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TP CH PHT TRIN KH&CN, TP 11, S 08 - 2008

Trang 51

NH GI CC TNH CHT CM QUAN CA C PH BUN M THUTV SO SNH VI TNH CHT CM QUAN CA C PH MT S KHU

VC A L KHC

Li Quc t(1), Ch Tha(2), Tng Th T Loan(1), L Minh Tm(1)Nguyn Hong Dng(1)

(1) Trng i hc Bch Khoa, HQG-HCM(2)Vin Nghin cu Nng Lm nghip Ty Nguyn

(Bi nhn ngy 10 thng 01 nm 2008, hon chnh sa cha ngy 12 thng 05 nm 2008)

TM TT: Trong nghin cu ny, chng ti tin hnh nh gi tnh cht cm quan cac ph Bun M Thut, cng nhso snh tnh cht cm quan ca c ph Bun M Thut vic ph mt s khu vc a l khc. Kt qu cho thy, tnh cht cm quan c ph ph thucvo v tra l ca c ph. Qua kt qu phn tch, cng nhn thy rng mt s mu c phmang thng hiu Bun M Thut c nhng tnh cht cm quan tt nh mi chocolate, migia v, mi caramel, mi g, mt sc cng cc chtiu cm quan thp, mt sth li cc trng mi thi, men thi, mi ho cht, v cht. Khi so snh c ph robusta v c pharabica akLak, c ph arabica c nhiu tnh cht cm quan tt cng nhcng cao.

1. T VN

Hin nay, sn lng c ph xut khu ca Vit Nam xp th hai trn th gii, sau Braxin.Theo thng k ca t chc cc nc xut khu c ph trn th gii (ICO), trong nin v 2006 2007, sn lng c ph nhn xut khu ca Vit Nam l 15,5 triu bao (60kg/bao), trong ,ch yu l c ph robusta. Thng 12/2005, B Khoa hc Cng ngh v Cc shu tr tucp chng cha l C ph Bun M Thut cho c ph akLak. S kin ny nh du bcpht trin vt bc ca ngnh c ph Vit Nam. Tuy nhin, c ph nhn robusta Vit Nam hinnay c cht lng khng n nh, nn gi thng thp hn so vi gi c ph ca cc nc khctrn th gii. Theo thng k ca ICO, khong 80% lng c ph b thi loi ra trn th trnggiao dch th gii c ngun gc t Vit Nam (bo co thng k hng nm ca ICO).

Phn tch m tnh lng (QDA) l mt k thut phn tch hu hiu trong vic nh gi,m t cc c tnh cm quan ca thc phm. Cc thnh vin trong hi ng nh gi cm quans xy dng v pht trin danh mc cc thut ng m t cc c tnh cm quan ca snphm; bc tip theo, h sc hun luyn nh lng cc tnh cht ca sn phm theodanh mc ca cc thut ng c thng nht trc [1, 2, 3].

Vit Nam, cc nghin cu trc y ch ch nh gi cc tnh cht cm quan ca snphm c ph bt thnh phm [3, 4], trong khi cc tnh cht cm quan ca c ph nhn chac quan tm nghin cu mt cch y . Trong nghin cu ny, chng ti tin hnh phntch cc c tnh cm quan ca c ph robusta c chng cha l c ph Bun M Thut v sosnh vi c tnh cm quan ca c ph robusta c trng nhng khu vc a l khc VitNam v trn th gii

2. NGUYN LIU V PHNG PHP NGHIN CU

C ph nhn robusta: do Vin Khoa hc K thut Nng lm nghi p Ty Nguyn

(EKMAT) cung cp. Ton b quy trnh ly mu c thc hin sao cho m bo tnh i din.Tng s mu c ph nhn robusta akLakc thu nhn ti cc a im khc nhau (v tra l cng nh quy trnh canh tc, thu hoch v schm bo theo ng yu cu trong quy


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Science & Technology Development, Vol 11, No.08 - 2008

Trang 52

nh ca c ph Bun M Thut) 10 mu. Cc mu ny c m ho l DLRo1, DLRo2,DLRo3, DLRo4, DLRo5, DLRo6, DLRo7, DLRo8, DLRo9, DLRo10. Cc mu c ph cckhu vc a l khc l ng Nai (DNRo), Lm ng (LDRo) v Gia Lai (GLRo). Trongnghin cu ny, chng ti s dng mt loi c ph nhn robusta Indonesia (IndoRo) do Tpon Neumann Group (c) cung cp.

- C ph Arabica: do Vin Khoa hc K thut Nng lm nghip Ty Nguyn (EKMAT)cung cp. Cc mu c thu nhn ti cc khu vc khc nhau ca tnh akLak v ton b quytrnh ly mu c thc hin sao cho m bo tnh i din. Tng s mu thu nhn ti cc khuvc a l khc nhau ca tnh akLak l 5 mu, c m ho l DLAr1, DLAr2, DLAr3,DLAr4, DLAr5.

- Ho cht: Cc cht chun mi, vc cung cp bi hng Merck (c), c s dng hun luyn hi ng.

- Chun b mu c ph: Tt c cc mu c ph u c rang bng thit b rang thng quayvi iu kin: 210oC trong thi gian 10 pht (ng vi mc rang nht).

- Hi ng nh gi cm quan: gm c 7 thnh vin c la chn trn csnh gi khnng nhn bit mi, v. Cc thnh vin c hun luyn kh nng nhn bit mi, hng v vtrn ho cht tinh khit v trn mu c ph. Ton b cc th nghim c nh gi ti phngth nghim cm quan theo tiu chun ISO 8589 m bo yu cu v ting n, nhit , nhsng v kh nng tp trung ca tng thnh vin trong qu trnh th nghim.

- Qu trnh hun luyn hi ng: Cc thnh vin trong hi ng c hun luyn nh gicc ch tiu cm quan ca c ph nh sau theo trnh t nh sau:

+ Hun luyn kh nng nhn bit v+ Hun luyn kh nng nhn bit mi.+ Hun luyn kh nng s dng thang im nh gi cc ch tiu.

- Phng php x l s liu:+ Phng php phn tch phng sai (ANOVA) [5].+ Phng php phn tch thnh phn chnh (PCA) [5].+ S dng phn mm R phin bn 2.5.1 [6]

- Phng php rt gn cc thut ngnh gi cm quan:Bc 1: loi b nhng thut ng c im trung bnh hnh hc xp x bng 0.

im trung bnh hnh hc ca tng thut ng cho bi c nhm i vi tng sn phm

c tnh theo cng thc : DspTspTBsp .= Trong :- TBsp: im trung bnh hnh hc ca tng thut ng nghin cu-Tsp: Tn s s dng thut ng tng i ca c nhm i vi tng sn phm

maxT

TTsp =

(T: tn s s dng tng thut ng ca c nhm i vi tng sn phm, Tmax:tn s ti a ca tng thut ngi vi tng sn phm)

Dsp: im tng i ca tng thut ng cho bi nhm, maxD

DDsp =

(D: tng im cho

bi nhm i vi tng ch tiu tnh trn tng sn phm, Dmax: tng im ti a cho bi nhmi vi tng ch tiu tnh trn tng sn phm)


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Trang 53

Bc 2: s dng phng php phn tch thnh phn chnh PCA (Principal ComponentsAnalysis) loi b nhng thut ng t ng gp vo vic phn bit cc sn phm.

Cc nguyn tc chnh thc hin s loi b l nh sau:- Xo b cc thut ng khng miu t tt khng gian cng nh s khc nhau gia cc sn

phm. Trong vic phn tch, iu ny c gii thch bng s t ng gp ca cc thut ngm t vo vic cu thnh trc chnh. Cn kim tra sng gp ca cc thut ng m t trn

cc trc khng bi mt thut ng m tc lp m c th cu thnh mt trc ring bit c qun tnh thp vi cc m t khc.- Xo b thut ng cng loi bi chng xut hin gn nhau trong hnh nh phn tch PCA.

Vic ny c thc hon thnh bng cch phn nhm cc thut ng m t.- Thay th 2 thut ng m ti lp (tng quan nghch) hoc nhng thut ng m ti

lp so vi trung tm trng lng trong khng gian m t.

3. KT QU V BN LUN

3.1. Thut ngnh gi cm quan cho c ph

Trn cscc kt qu nghin cu trc [1, 2, 3, 6] cng nh kt qunh gi sb cahi ng, c 24 thut ngc ngh m t tnh cht cm quan ca c ph (bng 1).

Bng 1.Danh mc sb cc thut ngc s dng nh gi tnh cht cm quan ca cph

STT Nhm thut ng S thut ng Tn thut ng1 Nhm thut ng v

mi

18 Mi ng vt, mi tro, mi chy (khi),mi ho cht (thuc ty), mi chocolate,mi caramel, mi ng cc (bnh mnng), mi t mc, mi thi, mi menthi, mi tri cy, mi c, mi hoa c, micao su, mi gia v, mi ru, mi thuc l,mi g

2 Nhm thut ng vv

4 V chua do acid, v chua do ln men, vng, v cht

3 Nhm cc thut ngkhc

2 Th cht nc chit, cm gic se

rt gn 24 thut ng trn, chng ti tin hnh nh gi 24 ch tiu cm quan ca 4 muc ph. Trn cskt qu thu c, 24 thut ng trn c rt gn li theo trnh t trnhby trong phn 2. Kt qu thu c bao gm 14 thut ng rt gn nh sau:

Bng 2.Danh mc cc thut ng rt gn c s dng nh gi tnh cht cm quan cac ph

STT Nhm thut ng S thut ng Tn thut ng1 Nhm thut ng v

mi

11 Mi chy kht, mi ho cht, michocolate, mi caramel, mi t mc, mithi, mi men thi, mi c, mi hoa c,mi gia v, mi g

2 Nhm thut ng v v 3 V chua do ln men, vng, v cht


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kim tra mc chnh xc ca vic s dng danh mc cc thut ng rt gn so vidanh mc sb ban u, chng ti tin hnh nh gi cc tnh cht cm quan ca 4 mu cph da trn hai danh mc thut ng. Sau , chng ti s dng phng php phn tchthnh phn chnh (PCA) phn tch kt qunh gi. Kt qu chng ti thu c nh trnhnh 1. Theo , khi ta rt gn t 24 thut ng cn 14 thut ng, s phn b ca 4 mu c phni trn trong mt phng tng quan l ging nhau. Do , ta c th s dng 14 thut ngrt gn nh gi tnh cht cm quan ca c ph.

Nh vy, trong cc th nghim tip theo, tnh cht cm quan c ph sc nh gi datrn 14 thut ng trn.

3.2. nh gi kh nng phn bit cc ch tiu

Theo kt qu trn bng 3 th cc ch tiu mi g, mi ho cht, mi caramel, mi t mc,mi chy kht, mi chocolate, mi gia v , v chua, vng, v cht c phn bit r gia ccsn phm vi nhau (gi tr P 0.05). iu ny cng chng t rng cc ch tiu ny khngcho php phn bit tt cc sn phm vi nhau ng vi hi ng ny.

Bng 3.Kh nng phn bit cc ch tiu

Ch tiu Sn phmMi g 1.529e-34

Mi ho cht 1.058-30Mi caramel 1.424e-30

V chua 4.464e-26

Mi t mc 2.363e-25Mi chy kht 1.459e-24

Mi chocolate 3.322e-22

-4 -2 0 2 4

-4

-2

0

2

4

I n d iv i d u a l s f a c to r m a p ( P C A )

D imens ion 1 (45 .5% )

Dimension2(34.5

5%)

dak lak

longkhanh

c a t i mo r

indonex ia

-4 -2 0 2 4

-3

-2

-1

0

1

2

Individuals factor map (PCA)

Dimension 1 (47.86%)

Dimension2(26.4

1%)

daklak

longkhanh

catimor

indonexia

Hnh 1: So snh kt qunh gi cc tnh cht cm quan ca 4 mu c ph khi s dng danh mc cc thutng sb (A) v danh mc thut ng rt gn (B)

A B

Thnh phn chnh th 1

Thn

hphnchnhth

2

Thnh phn chnh th 1

Thnh

phnchnhth2


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Trang 55

Vng 8.297e-22V cht 1.692e-16

Mi gia v 0.02044Mi thi 0.1032

Mi hoa c 0.3905Mi men thi 0.5639

Mi c 0.90963.3. nh gi mc ng thun ca hi ng

Mt trong nhng vn quan trng trong vic nh gi cm quan da trn hi ngchuyn gia l tnh ng thun ca hi ng. y l csnh gi kt qu ca qu trnh hunluyn (training) hi ng cng nhnh gi mc tin cy kt qu thu c. Kt qu trnhnh 2 cho thy mc dao ng ca kt qu l khng cao. Cc ellipse u c kch thc ca2 trc tng i nh (tr hai mu DLRo4 v DLRo10). Nh vy, qua kt qu phn tch, mc tp trung ca kt qunh gi cm quan l c th chp nhn c.

Hnh 2. Mc tp trung ca kt qunh gi ca hi ng

3.4. nh gi c tnh cm quan ca cc sn phm c ph robusta Bun MThutv mt s khu vc a l khc.

Theo kt qu trn hnh 3 (vng trn tng quan), c th phn cc ch tiu nh gi c phthnh nm nhm ch tiu, c th nh sau: nhm ch tiu 1 bao gm cc ch tiu mi ho cht,v cht, v chua; nhm ch tiu 2 bao gm cc ch tiu mi chy kht, mi gia v, mi caramel;nhm ch tiu 3 bao gm cc ch tiu mi g, mi chocolate; nhm ch tiu 4 bao gm cc ch

tiu mi hoa c, mi t mc, vng v nhm ch tiu 5 bao gm cc ch tiu mi men thi,mi thi.

-5 0 5 10

-2

0

2

4

6

Dim 1 (30.84%)

Dim

2(26.1

3%)

Con f idenc e el lipses for the mean points

DLRo1

DLRo10DLRo2

DLRo3

DLRo4DLRo5

DLRo6

DLRo7

DLRo8

DLRo9DNRo

GLRo

IndoRo

LDRo

T

hnhphnchnh

th

2

Thnh phn chnh th 1


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Trang 56

Theo kt qu trn mt phng sn phm, cc mu c ph akLak c thc phn thnh3 nhm. Nhm c ph nhn 1 bao gm cc mu DLRo1, DLRo4, DLRo5; nhm c ph nhn 2bao gm cc mu DLRo2, DLRo3, DLRo6, DLRo7, DLRo8; nhm c ph nhn 3 bao gmcc mu DLRo9, DLRo10. S phn nhm ny c th l do iu kin a l ca cc mu c ph( cao, th nhng) hoc iu kin kh hu (lng ma, iu kin nhit ). Cc yu t vak trn nh hng n thnh phn ho hc ca c ph nhn, c bit l cc cu t to hng vto v.

Theo kt qu trn hnh 3 v hnh 4, nhm c ph nhn 1 c c trng bi cc tnh chtcm quan nh c v chua, v cht, mi men, mi men thi, mi ho cht. Nhm c ph nhn 2c c trng bi cc tnh cht cm quan nh mi men, mi men thi, mi hoa c, vng.

Tuy nhin, cng cc tnh cht cm quan ca nhm ny tng i thp (v tr phn b gntm). Nhm c ph nhn 3 c c trng bi cc tnh cht cm quan tt nh mi chocolate,mi gia v, mi caramel, mi g, mi chy kht (cc mu DLRo9, DLRo10). Theo ngun gcca mu, y l cc mu c xut x t khu vc a l c c ph ni ting v cht lng hngvakLak (Bun H).

Cc mu c ph thuc khu vc a l khc cng c nhng c trng khc so vi c ph akLak. C ph robusta Gia Lai c c trng bi mi caramel, mi chocolate, mi chykht, mi gia v, vi cng cao hn so vi nhm 3 ca c ph akLak. C ph robustaIndonesia c cc c trng nh mi hoa c, mi t mc, mi g, vng vi cng caohn nhiu vi nhm 2 ca c ph akLak. C ph robusta ng Nai c cc c trng cmquan ging nh nhm 2 c ph akLak (v tr phn b ca c ph robusta ng Nai nm trongnhm 2 ca c ph akLak). Cn mu c ph robusta ca Lm ng (LDRo) th c cc tnhcht cm quan ging nh tnh cht cm quan ca nhm 1 c ph akLak.

Nh vy, qua kt qu phn tch trn, c th nhn xt rng, c ph robusta mang thnghiu Bun M Thut c tnh cht cm quan ph thuc vo khu vc a l khc nhau, v qua

-1.5 -1.0 -0.5 0.0 0.5 1.0

-1.0

-0.5

0.0

0.5

1.0

Dimension 1 ( 30.84 %)

Dimension2

(26.1

3%)

Variability of the variables

muichaykhet

muihoachat

muichocolatemuicaramel

muidatmoc

muihoacomuithoi

muimenthoimuigiavi

muigo

vidangvichua

vichat

-1.0 -0.5 0.0 0.5 1.0

-1.0

-0.5

0.0

0

.5

1.0

Variables factor map (PCA)


Dimension2(26.1

3%)

muichayk

muihoachat

muichocolate

muicaramel

muidatmoc

muihoaco

muithoi

muimenthoi

muigiavi

muigo

vidang

vichua

vichat

Hnh 3: S tng quan ca cc ch tiu cm quan

Thnhphnchnhth

2

Thnh phn chnh th 1

Thnhphnchnhth

2

Thnh phn chnh th 1


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kt qu nghin cu ny, vn cha tm thy nhng tnh cht cm quan c trng, i din choc ph mang thng hiu Bun M Thut.

3.5 So snh tnh cht cm quan ca c ph robusta vi c ph arabica

Trong nghin cu ny, chng ti cng tin hnh so snh tnh cht cm quan ca c phrobusta vi tnh cht cm quan ca c ph arabica. Kt quc th hin trn hnh 5 v hnh 6.Theo , ta c th chia cc tnh cht cm quan kho st ra thnh 5 nhm tng t nhphn 3.4. Trong 5 mu c ph arabica kho st, c th chia ra thnh 2 nhm. Nhm 1 bao

gm cc mu DLAr1, DLAr3, DLAr5 (c trng bi cc tnh cht mi chocolate, mi chykht, mi caramel, mi gia v); nhm 2 bao gm cc mu DLAr2, DLAr4 (c trng bi cctnh cht mi hoa c, mi t mc, mi g, vng). Qua kt qu trn, c th nhn thy rngtnh cht cm quan ca c ph arabica cng ph thuc vo v tr a l ca khu vc canh tc.D cc mu c ph arabica c thu nhn ti akLak, nhng li cc khu vc khc nhau vv tr a l, nn tnh cht cm quan ca chng khc nhau (v tr phn b trn mt phng kh xanhau).

Nh vy, qua kt quphn 3.4 v 3.5, c th kt lun rng v tr a l c nh hng rtnhiu n tnh cm quan ca c ph. Nhn xt ny cng ph hp vi kt qu nghin cu camt s tc gi khc. Cc tc gi cho rng, v tr a l c nh hng rt nhiu n thnhphn ho hc, c bit l cc thnh phn c nh hng nhiu n s to thnh hng v trongqu trnh ch bin nh acid amin, cc glucid th p phn t (glucose, fructose), trigonelline,chlorogenic acid [7, 8].

Chng ta cng c th nhn thy rng, so vi c ph robusta akLak, c ph arabica cnhiu tnh cht cm quan c xem l ph hp hn so vi th hiu ca ngi s dng nh mi

Hnh 4: S phn b ca cc mu c ph trong mt phng tng quan 1 -2

Thnhphnchnhth

2

Thnh phn chnh th1


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Trang 58

chocalate, mi g, mi hoa c, vng. y l l do ti sao c ph arabica c a chungnhiu hn so vi c ph robusta. iu ny c thc gii thch l do trong c ph nhnarabica, hm lng cc cu t tin to hng a dng hn (v c s lng v cht lng) sovi c ph nhn robusta. Do , sau qu trnh ch bin, cc cu t hng c hnh thnhnhiu hn, to ra nhiu tnh cht v mi v tt [7, 8].

4. KT LUN

Qua kt qu nghin cu, c th rt ra mt s kt lun nh sau:- Tnh cht cm quan ca c ph ph thuc vo v tr a l ca vng canh tc.- C ph robusta mang thng hiu Bun M Thut c tnh cht cm quan a dng, ph

thuc vo tng khu vc a l c th.- So vi c ph robusta, c ph arabica akLak c mt s tnh cht cm quan tt vi

cng cao.

-6 -4 -2 0 2 4 6

-2

0

2

4

6

Mat phang san pham


Dimension2(24.5

3%)

Individuals factor map (PCA)

DLRo1

DLRo10DLRo2

DLRo3

DLRo4

DLRo5

DLRo6DLRo7

DLRo8

DLRo9

DNRo

GLRo

IndoRo

LDRo

DLAr1

DLAr3

DLAr4

DLAr5

DLAr6

-1.0 -0.5 0.0 0.5 1.0

-1.0

-0.5

0.0

0.5

1.0

Vong trong tuong quan


Dimension2(24.5

3%)

Variables factor map (PCA)

muichayk

muihoachat

muichocolate

muicaramel

muidatmoc

muihoaco

muithoi

muimenthoi muigiavi

muigo

vidang

vichua

vichat

Hnh 5: S tng quan ca cc ch tiu cmquan theo kt qunh gi ca hi ng

chuyn gia

X l trc inHnh 6: S phn b ca cc mu c ph trong mt

phng tng 1 -2 khi so snh gia c ph arabica vic ph robusta

hnh

phnchnh

th2

Thnh phn chnh th 1

hnh

phnchnh

th2

Thnh phn chnh th 1


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STUDY ON THE SENSORY PROPERTIES OF COFFEE IN BUON METHUOT AND COMPARING WITH COFFEE FROM OTHER REGIONS

Lai Quoc Dat(1), Che Thi Da(2),Tong Thi To Loan(1),Le Minh Tam(1)Nguyen Hoang Dung(1)

(1) Unversity of Technology, VNU-HCM

(2)Western Highland Agro Science Technology Research Institute

ABSTRACT: This study focused on sensory properties of Buon Me Thuot coffee and

comparing it with coffee from other regions. As those results, sensory properties of coffee

depended closely on region where it was cultivated. Some samples of Buon Me Thuot coffeehad good sensory properties such as the smell of chocolate, the spices of additive, the smell of

wood, the smell of caramel. Some of them had bad sensory properties such as stink, the smell

of chemical, astringency. Some of them had the low intensity of the sensory properties. In

comparison with robusta coffee, arabica coffee had better sensory properties with the higherintensity.

TI LIU THAM KHO

[1]. Feria Morale Alejandro M., Examining the case of green coffee to illustrate thelimitations of grading systems/expert tasters in sensory evaluation for quality control,

Food Quality and Preference, 12:355-367

[2]. Nguyen Thanh Tung, Nguyen Hoang Dung, Contribution of determine the coffeeprofile and customer preference of the Vietnamese and European coffees, Proceeding

of the 8th Asean food conference, p. 894 896, (2003).

[3]. Sijmen de Jong, Generalized Procrustes Analysis of coffee brands test by Europeansensory panels, Food Quality and Preferences Journal, Vol.9, p 111 -114, (1998).

[4]. Nguyen Hoang Dzung, Luu Dzuan, Ha Duyen Tu, The role of sensory evaluation infood quality control food research and development: a case coffee study, Proceeding

of the 8th Asean food conference, p. 862 866, (2003).

[5]. Herv Abdi, Dominique Valentin, Mathmatiques pour les sciences cognitives,Presses Universitaires de Grenoble (PUG), (2006)

[6]. The R Foundation for Statistical Computing, ISBN 3-900051-07-0, (2007)

[7]. R. J. Clarke and R. Macrae, Coffee, Vol.1: Chemistry, Elsevier applied sciencepublishers Ltd, London and Newyork, (1987).

[8]. R. J. Clarke and R. Macrae, Coffee, Vol.2: Technology, Elsevier applied sciencepublishers Ltd, London and New York, (1987).

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