Search

In order to investigate the effect of long-term consumption of yak milk on the intestinal flora and metabolism and to explore the correlation between acclimation to monodiet and yak milk intake in high-altitude pastoral areas, this study used metagenomics and metabolomics to evaluate the gut microbial community structure and metabolites of mice fed yak milk or Holstein cow milk. Results showed that compared with the control group (normal saline solution), at the phylum level, ingestion of yak milk improved the relative abundance of Actinobacteria (33.27%), Bacteroidetes (24.31%) and Verrucomicrobia (11.08%), while ingestion of Holstein cow milk increased the relative abundance of Firmicutes (43.74%) and Bacteroidetes (24.75%). At the genus level, yak milk consumption increased the relative abundance of Ackermania (11.80%), Bacteroides (6.09%) and Limosilactobacillus (4.77%), while Holstein cow milk consumption increased the relative abundance of Lactobacillus (28.62%), Duncaniella (6.15%) and Limosilactobacillus (6.49%). Both yak and Holstein cow milk up-regulated carbohydrate and nucleotide metabolism. Furthermore, yak milk significantly up-regulated amino acid metabolism, cofactor and vitamin metabolism, energy metabolism, the biosynthesis of secondary metabolites, and the biosynthesis and metabolism of peptidoglycan. Metabolomics revealed that yak milk increased the contents of metabolites such as VB1, (+/-) 12 (13)-DiHOME, coenzyme Q2 and sulfonymethazine, as well as steroid hormone biosynthesis, cofactor biosynthesis, 2-oxyarboxylate metabolism, VB6 metabolism and phenylalanine metabolism in mice. Investigation of intestinal tissue morphology showed that the intestinal wall became thicker with increasing diversity and richness of the gut microbiota and the intestinal villi became longer and denser without deformity or breakage. In conclusion, yak milk has a positive effect on the intestinal flora and metabolism in mice, and this study provides a scientific basis for further development and utilization of yak milk.

To investigate the properties and calcium-holding capacity of yak casein phosphopeptide (CPP), this experiment was carried out using yak casein as the raw material, with trypsin being used for enzymatic hydrolysis. Static adsorption test was performed to determine the eluent, and the effects of sample amount, sample flow rate and eluent concentration on the purification process of CPP. The basic composition, functional properties, and in vitro inhibitory capacity against calcium phosphate and ferrous ion precipitation of purified CPP were examined. A low-calcium mouse model was established, and the ability of CPP to promote calcium absorption in mice was investigated using body weight, organ index, serum biochemical parameters, femur index, bone density and bone calcium as the indicators. The experimental results showed that the best purification effect on the CPP was obtained under the following conditions: 0.2 mol/L dilute hydrochloric acid as the eluent, 3 mL/min as the loading flow rate, and 100 mL as the loading volume, leading to a nitrogen to phosphorus molar ratio of 6.8, a phosphorus recovery of 95.5%, a glutamic acid content of 18.55% and a serine content of 6.01%. In vitro calcium promotion experiments showed that the purified CPP could effectively prevent the precipitation of calcium phosphate and ferrous ions. The results of animal experiments showed that after 28 d of feeding, the organ indices of all mice were within a reasonable range. After purification, CPP showed no chronic toxicity. The medium- and high-dose groups had significantly higher blood calcium and phosphorus levels than those of the model group (P<0.05), and had extremely significantly lower alkaline phosphatase (ALP) values than those in the model group (P<0.01). The femoral bone index in the high-dose group was significantly higher than that in the calcium carbonate group (P<0.05). The bone calcium and bone density of the medium- and high-dose CPP groups were significantly higher than those of the model group (P<0.05). In conclusion, this experiment can provide a theoretical basis for the development of functional yak milk foods and a reference for the subsequent research on yak milk's bioactive peptides. [ABSTRACT FROM AUTHOR]

A single-nucleotide polymorphism (SNP) is a genome-level trait that arises from a variation in a single nucleotide, leading to diversity in DNA sequences. SNP screening is commonly used to provide candidate genes for yak breeding efforts. Integrin Subunit Alpha 9 (ITGA9) is an integrin protein. It plays an important role in cell adhesion, signalling, and other processes. The aim of this study was to discuss the association between genetic polymorphisms in the ITGA9 gene and milk quality traits and to identify potential molecular marker loci for yak breeding quality. We genotyped 162 yaks using an Illumina Yak cGPS 7K liquid chip and identified the presence of polymorphisms at nine SNP loci in the ITGA9 gene of yaks. The results showed that the mutant genotypes in the loci g.285,808T>A, g.306,600T>C, and g.315,413C>T were positively correlated with the contents of casein, protein, total solids (TS), and solid nonfat (SNF) in yak milk. In other loci, heterozygous genotypes had a positive correlation with nutrient content in yak milk. Then, two ITGA9 haplotype blocks were constructed based on linkage disequilibrium, which facilitated a more accurate screening of ITGA9 as a candidate gene for yak milk quality improvement. In conclusion, we identified SNPs and haplotype blocks related to yak milk quality traits and provided genetic resources for marker-assisted selection in yak breeding. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Science & Biotechnology is the property of Journal of Food Science & Biotechnology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Yaks are the large herbivorous ruminants that live in high mountain pastures at altitudes from 2,000 to 4,000 m above sea level. This environment is quite harsh, and yaks calmly tolerate extreme cold — down to minus 40 ºС. The main food of yaks are herbaceous plants, the vegetation season of which in a cold mountain climate is short, about 3–4 months, and therefore they feed mostly on wilted pasture, which is, in principle, sufficient for these animals. At the end of winter, when the amount of pasture feed decreases, the animals become malnourished and lose weight. Therefore, yak farmers often face the need to feed their animals in winter. A complete ration of an animal, along with other factors, has a significant impact on the composition of milk and its productive ability. The aim of the work is to study the chemical composition, in particular the protein fraction, of the milk of yaks living in the mountainous regions of Kyrgyzstan in comparison with the milk of yaks from different regions of the world. The object of the study was milk of yaks inhabiting the highland regions of Naryn province of Kyrgyzstan. Samples were collected and tested according to standard methods. Studies have shown that the milk of yaks from the Kyrgyz population contains more protein (5.66%) than milk from yaks in the mountains of China, Russia and Mongolia (4.95, 4.55 and 5.3%, respectively). Milk we studied is high in amino acids such as methionine, lysine, proline, phenylalanine, and alanine. Seasonal (spring, summer) changes in the protein composition (whey proteins, casein proteins), amino acid profile, total nitrogen, non-protein nitrogen of yak milk were also studied. The total content of amino acids in the milk of Kyrgyz female yaks is noticeably higher in spring (6189.96 mg/100 g) than in summer (5101.47 mg/100 g). The research results presented in this article showed that the milking season and the associated feeding ration of yaks affects the composition of milk, which is associated with the nutritional value of grass feed and its nutrient content. Spring milk contains more proteins and amino acids than summer milk, which is due to the high protein content of plants in the spring period before the flowering phase. Milk of Kyrgyz yak with proven high nutritional and biological value is an alternative to cow milk.

Yak milk is a valuable raw material for the production of functional food. Investigation of the fermentation process with commercial starter cultures is conducted to find suitable starters for producing fermented yak milk products on an industrial scale using modern rheological, microbiological, and sensorial methods. According to the acidification curve and rheological measurement, the gel-forming time of yak milk with mesophilic, thermophilic and mixed (meso-thermophilic) starter cultures was not significantly different from cow milk; but, yak milk had a significantly higher gel strength in all cases. The viable bacteria count of fermented samples with thermophilic starters was 8.23 log CFU·mL-1 for cow milk and 9.12 log CFU·mL-1 for yak milk. During cold storage (72 h), the CFU in yak milk remained higher (98.48% - 101.22%) during the storage period than that of cow milk (90.33% - 95.06%). The sensorial property scores of yak milk fermented with mixed starters were the highest, followed by those of milk fermented with mesophilic and thermophilic starter cultures. The obtained parameters show that mesophilic and mixed cultures are advantageous in terms of sensorial and probiotic properties, and thermophilic culture - in terms of gel strength. All this information is useful for the development of new dairy products. [ABSTRACT FROM AUTHOR]

Copyright of Storage & Process is the property of Tianjin Academy of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study identified characteristic whey proteins from Zhongdian Yak (ZY), Diqing Yellow Cattle (DYC), and Cattle Yak (CY), revealing insights into their potential functions and released peptides. A total of 118 whey proteins were quantified in milk obtained from the three breeds of cattle, including seven characteristic proteins (IGL@ protein, 40S ribosomal protein S9, calreticulin, etc.) in CY milk and two characteristic proteins (RNA helicase and uncharacterized protein (A0A3Q1LFQ2)) in ZY milk. These characteristic proteins are involved in the phagosome and Fc gamma R-mediated phagocytosis pathways, exhibiting immunoprotective activities, verified through molecular docking. Furthermore, the molecular docking results showed five whey proteins (IGL@ protein, rho GDP-dissociation inhibitor 1, small monomeric GTPase, action-like protein 3, and adenylyl cyclase-associated protein) interacted with TLR4 through multiple hydrogen and hydrophobic bonds. Therefore, these proteins may exert immunomodulatory functions by inhibiting TLR4. Meanwhile, whey proteins produced bioactive peptides, such as antioxidant peptides and ACE inhibitory peptides after simulated gastrointestinal digestion (SGID). The whey proteins and bioactive peptides from CY exhibited more types and activities than the ZY and DYC whey proteins. This study provides a theoretical basis for promoting formula milk powder production.

ABSTRACT: The Ca2+-selective epithelial channel TRPV5 plays a significant role in renal calcium reabsorption and improving osteoporosis (OP). In this study, we investigated the mechanisms of yak milk on osteoporosis mice in TRPV5-mediated Ca2+ reabsorption in the kidney. We observed that treatment of OP mice with yak milk reconstructed bone homeostasis demonstrated by increasing the levels of OPG as well as decreasing the levels of TRAP and ALP in serum. Additionally, yak milk reduced the level of parathyroid hormone (PTH) and elevated 1,25-(OH)2D3 and calcitonin (CT), and inhibited the excretion of Ca/Cr and Pi/Cr in OP mice, which explained by regulating hormone levels and thus enhance the renal Ca2+ reabsorption. Further analysis exhibited that yak milk upregulated the expression of TRPV5 protein and mRNA as well as calbindin-D28k in OP mice kidneys. Overall, these outcomes demonstrate that yak milk enhances renal Ca2+ reabsorption through the TRPV5 pathway synergistically with calbindin-D28k, thus ameliorating OP mice. This provides a new perspective for yak milk as a nutritional supplement to prevent osteoporosis.

Flavor is a crucial parameter for assessing the sensory quality of yak milk. However, there is limited information regarding the factors influencing its taste. In this study, the effects of endogenous lipoprotein lipase (LPL) on the volatile flavor components of yak milk under storage conditions of 4 °C, 18 °C and 65 °C were analyzed via headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with orthogonal partial least-squares (OPSL) discrimination, and the reasons for the changes in yak milk flavors were investigated. Combined with the difference in the changes in volatile flavor substance before and after the action of LPL, LPL was found to have a significant effect on the flavor of fresh yak milk. Fresh milk was best kept at 4 °C for 24 h and pasteurized for more than 24 h. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were employed to characterize the volatile components in yak milk under various treatment conditions. Twelve substances with significant influence on yak milk flavor were identified by measuring their VIP values. Notably, 2-nonanone, heptanal, and ethyl caprylate exhibited OAV values greater than 1, indicating their significant contribution to the flavor of yak milk. Conversely, 4-octanone and 2-heptanone displayed OAV values between 0.1 and 1, showing their important role in modifying the flavor of yak milk. These findings can serve as monitoring indicators for assessing the freshness of yak milk. [ABSTRACT FROM AUTHOR]

Dairy products are susceptible to modifications in protein oxidation during heat processing, which can lead to changes in protein function, subsequently affecting intestinal health. Despite being a unique nutritional source, yak milk has not been thoroughly examined for the effects of its oxidized proteins on intestinal microbiota and metabolism. Hence, this study employed different heat treatment methods (low-temperature pasteurization, high-temperature pasteurization, and high-temperature sterilization) to induce oxidation in yak milk proteins. The study then assessed the degree of oxidation in these proteins and utilized mice as research subjects. Using metagenomics and metabolomics methods, this study examined the structure of intestinal microbial communities and metabolic products in mice consuming oxidized yak milk. The results showed a decrease in carbonyl and total thiol contents of yak milk proteins after different heat treatments, indicating that heat treatment causes oxidation in yak milk proteins. Metagenomic analysis of mouse intestinal microbiota revealed significant changes in 66 genera. In the high-temperature sterilization group (H), key differential genera included Verrucomicrobiales, Verrucomicrobiae, Akkermansiaceae, and 28 others. The high-temperature pasteurization group (M) mainly consisted of Latilactobacillus, Bacillus, and Romboutsia. The low-temperature pasteurization group (L) primarily comprised of Faecalibacterium, Chaetomium, Paenibacillaceae, Eggerthella, Sordariales, and 33 others. Functionally, compared to the control group (C), the H group upregulated translation and energy metabolism functions, the L group the M group significantly upregulated metabolism of other amino acids, translation, and cell replication and repair functions. Based on metabolomic analysis, differential changes in mouse metabolites could affect multiple metabolic pathways in the body. The most significantly affected metabolic pathways were phenylalanine metabolism, vitamin B6 metabolism, steroid hormone biosynthesis, and pantothenate and CoA biosynthesis. The changes were similar to the functional pathway analysis of mouse metagenomics, affecting amino acid and energy metabolism in mice. In summary, moderate oxidation of yak milk proteins exhibits a positive effect on mouse intestinal microbiota and metabolism. In conclusion, yak milk has a positive effect on mouse intestinal microflora and metabolism, and this study provides a scientific basis for optimizing dairy processing technology and further developing and applying yak milk. [ABSTRACT FROM AUTHOR]

The Ca2+-selective epithelial channel TRPV5 plays a significant role in renal calcium reabsorption and improving osteoporosis (OP). In this study, we investigated the mechanisms of yak milk on osteoporosis mice in TRPV5-mediated Ca2+ reabsorption in the kidney. We observed that treatment of OP mice with yak milk reconstructed bone homeostasis demonstrated by increasing the levels of OPG as well as decreasing the levels of TRAP and ALP in serum. Additionally, yak milk reduced the level of parathyroid hormone (PTH) and elevated 1,25-(OH) 2 D 3 and calcitonin (CT), and inhibited the excretion of Ca/Cr and Pi/Cr in OP mice, which explained by regulating hormone levels and thus enhance the renal Ca2+ reabsorption. Further analysis exhibited that yak milk upregulated the expression of TRPV5 protein and mRNA as well as calbindin-D 28k in OP mice kidneys. Overall, these outcomes demonstrate that yak milk enhances renal Ca2+ reabsorption through the TRPV5 pathway synergistically with calbindin-D 28k , thus ameliorating OP mice. This provides a new perspective for yak milk as a nutritional supplement to prevent osteoporosis. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper presents a comparative characteristic of the fermentation processes of yak and cow milk samples with a high fat content of 1.5% and 6% with a multicomponent starter culture, which includes Lactobacillus acidophilus, Bifidobacterium animalis subsp Lactis and Streptococcus thermophilus. Acid formation in the process of milk fermentation under the influence of the starter microflora was assessed by the dynamics of changing in titratable (Ac) and active (pH) acidity over time. The course of the formation of the structure of the resulting clot was monitored on a rheometer, fixing the viscosity characteristics of the fermented milk clot in dynamics. It has been established that the increase in acidity occurs more intensively in yak milk in comparison with cow's milk with a corresponding acceleration of the formation of a fermented milk clot. In conclusion, the resulting clots were subjected to sensory analysis with the identification of the best sample, which was fermented yak milk with a fat mass fraction of 6%. [ABSTRACT FROM AUTHOR]

In order to explore the antibacterial mechanism of Weissella confusa ZW21, a strain of lactic acid bacteria from yak milk with good antibacterial activity, its whole genome sequence was analyzed and its antibacterial activity-related functional genes were mined. In this study, the whole genome of W. confusa ZW21 was sequenced and analyzed on the Illumina NovaSeq PE150 platform, and the basic functions of the genome were annotated in the Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Cluster of Orthologous Groups, Non-Redundant Protein databases. The results showed that: (1) the genome size of W. confusa ZW21 was 2.44 Mb, and the GC content was 45.66 %; (2) 2 175 encoding genes were predicted, with a total length of 1 947 771 bp and an average length of 896 bp; and (3) the encoding genes were annotated in the functional database for basic functional annotation and metabolic pathway gene information annotation of the strain’s genome, revealing that the genome contained eight bacteriocin-related genes (such as Colicin V and Lactococcin); three antioxidant activity-related genes; signaling pathways that regulate immunity and inflammation such as the nucleotide oligomerization domain (NOD)-like receptor and peroxisome proliferators-activated receptor (PPAR) signaling pathways, and antifolate encoding genes. In summary, the whole genome sequencing and analysis of W. confusa ZW21 can provide a basis for studying its antibacterial mechanism.

To evaluate the effects of different starter cultures and different fermentation substrates on the quality of fermented milk, the samples were prepared with Bifidobacterium animalis subsp. lactis (Ba) in co-cultures with traditional yogurt starter cultures (SL), and the acidification profile, viable bacteria count, water-holding capacity, proteolytic activity, rheological property, physical stability, microstructure, volatiles and sensory characteristic of fermented cow milk, fermented yak milk and fermented milk mixtures of cow to yak milk ratios of 1:1 were investigated. The results showed that for the same fermentation substrates, Ba-SL significantly improved the acidification property and viable bacteria count of fermented milk (P0.05). Ba-SL significantly enhanced the water-holding capacity of fermented cow milk and fermented mixed milk (P

A single-nucleotide polymorphism (SNP) is a genome-level trait that arises from a variation in a single nucleotide, leading to diversity in DNA sequences. SNP screening is commonly used to provide candidate genes for yak breeding efforts. Integrin Subunit Alpha 9 (ITGA9) is an integrin protein. It plays an important role in cell adhesion, signalling, and other processes. The aim of this study was to discuss the association between genetic polymorphisms in the ITGA9 gene and milk quality traits and to identify potential molecular marker loci for yak breeding quality. We genotyped 162 yaks using an Illumina Yak cGPS 7K liquid chip and identified the presence of polymorphisms at nine SNP loci in the ITGA9 gene of yaks. The results showed that the mutant genotypes in the loci g.285,808T>A, g.306,600T>C, and g.315,413C>T were positively correlated with the contents of casein, protein, total solids (TS), and solid nonfat (SNF) in yak milk. In other loci, heterozygous genotypes had a positive correlation with nutrient content in yak milk. Then, two ITGA9 haplotype blocks were constructed based on linkage disequilibrium, which facilitated a more accurate screening of ITGA9 as a candidate gene for yak milk quality improvement. In conclusion, we identified SNPs and haplotype blocks related to yak milk quality traits and provided genetic resources for marker-assisted selection in yak breeding.

Objective: The research aimed to reveal the changes of biogenic amines in cheese made from different refrigerated milk during ripening and evaluate its quality safety. Methods: The hard cheese made from yak milk refrigerated for 24, 48 and 72 hours was taken as the research object, and the biogenic amines in cheese during ripening were determined by high performance liquid chromatography. Results: During the ripening period from 0 to 6 months, the content of biogenic amine in hard cheese made from different refrigerated yak milk showed an increasing trend. When the cold storage time of yak milk was extended from 24 h to 72 h, total biogenic amines, 2-phenylethylamine, cadaverine, tyramine and putrescine in cheese also increased in turn. The biogenic amines in the cheese made from raw milk refrigerated for 72 hours after ripening for 4 months were significantly higher than those in the other two groups of cheese. The contents of total biogenic amines and tyramine yak milk hard cheese matured for 6 months were （212.94±8.03） mg/kg and （81.04±3.92） mg/kg respectively. Conclusion: With the prolongation of the cold storage time of raw milk and the ripening time of cheese, the biogenic amine content in cheese increased. However, when the cold storage time of raw milk was less than 72 h, the biogenic amine content in its cheese was lower than the content recommended by scholars.

ABSTRACT: Yak milk is rich in essential milk proteins of nutritional and therapeutic value. In this study, whey proteins of milk from 3 yak breeds (Gannan, GN; Huanhu, HH; Maiwa, MW) in China were comprehensively identified and compared using a data-independent acquisition quantitative proteomics approach. A total of 632 proteins were identified in yak milk whey samples, in which immune-related proteins were abundant. Compared with other milks, more proteins were involved in oxidation-reduction process and with ATP binding. In addition, we identified 96, 155, and 164 differentially expressed proteins (DEP) for GN versus HH, GN versus MW, and HH versus MW, respectively. “Phagosome” and “complement and coagulation cascades” were the most significant pathways for DEP of GN versus HH and GN or HH versus MW yak milk based on the Kyoto Encyclopedia of Genes and Genomes pathway analysis. Protein-protein interaction network analysis showed that DEP for the 3 comparisons had significant biological interactions but were associated with different functions. The results provide useful information on yak milk from different breeds in China, and elucidate the biological functions of yak milk proteins.

Yak milk is a characteristic animal product of yaks in the Qinghai-Tibet Plateau. Although yak milk production is low, it is richer in nutrients such as protein, fat, and lactose, a more comprehensive range of bioactive components, and unique microbial resources than Holstein cow milk. The plateau environment makes yak milk resistant to hypoxia, anti-fatigue, antioxidant, antibacterial, and relieves chronic diseases. In this paper, based on the systematic analysis of yak milk research results in the past 20 years using CiteSpace 6.1.R2, we reviewed yak lactation performance and nutritional efficacy of yak milk. This paper summarizes the improvement of traditional yak dairy processing technology, and also focuses on the microbial diversity of yak milk sources and their beneficial effects. The purpose of this review is to provide scientific support for the development of a quality yak milk industry on the Tibetan plateau.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the effects of freezing yak milk at −20 °C and −40 °C for 30, 90 and 180 days on the fermentation characteristics and storage quality of the corresponding yogurt were discussed. The results showed that, compared with that of yogurt made from fresh yak milk, the lactic acid bacteria (LAB) growth and acid production rate of the yogurt in the −20 °C group decreased at 90 d. The water-holding capacity, viscosity and hardness decreased during storage, and a sour taste was prominent, while no significant changes were observed in the −40 °C group. At 180 d of freezing, the post-acidification of the yogurt in the −20 °C and −40 °C groups increased after 21 d of storage. Compared with the −40 °C group, the −20 °C group showed a significant decrease in LAB counts, a decrease in pH value to 3.63–3.80 and poor texture and sensory quality. [ABSTRACT FROM AUTHOR]

The purpose of this paper was to study the effect of phenological phases on forage nutrient composition, rumen fermentation parameters and content of conjugated linoleic acid (CLA) in milk of grazing yak. In this study, 10 female Gannan yaks with an average body weight of 234.9±10.5 kg were selected for research purpose (natural grazing) in Gannan Pastoral Area of Gansu Province. The forage, rumen fluid and milk samples were collected during green-up time, flowering time and withering time of forage to determine nutrient composition of forage, fermentation parameters of rumen fluid, and CLA in milk fat. The correlation analysis was studied in order to find out the influence of forage and rumen fluid parameters on the content of CLA in milk of grazing yak. The results showed that the phenological phases significantly affected the content of lauric acid, myristic acid, palmitic acid, stearic acid, linoleic acid, linolenic acid, total fatty acid, polyunsaturated fatty acids (PUFAs) and total volatile fatty acid (TVFA) (P<0.05), and these were significantly higher in flowering time (P<0.05). The content of fatty acid and total fatty acid in yak milk were significantly higher in flowering time than green-up time and withering time (P<0.05). The phenological phases significantly affected the content of CLA isomer c9t11, t10, c12 and CLA in yak milk (P<0.05), and these were significantly higher in grazing yak milk at flowering time than green-up time and withering times (P<0.05). The rumen pH, acetic acid, propionic acid, acetic/propionic acid, isobutyric acid, butyric acid, isovaleric acid, valeric acid, total volatile acid and trans-11-oleic acid in the rumen of yak were also significantly affected by phenological phases (P<0.05). There was a significant positive correlation of rumen pH, forage crude protein, crude fat, nitrogen free extract, tannic acid and total fatty acid with CLA content in grazing yaks (P<0.05). A significant negative correlation (P<0.05) of crude fiber and crude ash with CLA content in milk of grazing yak was recorded, while no significant correlation (P>0.05) of PUFAs and TVFA with CLA content was observed. This study is helpful to improve the grazing management of alpine grassland and the production performance of yaks (milk yield and milk quality). [ABSTRACT FROM AUTHOR]

Yak milk is a dietary source of high-quality protein in the plateau region of China but as yet uncharacterized oxidative changes occur during heat treatment. Therefore, oxidation of and proteomic changes to milk proteins from plateau pasture-fed yaks after at different temperatures were investigated. Content of carbonyl groups, surface hydrophobicity increased, and total sulfhydryl, disulfide bond content decreased. Endogenous fluorescence intensity decreased after at increasing temperatures, indicating increased particle size, and absolute values of the zeta potential decreased. Analysis by Fourier transform infrared spectroscopy showed changes of the secondary structure, with relative content of α-helices increasing and then decreasing, β-sheet showed a trend of decreasing and then increasing while the relative content of random curl did not change. The close range of the β-turn gradually decreased, breaking the protein microstructure, and folding stacking occurred. Proteomics analyses showed a temperature dependent effect. Sixty-two proteins were suppressed and 49 elevated with 4 pathways up-regulated and 7 down-regulated at 65 °C. Thirty-one proteins were suppressed and 37 elevated with 5 pathways up-regulated and 4 down-regulated at 90 °C. The most extensive changes were observed at 120 °C, when 327 proteins were suppressed and 308 elevated with 11 pathways up-regulated and 33 down-regulated.

Organic milk has a high risk of food fraud as it can easily be adulterated with non-organic milk. This study aimed to identify metabolite markers for assessing the authenticity of organic milk from Jersey and Yak. In the untargeted strategy, ultra-high performance liquid chromatography-Q Exactive HF-X mass spectrometer coupled with chemometrics analysis was used to screen and identify tentative markers of organic milk from Jersey and Yak. In the targeted strategy, a quick and easy method of ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) was developed to quantify three markers. The peptide of Thr-Ala-Val and D-biotin were determined to be metabolite markers for distinguishing organic and non-organic Jersey milk, whereas trimethylamine N-oxide was determined to be a metabolite marker for distinguishing organic and non-organic Yak milk. These findings provide critical information to facilitate assessments of organic milk authenticity.

Yak milk is rich in essential milk proteins of nutritional and therapeutic value. In this study, whey proteins of milk from 3 yak breeds (Gannan, GN; Huanhu, HH; Maiwa, MW) in China were comprehensively identified and compared using a data-independent acquisition quantitative proteomics approach. A total of 632 proteins were identified in yak milk whey samples, in which immune-related proteins were abundant. Compared with other milks, more proteins were involved in oxidation-reduction process and with ATP binding. In addition, we identified 96, 155, and 164 differentially expressed proteins (DEP) for GN versus HH, GN versus MW, and HH versus MW, respectively. "Phagosome" and "complement and coagulation cascades" were the most significant pathways for DEP of GN versus HH and GN or HH versus MW yak milk based on the Kyoto Encyclopedia of Genes and Genomes pathway analysis. Protein-protein interaction network analysis showed that DEP for the 3 comparisons had significant biological interactions but were associated with different functions. The results provide useful information on yak milk from different breeds in China, and elucidate the biological functions of yak milk proteins. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the nutritional properties of yak milk in various areas of Gannan. The milk composition analyzer, automatic amino acid analyzer, and flavor analyzer were used to detect the conventional nutrients, amino acids, and volatile flavor substances of 249 yak milks in Meiren grassland, Xiahe grassland, and Maqu grassland (hereinafter referred to as Meiren yak, Xiahe yak, and Maqu yak) in the Gannan area. The results showed that the fat content of Meiren yak milk was significantly higher than that of Maqu yak and Xiahe yak (p < 0.05). The protein content of Meiren yak milk was significantly higher than that of Xiahe yak (p < 0.05), but not significantly different from that of Maqu yak (p > 0.05). The casein content in the milk of Maqu yak was significantly higher than that of Meiren yak and Xiahe yak (p < 0.05). There was no significant difference in the lactose content of yak milk in the three regions (p > 0.05). The content of glutamic acid in the milk of Meiren yak, Xiahe yak, and Maqu yak was noticeably high, which was 1.03 g/100 g, 1.07 g/100 g, and 1.10 g/100 g, respectively. The total amino acid (TAA) content was 4.78 g/100 g, 4.87 g/100 g, and 5.0 g/100 g, respectively. The ratios of essential amino acids (EAA) and total amino acids (TAA) in the milk of Meiren yak, Xiahe yak, and Maqu yak were 42.26%, 41.27%, and 41.39%, respectively, and the ratios of essential amino acids (EAA) and nonessential amino acids (NEAA) were 73.19%, 70.28%, and 70.61%, respectively. In the yak milk samples collected from three different regions, a total of 34 volatile flavor compounds were detected, including 10 aldehydes, five esters, six ketones, four alcohols, two acids, and seven others. The main flavor substances qualitatively obtained from Meiren yak milk were ethyl acetate, n-valeraldehyde, acetic acid, heptanal, and n-hexanal. Xiahe yak milk mainly contains ethyl acetate, isoamyl alcohol, n-valeraldehyde, heptanal, and ethyl butyrate. Maqu yak milk mainly contains ethyl acetate, n-valeraldehyde, isoamyl alcohol, heptanal, ethyl butyrate, and n-hexanal. Principal component analysis showed that the flavor difference between Xiahe yak and Maqu yak was small, while the flavor difference between Xiahe yak, Maqu yak, and Meiren yak was large. The findings of this research can serve as a foundation for the future advancement and application of yak milk. [ABSTRACT FROM AUTHOR]

The yak is a special species that inhabits the Qinghai-Tibet Plateau and its surrounding areas. Its unique habitat gives yak milk certain distinct characteristics compared to regular cow milk. Yak milk not only has a high nutritional value but also holds potential benefits for human health. In recent years, there has been increasing research attention on yak milk. Studies have found that the bioactive components in yak milk have various functional properties, including antioxidant, anticancer, antibacterial, blood pressure-lowering, anti-fatigue, and constipation-relieving effects. However, more evidence is needed to confirm these functions in the human body. Therefore, by reviewing the current research status on the nutrition and functionality of yak milk, we aim to reveal its enormous potential as a source of nutritional and functional substances. This article primarily analyzed the nutritional composition of yak milk and the functional effects of its bioactive components, categorically elucidated the mechanisms behind its functional activities, and provided a brief introduction to related yak milk products. Our objective is to deepen people's understanding of yak milk and provide some references for its further development and utilization. [ABSTRACT FROM AUTHOR]

Copyright of Food & Machinery is the property of Food & Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

ABSTRACT: The effect of milk on bone health is controversial. In this study, the effects of yak milk in mice with retinoic acid-induced osteoporosis (OP) were evaluated. Yak milk was provided to OP mice as a nutrition supplement for 6 wk. The results showed that yak milk significantly reduced bone turnover markers (tartrate acid phosphatase and alkaline phosphatase). The yak milk treatment was also associated with remarkably increased bone mineral density, bone volume, trabecular thickness, and trabecular number, as well as improved biomechanical properties (maximum load and stress) of the tibia. Furthermore, yak milk mitigated the deterioration of the network and thickness of trabecular bone in treated OP mice compared with the OP model group. The results indicated that yak milk could improve bone mass and microarchitecture through the inhibition of bone resorption in OP mice.

This research was aimed to assess the distribution of calcium, phosphorus and magnesium within the casein micelles of yak milk. To this aim, nine bulk yak milk samples (Y-milk), collected in three yak farms located in the Chinese province of Qinghai, were compared to nine bulk cow milk samples used as a reference. A quite similar content of colloidal calcium (0.80 vs. 0.77 mmol/g of casein; p > 0.05), a higher content of magnesium (0.05 vs. 0.04 mmol/g of casein; p ≤ 0.01) and a lower content of colloidal phosphorus (0.48 vs. 0.56 mmol/g of casein; p ≤ 0.01) between yak and cow casein micelles were found. Moreover, the yak casein micelles showed a lower value of prosthetic phosphorus (0.20 vs. 0.26 mmol/g of casein; p ≤ 0.05) compared to the cow micelles. The lower values of colloidal and prosthetic phosphorus in yak casein micelles suggest that the yak casein is less phosphorylated than the cow one. [ABSTRACT FROM AUTHOR]

Flavor is a crucial parameter for assessing the sensory quality of yak milk. However, there is limited information regarding the factors influencing its taste. In this study, the effects of endogenous lipoprotein lipase (LPL) on the volatile flavor components of yak milk under storage conditions of 4 °C, 18 °C and 65 °C were analyzed via headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) combined with orthogonal partial least-squares (OPSL) discrimination, and the reasons for the changes in yak milk flavors were investigated. Combined with the difference in the changes in volatile flavor substance before and after the action of LPL, LPL was found to have a significant effect on the flavor of fresh yak milk. Fresh milk was best kept at 4 °C for 24 h and pasteurized for more than 24 h. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were employed to characterize the volatile components in yak milk under various treatment conditions. Twelve substances with significant influence on yak milk flavor were identified by measuring their VIP values. Notably, 2-nonanone, heptanal, and ethyl caprylate exhibited OAV values greater than 1, indicating their significant contribution to the flavor of yak milk. Conversely, 4-octanone and 2-heptanone displayed OAV values between 0.1 and 1, showing their important role in modifying the flavor of yak milk. These findings can serve as monitoring indicators for assessing the freshness of yak milk.

Dairy products are susceptible to modifications in protein oxidation during heat processing, which can lead to changes in protein function, subsequently affecting intestinal health. Despite being a unique nutritional source, yak milk has not been thoroughly examined for the effects of its oxidized proteins on intestinal microbiota and metabolism. Hence, this study employed different heat treatment methods (low-temperature pasteurization, high-temperature pasteurization, and high-temperature sterilization) to induce oxidation in yak milk proteins. The study then assessed the degree of oxidation in these proteins and utilized mice as research subjects. Using metagenomics and metabolomics methods, this study examined the structure of intestinal microbial communities and metabolic products in mice consuming oxidized yak milk. The results showed a decrease in carbonyl and total thiol contents of yak milk proteins after different heat treatments, indicating that heat treatment causes oxidation in yak milk proteins. Metagenomic analysis of mouse intestinal microbiota revealed significant changes in 66 genera. In the high-temperature sterilization group (H), key differential genera included Verrucomicrobiales, Verrucomicrobiae, Akkermansiaceae, and 28 others. The high-temperature pasteurization group (M) mainly consisted of Latilactobacillus, Bacillus, and Romboutsia. The low-temperature pasteurization group (L) primarily comprised of Faecalibacterium, Chaetomium, Paenibacillaceae, Eggerthella, Sordariales, and 33 others. Functionally, compared to the control group (C), the H group upregulated translation and energy metabolism functions, the L group the M group significantly upregulated metabolism of other amino acids, translation, and cell replication and repair functions. Based on metabolomic analysis, differential changes in mouse metabolites could affect multiple metabolic pathways in the body. The most significantly affected metabolic pathways were phenylalanine metabolism, vitamin B6 metabolism, steroid hormone biosynthesis, and pantothenate and CoA biosynthesis. The changes were similar to the functional pathway analysis of mouse metagenomics, affecting amino acid and energy metabolism in mice. In summary, moderate oxidation of yak milk proteins exhibits a positive effect on mouse intestinal microbiota and metabolism. In conclusion, yak milk has a positive effect on mouse intestinal microflora and metabolism, and this study provides a scientific basis for optimizing dairy processing technology and further developing and applying yak milk.

The purpose of this study was to investigate the construction of curcumin encapsulated nanocomposite based on bovine serum albumin (BSA) could be a potential strategy to improve the ripening quality of yak cheese. The moisture, ash, crude protein, crude fat, pH value, pH4.6 acetate buffer soluble nitrogen, 12% trichloroacetic acid solution soluble nitrogen, thiobarbituric acid reactant, acid value and sensory index of yak milk cheese were determined. The results showed that the presence of curcumin-BSA nanocomplex could significantly improve the moisture and protein content of yak milk cheese (P

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to investigate the nutritional composition and volatile substances of yak milk after fermentation and post-fermentation, the changes of nutrients and volatile substances of yak milk, fermented yak milk and post-fermented yak milk were measured, and the nutrition and quality of yak milk were evaluated. The results showed that the lactose content of yak milk after fermentation was significantly decreased (P < 0.05), and the decreased rate was 39.43% . The contents of total, essential, non-essential and delicious amino acids of yak milk after fermentation were significantly increased (P < 0.05), and the increased rate were 64.26%, 57.52%, 69.33% and 56.67%, respectively. The content of fatty acid of yak milk after fermentation has no significantly difference (P > 0.05), but the types and relative contents of alcohols, aldehydes and esters in yak milk after ferentation were greatly decreased. There were no significant differences in lactose, amino acid and fatty acid contents between post-ferentation and ferentation of yak milk (P > 0.05), but the types and relative contents of alcohols, phenols, esters and ketones in post-ferentated yak milk greatly increased compared to fermented yak milk. In summary, fermentation improved the nutritional value of yak milk in some extent, and post-fermentation promoted the accumulation of volatile substances of yak milk. Fermentation and post-fermentation had positive effect on the improvement of nutrition and quality of yak milk.

In this study, the effects of freezing yak milk at −20 °C and −40 °C for 30, 90 and 180 days on the fermentation characteristics and storage quality of the corresponding yogurt were discussed. The results showed that, compared with that of yogurt made from fresh yak milk, the lactic acid bacteria (LAB) growth and acid production rate of the yogurt in the −20 °C group decreased at 90 d. The water-holding capacity, viscosity and hardness decreased during storage, and a sour taste was prominent, while no significant changes were observed in the −40 °C group. At 180 d of freezing, the post-acidification of the yogurt in the −20 °C and −40 °C groups increased after 21 d of storage. Compared with the −40 °C group, the −20 °C group showed a significant decrease in LAB counts, a decrease in pH value to 3.63–3.80 and poor texture and sensory quality.

The effect of milk on bone health is controversial. In this study, the effects of yak milk in mice with retinoic acid-induced osteoporosis (OP) were evaluated. Yak milk was provided to OP mice as a nutrition supplement for 6 wk. The results showed that yak milk significantly reduced bone turnover markers (tartrate acid phosphatase and alkaline phosphatase). The yak milk treatment was also associated with remarkably increased bone mineral density, bone volume, trabecular thickness, and trabecular number, as well as improved biomechanical properties (maximum load and stress) of the tibia. Furthermore, yak milk mitigated the deterioration of the network and thickness of trabecular bone in treated OP mice compared with the OP model group. The results indicated that yak milk could improve bone mass and microarchitecture through the inhibition of bone resorption in OP mice. [ABSTRACT FROM AUTHOR]

Whey proteins are N-glycosylated proteins that play important roles in a variety of biological processes including immune defense. However, the N-glycosylation of yak colostrum (YC) and mature milk (YM) whey proteins is unknown. Therefore, this study systematically compared and analyzed YC and YM whey N-glycoproteomes using the 4D label-free technique. We identified 162 glycoproteins, 222 glycosylated peptides, and 234 glycosylation sites in YC and YM, of which 59 glycoproteins were differentially expressed in YC and YM. According to gene ontology annotation and KEGG pathway metabolism analysis, the differentially expressed N-glycoproteins were highly enriched in "cell adhesion", "extracellular region", and "calcium binding", and were mainly involved in the extracellular matrix (ECM)-receptor interaction pathway. The immunity-related N-glycoproteins, such as platelet glycoprotein 4 (CD36) and polymeric immunoglobulin receptor (PIGR), were observed to be different between YC and YM. The results revealed the glycosylation sites, composition, and biological functions of YC and YM whey N-glycoprotein, which supplemented our understanding of the N-glycosylation of yak whey proteins.

Due to the scarcity of yak milk in Tibetan areas, local herders primarily use traditional freezing methods for preservation. However, the extent of microbial contamination in raw yak milk during frozen storage and its impact on milk quality remains largely unexplored. This study analyzed the changes in bacterial populations and quality of raw yak milk stored at -18 °C for 6 months. The results indicated that, compared to fresh milk, the freshness of yak milk showed no significant change after 2 months of frozen storage (P > 0.05). After 4 months, the bacterial diversity of flora in yak milk increased significantly, with Pseudomonas and Acinetobacter emerging as the dominant psychrophilic bacteria. Correspondingly, the expression of metabolic pathways related to quality deterioration increased, with a significant increase in physicochemical indicators such as acidity, proteolysis degree, acid value and fat oxidation degree (P < 0.05). Extending the frozen storage to 6 months resulted in a slight but no significant decrease in bacterial diversity, with no significant difference in quality deterioration compared to the 4-month group (P > 0.05). Correlation analysis further revealed that Acinetobacter and Psychrobacter were significantly positively correlated with quality deterioration of frozen milk (P < 0.05). In summary, when frozen for more than 4 months, raw yak milk exhibited the highest bacterial diversity and predicted the most abundant metabolic pathways, with dominant psychrophilic bacteria massive proliferation leading to a decline in quality and safety., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The bacterial community dynamics and metabolomic profiles in raw yak (Y) milk and cattle-yak (CY) milk during refrigeration at 4 °C were investigated, followed by the elucidation of interspecific differences in milk storage. Bacterial communities and succession patterns were significantly different between the two milk types during refrigeration, with Lactococcus and Pseudomonas being the key distinguishing genera. Moreover, higher network complexity and tighter interactions were observed for the microbial community in CY milk than in Y milk. Furthermore, 7 proteases and 1 lipase potentially contributed to milk spoilage. The metabolomic profiles significantly differed between the milk types during refrigeration. Extended storage time decreased the relative abundances of organic nitrogen compounds and lipids and lipid-like molecules, with a concomitant increase in organic acids and derivatives, particularly in Y milk. Moreover, 9 metabolites, whose levels gradually increased with storage time, were strongly correlated with psychrophiles and thus considered potential markers of deterioration in plateau-characteristic milk. These findings offer a theoretical foundation for augmenting the quality and safety of plateau-characteristic milk and its derivatives, while also helping us understand the microbial and metabolic dynamics in raw milk under extreme environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The yak is a special species that inhabits the Qinghai-Tibet Plateau and its surrounding areas. Its unique habitat gives yak milk certain distinct characteristics compared to regular cow milk. Yak milk not only has a high nutritional value but also holds potential benefits for human health. In recent years, there has been increasing research attention on yak milk. Studies have found that the bioactive components in yak milk have various functional properties, including antioxidant, anticancer, antibacterial, blood pressure-lowering, anti-fatigue, and constipation-relieving effects. However, more evidence is needed to confirm these functions in the human body. Therefore, by reviewing the current research status on the nutrition and functionality of yak milk, we aim to reveal its enormous potential as a source of nutritional and functional substances. This article primarily analyzed the nutritional composition of yak milk and the functional effects of its bioactive components, categorically elucidated the mechanisms behind its functional activities, and provided a brief introduction to related yak milk products. Our objective is to deepen people’s understanding of yak milk and provide some references for its further development and utilization.

This study aimed to investigate the nutritional properties of yak milk in various areas of Gannan. The milk composition analyzer, automatic amino acid analyzer, and flavor analyzer were used to detect the conventional nutrients, amino acids, and volatile flavor substances of 249 yak milks in Meiren grassland, Xiahe grassland, and Maqu grassland (hereinafter referred to as Meiren yak, Xiahe yak, and Maqu yak) in the Gannan area. The results showed that the fat content of Meiren yak milk was significantly higher than that of Maqu yak and Xiahe yak (p < 0.05). The protein content of Meiren yak milk was significantly higher than that of Xiahe yak (p < 0.05), but not significantly different from that of Maqu yak (p > 0.05). The casein content in the milk of Maqu yak was significantly higher than that of Meiren yak and Xiahe yak (p < 0.05). There was no significant difference in the lactose content of yak milk in the three regions (p > 0.05). The content of glutamic acid in the milk of Meiren yak, Xiahe yak, and Maqu yak was noticeably high, which was 1.03 g/100 g, 1.07 g/100 g, and 1.10 g/100 g, respectively. The total amino acid (TAA) content was 4.78 g/100 g, 4.87 g/100 g, and 5.0 g/100 g, respectively. The ratios of essential amino acids (EAA) and total amino acids (TAA) in the milk of Meiren yak, Xiahe yak, and Maqu yak were 42.26%, 41.27%, and 41.39%, respectively, and the ratios of essential amino acids (EAA) and nonessential amino acids (NEAA) were 73.19%, 70.28%, and 70.61%, respectively. In the yak milk samples collected from three different regions, a total of 34 volatile flavor compounds were detected, including 10 aldehydes, five esters, six ketones, four alcohols, two acids, and seven others. The main flavor substances qualitatively obtained from Meiren yak milk were ethyl acetate, n-valeraldehyde, acetic acid, heptanal, and n-hexanal. Xiahe yak milk mainly contains ethyl acetate, isoamyl alcohol, n-valeraldehyde, heptanal, and ethyl butyrate. Maqu yak milk mainly contains ethyl acetate, n-valeraldehyde, isoamyl alcohol, heptanal, ethyl butyrate, and n-hexanal. Principal component analysis showed that the flavor difference between Xiahe yak and Maqu yak was small, while the flavor difference between Xiahe yak, Maqu yak, and Meiren yak was large. The findings of this research can serve as a foundation for the future advancement and application of yak milk.

Copyright of Modern Food Science & Technology is the property of Editorial Office of Modern Food Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aimed to reveal the change patterns of the phosphorylation modification status of yak whey phosphoproteins during lactation and their physiological effects. Herein, we comprehensively characterized whey phosphoproteome in yak colostrum and mature milk using an ultra-high throughput phosphoproteomics approach incorporating trapped ion mobility technology. A total of 344 phosphorylation sites from 206 phosphoproteins were identified, with individual site modification predominating. Notably, 117 significantly different phosphorylation sites were distributed on 89 whey phosphoproteins. Gene ontology analysis indicated that these significantly different whey phosphoproteins (SDWPPs) were mainly annotated to carbohydrate metabolic process, membrane, extracellular region and calcium ion binding. Metabolic pathway enrichment analysis demonstrated that SDWPPs were critically involved in protein processing in endoplasmic reticulum, NOD-like receptor signaling pathway and N-glycan biosynthesis. Our results elucidate the phosphorylation profiles of yak whey phosphoproteins at different lactations and their adaptive regulatory role in meeting the nutritional requirements of yak calves during development. [Display omitted] • Differences in whey phosphoproteins in yak colostrum and mature milk were revealed. • A total of 344 phosphorylation sites on 206 whey phosphoproteins were identified. • 117 phosphorylation sites on 89 whey phosphoproteins were differentially regulated. • Beta-lactoglobulin and lactoperoxidase were first characterized as phosphoproteins. • Phosphorylation may regulate the function of whey phosphoproteins during lactation. [ABSTRACT FROM AUTHOR]

The gold standard of milk is human milk, not cow milk. The present study expects to explored the comprehensive nutritional value of different kinds of milk and the differences between them through multi-omics analysis and found functional components that are more similar to human milk. This study employed untargeted LC-MS/MS metabolomics, untargeted LC-MS/MS lipidomics, and 4D label-free proteomics analysis techniques. The findings revealed substantial disparities in metabolites, lipids, and proteins among the five types of milk. Notably, pig milk exhibited a remarkable abundance of N -acetylneuraminic acid (Neu5Ac) and specific polar lipids. Yak milk stood out with significantly elevated levels of creatine and lipoprotein lipase (LPL) compared to other species. Buffalo milk boasted the highest concentrations of L-isoleucine, echinocystic acid, and alkaline phosphatase, tissue-nonspecific isozyme (ALPL). The concentrations of iminostilbene and osteopontin (OPN) were higher in cow milk. • In this study, 4D-Label-Free proteomics technique was used. • Neu5Ac and specific polar lipids are significantly present in YXP. • Creatine and LPL are important nutrients in QHY. • In GXB, L-isoleucine and echinocystic acid are key nutrients. • Iminostilbene and OPN have significant advantages in HST. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lipid differences between yak colostrum (YC) and mature milk (YM) were analyzed. • A total of 851 lipid species from 28 lipid subclasses were identified. • Forty-three significantly different lipids (SDLs) between YC and YM were screened. • These SDLs were mainly enriched in the glycerophospholipid metabolic pathway. • Lipid species information for GLs, STs, GPs, SPs, and FAs in YC and YM was added. Yak milk is essential to maintain the normal physiological functions of herders in Tibetan areas of China. However, the lipid components of yak colostrum (YC) and mature milk (YM) have not been systematically studied. We employed a quantitative lipidomics to comprehensively describe the alterations in the milk lipid profile of lactating yaks. Herein, totally 851 lipids from 28 lipid subclasses in YC and YM were identified and screened for 43 significantly different lipids (SDLs; variable importance in projection > 1, fold change < 0.5 or > 2 with P < 0.05), with cholesterol ester (CE, 16:0) and triacylglycerol (TAG, 54:6 (20:5), 50:1 (16:0), 56:6 (20:5)) were the potential lipid biomarkers. Fourteen SDLs were modulated downwards, and 29 SDLs were modulated upwards in YM. Moreover, by analyzing lipid metabolic pathways in these SDLs, glycerophospholipid metabolism was the most critical. Our results furnish integral lipid details for evaluating yak milk's nutritional quality. [ABSTRACT FROM AUTHOR]

This research was aimed to assess the distribution of calcium, phosphorus and magnesium within the casein micelles of yak milk. To this aim, nine bulk yak milk samples (Y-milk), collected in three yak farms located in the Chinese province of Qinghai, were compared to nine bulk cow milk samples used as a reference. A quite similar content of colloidal calcium (0.80 vs. 0.77 mmol/g of casein; p > 0.05), a higher content of magnesium (0.05 vs. 0.04 mmol/g of casein; p ≤ 0.01) and a lower content of colloidal phosphorus (0.48 vs. 0.56 mmol/g of casein; p ≤ 0.01) between yak and cow casein micelles were found. Moreover, the yak casein micelles showed a lower value of prosthetic phosphorus (0.20 vs. 0.26 mmol/g of casein; p ≤ 0.05) compared to the cow micelles. The lower values of colloidal and prosthetic phosphorus in yak casein micelles suggest that the yak casein is less phosphorylated than the cow one.

Based on CNKI, the article uses CiteSpace V software to analyze 460 literatures related to yak milk in China from 1992 to 2020, draw knowledge maps such as authors, institutions, keywords and so on, to explore the relationship between yak milk development research institutions, research hotspots and future development trends. The results show that the research scholars and institutions related to yak milk have carried out relatively close cooperation and exchanges, and formed cooperative groups in the region. The specific manifestation was that there are academic exchanges on yak milk in Gansu Research Center, but there is less cooperation with other high-yield institutions. Before 2015, the research hotspots were mainly white yak milk, milk protein, etc. After 2015, the research hotspots turned to casein, hard cheese, etc. Among them, the processing of dairy products such as hard cheese becomes a continuous research frontier hotspot. Therefore, yak milk research is changing from yak milk nutritional components, efficacy and other aspects to yak milk product processing and other aspects. Relying on the strength of science and technology, developing traditional dairy products into functional and characteristic products, and making use of product advantages to create high-end brands will become an important direction for the research and development of yak milk. [ABSTRACT FROM AUTHOR]