Rapid determination of α-lactalbumin in raw cow's milk and recombined milk using an immunochromatographic assay strip analysis method

alpha-Lactalbumin (alpha-La) is a common allergenic protein in dairy products, posing a potential hazard to human health. Therefore, there is an urgent need to develop an efficient and sensitive analytical method to assess the alpha-La content in food. After screening by cell fusion assay, we obtained a pair of monoclonal antibodies (mAbs) (mAb 1 and 9). The calculated limit of detection of the sandwich enzyme-linked immunosorbent assay (ELISA) was 3.99 ng/mL. By labeling mAbs with colloidal gold, we developed a sensitive and rapid immunochromatographic assay (ICA) strip method for the detection of alpha-La in dairy products. The established ICA strips showed high sensitivity and specificity for the detection of alpha-La, with a calculated limit of detection and a visual limit of detection of 10.33 and 50 ng/mL, respectively. The average recoveries for the determination of raw cow's milk and recombined milk using ICA strips ranged from 97.60% to 102.96%. The ICA strips showed good correlation with the high-performance liquid chromatography (HPLC) method when analyzing actual samples. The above results indicated that both methods can be used for the determination of alpha-La in dairy products.