Influence of genetic variants of beta lactoglobulin and kappa casein on milk composition and cheesemaking capacity
Rahali, V.; Menard, J.L.
Lait 71(3): 275-298
1991
ISSN/ISBN: 0023-7302 Accession: 007456288
The influence of genetic polymorphism of .beta.-lactoglobulin (.beta.-Lg) and .kappa.-casein (.kappa.Cn) on milk composition and cheese-making capacity was investigated in 83 Camembert-type cheeses, issued from 230 Friesian cows' milk. Eight genetic combinations between .beta.-Lg and .kappa.-Cn were studied; the chemical composition of milks, curds and wheys was assessed, as well as the results and retention percentages of components during cheese processing; a Formagraph was used to determine coagulation properties. The positive influence of BB-genotype for .beta.-Lg is essentially shown in casein rate in milk (+4.7% compared to the AA-genotype) and total nitrogen retention in curd (+ 2.9%). Beneficial effects of BB-genotype for .kappa.-Cn are greater, especially as regards clotting time and maximum curd firmness (respectively -24% and +37% compared to the AA-genotype); these are explained, among other factors, by a more favourable proteic composition. The result is a better recovery of chemical components in curds characterized by the BB-genotype for .kappa.-Cn. The A-B genotype is in between. Discriminating factorial analysis shows that the effects of genetic variants of .beta.-Lg and .kappa.-Cn are additive. Genetic combinations have been graded according to their cheese-making quality, the BB/BB genotype for both proteins ranking first.