Effects of Heat and Pulsed Electric Fields on Bioactive Components and Color of Green Tea Infusions

2008 ◽  
Vol 4 (5) ◽  
Author(s):  
Mo Wang ◽  
Ruijin Yang ◽  
Wei Zhao
Keyword(s):  
Heat Treatment ◽  
Amino Acids ◽  
Green Tea ◽  
Electric Fields ◽  
Free Amino Acids ◽  
Free Amino ◽  
Pulsed Electric Fields ◽  
Bioactive Components ◽  
Conventional Heat Treatment ◽  
Tea Infusions

Green tea is an unfermented tea containing a higher quantity of bioactive components. It has received a great deal of attention due to many biological activities, such as antioxidative, anticarcinogenic and antitumour activities. However, deterioration in quality after heating processes, in particular sterilization, was technical barrier for commercial ready-to-drink green tea production. It has already been demonstrated that pulsed electric fields (PEF) processing can alternatively be applied to deliver safe and shelf-stable products. In this paper the effect of conventional heat treatment (121 oC, 3min) and PEF treatment on the bioactive components (polyphenols, catechins and free amino acids) and color of green tea infusions was studied. There was a significant (P<0.05) decline in polyphenols, total catechins and total free amino acids induced by heat treatment, and the green tea infusions darkened and became less green and deeper yellow after the heating. Compared to heat processing, PEF can efficiently retain the bioactive components and original color of green tea infusions.

High-intensity pulsed electric fields or thermal treatment of broccoli juice: the effects of processing on minerals and free amino acids

2020 ◽  
Vol 246 (3) ◽  
pp. 539-548
Author(s):  
Rogelio Sánchez-Vega ◽  
Teresa Garde-Cerdán ◽  
María Janeth Rodríguez-Roque ◽  
Pedro Elez-Martínez ◽  
Olga Martín-Belloso
Keyword(s):  
Amino Acids ◽  
Thermal Treatment ◽  
Electric Fields ◽  
High Intensity ◽  
Free Amino Acids ◽  
Free Amino ◽  
Pulsed Electric Fields

scholarly journals MONITORING THE GROWTH AND QUALITY OF JAPANESE GREEN TEA BY UAV IMAGERY

AGROFOR ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Ayako SEKIYAMA ◽  
Kiyohisa SATO ◽  
Sawahiko SHIMADA ◽  
Tomonori FUJIKAWA
Keyword(s):  
Amino Acids ◽  
Green Tea ◽  
Free Amino Acids ◽  
Free Amino ◽  
Vegetation Index ◽  
Chemical Component ◽  
Free Sugars ◽  
Optimal Harvest ◽  
Total Free Amino Acids ◽  
Tea Leaf

The optimal harvest season of Japanese green tea in Japan is judged by individual farmers based on their experiences. To confirm that optimal season, it requires a lot of efforts such as sampling of tea flushes by plucking, chemical component measuring by near-infrared spectroscopic analysis. Thus, an efficient method to determine the optimal season which can cover a wide area at once is considered highly helpful for farmers. This research measured normalized difference vegetation index (NDVI) of tea flushes by a multi-spectrum sensor mounted on an unmanned aerial vehicle. At the same time, chemical component of tea flushes was measured to compare with the result of NDVI. The result showed that the value of NDVI for the optimal harvest season of tea-leaf is 0.6 to 0.7. The result of chemical component measuring showed the increase of total free amino acids and reduction of total free sugars while tea-leaf ripens. Therefore, there was a positive relation between the value of NDVI, and total free amino acids and total free sugars. It indicates a high possibility to predict the optimal harvest season of tea flushes by NDVI.

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