Estimating the quantity of egg white and whey protein concentrate in prepared crabstick using ELISA

Indirect enzyme-linked immunosorbent assays (ELISA) technique was used to identify and quantify the use of dried egg white (DEW) and whey protein concentrate (WPC) in crabsticks. The use of SDS-PAGE for the quantification of protein additives has had limited success due to the high shear and high temperature processes of surimi crabstick. Monoclonal (anti-heat-denatured ovalbumin) and polyclonal (anti-β-lactoglobulin) antibodies were used. Antibodies showed no significant cross-reactivity with non-target crabstick proteins. An optimised extraction solution of 10% SDS and 2.5% 2-ME yielded high extractability with improved consistency. Quantification of DEW and WPC was achieved using the optimised extraction solution and indirect ELISA. Estimated DEW values were within 7% of actual values, WPC samples were within 17%. Inter-assay coefficients of variance for DEW ranged from 0.9% to 3.1% and those of the WPC were 1.0-8.0%.