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Start Over Author "J.T. Yang" Journal journal of dairy science
2 results on '"J.T. Yang"'

1. Study on physicochemical properties, fatty acids, texture, antioxidant and antibacterial activities of ghee from different regions

Author

Y. Tian, B. Ding, Z.R. Ma, J.T. Yang, G.T. Ding, and H.N. Liu

Subjects
yak ghee, different regions, quality characteristics, fatty acid, antioxidant activity, Dairy processing. Dairy products, SF250.5-275, Dairying, SF221-250
Abstract

ABSTRACT: Due to the lack of basic information on Chinese ghee and the increasing demand of consumers for natural oils, this study aims to explore and distinguish the quality characteristics of ghee in different regions of China. Ghee samples from 16 regions of Qinghai Province, Gansu Province, Xinjiang Uyghur Autonomous Region, and Tibet Autonomous Region were selected and their physicochemical properties, fatty acids, texture, antioxidant and antibacterial activities were determined. The results showed that: (1) The physicochemical properties of ghee were different from different regions, but the freshness and fat content are generally high. The results of iodine value and saponification value suggest that the fatty acid composition is good; (2) The unsaturated fatty acid/saturated fatty acid content of ghee in Tibet and Xinjiang ranges from 63.05% to 79.13%, which is better than that in other regions; (3) Gansu Diebu ghee has the highest hardness (40.69 N); (4) Ghee from different regions has good antioxidant activity, DPPH free radical scavenging activity is 30.45% to 58.06%, ABTS free radical scavenging activity is 41.14% to 65.53%, and has varying degrees of inhibition on gram-positive bacteria. In addition, yak ghee, cattle-yak ghee and cow ghee have better fatty acid composition and antibacterial ability than scalper ghee. The results of this study distinguish the differences in the quality characteristics of yak ghee in different geographical regions. Therefore, it can provide a theoretical basis for the origin tracing and quality-oriented improvement of yak ghee.

Published
2023
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2. Effect of pH on dissociation of casein micelles in yak skim milk

Author

J.T. Yang, Weibing Zhang, P.C. Wen, D. Sun, G.D. Zhang, and M. Yang

Subjects
Potassium, chemistry.chemical_element, Manganese, Zinc, Calcium, Micelle, Dissociation (chemistry), 0404 agricultural biotechnology, Casein, Genetics, Animals, Micelles, Magnesium, 0402 animal and dairy science, Caseins, Phosphorus, 04 agricultural and veterinary sciences, Hydrogen-Ion Concentration, 040401 food science, 040201 dairy & animal science, Milk, Spectrometry, Fluorescence, chemistry, Solubility, Microscopy, Electron, Scanning, Animal Science and Zoology, Cattle, Food Science, Nuclear chemistry
Abstract

The dissociation of yak casein (CN) micelles was evaluated by scanning electron microscopy, particle size, fluorescence properties, and soluble mineral and CN molecule content at pH 4.6 to 8.2. The results showed that the size of CN micelles remained constant with decreasing pH from 8.2 to 5.8 but sharply increased at pH ≤5.4. Casein micelles began to aggregate at pH 5.4, and the serum magnesium, potassium, iron, zinc, copper, and manganese levels had their minimum values at this pH level. During acidification, colloidal calcium phosphate dramatically disassociated from yak CN micelles, but the soluble CN monomer content decreased slightly. During alkalization, the soluble calcium and phosphorus content decreased below pH 6.8 but increased with pH increases from 6.8 to 8.2. However, the soluble CN content increased markedly during alkalization. The emission wavelength of 8-anilino-1-naphthalenesulfonic acid sodium salt fluorescence decreased during both acidification and alkalization from pH 6.6, whereas the opposite was found for intrinsic fluorescence.

Published
2017

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