Sri Lanka J. Tea Sci. Vlume 76, Part (1/2) Quality characteristics f Black Tea Prcessed by Orthdx Rtryane Type f Manufacture at Different Degrees f Wither 1 2 1 D C J Suduwellage, W S Btheju and D C Abeysinghe C Department f Plantatin Management, Faculty f Agriculture and Plantatin Management, Wayamba University f Sri Lanka, Makandura, Gnawilla, Sri Lanka, 2 Prcess Technlgy Divisin, Tea Research Institute f Sri Lanka, Talawakelle, Sri Lanka) ABSTRACT Quality characteristics f made tea prduced by Orthdx Rtrvane (RV) mix type f tea prcessing at five different degrees f wither (36%, 40%, 43%, 45% and 47%) was studied in labratry scale experiment. Graded tea samples (BOP, BOPF and Dust N. 1) were rganleptically assessed and analyzed fr chemical quality parameters such as theaflavins (TF) and thearubigins (TR). Results were statistically analyzed. Tasters' scre results revealed that the blackness f Dust N. 1 was significantly lw at 47% wither cmpared t 40%. Hwever, there was n significant difference-in blackness f BOP and BOPF grades at different degrees f wither. Overall quality f BOPF and Dust N. 1 was significantly lw when the degree f wither was 36%. Further ungraded teas had significantly lw TF cntent and significantly high TF:TR when the degree f wither reduced frm 40% t 36%. This cncluded that very lw degree f wither was nt suitable t prduce Orthdx RV mix type f tea manufacture. Based n the abve results frm labratry scale experiment, three different degrees f wither (40%, 43% and 45%) were selected fr the cmmercial scale experiment with Orthdx Rtrvane (RV) mix type f rlling prcess. Results f the experiment revealed that BOPF and Dust N. 1 had significantly higher blackness at 40% wither cmpared t 45%. Hwever, there was n significant difference in blackness f bth BOPF and Dust N. 1 at 40% and 43% while blackness f BOP was nt significantly affected by three degrees f wither. This paper was presented at the 10 Agricultural Research Sympsium in Wayamba University f Sri Lanak, n August 12 th -13 rd, 2010. 22
Overall quality f BOP was significantly higher at 40% and 43% degrees f wither than at 45%. Hwever, BOPF had significantly higher verall quality at 40% wither. Dust N. 1 did nt shw significant difference in verall quality at three different degrees f wither. Bth BOP and BOPF at 40% and 43% withers fetched higher prices. Hwever, Dust N. 1 btained higher price at 43% degree f wither. Therefre, it can be cncluded that a degree f wither between 40% and 43% wuld be mre beneficial fr Orthdx RV mix type f tea manufacture in the up-cuntry regin. Key wrds: Degree f wither, rthdx rtrvane mix type f manufacture, verall quality, theaflavins, thearubigins INTRODUCTION Tea, Camellia sinensis (L.) O. Kuntze is the mst ppular nn-alchlic and healthy beverage acrss the glbe and an imprtant revenue surce. Tea can be grwn under wide range f agr eclgical regins (AERs) in Sri Lanka, bradly categrized under three grups accrding t the elevatin f cultivatin namely Lw, Medium, and High grwn teas. The black tea, which is prduced in Sri Lanka is knwn as 'Ceyln Tea'. Mre than 92% f tea prduced in Sri Lanka is black tea. Three types f black tea prcessing methds viz. Orthdx, Orthdx and Rtrvane (RV) mix type and CTC (Crush, Tear and Curl) are ppular in Sri Lankan tea industry. Orthdx and RV mix type f tea prcessing is the mst ppular methd in Up cuntry Western and Nuwara-Eliya regins and ver 50% f the tea factries in Uva regin are als nw practicing this manufacturing methd. The steps in black tea prcessing can be bradly categrized as withering, rlling, fermentatin, drying and sifting. Withering is the first and mst imprtant unit peratin in black tea manufacture. Quality and the price valuatin f Orthdx Rtrvane mix type f tea prduced in Up cuntry regin are determined by clr and strength f tea liqur, which brews int the tea cup and als the blackness f made tea (Muthugalage, 2008). Tea tasting is the mst cmmn evaluatin methd t judge its price and quality. Chemical cmpnents, which are respnsible fr the quality f black tea, are xidized plyphenls such as theaflavins (TF) and thearubigins (TR), caffeine, amin acids, carbhydrates etc. (Sandersn, 1965). During the rlling peratin, plyphenlxidase and plyphenls are mixed tgether and prduce TF and TR, which directly affect the quality f made tea (Owur, 1987). The TF:TR rati is nrmally used t evaluate the quality f made tea. When the fermentatin perid increases, TF cntent decreases with a crrespnding increase in TR cntent and as a result, TF:TR rati als increases (Rberts and Smith, 1963). 23
Presently tea factries in the Western regin adapt sfter wither t prduce tea with mre blackness by Orthdx and RV mix type f tea prcessing. Previus studies have als shwn that sfter wither (40-43% degree f wither) was mre preferable t prduce gd quality tea using methds f Orthdx r Orthdx and RV mix types prcessing (De Silva and Kirtisinghe, 1966; Thevathasan and Kirtisinghe, 1974). T verify this cnclusin further and t determine mst suitable degree f wither fr the present style f Orthdx and RV mix type f tea prcessing that prduces higher percentage f small grades, a study was cnducted t assess the quality characteristic f tea prduced at different degrees f wither using Orhtdx and RV mix type f tea prcessing. MATERIALS AND METHODS The experiments were cnducted at the Prcess Technlgy Divisin and St. Cmbs tea factry managed by the Tea Research Institute f Sri Lanka (TRISL), Talawakelle, Sri Lanka. Labratry scale experiment Fur different tea cultivars ppular in the Western regin namely TRI 2025, TRI 2023, DT 1 and DN were selected frm the fields in St. Cmbs estate (altitude 1382 m, latitude 6 55' N and lngitude 80 40 E) in a clse prximity accrding t the fllwing rati satisfying cultivar mix in the regin. TRI 2025 : TRI 2023 : DT 1 : DN = 2 : 1 : 2 : 2 Tea leaf was plucked (-4.0 kg) frm each cultivar ensuring ver 65% f gd standard f leaf and t match the abve rati fr each trial and a knwn quantity f leaf sample (50 g) frm the mixed leaves was drawn t determine initial misture cntent f green leaves. The balance was equally divided int five fractins (Fi, F 2, F 3, F 4 and F 5 ). Each fractin was then withered t the fllwing degrees f wither by using Envirnmentally Cntrlled Chamber (ECM). In this 0 chamber, predetermined temperature (23 C) and RH (75%) were set thrughut withering perid. Degree f wither defined as the rati f made tea t withered leaf (MT/WL) n percentage basis was F,=36% F 2 = 40% F 3 = 43% F 4 = 45% F 5 = 47% Misture cntent (w. b.) f tea leaves during withering prcess was tested by drawing a sample (50 g) frm each fractin and using the micrwave ven methd (Mhamed et ah, 2003).Each withered leaf sample was separately rlled using miniature Orthdx and RV rllers. Macerated tea particles were sieved using 2.5 mm hand sieve t extract dhls. The dhl samples were fermented using ECM which was pre-adjusted t 25 C and 95% RH fr all dhl samples. Fermentatin perid varied frm 2 l A- 2 3 A hr. Once the fermentatin was 24
prgressed t its ptimum level (cppery brwn clr particles having typical smell), fermented dhl samples were fired using miniature fluidized bed drier 0 (FBD). The inlet and exhaust temperatures f the drier were maintained at 125 C 0 and 98 C respectively. The extractin f fiber frm each fired tea sample was dne using a miniature fiber extracting machine. Made tea samples were then graded using hand sieves with n. 12,16 and 32 meshes. The graded tea samples were packed separately in triple laminated aluminium fil bags prir t sending fr tea tasters' evaluatin. Samples were als analyzed fr chemical quality parameters. This experiment was repeated five times and results were analyzed. Cmmercial scale experiment Three cmmercial scale withering trughs (58'x 6'), lcated clsely at the factry were selected and 800 kg f green leaves was laded in each trugh. The leaf standard was determined using leaf cunting methd (Ann, 1998). Leaves in each trugh were withered by maintaining dry bulb temperature in the range f 22-25 C and the hygrmetric difference in the range f 6-9 F and the degree f wither f leaves was brught t the fllwing levels. T,= 40% T 2 = 43% T 3 = 45% When the leaves in each trugh reached the pre-determined misture cntent as per the degree f wither (leaf misture was intermittently tested using micrwave ven methd), the withered leaf was weighed and charged t 46.5" Orthdx rller fr pre-cnditining rlling. Rlled leaf was cnveyed t 15" Rtrvane (RV) rller setting 'Iris' end plates clsing 30% aperture and then passed thrugh twin 8" RV rllers with full pressure clsing the aperture abut 90%. The macerated leaves were passed again thrugh twin 8" RV rllers having 'Cne arrangement' and cnveyed via ball breaker t the rll breaker machine which cnsisted f n. 8 meshes. Extracted 1 st dhl was weighed and spread n stainless steel table fr fermentatin. The bulk was further macerated using 8" RV rller with full pressure t extract the 2 nd dhl which was als weighed and spread fr fermentatin. Likewise, prcess was cntinued until the quantity f bulk was abut 10% f the ttal quantity f withered leaf charged fr ne batch. Hygrmetric difference in the rlling rm was maintained t be less than 3 F. After the crrect fermentatin perid (2Vi-2% h) which was judged by smelling the dhl and bserving dhl clr, dhls were immediately fed t cmmercial scale FBD having inlet temperature, 122-127 C and the utlet temperature 93-98 C. The dried teas were separately graded and three main grades viz. BOP, BOPF and Dust N. 1 were cllected and packed in triple laminated aluminum fil bags 25
until the samples were analyzed fr chemical quality parameters and als sent fr tasters' evaluatin. This experiment was repeated three times. Organleptic assessment (Tasters' evaluatin) The blackness and the liquring prperties f each graded tea sample were evaluated by tw independent prfessinal tea tasters in Clmb. In additin t that, tasting panel at the Prcess Technlgy Divisin als evaluated the samples. A mdified versin f evaluatin frm (Annexure 1) was prepared fr this study and it was used t evaluate the different characteristics f tea. Analysis f chemical quality parameters Rberts and Smith (1963) methd was used t analyze the chemical quality parameters f tea samples. In labratry scale experiment, ungraded tea samples were used while samples f BOP, BOPF and Dust N. 1 grades were separately analyzed in the cmmercial scale experiment. Statistical analysis All data were statistically analyzed using ANOVA fllwed by Duncan's Multiple Range Test at P < 0.05 using SAS 8.3 sftware (SAS Inc., Cary, USA). RESULTS AND DISCUSSION The blackness f graded tea, infused leaf clr, liqur clr, strength and quality f liqur and verall quality estimated based n tasters' reprts f three different main grades (BOP, BOPF and Dust N. 1) prcessed at five different degrees f wither in labratry scale experiment are given in Table 1. Overall quality was calculated based n tasters' scre assigned fr each characteristic such as blackness, liqur clur, liqur strength and liqur quality and infused leaf clur. When the degree f wither was 40%, the blackness f Dust N. 1 btained significantly higher scre cmpared t 47% degree f wither (Table 1). Hwever, n significant difference was bserved fr BOP and BOPF at five different degrees f wither studied. The Dust N. 1 btained the lwest scre, when the degree f wither was 47%. Past research wrk n Orthdx rlling has als shwn that liqur quality is imprved due t lwer temperatures attained by the rlled leaf mass f sfter withered leaf than that f harder withered leaf (Thevathasan and Kirtisinghe, 1974). Results btained frm the labratry scale experiment shwed that bth BOPF and Dust N. 1 grades had significantly higher verall quality at 40% degree f wither than at 36% wither (Table 1). In the present market scenari, these tw grades fetch higher prices. 26
Table 1. The blackness, infused leaf clr, clr, strength and quality f liqur and verall quality f graded tea prcessed at five different degrees f wither Degree f wither (%) Characteristics Grade 36 40 43 45 47 Level f significance (p=0.05) Blackness f BOP 3.66a 3.92a 3.72a 3.85a 3.68a ns Graded tea BOPF 3.73a 4.43a 3.67a 4.02a 3.73a ns Dust 1 3.72aft 4.33a 3.55a6 3.95a6 3.426 0.1768 Infused leaf BOP 3.80a 3.60a 3.50a 3.40a 3.30a ns Clr BOPF 3.60a 3.60a 3.50a 3.50a 3.30a ns Dust 1 3.80a 3.70a 3.60a 3.50a 3.50a ns Liqur clr BOP 3.00ft 3.20a6 3.30a6 3.40a6 3.60a 0.1971 BOPF 3.10a 3.40a 3.50a 3.60a 3.50a ns Dust 1 3.10a 3.20a 3.50a 3.30a 3.40a ns Liqur strength BOP 3.30a 3.60a 3.50a 3.60a 3.80a ns BOPF 3.506 3.80a6 4.10a6 4:20a 4.10a6 0.1599 Dust 1 3.90a 4.50a 4.30a 4.50a 4.60a ns Liqur quality BOP 4.50a 5.10a 4.80a 5.10a 4.70a ns BOPF 4.40a 5.00a 4.70a 4.90a 5.10a ns Dust 1 4.606 5.40a 4.90a6 5.00a6 4.80a6 0.1693 Overall quality BOP 18.07a 19.52a 18.98a 19.45a 19.22a ns BOPF 18.476 20.37a 19.63a6 20.32a 19.87a6 0.0492 Dust 1 19.05c 21.03a 20.22a6 20.55a6 19.856c 0.0120 Means with a same letter within the clumn are nt significantly different at PO.05 The TF cntent and TF:TR rati f made tea estimated using the data fr chemical quality parameters at five different degrees f wither in the labratry scale experiment are given in Figure 1. Significantly lwer TF cntent and higher TF:TR rati was fund in the made tea prcessed at 36% degree f wither than at 40% t 45% degrees f wither (Figure 1). When the degree f wither was 40% and abve, n significant variatin f TF and TF:TR rati were bserved. The highest TF cntent and the lwest TF:TR rati were btained when the degree f wither was 40%. 27
Labratry scale experimental data revealed that when degree f wither was reduced belw 40%, the verall quality including blackness f BOPF and Dust N. 1 were significantly reduced (Table 1). This cnclusin was further elabrated by analyzing the data n chemical quality parameters in which the TF cntent was significantly lwer and TF:TR rati was significantly higher in teas prcessed frm very sfter withered leaves (36%). On the ther hand, when the degree f wither increased frm 40% t 47% the blackness f Dust N. 1 significantly reduced. Increasing the wither frm sfter (40%) t harder (47%) at the present style f Orthdx Rtrvane mix tea manufacture which is intended t prduce mre Dust N. 1, has a negative impact fr its quality. (a) 36 40 43 45 47 Degree f wither (%) (b) Figure 1. (a) TF cntent and (b) TF:TR rati f made tea prcessed at five different degrees f wither in labratry scale experiment 28
The cmmercial scale experiment was carried ut with selected three different degrees f wither (40%, 43% and 45%). Blackness and verall quality based n tasters' scre and chemical quality parameters f BOP, BOPF and Dust N. 1 samples manufactured at three different degrees f wither under cmmercial (factry) scale experiments are presented in Table 2. There was n significant difference in blackness f BOP grade amng three different degrees f withers. Hwever, when the degree f wither was 40%, a significantly high blackness was bserved with BOPF and Dust N. 1 as against 45%. Hwever, n significant difference was bserved with same grades between 40% and 43% degrees f wither. Table 2. The blackness f graded tea prcessed at three different degrees f wither in cmmercial scale experiment Degree f wither (%) Tea grade BOP BOPF Dust N. 1 40 4.50a 4.61a 4.72a 43 3.66a 3.84aA 4. Hat 45 3.50a 3.676 3.66b Means with a same letter within the clumn are nt significantly different at P<0.05 Liqur clur and strength f BOP and Dust N. 1 prduced at three different degrees f wither had n significant difference (Figure 2). Fr BOPF, a significantly higher clur was bserved at 43% cmpared t 40% wither, whereas a significantly higher strength was btained at 40% cmpared t ther tw degrees f wither. De Silva and Kirtisinghe (1966) has shwn a significantly higher liqur clur f BOP with sfter (40.7%) and medium wither (43.4%) ver harder wither (46.7%). Hwever, liqur strength f BOP and BOPF was nt significantly affected by three different degrees f wither. The rlling prcess which prduces higher percentage f small grades adapted presently in Orthdx Rtrvane mix tea prcessing is mre vigrus than in the past. Therefre, BOP grade prduced in 1970s'-1980s' may have mre clur and strength. When cmparing verall quality f BOP at three different degrees f wither, a significantly lwer value was btained at 45% wither and there was n significant difference between 40% and 43% wither (Figure 3). The BOPF prduced at 40% wither had given significantly higher verall quality than ther tw degrees f wither. Hwever, verall quality f Dust N. 1 was nt affected by three different degrees f wither (40%-45%) studied. 29
»BOP BOPF Dust 1 : c C 43 45 Degree f wither (%) Figure 2. Tea liqur clur (C) and strength (S) f graded tea manufactured at five different degrees f wither in cmmercial scale experiment (means with a same letter are nt significantly different at P<0.05) 22 -i 3- d fn BOP BOPF Dustl H 40 43 Degree f wither (%) 45 Figure 3. The verall quality f graded tea manufactured at five different degrees f wither in cmmercial scale experiment (means with a same letter are nt significantly different at P<0.05) N significant difference was bserved fr TF cntent and TF:TR rati fr BOP (Table 3). Bth BOPF and Dust N. 1 cntained a significantly higher TF at 40% wither than at 45% wither. TF:TR rati was significantly lwer fr Dust N. 30
1 at 40% wither than at 45% wither. When TF cntent was high, TF:TR rati reaches clser t 1:10 that results in higher quality (Rbert and Smith, 1963). Table 3. TF cntent and TF:TR rati f graded tea prcessed at three different degrees f wither under cmmercial scale experiment Degree f Tea grade wither (%) BOP BOPF Dust N. 1 TF TF:TR TF TF:TR TF TF:TR 40 4.50a 1:12.43a 4.61a 1:14.43a 4.72a 1:14.69ft 43 3.66a 1:14.83a 3.84aft 1:15.15a 4.11aft l:16.66aft 45 3.50a 1:15.72a 3.67ft 1:15.52a 3.66ft 1:18.38a Means with a same letter within the clumn are nt significantly different at PO.05 Table 4 presents the price f BOP, BOPF and Dust N. 1. N significant difference was bserved fr all three main grades prduced at three different degrees f wither studied. Nevertheless, BOP, BOPF and Dust N. 1 grades at 40% degree f wither fetched cmparatively higher prices than ther tw degrees f wither. Table 4. Mean price f BOP, BOPF and Dust N. 1 prcessed at three different degrees f wither in cmmercial scale experiment Optrrf»f» nf wither (9/n\ Mean price (Rs.) BOP BOPF Dust N. 1 40 326.07 326.67 398.33 43 315.00 320.00 385.00 45 307.50 317.50 376.67 CONCLUSIONS Results f the labratry scale experiment cncluded that the verall quality f tea prcessed at 36% and 47% degrees f wither is prer than that f tea prcessed at 40^45% degrees f wither. Further investigatin by cmmercial scale experiment revealed that the ptimum degree f wither fr prductin f gd quality tea by Orthdx Rtrvane mix type f tea prcessing is 40-43%. ACKNOWLEDGEMENTS The authrs wish t express their gratitude t Mr. Yshan Fernand, Frbes & Walker Tea Brkers (Pvt) Ltd. and Mr. Anil Ck, Asia Siyaka Cmmdities (Pvt) Ltd fr tasting the tea samples f this research prject. The authrs wuld als like t acknwledge Mr. Mahasen Ranathunga, Senir Research Officer, Plant Breeding Divisin in TRISL, fr the supprt given t analyze the data. 31
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