Analysis of polyphenols using capillary zone electrophoresis and HPLC: Detection of soy, lupin, and pea protein in meat products

The analysis of polyphenols, which are characteristic of certain legumes, e nables a rapid and sensitive detection of legume proteins in meat products. Separation of specific isoflavones can be achieved by capillary zone elect rophoresis (CZE) or high-performance liquid chromatography (HPLC), both cou pled with a photodiode array detector (DAD). The use of CZE in the identifi cation process is an appropriate means of rapid screening; the HPLC is less dependent on matrix effects and clearly more sensitive. Additives of soy p rotein isolates up to 0.1% could be detected in meat products, even in saus ages heated to a high temperature or with hydrolyzed soy proteins. A solid- phase extraction procedure with polyamide cartridges has been developed to concentrate polyphenols. A similar detection of lupin protein is possible i n principle. In the case of pea protein, a reliable detection was not possi ble depending on the coincidental appearance of polyphenols as indicating s ubstances.