YAROSLAV SHEVCHENKO1^*, IRENE HEMMERICH¹, JULIA HELFERT², IRYNA SMETANSKA²

1. Technische Unversität Berlin, Department Methods of Food Biotechnology
Königin-Luise-Str. 22 , D-14195 Berlin

2. Hochschule Weihenstephan-Triesdorf Hochschule Weihenstephan-Triesdorf
Fakultät Landwirtschaft, Steingruberstraße 2, D-91746 Weidenbach

Abstract

Green tea is a derivative of Camellia sinensis a tea plant native to many countries in Asia (China, India, and Japan). Depending on harvesting and handling of the plant material of Camelia sinensis we distinguish between several types of green tea. These types have different oxidization grade which forms the different antioxidant properties of the teas. In many cases, especially in Europe, some consumers find the taste of the real green tea rather peculiar. The palatability of many food products goes hand in hand with sweetness of the products. In order to increase the sweetness of the green tea we add a certain quantity of stevia leaves. Stevia rebaudiana Bertoni is a perennial plant that originates from Latin America (Paraguay). It possesses the unique property to accumulate sweet tasting steviol glycosides. These substances are sweeter than sugar, but at the same time they do not introduce any calories into human body. The objective of our research is to test the antioxidant properties of different green tea combinations with and without stevia. The mixtures of different green teas produced extracts of different antioxidant activity. The tea with the lowest antioxidant activity (oolong) improved its antioxidant profile in the mixture with stevia. The lower the initial antioxidant profile of the tea, the better improvement was achieved after mixing it with stevia. These results can be used by food industry for formulating sugar free ice-tea products.

INTRODUCTION

Tea is the most popular drink on the planet after water. It shaped countries, economies and landscapes and nowadays it keeps influencing the life of million people. Despite the large variety of teas on the market, the real tea comes only from one plant Camellia sinensis. Green tea is a derivative of C. sinensis a tea plant native to many countries in Asia (China, India, and Japan). Depending on harvesting and handling of the plant material of C. sinensis we distinguish between several types of green tea. These different types have dissimilar oxidization grade which forms the diverse antioxidant properties of the teas (1, 7). The high phenolic content in green teas is attributed to many positive health effects including anti-inflammatory activity, free radical scavenging and preventing the general oxidative stress (13). Several medical studies have also confirmed positive effects of green tea extracts in preventing and treating of neurodegenerative diseases (2, 11). The authors of this article are convinced that the large scale introduction of green tea and green tea products into diet of Europeans could have a beneficial health effect in the ...