Protein composition of yak milk

Abstract

-The protein composition of 24 individual Maiwa yak milk samples that were collected in the Sichuan province of China was determined by reversed-phase high-performance liquid chromatography. Yak milk differed from cow milk by its high concentration of total proteins (46.2-58.4 g·L −1 ), total casein (40.2 g·L −1 on average) and the proportion of individual caseins. The high content of β-casein (more than 45%) and consequently the lower proportion of α s -casein (about 40%) together with a small increase in κ-casein (15%) appear to make this milk more favorable for infant nutrition as used by the Tibetan nomads. Also, the whey proteins, β-lactoglobulin and serum albumin, showed similarities in centesimal composition with the homologous cow whey proteins. However, this initial study on yak milk proteins has highlighted the lack of knowledge in the literature and underlines that much research is required to optimize the utilization of all components of this milk for people living in extreme climatic environments.yak milk / casein / whey protein / HPLCRésumé -Composition protéique du lait de yak. La composition protéique de 24 échantillons de lait de yak de race Maiwa, collectés dans la province de Sichuan en Chine, a été déterminée par chromatographie liquide haute performance. Par rapport au lait de vache, le lait de yak présentait des teneurs nettement plus élevées en protéines totales (46.20-58.40 g·L Article published by EDP Sciences caséine κ, environ 15 %. Ces proportions proches de celles existant dans la caséine du lait humain sont probablement la raison de la consommation usuelle de ce lait par les nourrissons des nomades tibétains. Les déterminations des protéines solubles également réalisées dans le cadre de cette étude montraient une forte similarité de composition en β-lactoglobuline et sérum albumine par rapport aux protéines homologues du lait de vache. Ces premiers résultats sur les protéines du lait de yak mettent en évidence la faiblesse des connaissances disponibles sur ce sujet et a contrario l'effort de recherches qui se doit d'être réalisé pour une utilisation la mieux adaptée possible des composants de ce lait aux besoins des populations vivant dans un environnement climatique extrême.lait de yak / caséine / protéine de lactosérum / HPLC

Science of Camel and Yak Milks: Human Nutrition and Health Perspectives

“…Yak milk has greater contents of total proteins (4.6% -5.8%), total casein (4.0%) and individual caseins than cow milk. The higher β-casein (45%) and the lower α-s-casein (40%) along with somewhat higher κ-casein (15%) make yak milk a favorable food for infants as traditionally consumed by Tibetan nomads [37]. Yak milk's whey proteins, β-lactoglobulin and serum albumin compositions are rather similar to homologous cow whey proteins.…”

“…Along with high proteins, yak milk has high acidity. Saturated and unsaturated FA comprise respectively 22% and 55.2% of total fat, with greater content of low molecular weight volatile acids, compared to cow milk [37]. Mongolians produce from yak milk butter as well as fermented and protein products.…”

Heat stability improvement of antimicrobial whey proteins fromyak milk and colostrum at various acidic conditions

“…China is the largest producer of yaks in the world, with approximately 14.7 million, constituting to more than 95% of world yaks with annual yield of about 70,000 tonnes of milk (Zhong et al 2006). However, the yield of yak milk is low ranging from 147 to 487 kg per lactation period, compared to cow's milk, yak milk contains high content of proteins (4.9 -5.3%), total solids (16.9 -17.7%), fat (5.5 -7.2%), lactose (4.5 -5.0%) and minerals (0.8 -0.9%) (Dong et al 2007;Li et al 2010;Nikkhah, 2011).…”

Effect of microbial transglutaminase crosslinking on the functional properties of yak caseins: a comparison with cow caseins

“…It was showed that yak milk has a high concentration of total proteins (46.2-58.4 g.L −1 ) and total caseins (40.2 g.L −1 ) (Li et al 2010). The high content of β-casein (more than 45%) and consequently the lower proportion of αs-casein (about 40%) together with the high content of κ-casein (15%) in yak milk make it with a good proportion of individual caseins, which is similar to the proportion found in human milk and more favorable for infant nutrition (Li et al 2010). It also found the high content of minerals and micellar size of yak milk (Wang et al 2013;Yang et al 2014b).…”