Colloidal Gold Immunochromatographic Assay for Rapid Detection of Bovine β-lactoglobulin in Goat Milk Formulas

The aim of this study was to develop a colloidal gold-based immunochromatographic assay for rapid detection bovine β-lactoglobulin(β-lg)in commercial goat milk formulas. Firstly,an anti-β-lg monoclonal antibody(mAb)was prepared using the hybridoma technique with 50% inhibitory concentration(IC₅₀)value of 5.87 μg/mL. To develop an immunochromatographic test strip for detection β-lg,gold labed β-lg mAbs were sprayed on gold conjugation pad,and nitrocellulose membrane was lined with β-lg and goat anti-mouse immunoglobulins as test line(T-line)and control line(C-line). The limit of detection(LOD)value of the test strip was 50 μg/mL for β-lg,and no effective cross-reactivities with other matrix ingredients were observed. The LOD of adulteration of whole goat milk powder with cow’s nonfat skim milk(NFSM),desalted whey powder(DWP)and whey protein powder(WPP)were 5%,5% and 0.1%,respectively. Furthermore,9 commercial goat milk formulas were analyzed by this assay,and the results were in accordance with that obtained by commercial enzyme linked immunosorbent assay(ELISA)kit. The assay includes a rapid and simple treatment of sample,could be finished in 5 min,which could be evaluated by naked-eye,was qualified for on-site monitoring goat formula milk adulteration.