Correlation Chemical Sensory Evaluation Develop Higher Quality Tea Biology Essay

The rule of life in verve requires ingestion of nutrient merchandises of good quality. Amongst the nutrient classs beverages form a major group of the nutrient industry. The drink industry in South Africa is huge and amongst the drinks hot tea is steadily turning in popularity. Hot tea contributes 5 % of the entire value a‚¬ 500 billion ( non-alcoholic ; excepting milk, pat and packaging majority H2O ) of the drinks worldwide ( Unilever, 2009 ) . Tea in the commercial sense would mention to a blend of single grades/types of refined tea foliages sourced from different tea estates. These are combined harmonizing to specifications ( determined by the nutrient company ) to give a merchandise with an expected gustatory sensation, coloring material, olfactory property etc.

In conformity to one ‘s duty as a nutrient engineer, supplying nutrient merchandises including tea that is of good nutritionary and centripetal quality is the end. The quality attributes of tea would be described in footings of gustatory sensation ( including spirit and strength ) ; colour/hue, olfactory property and oral cavity feel of the brewed tea.

However, keeping criterions of good quality is non ever sustainable as conditions of sourcing and treating are susceptible to alter due to corporate factors. Thus the thrust for uninterrupted betterment. In peculiar Unilever ‘s portion of the universe black tea being over 20 % ( Unilever, 2009 ) has been in recent months having consumer ailments ( with noticeable addition ) of a popular branded black teabag ( for intent of this survey will be referred to as Brand B ) in footings of non-conforming gustatory sensation. With farther Pareto analysis, this found that the consumer complained of weak savoring tea.

Therefore the research to be conducted entitled “ The correlativity of chemical and centripetal analysis inured to develop a high quality tea merchandise ” will be for the intent to insulate the major factor specifically between the porousness of the filter paper used versus the dose of tea that could perchance act upon the strength of Brand B tea.

The procedure will affect readying of samples of Brand B tea packaged in two other types of filter paper ( for the intent of look intoing the influence of filter paper porousness ) every bit good as samples of the same tea in changing weights packaged in the current filter paper used for the trade name. These samples will so be tested against each other with analysis of their soluble solid output, the polyphenol content and the hiting received during centripetal analysis by experts of the company.

The overall end in the commercial sense will be to implement actions, stemming from the survey that would suppress the factor that most impacts on diminishing the strength of the tea. Thus the consumer ailments will diminish ensuing in the company accomplishing one of its marks for the twelvemonth. In add-on if the consequences show that a lessening in dose of tea will increase the strength to a consumer satisfactory degree so the company will be salvaging a noticeable sum of money on natural tea. Obviously the antonym could take topographic point if this would be untrue. On the other manus if porousness of filter paper consequences in being the major deserting factor so the action to alter the type of filter paper used could take to be nest eggs or excess outgo of about R8781750 ( Unilever, 2008 ) on filter paper.

1.1 Basicss on Tea

Tea comes from the botanical shrub Camellia Sinensis a white floral evergreen autochthonal to the rain woods of Asam, Northern Burma & A ; South West China but has since been cultivated across the universe including South Africa. The tea shrub is an highly stalwart & A ; sturdy bush that adapts good to different climes. With the economic life-span of 100 old ages it yields 40g of black tea per twelvemonth. . ( Bernard & A ; Hajkoop, 1997 )

The quality of tea depends on the tea bring forthing country, the country of the plantation it grows in, different times of planting, different plantation owners, assortment of seeds and ringers. These factors determine the concluding spirit, thickness & A ; coloring material of tea.

The fabrication procedure which converts the immature fresh foliages into tea was developed by the Chinese in ancient times. However now differences in agitation green goodss three chief sorts of tea.

Unfermented green tea, which is steamed or pan dried

Semi-fermented Oolong tea or ruddy tea

Fully fermented black tea

Industry of black tea involves five stages i.e. atrophy, turn overing or cutting, fermenting, drying and rating.

Withering- It involves distributing the foliages over a bed which is 22cm deep and coercing circulation of air with the usage of fans. The procedure takes 12-24 hours. The intent is to cut down wet, with moisture loss of 20 to 45 % . Withering makes the leaf soft and flaccid and facilitates cutting. It induces assorted biochemical alterations which assistance agitation, such as increasing polyphenol oxidase and enzyme activity, easing cell wall permeableness, commanding the caffeine degree, liberating aminic acids and increasing olfactory property development.

Cuting ( CTC ) – Film editing, rupturing and curving involves go throughing the shriveled foliages through braces of unstained steel mangle-like rollers, etched with sharp-edged intermeshing helicoidal channels. These shred the foliages into little pieces. This procedure serves to tear and open cells of the bud, root and go forth tissue to squash out and blend the cell content and juices.

Fermenting- Here the chopped foliages are left to ferment, no biological agents are added. Tea agitation is basically the transition of a simple substrate happening within the cells of the immature shoots into more complex substances under the influence of natural enzymes. A noticeable coloring material alteration takes topographic point as the chopped green foliages change to a brown coloring material.

Drying- Drying purposes to halt agitation at the optimal point of coloring material, gustatory sensation and olfactory property development. It besides produces a dry stable merchandise. Fluid bed driers are used to dry tea, where the tea enters at a temperature of 100°C and issues with a wet content of 2 to 3 % , giving 400 kg of tea per hr.

Grading- The dried tea foliages are sorted into a figure of classs of unvarying atom size utilizing vibrating screens. At the same clip, pieces of chaff & A ; fibre are removed to show a cleaner merchandise.

These graded teas are received by the site to box as teabags.Unilever packs over 100 000 metric tons or 30 % of its tea volume in teabags, chiefly for black and flavoured tea. The teas are packaged on equipment which are supplied by three industries viz. , Teepack, IMA & A ; MAISA ( Bernard & A ; Hajkoop, 1997 ) , the PMB site uses equipment supplied from IMA, who manufacture a scope of Heat-seal machines.

1.2Black Tea Rating

Broken black tea is classified into four different classs i.e. whole foliage, broken foliage, fannings and dust ( FML, 2001 ) . An illustration of whole foliage would be FOP or flowery orange pekoe which consists of mulct, stamp, immature foliages rolled with a certain proportion of “ tips ” . These tips, being the really terminal of the buds leaves, represent a warrant of quality.

Fannings black tea is made from smaller, level pieces of broken orange pekoe and used to do quick-brewing, flavoured, robust teas with good coloring material. Dust black tea consists of bantam spots of broken foliage used to brew strong tea rapidly, popular for black teabags.

1.3 Why do we intermix?

Blending tea ensures that consumers are given a consistent quality and gustatory sensation from a variable natural tea stuff, in the needed volumes and the lowest possible monetary value. A blend is a combination of different types of tea to keep the flavour consistence. Due to the big fluctuations in tea spirits from individual estates ( altering from twenty-four hours to twenty-four hours ) , teas have to be blended to accomplish a consistent spirit and coloring material through the twelvemonth. Twenty or more original teas can do up one blend.

1.4 CTC and Orthodox

CTC and Orthodox are procedure through which the complex series of chemical alterations known as oxidization are initiated. The procedures are both effectual and bring forth teas with differing features. Orthodox treating involves the tea leaves rolled easy utilizing traditional peal tabular arraies that mimic the action of manus turn overing. This break of the foliage cells causes slow oxidization. The procedure takes about four hours. The consequence is rolled foliages, larger in size and necessitating a longer brewing clip in order to obtain all the spirit and coloring material. By and large the tea is light and clear ruddy in coloring material, preferred by those who like loose tea. ( Unilever, 2009 )

CTC stands for cut, tear and coil. The tea foliages are passed through a series of cylindrical rollers with little crisp dentitions that cut, tear and curl the foliages. The procedure gives the intense coloring material and little tea leave size that teabag brewing requires, due to a rapid oxidization procedure ( about 90 min ) . The finished merchandise brews rapidly, gives a rapid rich ruddy coloring material bringing and has a higher degree of soluble solids on leaf surface.

Table 1 Average chemical composing of Orthodox and CTC black teas from Assam ( FML, 2001 )


Orthodox teas

CTC teas

Water soluble solids %



Theaflavins %



Thearubigin %



Entire lipoid



Flavour volatilised



The tabular array above presents the relevant bio-chemicals that black tea contains, as will be mentioned subsequently on, certain chemicals listed ( polyphenols ) above are responsible for the strength of the tea therefore the measure of these chemicals present find the brewing strength of the tea. Commercially CTC tea is used to bring forth teabags and this is suitably so as the tabular arraies shows that CTC teas contain more polyphenols which is needed to counterbalance for the filter paper porousness that may impede the extract of the tea therefore taking to a weaker brew.

1.5 Composition of black tea

Depending on works cultivar, clime, dirt and cultivation patterns, Potter and Hotchkiss ( 1995 ) stated there are about 1500 somewhat different sorts of tea foliages ; these can farther be modified in processing and contribute to differences in the concluding brew and supply chance for usage blending to harmonizing to commercial trade names.

Tea is comprised of three chief constituents i.e. caffeine, polyphenols and indispensable oils ( besides called aromatic or volatile oils ) . It must be noted that extra elements are introduced during tea processing. Polyphenols sometimes falsely referred to as “ tannic acids ” are responsible for the coloring material, alacrity, spirit and strength of teas, frequently associated with the footings organic structure and astringence. They account for one tierce of the soluble stuff in foliages, but differ in type between teas. Groups of related polyphenolic compounds are called catechins. In black teas, through agitation, the catechins have formed into larger, more complex constructions called theaflavin and thearubigins, which provide complex spirit and coloring material.

Essential oils contribute significantly to the aroma of tea and slightly to its gustatory sensation. They accumulate in the foliage as it grows, evaporate during and after industry. Exposed to strong heat, they will vanish wholly, which is why they are besides referred to as ‘volatile ‘ oils.

Unilever 2009 provinces caffeine stimulates the cardinal nervous system, promotes blood circulation and stimulates the kidneys to bring forth more urine. All types of tea contain 40mgs of caffeine per helping, depending upon blend and strength of brew.

Table 2 Chief constituents of black tea ( FML, 2001 )


Concentration ( g/100g )









Phenolic acids and Depsides


Amino acids








Mineral affairs




Components measured in wt % of extract solids.

1.6 Principle of Soluble Solids set uping strength of tea

As stated by the tabular array above black tea used for bring forthing teabags have a noticeable sum of polyphenols nowadays in the concluding merchandise. Since polyphenols are the rule constituents that give rise to the gustatory sensation ( strength and astringence ) of the tea, the research shows that logically the larger the sum of polyphenols nowadays in the tea the stronger the gustatory sensation it will give. ( Roberts and Smith, 1963-cited by Liang et al. , 2002 ) Other surveies besides showed that theaflavin content is an of import chemical compound finding the quality if black tea.

1.7 Properties of Filter Paper

Filter paper for teabags is composed of nutrient class approved oxygen-bleached or uncolored wood mush and a scope of semisynthetic fibers and chemicals with co-polymers to supply a sealable bed for heat sealable filter paper.

An ideal type of filter paper used for teabags would forestall all right dust atoms of tea from filtrating through the teabag, which at the same clip has the capacity for leting air or gas within the bag to readily get away so that the bag would readily drop to the underside of the cup instead than drift on top of the liquid when the teabag is being used. The filter paper should besides hold the wet strength necessary for a teabag and that is adequately porous so that the H2O will readily flux through the teabag for extract intents. With these belongingss in head, in order to do a desirable cup of tea, the air and gas should be discharged from the teabag during extract, for the presence of air or gas in the bag will do it to drift on the H2O in the cup alternatively of settling to the underside. The happening of this would impede the brew of a strong cup of tea.

1.8 Centripetal Quality of Tea-Relevant History

Research has show that there has ever been a nexus between soluble solid content ( SSC ) and the centripetal properties of tea as consumers and professionals perceive it. However most surveies have been conducted on tea samples sourced from different estates and non on a trade name of teabags that consumers will really see. Li et Al. ( 2007 ) states that SSC is one of the major features bespeaking the quality of black tea and to mensurate SSC they used analysis based on the Vis/NIR spectrometry.

However, Liang et Al. ( 2002 ) proved that there was important correlativity between the single quality properties of tea when comparing consequences from the chemical composing and color difference of tea ( through HPLC ) to the centripetal rating by tea taste testers.

In comparing to the methods to be employed for this survey, the rule is the same i.e. the aqueous extraction system nevertheless in industry the method is more conventional and less clip devouring. In footings of centripetal analysis the gustatory sensation panel is the most common method used in industry and the scientific community although Tudu et Al. ( 2009 ) had successfully attempted to use the electric olfactory organ for the rating of the olfactory property of tea.

2. Aim

To develop a higher quality tea merchandise by finding the most causative factor between the porousness of the filter paper versus the dose of tea in a teabag of Brand B that consequence in a weak tasting tea through the aqueous extraction of soluble solids, quantifying the polyphenol content and centripetal analysis of brewed tea.

To find the correlativity between chemical and centripetal analysis conducted on a higher quality tea merchandise.

3. Aims

To pull out and quantify the soluble solid content of tea samples packaged in different types of filter and at changing weights through an aqueous extraction system.

To measure the quality of tea samples of changing weights and packaged in different types of filter paper by centripetal analysis of brewed tea.

To find the polyphenol content of tea packaging at changing weights and different filter paper.

To find by statistical methods the most causative factor i.e. the filter paper or changing tea dose the outputs weak savoring tea.

4. Materials and Methods

4.1. Preparation of Samples

4.1.1. Porosity Testing-Samples

2.5g of Brand B tea will be sealed in 0.5g of filter paper. This will be done by turn uping and stapling near, the filter paper which will besides be attached to 20cm tag-string to help in the dunking procedure. Two types of filter paper ( g and a ) will be used, 8 samples will be prepared utilizing each filter paper. The control will be a sample of Brand B teabag weighing 2.5g packaged in the current filter paper used for the trade name.

4.1.2. Dosage testing-Samples

Three different dose ( weighted ) samples will be prepared utilizing the filter paper of Brand B. Four samples each of tea weighing 2.0g and 3.0g will be sealed and attached to a 20cm tag-string by turn uping and stapling together. The control will be teabags of Brand B which weighs 2.5g, this being the current criterion.

4.2. Aqueous extraction of Soluble Solids

Each type of sample prepared above will be used to pull out the soluble solid content.

Day 1

The oven will be pre-set to 103°C every bit good as the water-bath will be filled and switched on. Kettles will be filled with H2O until H2O furuncles ( 100 °C ) . The metal trays will so be labelled, weighed & A ; recorded. The prepared samples will be weighed and recorded. The teas will be transferred into beakers, the timer set at 3min, the tea will be liquored with 250ml of hot H2O, brewed for 3min. 50ml of tea will be transferred to metal trays which will be placed onto H2O baths to dry until extra liquid has evaporated. Then the trays will be placed in the oven at 103 °C for 16hrs. ( Unilever, 2005 )

Day 2

The trays will so be removed from the oven & A ; so placed into a dessicator

for 15min, the trays will so be weighed and recorded. The per centum of soluble solids will so be calculated utilizing the followers:

% soluble solids = wgt of residue x 5 X 100

Wgt of existent tea

( Unilever, 2005 )

4.3 Centripetal Analysis ( Unilever Bestfoods, 2003 )

4.3.1 Tea Batch readying

Appropriate tea savoring dishware ( cup with palpebras and bowls ) will be organised 5.6g of tea i.e. two teabags will be placed into the cup. The timer will be set at 3 proceedingss. Simultaneously de-ionised boiled ( 100A°C ) H2O of will be poured into the cups at a measure of 250ml and 5ml of milk to be added with the palpebras to cover. After the 3 proceedingss the covered cups will be tipped over to run out the tea into the bowls. There after the taste testers will slurp the liquid with a spoon to the dorsum of the oral cavity to measure the centripetal properties.

4.3.2 Scoring properties

The taste tester will measure the tea by sight ( coloring material ) , smell ( olfactory property ) and gustatory sensation ( flavour and strength ) . Each property will be scored utilizing points from 0.2 ( worst ) to 8 ( excellent ) .

4.4 Statistical Analysis

Each rating conducted will be allocated a per centum which will be used to give each sample a concluding mark. Percentage allotments will be Centripetal evaluation-50 % ; soluble solid content-20 % and Polyphenol content-30 % .

4.5 Polyphenolic content- HPLC

Sample readying

Each sample prepared as 4.1, will be brewed in a cylinder utilizing 125ml ( de-ionised ) H2O at 100A°C. Aliquots as per the HPLC conditions will be consumed from this brew.

HPLC conditions

The polyphenols will be analysed utilizing a Shimadzu LC-10 AD HPLC system fitted with a steinless steel column, length 25cm and diameter 4.6mm at ambient temperature. The injected volume will be 20Aµl. The nomadic stage will be acetonitrile: methyl alcohol ( 75:25, vol/vol ) with a flow rate of 1ml/min at a run clip of 5 min. The polyphenols will be determined utilizing a Shimadzu SPD-6AV UV-Vis sensor with wavelength of 294 nanometers. The peak country will be measured utilizing the Shimadzu C R5A recording equipment.

5. Work program



Research Subject


Formulate Research inquiry


On traveling hunt and aggregation of literature


Formulate purposes and nonsubjective


Write up proposal for undertaking


Prepare and present undertaking proposal

March 4th

Develop/organise method and stuff for experiment

March -Apr

Execute experiment and correlative consequences


Write up undertaking thesis


Present undertaking and findings