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Start Over Author "Yin,Jun" Journal food chemistry
35 results on '"Yin,Jun"'

33. Cream formation and main chemical components of green tea infusions processed from different parts of new shoots

Author

Yin, Jun-Feng, Xu, Yong-Quan, Yuan, Hai-Bo, Luo, Long-Xin, and Qian, Xiao-Jun

Subjects
*GREEN tea, *FOOD composition, *PLANT shoots, *POLYPHENOLS, *CAFFEINE, *CATECHIN, *ANALYTICAL chemistry
Abstract

Abstract: The formation of green tea cream and its chemical components were investigated. The green tea infusions were processed from different parts of new shoots: the bud and the first leaf, the second leaf and its implicative stem, the third leaf and its implicative stem, and the fourth leaf and its implicative stem, which were named as first part, second part, third part and fourth part, respectively. The results showed that the formation of tea cream and its settlement slowed down gradually from the first part to the fourth part, and that the amount of tea cream also decreased accordingly. The amount of tea cream was influenced remarkably by the chemical components in the green tea infusion. The main components of green tea cream were polyphenols (29.86 –78.66%), total sugar (14.47–27.62%) and caffeine (2.35–10.43%). Catechins (12.8–42.5%) were the main components of polyphenols which participated in tea cream formation. The main components in the catechins were found to be (−)-epigallocatechin (EGC), (−)-epigallocatechin gallate (EGCG), (−)-epicatechin (EC) and (−)-epicatechin gallate (ECG). Seven minerals were found in the tea cream, including Ca2+, K+, Mg2+, Mn2+, Na+, Zn2+ and Ni2+. [Copyright &y& Elsevier]

Published
2009
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34. The impact of Ca2+ combination with organic acids on green tea infusions

Author

Xu, Yong-Quan, Zhong, Xiao-Yu, Yin, Jun-Feng, Yuan, Hai-Bo, Tang, Ping, and Du, Qi-Zhen

Subjects
*CALCIUM ions, *ORGANIC acids, *GREEN tea, *TURBIDITY, *OXALIC acid, *POLYPHENOLS
Abstract

Abstract: The effect of Ca2+ in brewing water on the organic acid content, turbidity, and formation of tea cream and sediment in green tea infusions was studied. When the Ca2+ concentration of the brewing water was >40mgL−1, the green tea infusion became more turbid. The turbidity of the tea infusion was highly negatively correlated with the contents of oxalic acid (R =−0.89, p <0.01), quinic acid (R =−0.90, p <0.01) and tartaric acid (R =−0.82, p <0.01). Oxalic acid on its own interacted with Ca2+ at low concentrations, whereas polyphenols and protein did not. In conclusion, Ca2+ in brewing water influences the quality of a tea infusion by inducing tea cream and sediment formation from combination of Ca2+ and organic acids, such as oxalic acid, quinic acid and tartaric acid. Ca2+ and oxalate are the main metal ion and anion, respectively, involved in tea cream and sediment formation on tea infusion cooling or concentrating. [Copyright &y& Elsevier]

Published
2013
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35. Sediments in concentrated green tea during low-temperature storage.

Author

Xu, Yong-Quan, Chen, Gen-Sheng, Du, Qi-Zhen, Que, Fei, Yuan, Hai-Bo, and Yin, Jun-Feng

Subjects
*GREEN tea, *FOOD storage, *LOW temperatures, *MINERALS, *OXALATES, *FOOD chemistry
Abstract

Highlights: [•] Sediments in concentrated green tea included reversible and irreversible sediments. [•] Most reversible sediments formed before irreversible tea sediments during storage. [•] Reversible tea sediments contributed more than 90% of the total sediment. [•] Large amount of minerals (17.1%, w/w) were found in irreversible tea sediments. [•] Oxalate was the main component of the irreversible tea sediments. [ABSTRACT FROM AUTHOR]

Published
2014
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