Black tea thearubigins—their HPLC separation and preparation during in‐vitro oxidation

Abstract

INTRODUmIONThe maceration of green tea shoots during black tea manufacture results in the enzymic oxidation of catechins and their subsequent conversion to theaflavin (TF) and thearubigin (TR) compounds (Roberts 1958; Roberts and Myers 1959). Together these represent up to 30% of the dry weight of black tea, and their colour and astringency are major factors affecting the brightness, depth of colour, mouthfeel and overall quality of plain black teas (Hilton and Ellis 1972).

Monitoring of black tea fermentation process using electronic nose

“…A number of research and development initiatives have been reported on fermentation process of black tea (Opie, Robertson, & Clifford, 1990;Owuor & McDowell, 1994). These studies were based on chemical analysis, and on-line instrumental monitoring of the fermentation aroma profile of black tea has not been attempted.…”

Antioxidant Activity of Flavanols and Flavonoid Glycosides in Oolong Tea

“…Recently, three novel minor polyphenol compounds, theaflavate B, isotheaflavin-3 '-O-gallate and neotheaflavin-3-O-gallate, have been characterized in extracts from black tea (13). By contrast, thearubigins are extremely complex, heterogeneous mixture of pigments, and their structures are largely unknown (14). Thearubigins are predominant in black tea leaves (15-20% dry weight) and are believed to make the greatest contribution to taste, depth of color and body of a tea brew and therefore influencing the quality.…”

The chemistry and biochemistry of black tea production — the non-volatiles

“…By comparison, recent work by Opie et al (1990) utilizing the considerable advances which have been made in HPLC stationary phases and detection systems, has separated over 44 pigmented components from black tea liquors (Fig. 17.14), all but four or five of which by current definitions can be classed as thearubigins.…”