Abstract:
Diversification and value addition in tea has received considerable attention in recent past. This has been
occasioned by increased tea volumes in the world market, especially the aerated product that has led to
over flooding. Additionally, health benefits associated with diversified products such as green tea and
extracts has elicited a lot of interests in both the industry and external players in finding out alternative
ways of tea consumption. The aim of this study was to determine biochemical composition of the various
tea extract products generated at different points of a multistage extraction process. The extraction
process consisted of hot distilled water, methylene chloride and ethyl acetate steps. The products of
purple, yellow, green, black orthodox teas, matcha and the semi aerated oolong were used as raw
materials for the extracts. Total polyphenols content, individual catechins and caffeine content were
assayed using UV-spectrophotometer and High Performance Liquid Chromatography-Photo diode array
HPLC-PDA. Analysis of variance (ANOVA) was used for statistical purposes to detect significant
differences between the extraction methods with the least significant difference (LSD) used to separate
the means in the assayed tea samples. Results generated indicated that total polyphenols, individual
catechins and caffeine content were significantly different (p≤0.05) in the assayed tea samples. Water
extracts showed high total yield (82.2%), while methylene chloride recorded the least (2.63%). Ethyl
acetate tea extracts showed high phenolic content that ranged from 11. 4% to78.1%. Ethyl acetate extract
was rich in total catechins content (46.6% to 75.9%). Water extracts had significantly (p≤0.05) high
amounts of total catechins (12.3% to 27.6%) compared to residual extracts (5.4% to 8.9%) contrary to
methylene chloride extracts which had low total catechin contents (1.2% to 4.5%). Caffeine was
predominant in methylene chloride tea extracts and ranged from 29.97% to 58.99% pointing to high
solvent affinity. Based on this results, ethyl acetate proved to be the ideal solvent for obtaining extract
rich in polyphenols, and methylene chloride for isolation of natural caffeine. For high yield of all
polyphenols, water was found to be the solvent of choice of tea extracts without regarding the specific
class of compound to be isolated. This study confirmed that specialty tea extracts are a promising source
of bioactive compounds, suggesting they could be very attractive for use as dietary supplements,
cosmetic ingredients and in food industries.
