Tea: Varieties, Production, Functional Applications and Health Benefits

A special issue of Beverages (ISSN 2306-5710).

Deadline for manuscript submissions: closed (30 April 2016) | Viewed by 160015

Special Issue Editor

Food Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, Australia
Interests: functional food; bioactive compounds in food; waste utilization; antioxidant; extraction; microencapsulation
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Tea is one of the most popular beverages consumed worldwide. Tea is a major source of flavonoids, which have become well known as antioxidants and linked with various health benefits. Tea also contains caffeine and L-theanine, which have been found to associate with tea quality and health benefits. Many studies have been conducted or are under investigation on tea varieties, production, chemical components, and health promotion.

The objective of this Special Issue is to publish a compilation of original research and review papers on tea varieties, production, chemical components, healthy benefits, and other functional applications of tea and tea products. This Special Issue is expected to provide to readers with updated and comprehensive information on the varieties, production, functional applications and health benefits of tea.

Dr. Quan V. Vuong
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Beverages is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (6 papers)

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Research

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1477 KiB  
Article
Extraction of Mangiferin and Chemical Characterization and Sensorial Analysis of Teas from Mangifera indica L. Leaves of the Ubá Variety
by Natalia Medina Ramírez, Leticia Monteiro Farias, Francine Apolonio Santana, João Paulo Viana Leite, Maria Inês De Souza Dantas, Renata Celi Lopes Toledo, José Humberto De Queiroz, Hércia Stampini Duarte Martino and Sônia Machado Rocha Ribeiro
Beverages 2016, 2(4), 33; https://doi.org/10.3390/beverages2040033 - 23 Nov 2016
Cited by 15 | Viewed by 9999
Abstract
Mangiferin is present in various parts of Mangifera indica L. and has proven biological activities, such as antioxidant capabilities. The aim of this work was to evaluate the chemical composition of teas prepared from M. indica leaves, their potential use as a source [...] Read more.
Mangiferin is present in various parts of Mangifera indica L. and has proven biological activities, such as antioxidant capabilities. The aim of this work was to evaluate the chemical composition of teas prepared from M. indica leaves, their potential use as a source of mangiferin and their total phenolic compounds. Teas were prepared with young and mature leaves of M. indica at three (medicinal plant: solvent) ratios utilizing three different preparation techniques. The mangiferin content was analyzed via high-performance liquid chromatography (HPLC). The tea with the highest mangiferin content was characterized for its total phenolic content and antioxidant activity. The oxidative stability was also evaluated by quantifying mangiferin, total phenolics and antioxidant activity using two preservation treatments for 0, 24 and 48 h. Sensory analysis was performed to measure the acceptance of the tea. The type of leaf, preparation technique and concentration influenced the mangiferin content in the teas. The highest concentration of mangiferin was obtained through decoction at a 5% (w/v) medicinal plant concentration. This tea exhibited stability up to 48 h after preparation under both preservation treatments and provided a positive sensory acceptance for consumers with flavors added. In conclusion, teas made from M. indica leaves have great potential as sources of mangiferin and phenolic compounds. Full article
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947 KiB  
Article
Influence of Steep Time on Polyphenol Content and Antioxidant Capacity of Black, Green, Rooibos, and Herbal Teas
by Michael D. McAlpine and Wendy E. Ward
Beverages 2016, 2(3), 17; https://doi.org/10.3390/beverages2030017 - 01 Jul 2016
Cited by 33 | Viewed by 16097
Abstract
Potential health benefits of tea consumption are often attributed to the antioxidant activity of polyphenols. Whether steep time, often variable in a real-life situation, makes a biological difference in terms of polyphenol content and antioxidant activity is uncertain. The study objective was to [...] Read more.
Potential health benefits of tea consumption are often attributed to the antioxidant activity of polyphenols. Whether steep time, often variable in a real-life situation, makes a biological difference in terms of polyphenol content and antioxidant activity is uncertain. The study objective was to characterize eight popular and commercially available teas for total polyphenol content (TPC) and antioxidant capacity in relation to steep time. Dragonwell (DW), Sencha (S), English Breakfast (EB), Golden Monkey (GM), Green Rooibos (GR), Red Rooibos (RR), Chamomile (C), and Peppermint (P) loose leaf teas were individually steeped in water for 1–10 min at 1 min intervals. TPC increased with longer durations of steep time; however, the majority of polyphenols observed after 10 minutes were extracted in the first 5 min regardless of tea type. After 5 min of steeping, differences (p < 0.05) in TPC were observed across teas (JS~EB~P > DW > GM~GR~RR > C). Different teas also varied in their ability to inhibit the free radical 2, 2-diphenyl-1-picrylhydrazyl (DPPH) when normalized for polyphenol concentration (1 µg/mL) and there was no effect due to steep time. Predicted antioxidant capacity of teas also demonstrated significant differences among teas after 5 and 10 min. In conclusion, steep time modulates TPC but not the antioxidative capacity of tea polyphenols. Full article
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Review

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383 KiB  
Review
Green Tea and Its Extracts in Cancer Prevention and Treatment
by Johannes Schulze, Lena Melzer, Lisa Smith and Rolf Teschke
Beverages 2017, 3(1), 17; https://doi.org/10.3390/beverages3010017 - 15 Mar 2017
Cited by 10 | Viewed by 7989
Abstract
Green tea (GT) and green tea extracts (GTE) have been postulated to decrease cancer incidence. In vitro results indicate a possible effect; however, epidemiological data do not support cancer chemoprevention. We have performed a PubMED literature search for green tea consumption and the [...] Read more.
Green tea (GT) and green tea extracts (GTE) have been postulated to decrease cancer incidence. In vitro results indicate a possible effect; however, epidemiological data do not support cancer chemoprevention. We have performed a PubMED literature search for green tea consumption and the correlation to the common tumor types lung, colorectal, breast, prostate, esophageal and gastric cancer, with cohorts from both Western and Asian countries. We additionally included selected mechanistical studies for a possible mode of action. The comparability between studies was limited due to major differences in study outlines; a meta analysis was thus not possible and studies were evaluated individually. Only for breast cancer could a possible small protective effect be seen in Asian and Western cohorts, whereas for esophagus and stomach cancer, green tea increased the cancer incidence, possibly due to heat stress. No effect was found for colonic/colorectal and prostatic cancer in any country, for lung cancer Chinese studies found a protective effect, but not studies from outside China. Epidemiological studies thus do not support a cancer protective effect. GT as an indicator of as yet undefined parameters in lifestyle, environment and/or ethnicity may explain some of the observed differences between China and other countries. Full article
977 KiB  
Review
An Update on the Health Benefits of Green Tea
by Wanda C. Reygaert
Beverages 2017, 3(1), 6; https://doi.org/10.3390/beverages3010006 - 18 Jan 2017
Cited by 60 | Viewed by 32782
Abstract
Green tea, which is produced from the leaves of the Camellia sinensis plant, is one of the most popular beverages worldwide. Over the past 30 years or more, scientists have studied this plant in respect to potential health benefits. Research has shown that [...] Read more.
Green tea, which is produced from the leaves of the Camellia sinensis plant, is one of the most popular beverages worldwide. Over the past 30 years or more, scientists have studied this plant in respect to potential health benefits. Research has shown that the main components of green tea that are associated with health benefits are the catechins. The four main catechins found in green tea are: (−)-epicatechin (EC), (−)-epicatechin-3-gallate (ECG), (−)-epigallocatechin (EGC), and (−)-epigallocatechin-3-gallate (EGCG). Of these four, EGCG is present in the largest quantity, and so has been used in much of the research. Among the health benefits of green tea are: anticarcinogenic, anti-inflammatory, antimicrobial, and antioxidant properties, and benefits in cardiovascular disease and oral health. Research has been carried out using various animal models and cells lines, and is now more and more being carried out in humans. This type of research will help us to better understand the direct benefits of green tea. This review will focus primarily on research conducted using human subjects to investigate the health benefits of green tea. Full article
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560 KiB  
Review
The Effect of Dietary Supplementation of Green Tea Catechins on Cardiovascular Disease Risk Markers in Humans: A Systematic Review of Clinical Trials
by Sarah O. Lau, Ekavi N. Georgousopoulou, Jane Kellett, Jackson Thomas, Andrew McKune, Duane Mellor, Paul D. Roach and Nenad Naumovski
Beverages 2016, 2(2), 16; https://doi.org/10.3390/beverages2020016 - 21 Jun 2016
Cited by 14 | Viewed by 8400
Abstract
Green tea catechins (GTCs) are secondary plant metabolites that have been associated with health benefits in human trials. As such, they have the potential to reduce cardiovascular disease (CVD) risk; however, results are not consistent. This systematic review of the published data assessed [...] Read more.
Green tea catechins (GTCs) are secondary plant metabolites that have been associated with health benefits in human trials. As such, they have the potential to reduce cardiovascular disease (CVD) risk; however, results are not consistent. This systematic review of the published data assessed the putative effect of GTCs supplementation on anthropometric, blood pressure, and biochemical measures associated with CVD risk. It was conducted in accordance with the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines exploring four major electronic databases (MEDLINE, Cochrane Library, Web of Science, and Scopus). Studies were included if they were published in peer-reviewed journals in English from 1990 until October 2015, and were human double-blind randomized and placebo-controlled trials (RCTs). From 122,428 articles initially identified, after two levels of screening, seven studies met the inclusion criteria. The review revealed consistent and significant (p ≤ 0.05) reductions in body mass index (BMI), blood pressure and plasma lipids; however, this effect would have been less if between-group effects had been considered. The current evidence base also has considerable methodological limitations due to suboptimal statistical methods used in data analyses. Future research efforts must aim to rectify this paucity of evidence with well-designed and well-reported prospective studies. Full article
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448 KiB  
Review
l-Theanine as a Functional Food Additive: Its Role in Disease Prevention and Health Promotion
by Jackson Williams, Jane Kellett, Paul Daniel Roach, Andrew McKune, Duane Mellor, Jackson Thomas and Nenad Naumovski
Beverages 2016, 2(2), 13; https://doi.org/10.3390/beverages2020013 - 30 May 2016
Cited by 40 | Viewed by 83800
Abstract
Tea has been consumed for thousands of years and is an integral part of people’s daily routine, as an everyday drink and a therapeutic aid for health promotion. Consumption of tea has been linked to a sense of relaxation commonly associated with the [...] Read more.
Tea has been consumed for thousands of years and is an integral part of people’s daily routine, as an everyday drink and a therapeutic aid for health promotion. Consumption of tea has been linked to a sense of relaxation commonly associated with the content of the non-proteinogenic amino acid theanine, which is found within the tea leaves. The aim of this review article is to outline the current methods for synthesis, extraction and purification of theanine, as well as to examine its potential benefits related to human health. These include improvements in cognitive and immune function, cancer prevention, reduced cardiovascular risk and its potential usefulness as a functional food product. Full article
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