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The aim was to determine the genetic variation in the CSN1S1, CSN2, CSN1S2, CSN3 and LGB genes in Blanco Orejinegro cattle. 419 animals from 15 herds were genotyped with GGP Bovine 150 K (n= 70) and 50 K (n= 349) chips. Information was obtained from 43 SNPs in the mentioned genes and protein variants *B, *C and *D of αS1-CN; *A1, *A2, *B, *H2 and *F of β-CN; *A and *D of αS2-CN, *A, *A1, *B, *I and *H of κ-CN and *A, *B, *C, *D, *E, *F and *H of β-LG were reconstructed. Allele and genotypic frequencies were estimated for SNPs and for protein variants; Hardy-Weinberg equilibrium and FST values were evaluated for each of the SNPs under different structuring criteria. LD values and haplotypic frequencies were estimated for caseins. The most frequent variants were CSN1S1*B (0.804), CSN2*A2 (0.509), CSN1S2*A (0.997), CSN3*A (0.679) and β-LG*B (0.657). None of the variants showed deviations from HWE, but the CSN2*A2 allele showed a slight increasing trend over time. The FST values were low (0.035) regardless of the structuring criteria. Twenty-eight CSN1S1-CSN2-CSN1S2-CSN3 haplotypes were found, 22 of them with frequencies

O objetivo deste trabalho foi recuperar e fracionar as proteínas do soro de leite por meio da técnica de coacervação, utilizando o polissacarídeo carboximetilcelulose sódica (CMC). O soro de leite foi obtido da fabricação industrial do queijo tipo frescal. Foram estudados concentrações do polímero (0,1% a 0,9% CMC p/v) e valores de pH, a fim de se obter uma precipitação seletiva das proteínas do soro de leite, sendo as condições otimizadas para produção em piloto. Mediante ajuste gradual, foi possível obter, no pH 3, uma precipitação das proteínas totais (PT/CMC); no pH 4, da beta-lactoglobulina (beta-Lg/CMC) e, no pH 3,2, a maior proporção de alfa-lactoalbumina (alfa-La/CMC). Os coacervados foram separados, por aplicação de força centrífuga, e caracterizados em relação à composição centesimal e perfil eletroforético. O maior rendimento foi verificado no fracionamento da beta-lactoglobulina, com 86% de recuperação dessa classe de proteínas do soro desnatado. O coacervado beta-lactoglobulina-CMC (beta-Lg/CMC) apresenta maior conteúdo protéico, provavelmente em conseqüência da proporção estabelecida entre os hidrocolóides coacervados. O coacervado composto pela alfa-La/CMC apresentou menor conteúdo protéico e porcentagem de recuperação dessas proteínas presentes no soro.This work aimed to recover and fractionate milk whey proteins through the coacervation technique, using sodium carboxymethyl cellulose (CMC) polysaccharide. Milk whey was obtained from the manufactured cheese type "frescal". Polymer concentration (0.1-0.9% CMC w/v) and pH values were studied in order to obtain a selective precipitation of whey proteins; conditions were optimized to pilot scale production. After pH gradual adjustment the precipitation of total proteins (PT/CMC) was achieved for pH 3; for pH 4 beta-lactoglobulin (beta-Lg/CMC) precipitation and for pH 3.2 the greatest proportion of alpha-lactoalbumin (alpha-La/CMC) precipitation. Coacervates were separated by centrifuge force, and characterized in relation to their composition and electrophoretic profile. The highest yield was obtained from fractionation of beta-Lg/CMC with precipitation of 86% of this whey protein type. Highest protein content was showed by beta-Lg/CMC, probably due to the proportion among hydrocolloids. The alpha-La/CMC showed minor protein content and yield recuperation of this whey protein fraction.