Proximate, caffeine and tannin analyses in some brands of tea consumed in Kano Metropolis, Nigeria

Abstract

The determination of proximate, caffeine and tannin contents of five different (China, Kenya, India, Srilanka and Mambilla) tea leaves samples sold in Kano markets was conducted. The moisture content was generally high in all the tea samples and ranged from 5.6% in Mambila to 7.5% in India samples. Ash content was relatively low and ranged between 4.90% in Srilanka to 7.20% in Mambila and Kenya samples respectively. Crude fibre ranged from 14.00% in China to 18.82% in Srilanka samples, while ether extract content was within the range of 9.30% to 10.60% with the highest value found in Mambila sample and the least value in Kenya sample. Total nitrogen contents were low when compared with other workers' results and ranged from 0.88% in Kenya to 1.75% in Mambila and Srilanka samples respectively. Caffeine and tannin contents were found to be 1.4% in Kenya to 2.80% in China, 6.00% in Mambilla to 7.80% in India samples respectively.

Production and Quality Evaluation of Green and Black Herbal Teas from Moringa oleifera Leaf

“…There were significant (p<0.05) differences between the crude fibre content of all the samples. The powdered Moringa leaves had the highest crude fibre content (18.64%), which is in agreement with the crude fiber content (18.82%) reported for Srilanka tea (Mohammed and Sulaiman, 2009), while the fresh leaf had 1.09% crude fibre content. Crude fibre stimulates the movement of the bowel and helps to prevent constipation (Okanlawon, 2000).…”

“…The result revealed that black tea had the highest concentration of all the minerals compared to other samples, which could be attributed to the high percentage of ash present. Black Moringa leaf tea also had the highest ash content (Table 1), which is in agreement with the observation of Mohammed and Sulaiman (2009) that high content of ash is an indication of a good source of minerals. The production processes of black tea that involves withering which reduces moisture content of fresh leaf to one third (Jabeen et al, 2015), helps to reduce loss of juice during maceration that aids enzymatic oxidation process called fermentation (Hsu et al, 2011) and subsequently enhanced mineral retention compared to green tea.…”

“…Controlling the moisture content of tea products is an important factor in tea preservation, particularly for inhibition of microbial growth (Heong et al, 2011). According to Mohammed and Sulaiman (2009), high moisture content aids fungal growth. The ash content of a sample, which is an indication of its mineral content, does not necessarily indicate high quality, except when there is a favourable balance of the essential minerals (Ahmed et al, 1989).…”

“…When any type of tea leaf is steeped in hot water it brews a "Tart" (astringent) flavor that is characteristic of tannins, which is due to the presence of catechins and other flavonoids (Mohammed and Sulaiman, 2009). Powdered Moringa leaf and black Moringa tea samples had the highest tannin contents, which were not significantly (p>0.05) different from each other.…”

“…Powdered Moringa leaf and black Moringa tea samples had the highest tannin contents, which were not significantly (p>0.05) different from each other. Tannins are chemically distinct from other types of plant tannins such as tannic acid and tea extracts, which have been reported to contain no tannic acid inhibit the absorption of minerals, such as iron which may, if prolonged, lead to anaemia, if ingested in excessive quantities (Mohammed and Sulaiman, 2009). Osada et al (1997) recommended drinking tea and coffee between meals, because foods rich in vitamin C are known to help in neutralizing tannin effects on iron absorption.…”