Heat Stability of Bovine Milk Immunoglobulins and Their Ability to Bind Lactococci as Determined by an ELISA

Immunoglobulins obtained from bovine colostrum were heat treated at 70, 75, 80 and 85°C for 0‐90 min. An ELISA was developed to determine the susceptibility of lactococci to bind heat treated IgG, IgM and IgA. IgA was the most heat sensitive of the immunoglobulins. Treatment at 80°C for 25 min completely inactivated IgA as evidenced by the inability of lactococci to bind IgA. IgM was completely inactivated upon heating to 85°C for 20 min whereas IgG was completely inactivated at 85°C after 30 min. Laser Scanning Microscopy verified results with ELISA. Severe thermal treatment is needed to reduce immunogenicity of bovine milk to prevent lactococcal agglutination.