and 9 glucosides.
• Assembled a database revealing a wide range of isoflavone concentrations ( < 50 microg/g to > 20,000 microg/g).

Conclusions:

• Validated HPLC methods provide accurate and precise soy isoflavone quantification.
• Recommended normalizing isoflavone concentrations to aglycone mass for accurate reporting.
• The developed database serves as a valuable resource for soy food composition analysis.