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

Abstract

(Reçu le 11 mai 1992; accepté le 27 octobre 1992) Résumé -Les études réalisées sur des laits individuels de 3 races bovines traditionnelles exploitées en France (Montbéliarde, Normande et Tarentaise) confirment l'intérêt du polymorphisme de la caséine lC (x-On) sur l'aptitude des laits à la coagulation par la présure. L'homozygote BB contient plus de caséine totale. Il est plus riche en x-On, Il présente un temps de gélification par la présure plus court que l'homozygote AA ou les hétérozygotes AC, BC, AB et surtout une consistance du caillé, à un temps donné, plus ferme liée à un temps de raffermissement plus court. Que l'on réalise des comparaisons entre les génotypes de la x-On pour un même taux de caséine totale ou un temps de gélification ajusté par la quantité de présure, les laits des vaches x-en BB présentent toujours une meilleure aptitude à la coagulation (temps de raffermissement réduit et fermeté des gels accrue) par rapport aux autres vaches. La plus grande richesse en x-On des laits BB explique probablement ce résultat: la taille moyenne de leurs micelles de caséine est moindre ce qui provoque une organisation plus rapide du caillé.

Chemical composition and coagulation properties of modicana and holstein cows' milk

“…The greater curd firmness of Mo cows' milk is essentially due to its higher nitrogen content, as observed by a number of authors [16,22] and confirmed herein. The higher curd firmness of Modicana milk with the same nitrogen content could be attributed firstly to the polymorphism of casein κ, as evidenced in individual [9] or mixed milks [14]. Indeed, it is a known fact that the casein κ variant B is sharply more frequent in Modicana cows [6,13] than in Holstein cows [12] and it has been confirmed in this trial.…”

Effect of the botanical composition of hay and casein genetic variants on the chemical and sensory characteristics of ripened Saint-Nectaire type cheeses

“…This study confirmed the very beneficial effect of variant B of κ-and β-caseins on the rheological properties of coagulated milk [12,30]. However, the results of this trial seem to indicate that this beneficial effect on milk coagulation does not have any repercussions on the physico-chemical and sensory characteristics of the corresponding cheeses.…”

“…Yet, few studies have considered the intrinsic effect of the floristic composition of forage, an issue often raised by cheesemakers and the relevance of which to cheese quality has been suggested by some authors [14,25]. It is also a recognized fact that certain genetic variants of milk caseins have an influence on its clotting capacities [12,30,39]: this is true for variant B of β-and, especially, of κ-caseins, resulting in shorter clotting time and firmer curd. To our knowledge, no studies have been conducted on the effect of these variants on the sensory characteristics of cheese, whereas it is known that other genetic variants can perceptibly alter the physico-chemical and sensory characteristics of cheese [13,28].…”

Relationships between ruminant management and sensory characteristics of cheeses: a review

“…The smaller casein micelle diameter gives a denser and firmer casein network [89,108], which improves fat retention in the coagulum. Such was the case with the association of variant B of β and κ-casein in the Normande cattle breed [35,91] or with the variant A of α s1 -casein, compared with defective variants, in goats [107] or with the variant C of α s1 -casein in sheeps' milk [101]. The example of variant C of β-casein in the Tarentaise cattle breed is a good illustration of the mechanisms that can be at the origin of the texture differences noted.…”

“…The beneficial effect of variant B of κ and β-caseins on the rheological properties of clotted milk and on cheese yield has been evidenced in numerous studies [35,54,72]. Variant B reduces clotting and curd-firming times and leads to firmer rennet curd than variant A.…”