Polymorphisme de la caséine Κ de trois races bovines françaises et aptitude à la coagulation

Abstract

κ-Casein polymorphisms and milk rennet coagulation ability In an attempt to better understand the influence of κ-casein (κ-Cn) polymorphisms on the cheese-making properties of milk, distinct trials were carried out using 3 different breeds of cows (Montbéliard, Norman, Tarentais) among those commonly used in France for cheese-milk production. Results were similar for all breeds and confirmed the role of κ-Cn polymorphisms on the milk rennet coagulation ability. Milk with a higher casein content was obtained with the κ-Cn B variant compared to other κ-Cn variants. The κ-casein B milk also contained more κ-Cn. Its clotting time was shorter. The most significant difference between κ-Cn variants consisted of the curd firmness. κ-Cn B milk produced a solid curd. Organization of the gel also occurred more rapidly with κ-Cn B milk. For the same casein content or adjusted rennet coagulation time, the higher κ-Cn content of κ-Cn B milk probably explains its better firmness. Indeed, differences seemed to depend mostly on the average size of the casein micelles which was much smaller for κ-Cn B milk, resulting in a faster gel organization.