Effect of pH on heat stability of yak milk protein

To estimate how native herbage of three different phenological periods modify rumen performance and milk quality of yak grazing alpine meadow. In this study, milk composition and the diversity of the rumen microbial community were measured in 12 full-grazing female yaks on the Qinghai-Tibet Plateau (QTP). The nutrient composition of three phenological periods was determined: Vegetative stage (VS), bloom stage (BS), and senescent stage (SS). High-throughput sequencing of the bacterial 16S rRNA gene was used. The results showed that crude protein (CP) content of herbage in BS was higher than that in vs. and SS (p < 0.05), and neutral detergent fiber (NDF) content of herbage in SS was higher than that in vs. and BS (p < 0.05). Milk solids and fat contents were higher in the vs. and SS than in BS (p < 0.05). However, milk protein content was higher for the vs. and BS than those for SS (p < 0.05). The total volatile fatty acid (VFA), acetate, and propionate concentrations were higher in vs. and BS than in SS (p < 0.05). The community richness estimates (Chao1 estimator) of vs. were higher than that in BS and the SS (p < 0.05). The diversity indices (Shannon index) of the BS were higher than that vs. and the SS (p < 0.05). Spearman correlation analysis between the milk composition, ruminal fermentation parameters, and the relative abundances of the rumen bacteria showed that milk protein content, total VFA, acetate, and propionate concentrations were positively correlated with the relative abundances of the genera Desulfovibrio, Prevotella_1, and Butyrivibrio_2 and was negatively correlated with Olsenella, Ruminococcaceae_UCG.010, and Rikenellaceae_RC9_gut_group abundances. Collectively, the results revealed that there were significant differences in nutrient composition of herbage, chemical composition of yak milk, and microbial diversity in rumen at different phenological stages. The correlations between ruminal fermentation parameters, chemical constituents of yak milk, and some genera of ruminal bacteria might be indicative that the ruminal fermentation parameters and chemical constituents of yak milk are strongly influenced by the rumen bacterial community composition.

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A comparison of the heat stability of fresh milk protein concentrates obtained by microfiltration, ultrafiltration and diafiltration

Journal of Dairy Research ◽

10.1017/s0022029919000426 ◽

2019 ◽

Vol 86 (3) ◽

pp. 347-353 ◽

Cited By ~ 6

Author(s):

Isis Rodrigues Toledo Renhe ◽

Zhengtao Zhao ◽

Milena Corredig

Keyword(s):

Membrane Filtration ◽

Milk Protein ◽

Ionic Composition ◽

Protein Composition ◽

Heat Stability ◽

Casein Micelles ◽

Protein Concentrates ◽

Fresh Milk ◽

Dairy Protein ◽

The Impact

AbstractThe objective of this work was to evaluate the impact of changes during membrane filtration on the heat stability of milk protein concentrates. Dairy protein concentrates have been widely employed in high protein drinks formulations and their stability to heat treatment is critical to ensure quality of the final product. Pasteurized milk was concentrated three-fold by membrane filtration, and the ionic composition was modified by addition of water or permeate from filtration (diafiltration). Diafiltration with water did not affect the apparent diameter of the casein micelles, but had a positive effect on heat coagulation time (HCT), which was significantly longer (50 min), compared to the non diafiltered concentrates (about 30 min). UHT treatments increased the particle size of the casein micelles, as well as the turbidity of retentates. Differences between samples with and without diafiltration were confirmed throughout further analysis of the protein composition of the unsedimentable fraction, highlighting the importance of soluble protein composition on the processing functionality of milk concentrates.

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HEAT STABILITY OF PEANUT/MILK PROTEIN BLENDS

Journal of Food Processing and Preservation ◽

10.1111/j.1745-4549.1977.tb00329.x ◽

1977 ◽

Vol 1 (4) ◽

pp. 263-270 ◽

Cited By ~ 5

Author(s):

R. H. SCHMIDT ◽

P. H. MENDELSOHN

Keyword(s):

Milk Protein ◽

Heat Stability

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Fortification of milk protein content with different dairy protein powders alters its compositional, rennet gelation, heat stability and ethanol stability characteristics

International Dairy Journal ◽

10.1016/j.idairyj.2016.06.010 ◽

2016 ◽

Vol 61 ◽

pp. 220-227 ◽

Cited By ~ 22

Author(s):

Yingchen Lin ◽

Alan L. Kelly ◽

James A. O'Mahony ◽

Timothy P. Guinee

Keyword(s):

Protein Content ◽

Milk Protein ◽

Heat Stability ◽

Milk Protein Content ◽

Dairy Protein ◽

Ethanol Stability

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Antimicrobial peptides sourced from post-butter processing waste yak milk protein hydrolysates

AMB Express ◽

10.1186/s13568-017-0497-8 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 3

Author(s):

Jinjin Pei ◽

Hai Jiang ◽

Xinsheng Li ◽

Wengang Jin ◽

Yanduo Tao

Keyword(s):

Antimicrobial Peptides ◽

Milk Protein ◽

Protein Hydrolysates ◽

Processing Waste ◽

Yak Milk

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

Asian Journal of Dairy and Food Research ◽

10.18805/ajdfr.v3i1.3570 ◽

2016 ◽

Vol 35 (3) ◽

Cited By ~ 1

Author(s):

Shimo Peter Shimo ◽

W U Xiaoyun ◽

Ding Xuezhi ◽

Yan Ping

Keyword(s):

Whey Proteins ◽

Sodium Dodecyl ◽

Heat Stability ◽

Heat Denaturation ◽

Percentage Reduction ◽

Processing Conditions ◽

Yak Milk ◽

Acidic Conditions ◽

The Mean ◽

Mean Concentration

The aim of this study was to characterize the effect of heat denaturation on Immunoglobulin G (IgG) and Lactoferrin (LF) in yak milk and colostral liquid whey at medium acidic conditions in presence of protectants (CaCl2; Glycerol and Sodium Dodecyl Sulphate - SDS). Results indicated significant (P less than 0.05) heat stability improvement of IgG and LF in liquid whey samples at medium acidic and temperature (72 - 90oC) with less precipitates formation regardless of type of protectants added especially at pH 3.5 and 4.6. The mean concentration values for IgG percentage reduction (72 – 90oC; pH 3.5 – 5.5; protectants) ranged from 6 to 26% and 15 to 31% in yak milk and colostral liquid whey, respectively. The percentage of heat denaturation effect for LF ranged from 11 to 32%t and 14 to 38% in yak milk and colostral liquid whey, respectively. Application of glycerol in both environmental processing conditions was the most effective in heat stability improvement followed by SDS and CaCl2.

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Production, composition and manufacturing properties of milk from dairy cows fed hay and silages made from either wilted herbage or formaldehyde-treated herbage

Australian Journal of Experimental Agriculture ◽

10.1071/ea9790290 ◽

1979 ◽

Vol 19 (98) ◽

pp. 290 ◽

Cited By ~ 1

Author(s):

SC Valentine ◽

RB Wickes

Keyword(s):

Lactic Acid ◽

Dairy Cows ◽

Milk Fat ◽

Dry Matter ◽

Protein Production ◽

Milk Protein ◽

Heat Stability ◽

Dairy Farmers ◽

Ad Libitum ◽

Production Composition

Hay, normal silage, and silages prepared from herbage either treated with formaldehyde at 0.8% of the dry matter (DM) ('formaldehyde silage') or wilted to 31 % DM ('wilted silage') were all made from grass/clover herbage cut at the same time. Dairy cows were offered the feeds ad libitum together with 4.5 kg of a barley-meatmeal concentrate daily. The chemical composition, digestibility and DM intake of the feeds together with the production, composition and manufacturing properties of the milk were determined. Compared with normal silage, the formaldehyde silage and wilted silage had lower concentrations of total titratable acids, butyric acid and lactic acid. The DM intakes (g day-1kg -0.75 by COWS of normal silage (126.7) and wilted silage (133.7) were higher than those of formaldehyde silage (114.0) and hay (103.6). The yield of milk fat (kg day-1) was greater for the cows offered wilted silage (0.62) and hay (0.62) than for cows offered normal silage (0.58). The yield of milk protein (kg day-1) was greater for the cows offered wilted silage (0.54) and hay (0.54) than for those offered formaldehyde silage (0.50) and normal silage (0.47). The percentages of milk protein and solids not fat, respectively, were greater for the cows offered wilted silage (3.37, 8.83), formaldehyde silage (3.30, 8.83) and hay (3.30, 8.89) than for those offered normal silage (3.1 5, 8.61). No differences were found between treatments in the heat stability characteristics of the milk. However, the milk of cows fed normal silage produced a firmer rennet curd than the milk from cows fed hay, wilted silage or formaldehyde silage. Cows offered normal silage, formaldehyde silage, wilted silage and hay had liveweight gains (kg day-1) of 0.1 6, 0.35, 0.86 and 0.04, respectively. It is concluded that although the milk fat and protein production of cows fed wilted silage and hay were similar, dairy farmers may prefer to feed wilted silage to dairy cows especially in late lactation, because of the ability of the cows to consume more wilted silage and consequently increase liveweight in preparation for the next lactation.

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