Development of biotin-streptavidin amplified peptide antibody-based ELISA for quantification of αS1-casein in goat's milk

Alpha-s1-casein plays significant roles that determine the chemical, technological, and allergy properties of goat's milk. The well-known advantages of ELISA have made it becomes the gold method for the rapid detection of food biomolecules in diverse analytical settings. This study aims to develop a sandwich ELISA for quantification of alpha(S1)-casein in goat milk, utilizing peptide IgG-biotin as detection antibody. Under optimized condition, the calculated LOD and LOQ were 0.063 and 0.21 mu g/mL, respectively. Cross-reactivity test showed that the ELISA was able to discriminate between alpha(S1)-casein and other proteins albeit their high homology (similar to 85%). The recoveries of alpha(S1)-casein in real milk samples were within the acceptable range of 80-120%. The %CV (<20%) and Pearson correlation coefficient (r > 0.9) indicated good reliability of ELISA in correlation with HPLC. The ELISA will substantially benefit several parties for the assessment of goat alpha(S1)-casein in milk and milk products, which include goat breeders, goat's milk product manufacturers, diagnostic laboratories, and consumers.

Automated summary

This study developed a sandwich ELISA method for the quantification of α(S1)-casein in goat milk, which showed high sensitivity and accuracy. The ELISA was able to discriminate α(S1)-casein from other proteins and achieved acceptable recovery rates. This method can be used by goat breeders, milk product manufacturers, diagnostic laboratories, and consumers to assess the content of α(S1)-casein in goat milk products.