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%.