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Coffee and tea: Here's to health?

Published: December 20, 2019

Black tea leaves
Black tea leaves

Tea and coffee are popular beverages consumed worldwide for a variety of traditional and contemporary reasons.

At one time both of these beverages were expensive, but are now affordable to most people in western countries and are major export commodities for the countries in which they are cultivated.
Black and green teas (Camellia sinensis) are thought to originate from Asia in the North Burma/Southwest China area whereas the coffee plant is thought to originate from Africa and a few southern Asian islands.
C. Arabica and C. Canephora (robusta) are the two principle commercially cultivated species.
India has joined the earlier tea producing and exporting countries and coffee is now grown in many countries throughout India, Southeast Asia and the Americas.
Traditionally hot or boiling water was poured over cured tea leaves to produce an aromatic beverage which was used medicinally, but which has since become an everyday beverage.
Coffee was traditionally consumed at religious ceremonies, but like tea it is now considered an everyday beverage which can be consumed in a variety of forms mostly prepared from roasted coffee beans.
Types of tea and coffee
Although tea is thought to originate from a single tea cultivar there are many different types of tea which produce various flavours, and can be cooling, bitter, astringent, sweet nutty, floral or grassy.
Darjeeling and Chinese green teas are perhaps the most well known.
Once picked tea leaves wilt and begin to oxidize facilitated by enzymes contained in tea leaves. Oxidization leads to the breakdown of chlorophyll contained in tea leaves which in turn releases tannins causing the tea leaves to darken.
Contemporary tea, in general, is categorised depending on when the oxidation process is stopped which prevents further darkening of tea leaves. These categories include:

  • Unoxidized and unwilted: green
  • Unoxidzed, unwilted, allowed to yellow: yellow
  • Unoxidized and wilted leaves: white
  • Partially oxidized, wilted and bruised: Oolong
  • Fully oxidized, wilted, crushed or uncrushed: Black (Red in China)
  • Fully fermented green tea: Post fermented (Black in China)

Deactivation of oxidative enzymes by applying heat at a pre-determined stage...link to the full article to learn more.

Related Topics

Health  Metabolism  Food Choices  Phytochemicals 


Whitney, E. & Rady Rolfes, S. (2005). Understanding Nutrition. Belmont, CA: Thomson Wadsworth
.Gropper, S.S., Smith, J.L. & Groff, J.L. (2005). Advanced Nutrition and Human Metabolism (4thEd.). Belmont, CA: Thomson Wadsworth.
CSPI July/August 2014, March 2015, March 2010, October 2010, March 2007, November 2011, July/August 2011, May 2011, May 2012, July/August 2013, September 2013, May 2013 April 2008,
Wikipedia: Tea
Wikipedia: Coffee