Tea Time Science

November 13, 2014

CHICAGO-When it comes to tea production, the process is far from simple. In the November issue of Food Technology magazine published by the Institute of Food Technologists (IFT) IFT Fellow Neil H. Mermelstein takes readers through the step-by-step process of how tea is made.

All teas except herbal teas, mate, and red tea come from a single plant species, Camellia sinensi that originated in China, Tibet, and northern India. Tea is currently grown around the world, which results in many different varieties of flavors that vary by geographic region, harvest time, weather, soil, and manufacturing processes. It takes three to five years after being planted for a tea plant to reach maturity and the bud and two top youngest leaves are picked and transported for processing. Steps include:
  1. Withering: Tea leaves are spread on large screens called withering racks and forced-air dried for four to 18 hours to reduce moisture content to a specific 68 percent.
  2. Rolling and Crushing: For black tea, withered leaves are rolled and crushed in order to release an enzyme that produces oxidation.
  3. Oxidation: Leaves are placed in trays and stacked in racks and allowed to oxidize for a few hours until an enzyme, polyphenol oxidase in the leave causes the leaves to darken and develop the typical tea flavor.
  4. Firing: The leaves are then heated in large temperature-controlled ovens which stop the oxidative process and dries the leaves to four percent moisture content so that mold doesn’t occur during packing and transportation.
  5. Sorting and Grading: The dried leaves are then sorted by size and graded. Small cut leaves are generally used in tea bags, while larger leaves are sold as loose tea.
  6. Packing and Shipping: The sorted and graded tea is then packed and shipped to tea companies for direct sale to consumers or for further processing into tea-based products.
Fun Tea Facts:
  • Black tea is the most commonly consumed tea around the world; and 85 percent of tea consumed in the U.S. is black tea.
  • Lipton, sold by Unilever is the leading tea brand, sold in more than 150 countries. Other top brands include Tetley, Wissotzky Tea, Twinnings of London, and Bigelow Tea.
  • Quality of tea, like wine, depends on the cultivar, terroir, and manufacturing process; if one goes wrong the quality goes down.
  • Some tea plants have been around for 185 years.
View the full article in Food Technology here

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