Microwave heating of tea residue yields polysaccharides, polyphenols, and plant biopolyester

Shuntaro Tsubaki, Hiroyuki Iida, Masahiro Sakamoto, Jun Ichi Azuma

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73 Citations (Scopus)


Microwave heating was used to produce aqueous-soluble components from green, oolong, and black tea residues. Heating at 200-230°C for 2 min extracted 40-50% of polysaccharides and 60-70% of the polyphenols. Solubilization of arabinose and galactose by autohydrolysis occurred with heating above 170°C, whereas heating above 200°C was necessary to solubilize xylose. Catechins were soluble in water by heating at low temperature (110°C); however, new polyphenols having strong antioxidant activity were produced above 200°C. The amount of solubilized materials and antioxidant activity increased with increased fermentation of harvested tea leaves (green tea < oolong tea < black tea). Cutin, a plant biopolyester, remained in the residue after heating as did cellulose and lignin/tannin. The predominant cutin monomer that was recovered was 9,10-epoxy-18-hydroxyoctadecanoic acid, followed by dihydroxyhexadecanoic acid and 9,10,18-trihydroxyoctadecanoic acid.

Original languageEnglish
Pages (from-to)11293-11299
Number of pages7
JournalJournal of Agricultural and Food Chemistry
Issue number23
Publication statusPublished - Dec 10 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Agricultural and Biological Sciences


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