Non-alcoholic Beverages

Volume 6. The Science of Beverages

Alexandru Grumezescu, Alina Maria Holban, Alexandru Grumezescu, Alina Maria Holban

• Publisher: Woodhead Publishing
• Year: 2019
• ISBN:
  9780128157022
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Nonalcoholic Beverages, Volume Six in The Science of Beverages series, offers a wide-range of knowledge and expertise from research professionals around the world. The book focuses on the research and development of innovative products and new growing trends based on consumer demand for natural drinks that have health benefits. The book discusses the properties and benefits of developing nonalcoholic beverages, their production particularities, associated properties, physiochemical characteristics, and methods to help researchers and students learn about utilized nonalcoholic beverages.

• Presents a broad scope of topics and process solutions from experts in the beverages industry
• Covers the latest technologies and microbiological methods that enhance the health benefits of beverages
• Includes emerging trends in nonalcoholic beverages and offers a variety of safety and quality techniques for adding value to products

1

Tea, the “Ambrosia” Beverage: Biochemical, Cellular, Molecular, and Clinical Evidences

Piteesha Ramlagan^⁎,†; Darshini Narrain^⁎; Shameem Fawdar^⁎; Theeshan Bahorun^{⁎ *} ANDI Centre of Excellence for Biomedical and Biomaterials Research, University of Mauritius, Réduit, Republic of Mauritius
^† Department of Health Sciences, University of Mauritius, Réduit, Republic of Mauritius

Abstract

Besides water, tea (Camellia sinensis) is the most commonly consumed beverage in the world with a steadily increasing production load every year (5.3 billion kg for the year 2015). While it is an integral part of many people’s routine diet, it is also highly valued as a functional food due to its potential to mitigate chronic human diseases. Depending on the oxidation and fermentation techniques applied during processing, tea is commercially produced as six main varieties, namely black, green, white, yellow, oolong, and pu-erh. The polyphenolic richness of tea is accountable for its prophylactic effects, mainly in terms of antioxidant and antiinflammatory potentials both in vitro and in vivo. The underlying pathophysiology of a number of chronic diseases is attributed to oxidative stress and inflammation and attenuation of same constitutes an important target in managing diseased conditions. Polyphenols in green and black teas, mainly catechins, theaflavins, and thearubigins, have been shown to exert antioxidant, antiinflammatory, anticarcinogenic, antidiabetic, antiatherogenic, antimicrobial, and antineurodegenerative potential among others. The consumption of tea is gaining popularity preferentially as a medicinal beverage by virtue of its health-protective aspects, which are increasingly being evaluated scientifically. This chapter will comprehensively review the recent findings on the bioactivity of specific tea components in different diseased conditions. Particular emphasis will be laid on their prophylactic effects at biochemical, cellular, molecular, and clinical levels accompanied by a description of the molecular mechanisms underlying the claimed health benefits.

Keywords

Tea; Polyphenols; Prophylaxis; Molecular mechanisms

1.1 Introduction

Besides water, tea is the most commonly consumed beverage in the world (Carloni et al., 2013). It is appreciated for its aroma, taste, and cultural practices but more importantly for its health benefits (Kosińska and Andlauer, 2014). The different varieties of tea originate from the Camellia sinensis plant (Fig. 1.1) but are processed differently to produce six main varieties, namely black, green, white, yellow, oolong, and pu-erh (Kosińska and Andlauer, 2014). These teas are different in taste, appearance, and chemical composition (Chan et al., 2011). With a steadily increasing production load every year (5.3 billion kg for the year 2015) (Food and Agriculture Organization of the United Nations, 2015), about 78% of the world tea production accounts for black tea, 20% for green tea, and 2% for the other types of teas. Black tea is consumed worldwide while green, white, oolong, and pu-erh teas are consumed mainly in Asia although these are also becoming increasingly popular in Europe and North America over time (Kosińska and Andlauer, 2014). The surge in tea consumption, especially green tea, is attributed to numerous studies demonstrating their physiological benefits to human health. The prophylactic effects of tea consumption are mainly due to the presence of its secondary metabolites, mainly polyphenols (Da Salva Pinto, 2013). This chapter will comprehensively review the recent findings on the bioactivity of specific tea components under different diseased conditions. Particular emphasis will be laid on their prophylactic effects at biochemical, cellular, molecular, and clinical levels, accompanied by a description of the molecular mechanisms underlying the claimed health benefits.

Fig. 1.1 Tea plantation and fresh tea leaves.

1.2 Bioactive Components of Tea

Polyphenols are aromatic ring-containing compounds, with at least one hydroxyl (OH) group. The structure of polyphenols varies greatly, from simple phenolic acid molecules to polymerized condensed tannin compounds. The major classes of polyphenols found in teas are phenolic acids and flavonoids. Phenolic acids consist of a single aromatic ring and are divided into hydroxybenzoic and hydroxycinnamic acids (Fig. 1.2) (Manach et al., 2004; Pandey and Rizvi, 2009). Phenolic acids and related compounds such as gallic acid, chlorogenic acid, p-coumaric acid, galloylquinic acid, caffeoylquinic acid, p-coumaroylquinic acid, galloyl glucose, and gallic acid methyl ester have been detected in teas (Table 1.1) (Lin et al., 2008; Zhao et al., 2011). Flavonoids are the most studied group of polyphenols and are the most abundant class of compounds in teas (Zhang et al., 2011). They comprise two aromatic rings bound together by three carbon atoms to form an oxygenated heterocycle (Fig. 1.3A). Based on the heterocycle type involved, level of oxidation, site linking the B ring to the C ring, and pattern of substitution of the C ring (Xie and Chen, 2013), flavonoids are divided into different subclasses with flavonols and flavan-3-ols being more commonly present in teas. Flavonols can occur in glycosylated form while flavan-3-ols, the predominant subclass of flavonoid in tea, occur as aglycones. Polymerization of flavan-3-ols forms proanthocyanidins, also known as condensed tannin (Manach et al., 2004; Pandey and Rizvi, 2009). Some of the flavan-3-ols present in teas are galloca...