Unique bioactive polyphenolic profile of guava (Psidium guajava) budding leaf tea is related to plant biochemistry of budding leaves in early dawn

作者：Chang Chi Huang; Hsieh Chiu Lan; Wang Hui Er; Peng Chiung Chi^*; Chyau Charng Cherng; Peng Robert Y

来源：Journal of the Science of Food and Agriculture, 2013, 93(4): 944-954.

DOI：10.1002/jsfa.5832

• guava tea
• polyphenolics and flavonoids
• quercetin
• catechin
• gallic acid
• ellagic acid

BACKGROUND: Guava leaf tea (GLT), exhibiting a diversity of medicinal bioactivities, has become a popularly consumed daily beverage. To improve the product quality, a new process was recommended to the Ser-Tou Farmers%26apos; Association (SFA), who began field production in 2005. The new process comprised simplified steps: one budtwo leaves were plucked at 3:006:00 am, in the early dawn period, followed by withering at ambient temperature (2528 degrees C), rolling at 50 degrees C for 5070 min, with or without fermentation, then drying at 4550 degrees C for 7090 min, and finally sorted. RESULTS: The product manufactured by this new process (named herein GLTSF) exhibited higher contents (in mg g1, based on dry ethyl acetate fraction/methanolic extract) of polyphenolics (417.9 +/- 12.3) and flavonoids (452.5 +/- 32.3) containing a compositional profile much simpler than previously found: total quercetins (190.3 +/- 9.1), total myricetin (3.3 +/- 0.9), total catechins (36.4 +/- 5.3), gallic acid (8.8 +/- 0.6), ellagic acid (39.1 +/- 6.4) and tannins (2.5 +/- 9.1). CONCLUSION: We have successfully developed a new process for manufacturing GLTSF with a unique polyphenolic profile. Such characteristic compositional distribution can be ascribed to the right harvesting hour in the early dawn and appropriate treatment process at low temperature, avoiding direct sunlight.

• 出版日期2013-3-15