This study was conducted to compare the hydrolase activities in the milk of Tianzhu white yak and Gannan yak in Gansu. The results showed that the ACP activity in Tianzhu yak milk was significantly higher than that in...This study was conducted to compare the hydrolase activities in the milk of Tianzhu white yak and Gannan yak in Gansu. The results showed that the ACP activity in Tianzhu yak milk was significantly higher than that in Gannan yak milk （P〈0.05）; the AKP activity in Tianzhu yak milk was higher than that in Gannan yak milk, but not significant; and the AMC activity in Tianzhu yak milk was significantly lower than that in Gannan yak milk （P〈0.05）. There were no remarkable changes in the activities of the 3 hydrolases with the change of parity, i.e., the effects of parity on enzyme activities in milk were not significant. The comparative study on hydrolase activities in the milk of Tianzhu while yak and Gannan yak helps to understand the characteristics of the milk of the 2 yak breeds, and further provides certain reference basis for the development of yak milk.展开更多
[ Objective] To analyze the nutrient components of yak milk from different regions and provide a theoretical basis for further development and utilization of yak milk. [ Method] A total of 150 yak milk samples were co...[ Objective] To analyze the nutrient components of yak milk from different regions and provide a theoretical basis for further development and utilization of yak milk. [ Method] A total of 150 yak milk samples were collected from Tianzhu County, Maqu County and Tianjun County, and 90 yak milk samples were collected from three different yak farms in Tianzhu County. The content of milk protein, milk fat, fat solid, non-fat solid and lactose, as well as the density, freezing point and acidity were determined, respectively. [ Result] The milk protein content and milk fat content had significant differences between three regions. With the increasing altitude, the milk protein and milk fat were increased, but the content of fat solid, non-fat solid and lactose, density, freezing point and acidity had no obviously regular change. The milk protein content and milk fat content had no significant difference between three yak farms in Tianzhu County. [ Conclusion] The altitude may affect the milk protein content and milk fat content of yak milk.展开更多
Camels and yaks milks are rich in numerous bioactive substances that function beyond their nutritive value. Milk Camel milk is more similar to goat milk and contains less short-chain fatty acids than cow, sheep and bu...Camels and yaks milks are rich in numerous bioactive substances that function beyond their nutritive value. Milk Camel milk is more similar to goat milk and contains less short-chain fatty acids than cow, sheep and buffalo milks, and about 3 times greater vitamin-C than cow milk. One kg of camel milk meets 100% of daily human requirements for calcium and phosphorus, 57.6% for potassium, 40% for iron, copper, zinc and magnesium, and 24% for sodium. Camel milk helps treat liver problems, lowers bilirubin output, lightens vitamin inadequacy and nutrient deficiency, and boosts immunity. Camel milk reduces allergies caused by cow dairy products. Camel milk has low milk fat made mainly from polyunsaturated fatty acids. It lacks ?-lactoglobulin and is rich in immunoglobulins, compatible with human milk. Yak milk has 16.9 - 17.7% solids, 4.9 - 5.3% protein, 5.5 - 7.2% fat, 4.5 - 5.0% lactose, and 0.8 - 0.9% minerals. Yak milk fat is richer in polyunsaturated fatty acids, protein, casein and fat than cow milk. Yak milk casein is used to produce antihypertensive peptides with capacities for producing value-added functional foods and proteins. Continual system-atic education of milk science especially for non-cow species will be an obligation for health implications to be optimally perceived by human populations worldwide.展开更多
This study aimed to formulate Cheddar-style cheese from standardised yak milk(casein-fat ratio:0.7)and examined different quality parameters during 5 months ripening at 7±1℃.The chemical components viz.,fat,prot...This study aimed to formulate Cheddar-style cheese from standardised yak milk(casein-fat ratio:0.7)and examined different quality parameters during 5 months ripening at 7±1℃.The chemical components viz.,fat,protein,ash,and salt contents,increased significantly(p˂0.05),whereas the moisture content decreased considerably(p˂0.05)during ripening.Similarly,pH,titratable acidity[lactic acid(%by weight)],soluble protein(%),ripening index,tyrosine value(μg/g),total free fatty acids(μm/g),and peroxide value(mEq of O_(2)/kg)increased considerably(p˂0.05)during ripening.Yeast and mould count(logCFU/g)showed a significant(p˂0.05)increase,while the coliform count(logCFU/g)were undetectable at the end of ripening.Further,cheese textural attributes and colour value(L^(*),a^(*)and b^(*))also decreased significantly(p˂0.05).The protein hydrolysis pattern in cheese was detected using electrophoresis.The water-soluble extracts of cheese exhibited significant antioxidant activity.Palmitic(27.2%)and oleic acid(24.4%)were the prominent fatty acids detected in higher concentrations at the end of ripening.The majority of amino acids such as glutamic acid and histidine,were also retained in the cheese.The sensory ratings of cheese significantly increased as ripening proceeded,and the formulated product was acceptable for up to 120 days.展开更多
The milk protein polymorphisms were typed by polyacrylamide gel electrophoresis (PAGE)from 109 Maiwa and 100 Jiulong yaks, and the relationships among milk protein polymorphisms,milking traits and milk protein composi...The milk protein polymorphisms were typed by polyacrylamide gel electrophoresis (PAGE)from 109 Maiwa and 100 Jiulong yaks, and the relationships among milk protein polymorphisms,milking traits and milk protein compositions were studied. The results showed thatβ-CN,κ-CN andα-La were monomorphic,αs1-CN andβ-Lg were polymorphic, the dominantgenes were αs1-CN D and β-Lg E,respectively. The frequencies of αs1-CN D were 0.8073and 0.6000 and β-Lg E were 0.9770 and 0.9700 in two populations respectively.The meanheterozygosities were 0.1021 and 0.1867 in two populations. No significant effects onmilking traits and milk protein compositions were observed except for αs1-CN locus onfat percentage in Jiulong yak.展开更多
The change in lactation of Maiwa yak was studied based on the data of locating Maiwa yak in warm seasons during 2003- 2009. The results showed that the milk yield was increasing gradually during days 30- 70 after calv...The change in lactation of Maiwa yak was studied based on the data of locating Maiwa yak in warm seasons during 2003- 2009. The results showed that the milk yield was increasing gradually during days 30- 70 after calving,reached the peak at days 70- 110,and decreased gradually to no milking whenafter. The milk yield of Maiwa yak was greatly influenced by lactation age rather than the yearly effect.展开更多
Yaks of two lactating types, the half-Iactating yak and the total lactating yak, were investigated in their milk compositions, milk coagulation properties, and contents of three kinds of hormones, glucose, and protein...Yaks of two lactating types, the half-Iactating yak and the total lactating yak, were investigated in their milk compositions, milk coagulation properties, and contents of three kinds of hormones, glucose, and protein in plasma. The half-lactating Maiwa yak and Jiulong yak contained significantly higher contents of protein, fat, and activities of alkaline phosphatase and Y-glutamyl transpeptidase in milk than that of the corresponding total-lactating yak breeds, with reduced milk yield and similar lactose level and relative percentages of main milk protein components. The half-lactatin yak resembled yaks in a late stage of lactation in their biochemical composition of milk; however, significant differences were also observed, which indicated that the former was in a special stage of lactation quite different from dairy cows. Milk of the total-lactating or half-lactating yaks could be coagulated normally by adding chymosin, with a similar coagulation time. No significant difference was observed between prolactin and progesterone concentrations in plasma of the half-lactating yaks and total-lactating yaks; however, half-lactating yaks had significantly lower level of oestradiol-17 β in plasma than total-lactating yaks.展开更多
牦牛奶粉的掺假检测和产地识别有助于保障食品安全、维护消费者权益,是促进乳制品市场健康发展的重要举措。传统的DNA检测方法和稳定同位素分析技术的检测周期长,难以满足快速、低成本现场分析的需求。针对以上问题,本研究建立了一种基...牦牛奶粉的掺假检测和产地识别有助于保障食品安全、维护消费者权益,是促进乳制品市场健康发展的重要举措。传统的DNA检测方法和稳定同位素分析技术的检测周期长,难以满足快速、低成本现场分析的需求。针对以上问题,本研究建立了一种基于近红外光谱技术(Near-infrared Spectroscopy,NIRS)快速辨别牦牛奶粉掺假及产地的方法。收集了来自四川、甘肃、云南及青海的9个品牌的牦牛奶粉。在制备掺假样品之前,采用聚合酶链式反应(Polymerase Chain Reaction,PCR)技术和DNA凝胶电泳验证所收集的牦牛奶粉中是否掺杂了牛奶粉。完成验证后,进行掺假样品的制备以及近红外光谱数据的采集。采用K最邻近法(K-Nearest Neighbors,KNN)建立分类模型,偏最小二乘回归(Partial Least Squares Regression,PLSR)建立定量预测模型。通过优化光谱预处理方法和变量筛选方法进一步提升定量预测模型的预测能力。结果表明,KNN对牦牛奶粉掺假检测(纯牛奶粉、纯牦牛奶粉、掺杂着牛奶粉的牦牛奶粉)及产地识别(四川、甘肃、云南、青海)实现了100%的正确分类。掺假定量预测模型的校正集相关系数(R_(c))为0.9975,预测集相关系数(R_(p))为0.9913,预测集均方根误差(Root Mean Square Error of Prediction,RMSEP)为1.9823%,性能偏差比(Ratio of Performance to Deviation,RPD)为7.2522。本方法可快速、准确地预测牦牛奶粉中牛奶粉的掺杂以及牦牛奶粉产地的辨别,为牦牛奶粉的质量控制提供技术支持。展开更多
基金Supported by Agricultural Product Quality Safety Risk Assessment Project of China(GJFP201700701)~~
文摘This study was conducted to compare the hydrolase activities in the milk of Tianzhu white yak and Gannan yak in Gansu. The results showed that the ACP activity in Tianzhu yak milk was significantly higher than that in Gannan yak milk （P〈0.05）; the AKP activity in Tianzhu yak milk was higher than that in Gannan yak milk, but not significant; and the AMC activity in Tianzhu yak milk was significantly lower than that in Gannan yak milk （P〈0.05）. There were no remarkable changes in the activities of the 3 hydrolases with the change of parity, i.e., the effects of parity on enzyme activities in milk were not significant. The comparative study on hydrolase activities in the milk of Tianzhu while yak and Gannan yak helps to understand the characteristics of the milk of the 2 yak breeds, and further provides certain reference basis for the development of yak milk.
基金supported by the Spark Program of Gansu Province "Research and Development of Functional Active Substances of Yak Milk"(0910XCXA005)
文摘[ Objective] To analyze the nutrient components of yak milk from different regions and provide a theoretical basis for further development and utilization of yak milk. [ Method] A total of 150 yak milk samples were collected from Tianzhu County, Maqu County and Tianjun County, and 90 yak milk samples were collected from three different yak farms in Tianzhu County. The content of milk protein, milk fat, fat solid, non-fat solid and lactose, as well as the density, freezing point and acidity were determined, respectively. [ Result] The milk protein content and milk fat content had significant differences between three regions. With the increasing altitude, the milk protein and milk fat were increased, but the content of fat solid, non-fat solid and lactose, density, freezing point and acidity had no obviously regular change. The milk protein content and milk fat content had no significant difference between three yak farms in Tianzhu County. [ Conclusion] The altitude may affect the milk protein content and milk fat content of yak milk.
文摘Camels and yaks milks are rich in numerous bioactive substances that function beyond their nutritive value. Milk Camel milk is more similar to goat milk and contains less short-chain fatty acids than cow, sheep and buffalo milks, and about 3 times greater vitamin-C than cow milk. One kg of camel milk meets 100% of daily human requirements for calcium and phosphorus, 57.6% for potassium, 40% for iron, copper, zinc and magnesium, and 24% for sodium. Camel milk helps treat liver problems, lowers bilirubin output, lightens vitamin inadequacy and nutrient deficiency, and boosts immunity. Camel milk reduces allergies caused by cow dairy products. Camel milk has low milk fat made mainly from polyunsaturated fatty acids. It lacks ?-lactoglobulin and is rich in immunoglobulins, compatible with human milk. Yak milk has 16.9 - 17.7% solids, 4.9 - 5.3% protein, 5.5 - 7.2% fat, 4.5 - 5.0% lactose, and 0.8 - 0.9% minerals. Yak milk fat is richer in polyunsaturated fatty acids, protein, casein and fat than cow milk. Yak milk casein is used to produce antihypertensive peptides with capacities for producing value-added functional foods and proteins. Continual system-atic education of milk science especially for non-cow species will be an obligation for health implications to be optimally perceived by human populations worldwide.
文摘This study aimed to formulate Cheddar-style cheese from standardised yak milk(casein-fat ratio:0.7)and examined different quality parameters during 5 months ripening at 7±1℃.The chemical components viz.,fat,protein,ash,and salt contents,increased significantly(p˂0.05),whereas the moisture content decreased considerably(p˂0.05)during ripening.Similarly,pH,titratable acidity[lactic acid(%by weight)],soluble protein(%),ripening index,tyrosine value(μg/g),total free fatty acids(μm/g),and peroxide value(mEq of O_(2)/kg)increased considerably(p˂0.05)during ripening.Yeast and mould count(logCFU/g)showed a significant(p˂0.05)increase,while the coliform count(logCFU/g)were undetectable at the end of ripening.Further,cheese textural attributes and colour value(L^(*),a^(*)and b^(*))also decreased significantly(p˂0.05).The protein hydrolysis pattern in cheese was detected using electrophoresis.The water-soluble extracts of cheese exhibited significant antioxidant activity.Palmitic(27.2%)and oleic acid(24.4%)were the prominent fatty acids detected in higher concentrations at the end of ripening.The majority of amino acids such as glutamic acid and histidine,were also retained in the cheese.The sensory ratings of cheese significantly increased as ripening proceeded,and the formulated product was acceptable for up to 120 days.
基金supported by the Nationa1 Natura1 Science Foundation of China(39870607).
文摘The milk protein polymorphisms were typed by polyacrylamide gel electrophoresis (PAGE)from 109 Maiwa and 100 Jiulong yaks, and the relationships among milk protein polymorphisms,milking traits and milk protein compositions were studied. The results showed thatβ-CN,κ-CN andα-La were monomorphic,αs1-CN andβ-Lg were polymorphic, the dominantgenes were αs1-CN D and β-Lg E,respectively. The frequencies of αs1-CN D were 0.8073and 0.6000 and β-Lg E were 0.9770 and 0.9700 in two populations respectively.The meanheterozygosities were 0.1021 and 0.1867 in two populations. No significant effects onmilking traits and milk protein compositions were observed except for αs1-CN locus onfat percentage in Jiulong yak.
基金Supported by Special Fund from National Modern Agriculture Sci-tech System(CARS-38)National Science and Technology Program(2012BAD13B06)
文摘The change in lactation of Maiwa yak was studied based on the data of locating Maiwa yak in warm seasons during 2003- 2009. The results showed that the milk yield was increasing gradually during days 30- 70 after calving,reached the peak at days 70- 110,and decreased gradually to no milking whenafter. The milk yield of Maiwa yak was greatly influenced by lactation age rather than the yearly effect.
基金supported by the Chinese Natural Science Foundation(No.39870607)the key.lab of the Chinese Agricultural Ministry in Nanjing Agricultural University.
文摘Yaks of two lactating types, the half-Iactating yak and the total lactating yak, were investigated in their milk compositions, milk coagulation properties, and contents of three kinds of hormones, glucose, and protein in plasma. The half-lactating Maiwa yak and Jiulong yak contained significantly higher contents of protein, fat, and activities of alkaline phosphatase and Y-glutamyl transpeptidase in milk than that of the corresponding total-lactating yak breeds, with reduced milk yield and similar lactose level and relative percentages of main milk protein components. The half-lactatin yak resembled yaks in a late stage of lactation in their biochemical composition of milk; however, significant differences were also observed, which indicated that the former was in a special stage of lactation quite different from dairy cows. Milk of the total-lactating or half-lactating yaks could be coagulated normally by adding chymosin, with a similar coagulation time. No significant difference was observed between prolactin and progesterone concentrations in plasma of the half-lactating yaks and total-lactating yaks; however, half-lactating yaks had significantly lower level of oestradiol-17 β in plasma than total-lactating yaks.
文摘牦牛奶粉的掺假检测和产地识别有助于保障食品安全、维护消费者权益,是促进乳制品市场健康发展的重要举措。传统的DNA检测方法和稳定同位素分析技术的检测周期长,难以满足快速、低成本现场分析的需求。针对以上问题,本研究建立了一种基于近红外光谱技术(Near-infrared Spectroscopy,NIRS)快速辨别牦牛奶粉掺假及产地的方法。收集了来自四川、甘肃、云南及青海的9个品牌的牦牛奶粉。在制备掺假样品之前,采用聚合酶链式反应(Polymerase Chain Reaction,PCR)技术和DNA凝胶电泳验证所收集的牦牛奶粉中是否掺杂了牛奶粉。完成验证后,进行掺假样品的制备以及近红外光谱数据的采集。采用K最邻近法(K-Nearest Neighbors,KNN)建立分类模型,偏最小二乘回归(Partial Least Squares Regression,PLSR)建立定量预测模型。通过优化光谱预处理方法和变量筛选方法进一步提升定量预测模型的预测能力。结果表明,KNN对牦牛奶粉掺假检测(纯牛奶粉、纯牦牛奶粉、掺杂着牛奶粉的牦牛奶粉)及产地识别(四川、甘肃、云南、青海)实现了100%的正确分类。掺假定量预测模型的校正集相关系数(R_(c))为0.9975,预测集相关系数(R_(p))为0.9913,预测集均方根误差(Root Mean Square Error of Prediction,RMSEP)为1.9823%,性能偏差比(Ratio of Performance to Deviation,RPD)为7.2522。本方法可快速、准确地预测牦牛奶粉中牛奶粉的掺杂以及牦牛奶粉产地的辨别,为牦牛奶粉的质量控制提供技术支持。
