Food allergen analysis for processed food using a novel extraction method to eliminate harmful reagents for both ELISA and lateral-flow tests

Abstract

Enzyme-linked immunosorbent assay (ELISA) is commonly used to determine food allergens in food products. However, a significant number of ELISAs give an erroneous result, especially when applied to highly processed food. Accordingly, an improved ELISA, which utilizes an extraction solution comprising the surfactant sodium lauryl sulfate (SDS) and reductant 2-mercaptoethanol (2-ME), has been specially developed to analyze food allergens in highly processed food by enhancing analyte protein extraction. Recently, however, the use of 2-ME has become undesirable. In the present study, a new extraction solution containing a human- and eco-friendly reductant, which is convenient to use at the food manufacturing site, has been established. Among three chemicals with different reducing properties, sodium sulfite, tris(3-hydroxypropyl)phosphine, and mercaptoethylamine sodium sulfite was selected as a 2-ME substitute. The protein extraction ability of SDS/0.1 M sodium sulfite solution was comparable to that of SDS/2-ME solution. Next, the ELISA performance for egg, milk, wheat, peanut, and buckwheat was evaluated by using model-processed foods and commercially available food products. The data showed that the SDS/0.1 M sulfite ELISA significantly correlated with the SDS/2-ME ELISA for all food allergens examined (p< 0.01), thereby establishing the validity of the SDS/0.1 M sulfite ELISA performance. Furthermore, the new SDS/0.1 M sulfite solution was investigated for its applicability to the lateral-flow (LF) test. The result demonstrated the successful analysis of food allergens in processed food, showing consistency with the SDS/0.1 M sulfite ELISA results. Accordingly, a harmonized analysis system for processed food comprising a screening LF test and a quantitative ELISA with identical extraction solution has been established. The ELISA based on the SDS/0.1 M sulfite extraction solution has now been authorized as the revised official method for food allergen analysis in Japan.

Consumer-friendly food allergen detection: moving towards smartphone-based immunoassays

“…As ethanol-based extractions result in the incomplete extraction of gluten, it is desirable to use a cocktail extraction solution that contains a reducing agent and alcohol, which is capable of extracting monomeric and polymeric proteins from gluten [62–64]. Extraction procedures have been a detriment in the past, where hazardous and environmentally damaging extraction solutions such as 2-mercaptoethanol (2-ME) have been applied in food allergen extraction [65]. In order to step toward consumer-friendliness it is necessary to have extraction buffers that are safe to use and easy to dispose of.…”

Novel sensitive monoclonal antibody based competitive enzyme-linked immunosorbent assay for the detection of raw and processed bovine beta-casein

“…They verified that an extraction buffer containing 1% SDS and 1% 2-mercaptoethanol (2-ME) gave the highest recovery across all monitored allergens [ 29 ]. However, the reducing agent 2-ME has undesirable characteristics such as unpleasant odor, toxicity and the need of handling in a fume hood [ 35 , 36 ]. Because of this, we sought to carry out protein extraction from four food matrixes that are present in most food commodities: egg white, wheat, corn and soy bean, without 2-ME, and applying heat (60°C for 15 min) to the food sample resuspended in 1% SDS extraction buffer.…”

Optimization of Protein Extraction Method for 2DE Proteomics of Goat’s Milk

“…The buffer used in method B consisted of the elements necessary for protein solubilization, including urea as a chaotrope to disrupt the hydrogen binding, sodium dodecyl sulphate (SDS) as detergent to disaggregate the casein micelles, DTT to reduce the proteins disulfide bridges, and sodium chloride buffered in Tris-HCl, at pH 8.0, to increase the reduced milk protein stability. Method C was developed by a previous study as an effective allergen extraction method for processed food, in which a greener reductant, sodium sulfite, was used in place of the environmentally hazardous 2-mecarptoethanol (2-ME) [56]. As a reductant, sodium sulfite breaks down the disulfide bond by inhibiting free mercaptan groups and thus reducing the disulfide crosslinking [57].…”