IJERD – International Journal of Environmental and Rural Development (2021) 12-1

Research article
erd

Evaluation of Some Nutritional Values and Antioxidant
Activities of Dried Tea Leaves in Seasonally
CHAW SU HLAING*
Department of Chemistry, Taunggyi University, Taunggyi, Myanmar
Email: chaw88@gmail.com

A MAR WINT
Department of Chemistry, Taunggyi University, Myanmar

OHN MAR AYE
Department of Chemistry, Taunggyi University, Myanmar

MYO THIDA HTEIK
Department of Chemistry, Taunggyi University, Myanmar
Received 30 December 2020

Accepted 30 July 2021(*Corresponding Author)

Abstract Tea Leaf is one of the traditional food in Myanmar. It is eaten as well as drunk withtwo main forms which are wet tea leaf (Myanmar name, Lahpet so) and dried tea leaf
(Myanmar name, Lahpet chauk). Tea leaves can be picked starting from April until October. At
Namhsan area, Northern Shan State in Myanmar, tea leaves are generally divided into six kinds
depending on the plucked season. There are “Shwephi-Oo”, “Shwephi-Hnaung”, “Khakan-Oo”,“Khakan-Hnaung”, “Kha-Naing”, and “Kha-Hawt” or “Hnin Tet”. In this study, somenutritional value and antioxidant activities of six kinds of dried tea leaves in Namhsan region
were evaluated by the aiming of which kind of dried tea leaves have the best quality for
consumers. The analyses included examination of the dried tea leaves were their nutritional
value (carbohydrate, protein, and amino acids), assessment of selected minerals, caffeine,
catechin mixture, dietary fiber and total ash. Nutritional contents of tea leaves were examinedby preliminary phytochemical screening method and the selected mineral contents (Ca, Zn, Fe,Mn) were analyzed by atomic absorption spectrophotometry (AAS). Total ash contents were
determined by ignition method. Antioxidant activities of dried tea leaves were evaluated by the
DPPH free radical scavenging assay. Caffeine and catechin mixture (flavonoid) were extracted
by using chemical reagents such as dichloromethane and chloroform. From the observed results,
dried tea leaves in Namhsan region were rich in mineral contents (2.33-5.48 mg/kg of Ca, 1.401.94 mg/kg of Zn, 1.06-1.77 mg/kg of Fe and 8.06-21.06 mg/kg of Mn), 0.525-3.413% protein,
8-11.5% crude fiber, 4.20-7.39% total ash, 0.075-0.200% caffeine, 0.4-2.0% catechin mixture
and high antioxidant activities (2.3-5.9 g/L, IC50 value of DPPH scavenging assay) were found.
Based on the studied nutritional values and antioxidant activity results, Shwephi-Oo dried tea
leave was confirmed that the best quality.
Keywords dried tea leave, nutritional value, antioxidant activity, phytochemical screening,
free radical scavenging, AASINTRODUCTION
Tea is grown in different states of Myanmar, mainly in Shan state. The best quality and major
cultivation are in Namhsan region, Northern Shan State. The total tea plantation area is around 70,000
hectares with an annual production of 78 million Kg green leaves. Namhsan area is a mountainousⒸ ISERD

181

IJERD – International Journal of Environmental and Rural Development (2021) 12-1

region with deep slope that forms a natural drainage system, vital for tea plantation (website 1). There
are generally six kinds of tea seasonal names in use for the tea leaf. These are "Shwephi-Oo" if the tea
leaf is picked 3rd week of March to 2nd week of April,"Shwephi-Hnaung" if it is picked 3rd week ofApril to 2nd week of the May, "Khakan-Oo" if it is picked 3th week of May to 2nd week of July,"Khakan-Hnaung" if it is picked mid-July to 2nd week of August, "Kha-Naing" if it is picked 3rd weekof August to end-September, and,"Kha-Hawt" or “Hnin-Tet” if it is picked 1st October to endNovember. The period of these seasons may be differed in locally.
Tea leaves contain thousands of the chemical compounds. When tea leaves are processed, thechemical compounds within them break down, form complexes with one another and form newcompounds. The most important compounds in fresh tea leaves are polyphenols, amino acids, enzymes,
pigments, carbohydrates, methylxanthines, minerals and many volatile flavor and aroma compounds.
These components are responsible for producing teas with desirable appearance, aroma, and taste(Tony, 2019). All types of tea leaves (green tea, black tea, white tea, oolong tea, and pu-erh tea)
contain unique antioxidants called flavonoids. The most potent of these, known as Epigallocatechingallate (EGCG), may help against free radicals that can contribute to cancer, heart disease, and clogged
arteries. All these teas also have caffeine and theanine, which affect the brain and seem to heighten
mental alertness.
The more processed the tea leaves, usually the less polyphenol content. Polyphenols include
flavonoids. When the tea leaves are oxidized or fermented, so they have lower concentrations ofpolyphenols than fresh green tea leaves; but their antioxidizing power is still high (Julie, 2009). Tasteand aroma, as well as price and brand are the main factors impacting consumers’ preferences withregard to tea of their choice; on the other hand consumers less frequently pay attention to the chemicalcomposition and nutritional value of tea (Maria, 2017). Therefore, in this study, some nutritional values
and antioxidant activity of dried tea leaves were examined by dividing the six kinds based on theirplucked periods.
OBJECTIVE
This study assessed the nutritional values and antioxidant activities of dried tea leaves in seasonallyand confirmed the best quality dried tea leave based on the studied results.
MATERIALS AND METHODS
Sample Collection
Tea leaves were plucked in one of the tea farms from Zayangyi village in Namhsan region, Nothern
Shan State, Myanmar. “Shwephi-Oo” kind of tea leaves were plucked in 2nd week of April 2018,“Shwephi-Hnaung” was plucked in 4th week of April 2018, “Khakan-Oo” was plucked in 4th week of
May 2018, “Khakan-Hnaung” was plucked in 3rd week of July 2018, “Kha-Naing” was plucked in 3rd
week of August 2018 and, “Kha-Hawt” was plucked in 1st week of October 2018. After plucking, allkinds of tea leaves were cleaned and dried at room temperature for two weeks. The dried tea leaves
were stored in the air tight plastic bags before the analyses were performed.
Sample Preparation
Aqueous extract of all kinds of dried tea leaves were prepared for the drinking purpose of dried tea
leave infusion with boiling water.
Preliminary Phytochemical Analysis of Dried Tea LeavesⒸ ISERD

182

IJERD – International Journal of Environmental and Rural Development (2021) 12-1

Preliminary phytochemical investigations of aqueous extract of dried tea leaves were carried out toknow what chemical constituents were involved in the dried tea leaves according to the standard
procedure of qualitative test for preliminary phytochemical screening. The procedure and results arepresented in Table 1 and 2, respectively.
Table 1 Procedure for preliminary phytochemical screening
Constituents

Procedure

Observation

Alkaloid

Dragendroff’s test, Few mL of sample filtrate + 1-2mL of Dragendroff’s reagent

Reddish brown
precipitate

Carbohydrate

Barfoed’s test, 1 mL of sample filtrate + 1 mL of Barfoed’s reagent (heated for2min)

Red precipitate(monosaccharides)

Glycoside

Borntrager’s test, 2 mL of sample filtrate hydrolysate + 3 mL chloroform (shakenwell) + chloroform layer separate + 10 % ammonia solution

Pink colored solution

Protein andamino acids

Ninhydrin test, 2 mL of sample filtrate + 2 drops of Ninhydrin solution (10 mg
Ninhydrin + 200 mL acetone)

Purple colored solution(Amino acids)

Flavonoid

Conc. H2SO4 test, plant extract + conc. H2SO4

Orange color

Phenolic
compounds

Ferric chloride test, Extract aqueous solution + few drops of 5 % ferric chloride
solution

Dark green/bluish blackcolor

Tannins

Braymer’s test, 1 mL of sample filtrate + 3 mL distilled water + 3 drops of 10 %ferric chloride sol:

Blue-green color

Determination of Some Nutritional and Mineral Contents of Dried Tea Leaves
Some nutritional (protein, total ash and crude fiber) contents of dried tea leaves were examined. The
crude protein contents of the samples were determined by Macro-kjeldahl method (AOAC, 1990).
Total ash was obtained by igniting tea sample in muffle furnace until it is free from carbon (FoodChemistry, 2012). The 5 g of each dried tea leave sample was taken in a tarred silica dish/crucible. It
was heated at 100°C in an oven until moisture is expelled and incinerated at as low a temperature as
possible. Then the dish was placed in furnace at 525  20°C for about 1 hour and leave until white ash
is obtained. The dish was transferred in a desiccator for cooling and weighted the dish. The results
were expressed as % total ash.
The crude fiber contents in the dried tea leave samples were examined by the method given in“The chemical analysis of Foods” (Joslyn, 1970).
The selected mineral contents (Ca, Zn, Fe, and Mn) were analyzed by atomic absorption
spectrophotometer. 1 g of each dried tea sample was dissolved in 10 mL of 1 M nitric acid and boiled
to complete the dissolution and filtrated. The precipitate was washed with 1 M nitric acid and filtered.
The obtained filtrate was transferred to 25 mL volumetric flask and fill up to the level with double
distilled water. Then the digested solution was analyzed with AAS spectrophotometer (SHIMADZU
AA-7000). The results are described in Table 2.
Determination of Caffeine, Catechin Mixture and Antioxidant Activities of Dried Tea Leaves
Caffeine and catechin mixture (flavonoid) were extracted by using chemical reagents such asdichloromethane or chloroform and ethyl acetate. 10 g of ground tea leaves were extracted with 300
mL of pure water at 80 C for 40 min. Leaves were removed by filtration using a filter paper(Whatmann, No. 1). Aqueous tea infusion was initially partitioned with chloroform then secondⒸ ISERD

183

IJERD – International Journal of Environmental and Rural Development (2021) 12-1

partition was carried out with ethyl acetate (Row and Jin, 2006). Caffeine and catechin mixture were
calculated by the equation 1 and 2 respectively (Ezgi, 2015).
% Caffeine (w/w) = (mass of caffeine extract / mass of tea sample) x 100% Catechin (w/w) = (mass of catechin extract / mass of tea sample) x 100

(1)
(2)

Antioxidant activities of dried tea leaves were evaluated by the DPPH free radical scavenging
assay according to Lee et al, 2004. The results are described in Table 3. All experiments were
performed in the laboratory of Department of Chemistry, Taunggyi University, Southern Shan State,
Myanmar.
RESULTS AND DISCUSSION
Fig. 1 shows the collected six kinds of air dried tea leaves from one of the tea farm in Zayangyi Village,
Namhsan Region, Nothern Shan State, Myanmar.

Shwephi-Oo

Shwephi-Hnaung

Khakan-Oo

Khakan-Hnaung

Kha-Naing

Kha-Hawt

Fig. 1 The six kinds of dried tea leaves
Table 2 Preliminary phytochemical screening of six kinds of dried tea leaves
Sample(H2O extract)

Alkaloid

Carbohydrate

Glycoside

Protein andamino acids

Flavonoid

Phenolic
compounds

Tannins

Shwephi-Oo

+

-

+

+

+

+

+

ShwephiHnaung

+

-

+

+

+

+

+

Khakan-Oo

+

-

−

+

+

+

+

KhakanHnaung

+

-

_

+

+

+

+

Kha-Naing

+

_

+

+

+

+

Kha-hawt

+

_

+

+

+

+

-

*(+) = Present, (-) = absentⒸ ISERD

184

IJERD – International Journal of Environmental and Rural Development (2021) 12-1

The qualitative tests of preliminary phytochemical screening for aqueous extract of six kinds ofdried tea leaves showed the results which described in Table 2. According to these results, alkaloid,
protein and amino acids, flavonoid, phenolic compounds and tannins were observed in all kinds ofdried tea leaves. Glycoside was found in the two kinds, Shwephi-Oo and Shwephi-Hnaung.
Carbohydrate was found to be absent in all kinds of dried tea leaves. By viewing these results, it isrecommended that all kinds of dried tea leaves infusion with boiling water could significantly
contribute to the health management and our daily need of secondary metabolites.
Nutrients can be divided into two categories: macronutrients, and micronutrients. Macronutrientsare those nutrients that the body needs in large amounts. These provide the body with energy (calories).
There are seven main classes of nutrients that the body needs. These are carbohydrates, proteins, fats,vitamins, minerals, fibre and water. It is important that everyone consumes these seven nutrients on adaily basis to help them build their bodies and maintain their health. Micronutrients are those nutrientsthat the body needs in smaller amounts. There are 7 essential plant nutrient elements defined as
micronutrients [boron (B), zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), molybdenum (Mo),chlorine (Cl)]. They constitute in total less than 1% of the dry weight of most plants (website 2). Table
3 shows the observed results of some nutritional and mineral contents of six kinds of dried tea leaves.
From these results, it is found that the nutritional values are more or less differ from one anotheraccording to their plucked seasons. The protein (3.413%), crude fiber (11.5%) and zinc (1.9409 mg/kg)
contents are the richest in “Kha-Naing” kind. The richest iron content (1.7661 mg/kg) is found in“Khakan-Oo” kind. The other parameters, total ash (7.39%), calcium (5.4764 mg/kg) and manganese(21.0559 mg/kg) are observed as higher significance in “Shwephi-Oo” kind. Despite the little
difference in contents, on the basis of these observation, all kinds of tea leaves appeared that thepresence of significance sources of nutritional and minerals for daily necessary human diet.
Table 3 Some nutritional and mineral contents of six kinds of dried tea leaves
Amount of parameters
SampleShwephi-Oo
ShwephiHnaung
Khakan-Oo
KhakanHnaung
Kha-Naing
Kha-hawt

Protein (%)
0.525

Crude fiber(%)
8

Total ash
(%)
7.39

Ca
(mg/kg)5.4764Zn(mg/kg)1.5873Mn(mg/kg)21.0559Fe(mg/kg)1.3953

0.525

8

6.60

5.44131.507915.19111.3514

2.625

10.5

5.79

3.00481.886510.8227

1.7661

1.138

10

5.39

4.42261.40708.0566

1.0664

3.413
2.144

11.5
8

6.60
4.20

3.30612.33821.94091.7858

11.6994
11.1704

1.75691.5577

Table 4 shows the amount of caffeine, catechin mixture and antioxidant activities of six kinds ofdried tea leaves. The caffeine and catechin mixture contents were significantly higher in “Shwephi-Oo”
kind. Numerous studies have indicated that catechins and other polyphenols in tea exhibit powerfulantioxidant activities. They function as antioxidants in vitro by scavenging nitrogen species andreactive oxygen generated due to a variety of oxidative stress and by sequestering metal ions. The
stable organic free radical, DPPH, has been considered as a useful reagent for determining free radical
scavenging capacity of antioxidant materials (Tao, et al, 2019). The observed antioxidant results werecompared with that of ascorbic acid as standard materials. The IC50 values (the effective concentrationof 50% inhibition) were showed that all kinds of tea leaves have significance antioxidant activities.
Among them, “Shwephi-Oo” has highest caffeine, catechin and antioxidant activity. It is considerable
that “Shwephi-Oo” is the foremost plucked season kind at the beginning of summer. It was free fromrain and the leaves were fresh and best strength. Therefore, it is confirmed that the quality of tea leaves
depend upon the plucked season as well as other geographical conditions.
Ⓒ ISERD

185

IJERD – International Journal of Environmental and Rural Development (2021) 12-1

Table 4 The amounts of caffeine, catechin mixture and antioxidant activities
of six kinds of dried tea leaves
Amount of parameters
SampleShwephi-Oo
Shwephi-Hnaung
Khakan-Oo
Khakan-Hnaung
Kha-Naing
Kha-hawt

Caffeine (%)

Catechinmixture (%)

0.200
0.075
0.100
0.100
0.125
0.075

2.0
1.3
0.4
0.6
0.8
0.5

Antioxidant activity(DPPH scavenging assay, IC50 value), (g/L)
ascorbic acid (Standard)
2.3
2.7
4.8
1.2
4.1
4.7
5.9

CONCLUSION
From the experimental results, six kinds of dried tea leaves in Namhsan region have valuable
nutritional values and high antioxidant activity. Among them, the selected mineral contents, total ash,catechin mixture, caffeine content and antioxidant activity were found higher rich in “Shwephi-Oo”
than another five kinds of dried tea leave apart from protein, crude fiber, Zn and Fe contents. Therefore,“Shwephi-Oo” kind of dried tea leave is generally regarded as the best quality for consumers.
ACKNOWLEDGEMENTS
The authors would like to express special gratitude to Pro-rector Dr Win Win Ei, Taunggyi University
and our Ministry of Education for giving us the opportunity to present this research paper. I also thanks
to Professor and Head, Dr Ah Mar Yi, Department of Chemistry, Taunggyi University, our co-workers
and friends for their guidance, helpful and encouragements during this field. We also thank thereviewers of IJERD for their help in improving the quality of our research paper and their criticalreviews.
REFERENCES
AOAC. 1990. Official methods of analysis of the AOAC international. 15th edition, Association of Official
Analytical Chemists, Arlington, VA.
Chinnawat, S. 2016. The study of the amount of heavy metals in green teas determine by using atomic absorption
spectrophotometer. International Journal of System Application, Engineering & Development, 10, 20-24.
Ezgi, D., Gonul, S. and Munevver, S. 2015, Comparison of some extraction methods for isolation of catechinsand caffeine from Turkish green tea. International Journal of Secondary Metabolite, 2 (2), 16-25.
Food Chemistry. 2012. Determination of total ash, alkalinity of water soluble ash and water extractives in tea.
Lesson 30, Module 13.
Joslyn, M.A. 1970. Methods in food analysis, physical, chemical and instrumental methods of analysis. 2ndedition, Academic Press, New York, 109-140.
Julie, E. 2009. Types of tea and their health benefits. Nourish by WebMD.
Lee, S., Son, D., Ryu, J., Lee, Y.S., Jung, S.H., Lee, S.Y. and Shin, K.H. 2004. Antioxidant activities ofacanthopananax senticosus stems and their lignan components. Archives of Pharmacal Research, 27, 106-110.
María, P.T., Rita, Y.C., María, I.C. and José, L.V. 2019. A simple and a reliable method to quantify antioxidant
activity. In Vivo, Antioxidants MPDI Journal, 8, 1-11.
Row, K. and Jin, Y. 2006. Recovery of catechin compounds from Korean tea by solvent extraction, Bioresour.
Technol, 97, 790-793.

Ⓒ ISERD

186

IJERD – International Journal of Environmental and Rural Development (2021) 12-1

Tao, T., Ya-Juan, L., Jinhong, K., Cheng-Mei, Z. and Seong-Gook, K. 2019. Antioxidant activity and mainchemical components of a novel fermented tea, Retrieved from www.mdpi.com
Tony, G. 2019. Chemical compounds in tea. Tea Epicure Blog, Retrieved from https://www.nagarpyan.com/
plantation.htm; received date 11.12.2020. and https://mynutrition.wsu.edu>Nutrition Basicsat WSUⒸ ISERD187