Determination of soya proteins in food using an enzyme‐linked immunosorbent assay procedure

Abstract

Classical immunoanalytical techniques are based on native antigens and their precipitation with specific antibodies: they are not very appropriate for the investigation of processed denatured mixtures. This report describes an immunoassay based on the more recent but well-established enzyme-linked immunosorbent assay (ELISA) procedure, which in this case is specific for soya proteins that have been solubilised in urea and then 'renatured' by removing or diluting the denaturant. Levels of soya protein 100 g-I total protein (nominally 100%) were determined with 34 commercial soya products, using a standard reference antigen. Normal expected levels were observed with flours (average 107 %) and isolates (108 %), while results with concentrates (82 " , ) and texturates (79 %) were somewhat lower. Some specialised products gave little or no response, presumably because they are hydrolysed. Meat, milk, egg, wheat and field bean proteins displayed negligible interference. These preliminary results suggest that the ELISA procedure will provide a convenient general method for the qualitative characterisation and quantitative estimation of individual proteins in food products even after severe processing; it seems more attractive than many other methods reported. Imrnunoassay is capable of large numbers of inexpensive but sophisticated determinations of specific food components. The food analyst should regard ELISA (for the determination in situ of specific antigens in mixtures) as a powerful technique complementary to classical chromatographic and electrophoretic methods which depend on separation before determination.

Textured Soy Protein Quantification in Commercial Hamburger

“…The 7S fraction was chosen as the antigen because it presents higher immunogenicity and greater immunogenic stability than 11S (Tukur et al, 1996), although the content thereof is smaller. Hitchcock et al (1981) produced anti-protein antiserum from renatured soy protein, which responded more strongly to the 7S fraction and showed immunogenic resistance to denaturation. Gri$ths et al (1984) tested various commercial kits for quantifying soy in meat products, and found that all performed best with 7S.…”

“…The standard indirect ELISA method was developed on the basis of the reports of Hitchcock et al (1981), Ravestein and Driedonks (1986), Rittenburg et al (1987) and Medina (1988), with the objective of optimizing the working routine.…”

“…In view of its potential for use as an adulterant, soy protein has been studied by various workers, who have published immunoassay methods for identifying and quantifying it in meat products (Hitchcock et al, 1981;Ravestein and Driedonks, 1986;Rittenburg et al, 1987;Janssen et al, 1987;Medina, 1988). The simplest published method for extracting soy protein from meat is that of Medina (1988).…”

Opinion of the Scientific Panel on Dietetic products, nutrition and allergies [NDA] on a request from the Commission relating to the evaluation of allergenic foods for labelling purposes

“…Physicochemical methods (López-Tapia et al, 1999) and immunochemical methods (e.g., Hitchcock et al, 1981;Griffiths et al, 1984;Rittenburg et al, 1987, Yasumoto et al, 1990Macedo-Silva et al, 2001;Heppell et al, 1987;Brandon et al, 1991;Bando, et al, 1998) have been described. However, so far, the methods are not sensitive enough.…”

Tüketime Hazır Dönerlerde PCR ile Soya Proteininin Aranması

“…However, most reliable methods are based on detection of soy protein or DNA. Protein based methods includes, electrophoretic or serologic (ELISA) methods [7][8][9] while PCR is most widely used as DNA based methods [4,10] . Because DNA is more stable to processing conditions than protein, PCR methods are shown to be more reliable when used in processed foods [10] .…”