Tea: cultivation, processing and preparation

Tea: form bush to cup for your health

Tea is an aromatic infusion extracted from the dried leaves of Camellia sinensis, a member of the Theaceae family.
Tea is a beverage with very ancient origins, dating back to almost 4000 years ago, and it is one of the most consumed beverage worldwide, particularly in Asia, with an estimated per capita consumption of approximately 0.12 L/d.
Owing to its high consumption, even small effects on person’s health could have large effects on public health.

Cultivation of Camellia sinensis

Tea Fields
Fig. 1 – Tea Fields

Camellia sinensis is an evergreen plant, native to South, East, and Southeast Asia, which is currently cultivated in at least 30 countries, mainly in tropical or sub-tropical climates, even if some varieties grow in Cornwall, in Europe, and Washington State, in the USA.
In nature, if left undisturbed, Camellia sinensis can grow up to 15-20 meters (49-65 ft), while in plantations it is generally pruned to height less than a meter and a half, that is, like a small tree or bush, to facilitate cultivation and harvesting of the leaves.
It can also be cultivated in mountain, up to 1500-2000 meters (4900-6550 ft) above sea level. Many of the high-quality teas are produced from mountain crops, as the plant grows more slowly acquiring a better flavor.
Currently, the two most used varieties, of the four ones recognized, are:

  • Camellia sinensis var. sinensis, native to China;
  • Camellia sinensis var. assamica, native to India.

Processing of leaves

All the types of teas commercially available are produced from fresh leaves of the plant. During harvesting, young leaves are generally picked, as the older ones are considered to be inferior in quality.
The differences between the types of teas, e.g. green tea, oolong tea and black tea, depend on how Camellia sinensis leaves are processed after harvesting, since processing may cause a different degrees of oxidation of the substances present, in particular of catechins, a flavonoid subgroup, and the main responsibles of the benefits of green tea.
The organoleptic characteristics of the different types of tea are influenced, in addition to the processing of the leaves, even from the cultivar, the characteristics of the soil where the plant grown up, the methods of cultivation, the altitude, the climate, and the time of year in which the harvest of the leaves occurs.

How to prepare a perfect cup of tea

  • Due to the sensitiveness of dried leaves, it is good to store the packaging in cool dry place, free of fragrances that may alter its aroma.
  • Use fresh water and warm it to a temperature of 95-100°C for black tea, and about 90°C for green tea.
  • In order not to alter flavor, it is advisable to use a ceramic or porcelain teapot, avoiding those of steel. For teapot washing, avoid detergents, preferring water plus baking soda.
  • To prevent sudden changes in water temperature during the infusion, it is advisable to preheat the teapot pouring a bit of boiling water. Then, emptied the pot, add hot water (about 200-250 mL/filter).
  • How many filters/g of leaves to use? Typically, a filter (about 1.5-2 g) per person, or a teaspoon of loose tea leaves per person.
    If you prepare the beverage for some people, you add a filter/teaspoon more than the number of persons.
  • The infusion time should not exceed 10 minutes in order to avoid the development of bitter flavors; it should be 3-4 minutes for black tea, and 2-3 minutes for green tea.
    If you are using filters, you should remove them at the end of the infusion time.
    Approximately 30% of the material present in the leaves is extracted in the water.

Now, it’s time to enjoy your tea.

References

Asil M.H., Rabiei B., Ansari R.H. Optimal fermentation time and temperature to improve biochemical composition and sensory characteristics of black tea. Aust J Crop Sci 2012;6(3):550-8.

Huang W-Y., Lin Y-R., Ho R-F., Liu H-Y., and Lin Y-S. Effects of water solutions on extracting green tea leaves. ScientificWorldJournal 2013;Article ID 368350 doi:10.1155/2013/368350

Kuhnert N. Unraveling the structure of the black tea thearubigins. Arch Biochem Biophys 2010;501(1):37-51 doi:10.1016/j.abb.2010.04.013

Li S., Lo C-Y., Pan M-H., Lai C-S. and Ho C-T. Black tea: chemical analysis and stability. Food Funct 2013;4:10-18 doi:10.1039/C2FO30093A

Menet M-C., Sang S., Yang C.S., Ho C-T., and Rosen R.T. Analysis of theaflavins and thearubigins from black tea extract by MALDI-TOF mass spectrometry. J Agric Food Chem 2004;52:2455-61 doi:10.1021/jf035427e

Published by Dr. Nicola Tazzini

Nicola Tazzini, MS in Biology Sciences Doctor Tazzini graduated "Summa cum Laude" at the University of Pisa on Nov. 11th, 1996 after 1½ year, carried out in the laboratory of Biochemistry of the Department of Biochemistry and Physiology of the Faculty of Natural, Physical and Mathematical Sciences. The subject of his thesis was "Studies about the mechanism of cytotoxicity of the combination of deoxyadenosine and deoxycoformicine on a cell line derived from a human colon carcinoma" (see References). He registered as a Biologist at the University of Pisa on May 10th, 1998. He specialized "Summa cum Laude" in "Biochemistry and Clinical Chemistry" in Oct. 30th, 2001 at the Department of Biological Chemistry of the Faculty of Medicine and Surgery of the University of Parma. The subject of his thesis was: "Analyses of ematochemical, enzymatic and non-enzymatic parameters with antioxidant activity in young professional athletes". He has started his activity of Nutritionist on Feb. 02nd, 2002. He attended the following courses related to the activity of Nutritionist. 2000 1. Pasta in human nutrition. Associazione Biologi Nutrizionisti Italiani. 2. Course of forming and updating in nutrition and health: roll of Biologist. Associazione Scientifica Biologi Pisa. 2001 1. Elements of nutrition. Associazione Scientifica Biologi Pisa. 2002 1. Nutrition as healthy factors, professional update. Associazione Biologi Nutrizionisti Italiani. 2003 1. Nutrition as healthy factors- first part. Associazione Biologi Nutrizionisti Italiani. 2004 1. Nutrition as healthy factors- second part. Associazione Biologi Nutrizionisti Italiani. 2. Nutrition in childhood. Associazione Biologi Nutrizionisti Italiani. 3. Sport activity, growth and correct nutrition. Associazione Biologi Nutrizionisti Italiani. 4. Nutrition and tumor. PLANNING congressi Srl. 2005 1. Doping: guidelines and diagnostic assessments: legal, biochemical, medical and toxicological aspects. Restless Architech of Human Possibilities S.a.s. 2. Nutrition in the third age: nutritional issues and proper nutritional habits. Associazione Biologi Nutrizionisti Italiani. 3. Technical legislation evolution and ethics in development of the profession. Ordine Nazionale dei Biologi. 2006 1. Sport and nutrition. Syntonie S.r.l. 2. Nutrition and prevention: choose to stay healthy. Ordine Nazionale dei Biologi. 3. Pathology nutrition and legislation aspects. Syntonie S.r.l. 4. Nutrition: guidelines. Ordine Nazionale dei Biologi. 2007 1. Nutrition topics: food as welfare tool: physiological and pathological balance factors. Ordine Nazionale dei Biologi. 2008 1. Outdoor and indoor environment. Resources and balances. Ordine Nazionale dei Biologi. 2. Biologist ’profession in the current technical legislation evolution. Ordine Nazionale dei Biologi. 3. Prevention of childhood obesity: nutritional strategies from pregnancy to school age. Ordine Nazionale dei Biologi. 2009 1. Nutrition, the cornerstone. Nutritional and health needs in the era of the genome. S.I.N.U. 2010 1. The evolution of food safety. Ordine Nazionale dei Biologi. 2. Food safety and correct nutrition. Associazione Scientifica Biologi Pisa and Ordine Nazionale dei Biologi. 2011 1. Role of coffee in physiological and pathological states. CMGRP Italia S.p.A. Reference 1. Bemi V., Tazzini N., Banditelli S., Giorgelli F., Pesi R., Turchi G., Mattana A., Sgarrella F., Tozzi M.G., Camici M. Deoxyadenosine metabolism in a human colon-carcinoma cell line (LoVo) in relation to its cytotoxic effect in combination with deoxycoformycin. Int J Cancer 1998;75(5):713-20. doi:https://doi.org/10.1002/(SICI)1097-0215(19980302)75:53.0.CO;2-1 2. Cassandra Studio . Nutraceuti e cibi funzionali. Youcanprint, 2015 3. Singh A.N., Baruah M.M. & Sharma N. Structure based docking studies towards exploring potential anti-androgen activity of selected phytochemicals against prostate cancer. Sci Rep 2017;7(1):1955. doi:10.1038/s41598-017-02023-5 4. Wee T.T., Lun K.R. Teaching science in culturally relevant ways: ideas from Singapore teachers. World Scientific, 2014

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