Development of a sandwich enzyme-linked immunosorbent assay for the detection of β-lactoglobulin in thermally processed foods

beta-lactoglobulin (beta-Lg) is a major allergen of cow's milk causing severe reactions in allergic individuals. However, cow's milk or bovine whey are widely used as a raw material in the food industry. In this paper, a sandwich enzyme-linked immunosorbent assay (sELISA) targeting bovine beta-Lg in processed foods was established with a limit of detection (LOD) of 0.036 mg/kg and limit of quantification (LOQ) of 0.091 mg/kg. No cross-reactivity was found in 34 food ingredients, except for goat's milk. The recoveries obtained from the cookies, cakes, bread, and soymilk powder (50.79 +/- 2.18% to 148.44 +/- 5.34%) were in accordance with the AOAC standards. Additionally, the immunodetection recovery of beta-Lg in processed soymilk (boiled at 100 degrees C for 2 min) and sausages (steamed at 100 degrees C for 20 min) decreased to approximately 61.44 +/- 13.9% to 71.45 +/- 1.11% and 9.94 +/- 0.31% to 15.13 +/- 1.39% in relative to the raw soymilk and sausages, respectively. Moreover, 32 commercial food commodities were accurately detected by the established sELISA. Furthermore, the established method has higher sensitivity than commercial kits. The results demonstrated that the sELISA developed in this study is highly valuable for the quick and precise detection of beta-Lg in processed foods.