A competitive direct enzyme-linked immunosorbent assay (cd-ELISA) was developed for the rapid detection of deoxynivalenol (DON) in food and feedstuff. Polyclonal antibodies against DON were generated by immunizing rabbits with 3-HS-DON-BSA conjugates. In this assay, the sensitivity (measured as IC₅₀) and limit of detection (measured as IC₁₅) were 0.03 and 0.003 mg kg⁻¹, respectively. A total of eight sample types (barley, wheat, oat, maize, rice, flour, milk and feedstuff) were chosen to evaluate the cd-ELISA assay performance. The sample could be directly detected after extraction and dilution with double-distilled water. The limit of detection in the samples was in the range of 0.15–0.48 mg kg⁻¹. In the end, the spike and recovery results in both cd-ELISA and high-performance liquid chromatography (HPLC) were compared for assay validation. The recovery results ranged between 70% and 100%. A good correlation (R² = 0.9613) between ELISA and HPLC was obtained.

The declaration of lupine supplements is mandatory to avoid lupine allergy for sensitive individuals. However, reliable detection methods against lupine allergen remain critical to prevent the unintended consumption of allergen contaminated food. In this study, we have immunized an alpaca with lupine protein extracts and retrieved nanobodies (Nbs). Nevertheless, the target antigen has been recognized as Lup an 1, which has been classified as β-conglutin, and confirmed to connect with lupine allergy. After selection of the best Nb-pair, a sandwich enzyme-linked immunosorbent assay (ELISA) has been developed providing a linear range of 0.036–4.4 μg/mL with detection limit of 1.15 ng/mL. This immunoassay was confirmed by detecting the samples with spiked allergen, and a recovery from 86.25% to 108.45% with coefficient of variation (CV) less than 4.0% has been determined. Generally, this study demonstrated the selection of Nbs against allergen with crude protein content to develop the immunoassay for lupine surveillance in foods.

A fluorescence detection method based on quantum dot–aptamer–graphene oxide probes (QD–Apt–GO) was developed to detect β-lactoglobulin (β-LG) in foods. When β-LG was present in the samples, it specifically bound to the aptamer, inhibiting the binding of probes to graphene oxide (GO), and the fluorescence of the probes could be detected. When β-LG was not present, the probes could bind to GO through π–π stacking, and the fluorescence was consequently quenched. The detection range of the optimized assay for β-LG detection was 0.36–500 mg L⁻¹. The limit of detection (LOD) for β-LG was 96.91 μg L⁻¹. The method was also validated for food sample detection. In the spike and recovery experiments of Neocate amino acid infant formula, infant millet cookies, and infant rice porridge, the recoveries were in the range of 83.33–114.53%, which met the required range of the addition recoveries. At the same time, the results were consistent with those of commercial ELISA kits. Three types of random food products purchased from a local market were analyzed for β-LG via the developed assay and using a commercial ELISA kit. The results showed good accuracy and consistency between the proposed method and the commercial ELISA kit.