KHOA HQC
C 6 N G N G H IIMGHIEIVI CUU q u A TRllVH LEIV IVIEIV CHE VAlVG T l J CHE 5HAIV T U Y E T
Dio Thi Vidt Hi', lOiult HCru Thanh^, Nguydn Duy Thinh^
T6MTAT
Che vang tir cac gidng che Shan tuyet (Ha Giang) co the dupe chd bien thanh che len men (hay con gpi la che Pho Nhi) dat chat lupng tdt Qua nghien ciiu qua trinh len men Che vang tir cac gidng che Shan tuyet (Ha Giang) da cho thay do am ban dau cua che dua vao ii len men can phai dat khoang 35% la thich hpp.
Trong qua trinh len men do am giam dan xuong con khoang 25.2% 6 tuan thii 8. Nhiet dp tang dan tir tuan thii nhat den tuan thii 6. dat den 52,1-54,5°C, dat cue dai den 55,5''C b tuan thii 3, do la tiioi gian boat dpng cua vi sinh vat manh nhat 6 quy mo thi nghiem, da xac dinh dupe tiioi gian u phu hpp ddi voi che Shan tuydt (Ha Giang) la 42 ngay.
Tirkh6a: ChS, len men.
LDATVANDE
Nhieu cdng trinh nghien ciiu eua cic nhi khoa hpc Trung Qude ve chd ldn men (ehd Phd NhO vi tie dung eua nd ddi vdi sue khde con ngudi da kdt luin: udng ehd Phd Nhi ed tie dung lim giam mo trong miu. giam colexteron ed hai trong eo the eon ngudi, giam beo, phdng tti xo hda ddng mach, phdng tri benh nhdi miu ca tim, ha huyet ip, chdng lio hda.
chdng ung tiiu. chdng hire xa, lpi tieu. chdng tio bdn vi giai dupe rupn. Chinh vi vay nhu cau ve ehd Phd Nhr ngiy ting eao, chu yeu tieu tiiu d Vin Nam, Tii Xuydn, Quang Ddng, Tiy Tang, Hdng Cdng, Ma Cao.
Dai Loan. Trong nhirng nim sau nay ehe Phd Nhi dupe xuat sang Singapor, Malayxia, Nhit Ban, Dire, My.
Nguydn Udu de ehd bien che Phd Nhi chii ydu tti cic gidng che Shan (Vin Nam) ed li to. hup ed nhidu tuyet tting. miu li xanh vang. sing, ed him lugng ttmin vi chat hda tan cao. Cdng nghd che bidn ehe Phd Nhr rat khie vdi edng nghd che bien che xanh hoic ehe den. Ngudi ta thudng sir dung nguyen beu ehd vang hoic ehe xanh dupe ehe bidn tti gidng chd Shan tuydt, dem lim am, u ddng, lim khd, bao quan.
Qui trinh ii ddng vi dao trdn thue chat li qui ttinh len men ti; nhidn kdt hpp vdi qui ti-inh hoan tiiidn da tao ra san pham dde dao nay. Qui trinh ldn men (eua eic vi sinh vat) tao ra hing loat cae bien ddi hda hpc, lim cho vi chit giam, him lupng dudng vi eae chat hda ttm ttong nguydn lidu ting, mui vj ndng chit etia nguydn lieu ehuydn hda tiiinh huong vj dim d i cua sin pham. Thdi gian ldn men chinh ed thd keo dii tti 2-3 thing, phu tiiudc rat nhidu vio cic yd'u td khae
Truong Cao dJng Cong nghidp Th^xc pham Vi?t Tri Vi?n Cdng ngh? Sinh hpc - Cong ngh? Thvrc pham, Trudng D^i hpc Bach khoa Ha Npi
nhau nhir nhidt dp, dp am cua chd, dp am khdng khi, mdi trudng xung quanh.
Hidn nay. d Viet Nam mdt sd doanh nghidp nhu Cong ty TNHH Hung Cudng d Ha Giang. Cong ty Che Tim Chiu d Lam Ddng d i vi dang bit dau nghidn cim sin xuat ehe Shan tuyet ldn men tiieo edng nghd san xuat ehe Phd Nhi nhung sd luong cdn khidm tdn, chat lupng ehua on dinh do ehua cd cae nghien cim siu vd edng nghd ldn men ehe. De tting bude tao dupe san pham ehe ed chat lupng tdt tiieo cdng nghd vi chat lupng ehe Phd Nhi, d i tien hinh qui tt-inh ldn men tti che vang Shan ttiyet nhim on dinh vi ning eao chat lupng ehe ldn men cua Viet Nam.
I . Ddi TUOniG VA PHUONG PHAP NGHENCUU 1. Ddi tuprng
Nguydn lidu chinh duge sir dung de nghidn ciiu qui tt-inh ldn men li che ving Shan ttiydt eua Ha Giang.
2. Phuong phip nghidn ciru a. Bd tri cic thi nghiem
Xic dinh dp am thich hgp ban dau cua ehd dua vio ldn men CT-1: dp am ban dau 30%; CT-2: dd am ban dau 35%; CT-3: dp am ban dau 40%.
b. Phuong phip hda hpc
-Xic dinh dp am eiia che tiieo phuong phap say khd ddn khdi lugng khdng ddi; -Xac djnh chat hda tan tiieo phuong phip Voronxop nim 1946; Xic dinh him lugng tanin tiieo phuong phip Lewentiial; Xic djnh him lugng dam tiieo phuong phip Ken-dan; Xic dinh him lugng dudng khir tiieo phuong phap Bectt-and; Xac dinh him lugng axit-amin tiieo phuong phap Popop nim 1966.
+ Phuong phip dinh gii chat luong cam quan che: Theo tiiang diem 100 cua Trung Quoc.
76 N 6 N G
NGHIf
P V APHAT TRIEN
N O N GTHON - KY 2 - THANG 6/2011
KHOA HOC
C 6 N GNGHl
1 . KET QUA NGHEN CUU VA TliAG LUAN
1. Xic dinh c h i t lugng ehd v i n g l i m nguydn lidu chd bidn ehd Shan tuydt Idn men
Che v i n g ehe bien tir gidng che Shan tuyet noi tieng eua H i Giang, d i duge xuat khau fir nhiing nim 80 eua the ky trude, duge thi trudng Hdng Kdng ua chudng. Che ving cua Viet Nam d i duge c i c thuong gia Trung Qude mua vd de s i n xuat chd Phd Nhi. Theo n h i n xet ciia chuyen gia Trung Qude.
B i n g 1. T h i n h p h i n hda hpe cua
viing ehe Shan eua H i Giang cd die diem hinh thii chat lugng g i n gidng vdi hup chd Vin Nam l i to. ed thd che bien tiiinh ehd Phd Nhi ed chat lugng eao.
De x i c dinh chat lugng, trong nghien ciiu nay da lay 2 m i u ehe vang eiia 2 gidng Shan Chat Tien v i Shan Tham Ve. D i y l i hai gidng che phd bien hon ea tai tinh H i Giang v i dupe phin tich thinh phan hda hpe; ket qua the hidn d b i n g 1.
ehd ving H i Giang (% ch^t khd) Ten gidng ehe
Shan Chat Tidn Shan Tham Ve
Dp am 10,58 13,70
Tanin 28,15 27,93
Chat hda tan
45,32 44,07
Cateehin tdng sd (mg/g)
152,00 145,00
Nito tdng sd
3,67 3,52
Dudng khir 2.12 2,22
Axit amin tdng sd
2.19 2.31 Tir sd lieu trong bang 1 cho thay 2 gidng che
Shan tuyet ke trdn deu cho s i n pham ehd ving cd ham lugng tanin v i chat hda tan khong k h i e biet nhau nhieu v i deu d mire k h i eao. H i m lugng dam tong sd thap so vdi nguydn lieu bup ehd vung thap do khdng duge bdn phin m i chi khai thic tu nhien.
Ham lupng dudng khir. axit amin tuong ddi cao ndn khi che bien sd cho sin pham chat lupng cao. tao ndn huong vi hii hda. diu ngpt ed hau. Ket qua trdn cho thay, chat lupng ehd v i n g cua H i Giang phii hpp de che bien chd Phd Nhi.
2. Nghidn ciru x i c djnh dd ^ phii hgp cho q u i ttinh Idn men ehd v i n g
Che ving lim nguydn lidu dd ehd bidn chd Phd Nhi thudng cd dp am tti 11-12% l i ehua phii hpp vdi qua ttinh phit tridn v i ldn men de ehuydn hoa eic chat tao ra huong vj. m i u s i c d i e trung cua ehe Phd Nhi. De xic dinh dp am thich hgp cho chd ldn men, da tien hinh thi nghidm gdm 3 edng tiiire: CT-lehe
cd dd am 30%; CT-2 ehe ed dd am 35%; CT-3 chd ed dp am 40%.
+ Lim am chd: Rai ehd trdn ndn n h i mdt Idp d i y 20 em, dimg binh bom phun het lupng nude d i dupe tinh cho mdi cdng thire; vira phun vira dao dd e i n h ehd tham nude ddu, mdm ra.
+ Tien h i n h ii chd: Sau khi lim am, che dupe vun thinh timg ludng cd chieu eao khoang 30-40 em, phia trdn phu mdt lap vii diy, tham nude dd giii nhidt.
Phdng u ehd phai sach, cd didu hda nhidt dp dupe cii d i t d nhidt dd 25''C dd am khong khi 80%.
Trong q u i trinh u can dio rii dd chd duge toi xdp v i thoing khi, eir sau 7 ngiy thi dio ru mpt lan, ddng thdi lay mau, say khd dd phin tich didn bidn t h i n h phan hda hpc v i dinh gii cam quan. Thdi gian u: ddn tuan thir 8 (tuong irng 56 ngiy).
Ket q u i dinh g i i cam quan nhiing mau ehd dat chat lupng tdt nhat dupe thd hidn d b i n g 2.
Bang 2. Anh hudng eua dd i m v i thdi gian ldn men fa^ri eh^t lupmg cam quan cua ehd Dp am ciia che
len men (%)
30
35
40
Thdi diem dat chat lugng tdt nhat (ngay)
49
(irng vdi lan dao ru tiiu?)
42 (img vdi lan dao ru thu 6)
42 (img voi lan dao rii thu 6)
Mo ta va diem danh gia Mau nuoc
Dd nau, ttong, cd sac mau vang sang
13 diem Dd nau, ttong sang
14 didm Dd nau, ttong, cd sic mau niu sang
13 didm
Mill vi Thom thuan diu, dd chiu
25 didm Tham thuan dju, dd chju, die trung cua mill che ldn men tdt
27 diem Thom thuan dju, xuat hidn mill gd nh?
24 didm
Huong vi Chat dju, cd vj ngpt hau, huong vj ndng
24 didm Chit dju, cd vj ngpt hau, huong
ndng hai hda 25 didm Chit diu, cd vj ngpt hau, huong ndng
24 didm
Danh gii Khi 62 didm
Tdt ()6didm
Khi 61 didm
KHOA HQC CdNG N G H |
Ket qua bang 2 cho thay: Che ving trude khi ldn men can phii dugc lim am. Trong qui trinh u, che ving dan dan thay ddi tinh chat hda hpe vi lim thay ddi mill, vi vi miu sic. Nude che ehuyen dan tir miu ving sang miu dd niu. Cudng dp miu ving giam, cudng dp miu niu ting dan vi tao ra miu nude die trung cho ehd ldn men. Mui eua ehd ving eiing dan ehuyen thinh mui thom thuan, diu, die trung etia che ldn men. Vi chit cua che ving ehuyen sang vi chit ngpt, hda quydn vdi miii thom thuan, diu cua ehe, tao ra huong vi ndng am. Nhin ehung d 3 mire dp am eua cic thi nghidm, qui trinh ii deu tao ra ehe ldn men ed chat lugng tir khi trd ldn. Tuy nhidn d dd am 30%, dd dat dugc che cd chat lugng tdt nhat, thdi gian u phai keo dii tdi 49 ngiy. Trong khi dd d dd am 35% vi 40% dd ehd ldn men dat chat lugng tdt nhat thi can thdi gian ngin hon (42 ngiy).
Tiep tuc danh gia cam quan ehe len men, d i ip dung phuong phap so sinh cip ddi vi ket qui cho thay mau ehe len men d dd am 35% cho chat lupng tdt nhat; mic du miic chat lugng theo diem khdng Bing 3. Didn bidn nhidt dp vi dp
chdnh Idch nhau nhidu lim nhung cung tiiay ring khi ldn men d dp am eao (40%) tiii chat lugng ehe lai tiiap hon so vdi ldn men or dp am 35%. Nhu vay ldn men d dp am khoang 35% li tdt hon ca.
3. Su tiiay ddi cua nhipt dO v i dp im cua chd trong qui trinh ldn men chd
- De do nhidt dp eua khdi che, d i sir dung nhidt ke didn tti hidn sd. Dau cam bien eua nhidt ke duge cim siu vio trung tim eua khdi ehd. Dpe gii tti nhidt dd eua khdi ehd vio thdi diem trude lue dao ru ehe 10 -15 phut, vio tiidi didm nay qui binh len men d i duge tich nhidt sinh trong khdi chd u vi ehua bi tdn that trong qui trinh dao ru.
- De xic dinh dp am cua ehe, d i lay mau phin tich sau khi da dao ru vi trude khi rai ddu de ldn men ttep tuc. Khdi lugng che mdi lan lay miu phan tich li 0,5 kg.
Ket qui do nhidt dp v i xic dinh dd am cua ehe dupe trinh biy trong bang 3.
£m cua chd trong qui trinh ldn men Thdng sd
Thdi gian (ngiy) Nhidt dd(°C) Dd am (%)
Lan dio ru thiir 0
0 28,2 35,0
1 7 52,1 34,2
2 14 55,0 33,4
3 21 55,5 32,1
4 28 54,7 30,5
5 35 54,7 28,3
6 42 54,5 26,1
7 49 43,1 25,5
8 56 37,2 25,2
S M ' b l i n ail OO A m c d a c h * th»o »h«i B l « n ! • " " ' • n (%)
3 5 . 3 0 .
S^ 20 . 8 1 5 -
;> 10 - s -
0 10 20 30 40 Ttlirl flian (ngdy)
80
^
60
, . . , . „ . j
Si,r bl6n ail n h l ^ d ^ cOa kh6l chd thopttj lAnmen
20 30 40
Hinh 1. Svr bidn ddi nhipt dp Tir kdt qua trinh biy d bang 3 v i hinh 1 ed nhin xdt nhu sau:
Subidn ddi dp am: Trong sudt thdi gian ldn men, dp am cua khdi che ldn men lidn tuc giam xudng (tir ngiy ldn men thir nhat ddn ngay ldn men thii 42) vi d giai doan cudi (tir ngiy ldn men thii 42 ddn ngiy ldn men thu 56). mue dp giam dp am khdng nhidu vi gan nhu on dinh. Dp am cudi cimg ciia khdi che chi cdn khoang 25%. Nguydn nhin ciia su giam dp am la su bay hoi nude tir khdi che do su ting nhidt dg.
vi dd ^ ciia chd ldn men
Su bidn ddi nhiet da. Tir hinh vd minh hoa sir bien ddi nhidt dp eua khdi che tiieo thdi gian ldn men, cd tiid dd ding tiiay su bidn ddi nhidt dp cd 3 giai doan:
- Giai do^ tSng nhidt Nhi^t dp eua khdi che ting ldn khi nhanh 6 giai doan dau cua qui tt-inh ldn men (khoang 7 ngiy dau). Nhidt dp khdi ehe ting tir 28«C ldn ddn ti-dn 50°C, nguydn nhan li do su phat tridn manh md cua vi sinh vat va ddng thdi ciing xay ra qui ttinh oxy hda cic hgp chat polyphenol dudi
78 NONG NGHlfP VA PHAT TRIEN NONG THON - KY 2 - THANG 6/2011
KHOA HOC
C 6 N G N G H £ tie dung xiic tie cua cie men oxy hda khir do vi sinhvat sinh ra.
- Giai doan on dinh. Nhidt dd cua khdi che khi on dinh d mire eao (khoang 55°C) tti ngiy ldn men thu 7 den ngiy ldn men thii 42. Nguydn nhin lim khdi che ed nhidt dd eao li do vi sinh vit phit trien rat manh. Sir giam dd am va su ting nhidt dd trong khdi che ed mdi Udn quan k h i chit ehe vdi nhau. Dd chinh li giai doan ldn men ehe vang nhd vi sinh vit.
Nhidt dd eua khdi che ciing duge duy tri d miie on dinh vi sir duy tri niy keo dai khoing 35 ngiy. Qui trinh phat tridn eiia vi sinh vit d i lim tinh chat hda hpe eua li ehd bidn ddi rat siu sic, tao ra nhiing tinh chat rat die trung cho ehe ldn men.
- Giai doan giim nhiet Tir ngiy thii 42 nhidt dd Bing 4. Bidn ddi thinh phin hda
giim dan xudng, edn khoing 37*'C d ngiy ldn men tiiu 56. Sau ngiy thii 42 eudng dd hoat ddng eua vi sinh vit giim di vi vi thd nhidt dp ciia khdi che ciing giam theo.
4. Nghidn ciiu sv bidn ddi thinh phin hda hpc trong qui trinh ii chd ldn men
Lay miu phan tich. Thdi diem lay mau phin tich li mdi lan ket thuc dao ru vi trude khi chd dugc u trd lai. Cic miu che ddu dugc say khd nhanh den dd am 11%, duge bio quin can thin dd dua di phin tich. Sd miu thu dugc li 9 d cie lan dio ru 0,1, 2, 3, 4, 5, 6, 7, 8. Tdng edng 9 miu vi dupe xic djnh cic chi tidu:
him lugng tanin tdng sd, him lugng chat hda tan, him lugng dudng khir, him lugng nito tdng sd. Kdt qua thu dugc trinh biy trong bang 4.
hpc trong qui trinh ii chd ldn men Cic ehi tidu
Him lugng tanin (% CK) Him lupng chat tan (% CK)
Ham lupng dudng khu tdng sd (% CK) Him lugng nito tdng sd (% CK)
Lan dio ru thii vi thdi gian ldn men 0
0 28,2 43,8 4,3 3,7
1 7 21,9 38,5 3.6 3.3
2 14 18.8 39.3 3,1 4,1
3 21 16,9 40,4 2,8 4,3
4 28 15,5 43,2 2,7 4,4
5 35 14,2 42.1 2.8 4.2
6 42 13,5 39,2 2,9 3,9
7 49 12,9 35,3 3,1 3,6
8 56 12,7 28,3 3,2 3,1 Sir bidn ddi him lupng cie chat: tanin, chat hda
tan, dudng khu vi nito tdng sd trong thdi gian u ldn men cd nhirng quy luat khie nhau:
Ddi vai tanin: Him lugng tanin giam Udn tuc tir dau qua trinh u ddn khi ket thuc. Tuy nhidn tdc dp giim tuong ddi nhanh d ngiy dau tidn ddn khoang ngay ldn men thir 30, sau dd ed xu hudng chim dan lai. Nguydn nhin eua su giam him lugng tanin trong qui trinh ldn men li do mdt phan tanin bj oxy hda, chuyen thinh teaflavin (TF) vi sau dd ehuydn thinh tearubigin (TR) vi teabrow (TB) lim cho nude che chuyen dan tir miu ving thinh miu niu.
Mit khie, mdt phan tanin ket hgp vdi protein cd ttong li che dd tao ra chat khdng tan, die bidt li su ngung tu giira tearubigin (TR) vdi protein rat manh, didu dd cung lim cho him lugng tanin giam khi nhidu vi b i che ed miu niu eing dim dan. Su chuyen hda tanin trong ehe d i tiiay thd vi chit manh cua ehe ving thinh vi chit diu, ngpt hau die trung cho che ving ldn men. Dieu niy ed y nghla quan ttpng ddi vdi chat lugng ve vi eua che ldn men. Tuy nhidn, tdng lugng tanin edn lai trong ehe d ngiy ldn men tini 56 ehi cdn 12,7%, ttic li ehi bing khoing 45%
him lugng ciia che vang ban dau, \\ ehe trd ndn rat nhat. nuoc cd mau niu dd qui dim, lim chat lugng
ehe ldn men giam di ro rdt. Theo kdt qui dinh gii cam quan, d ngiy ldn men thir 42, chat lugng ciia che ldn men tdt nhat, cd nghla li ham lugng tanin trong ehe cdn khoing 13,5%, tiie li bing khoang 48% him lugng tannin ban dau
Ddi vdi chat hda tan. Him lugng cic chat hoi tan bien ddi khdng theo quy luat eua tanin; d nhirng ngay diu tidn cua qui trinh ii, him lugng chat hda tan giim di ddn ngiy thii 7, sau dd ting dan ddn ngiy thu 28 vi dat tti sd eao nhat. sau dd him lugng chat tan giam dan. Nguydn nhin cua su thay ddi nay, cd thd dupe giai thich nhu sau: trong thdi gian dau, vi sinh vit ttong khdi chd phit tridn rat manh lim nhidt dp cua khdi che ting nhanh (tii 28"C ldn ddn 52*'C).
Vi sinh vit d i sii dung nhiing chat hda tan ttong chd lim ngudn dinh du&ng dd phit tridn (dudng hda tan, protein khoang 35%, lue niy trong chd lai xiy ra qui trinh thuy phin cie chat cd trong ehd va didu niy d i ehuyen mdt sd chat khdng tan thinh chat hda tan vi lim cho chat hda tan trong chd ting ldn nhung sau dd lai giam dan, nguydn nhin li do eic chat TF vi TR lidn kdt vdi protein khdng tan trong li ehd vi tao ra eic chat ngung tu khdng hda tan.
Ddi vdi duong khir. Him lugng dudng khir trong thdi gian u chd: him lugng dudng khir giam dan tir
KHOA HOC
C 6 N GNGHE
ngiy dau tidn den ngiy thu 28. Trong thdi gian niy, dudng khir li ddi tugng dinh duong eua vi sinh vit ndn ham lupng eua ehung giam di, sau dd him lugng cua dudng khir lai ting ldn mdt chut vao nhiing gid ldn men cudi do xay ra sir thiiy phan tinh bdt thanh dudng dudi tic dung cua vi sinh vit. Sir hinh thanh vi bidn ddi him lugng dudng khir cd tic dung rat ldn trong vide tao ra mui vi mdt phan tao ra vi ngpt cho che ldn men.
Nita tdng sd: Ham lupng nito tdng sd ting ldn dan tir ngiy dau eiia qui trinh u vi dat tti sd ldn nhat ngiy thii 28 sau dd giam dan cho den khi ket thuc qua trinh u. Nguyen nhan ciia sir thay ddi ham lugng nito tdng sd li do sir phit trien manh ciia he vi sinh vat trong qui trinh ldn men che. Cic vi sinh vit d i phin giii cie hpp chat chira nito khdng tan thinh trang thii hda tan dd ehung sir dung lim ngudn nito cho phit trien te bio. ddng thdi ehung ciing cd kha ning tao ra nhung hpp chat chira nito, vi the lam cho him lupng eua chat niy ting ldn. Sir bien ddi him lugng nito din den sir hinh thinh vi chuyen hda cie axit amin trong ehe. Chinh sir ehuyen hda cie axit amin d i ddng vai trd rat quan trpng trong qui trinh hinh thinh chat thom trong ehd ldn men vi cung gdp phan tao ra vi ngpt cua che sin pham. O giai doan cudi. him lugng nito trong ehe da giam di li do sir tao ra cie chat ngung tu vdi tanin chd.
IV. KET LUAN VA DE NGHj
1. Che ving duge chd bien tir cie gidng ehd Shan (Hi Giang) ed the sii dung de ehe bidn ehd Phd Nhi chat lupng tdt.
2. Dp am ciia nguydn lidu che ldn men khoang 35% li phii hpp.
3 Trong qui trinh ldn men (tir cudi tuan thu nhat den tuan thu 6) li thdi gian vi sinh vat hoat ddng manh nhat nen nhidt dp ldn men se ting ldn tti
52,1°C-55,5°C.
4. Thdi gian ldn men che khoang 42 ngay. tt-ong dieu kidn nhidt dp mdi txubng dat 25°C se cho chat lugng che tdtt khi nhidt dp mdi ttirdng ting ldn tiii tiidi gian u se nit ngin hon vi chat lugng che cd tiie bi giam di.
5. Trong qui ttinh ldn men che, him lugng eic chat deu tiiay ddi do tham gia vio cic phan ung sinh hda de tao ndn chat lugng die trung cua che sin pham; trong dd ham lugng tanin giam cdn lai bing 45% so vdi him lugng ban dau, edn sir bien ddng vd him lugng eua cic chat hda tan: dudng, dam li khdng dang ke.
TAI UEU THAM KHAO
1. Hoing Cu - Nguydn Hiru La (2003). Die diem sinh hoi ciia mpt sd gidng ehd Shan chpn lpe tai Phu Hd- Tap chi Ndng nghiep v i Phit trien ndng thdn.
2 . Dd Vin Ngpc, Nguydn Hiiu La vi cdng tic vidn (2006). Nghidn euu tuyen chpn che Shan viing cao giai doan 2(X)1- 2005. Ket qua nghien ciru khoa hpe cua Vidn Khoa hpe Ky thuat Ndng Lam nghidp mien nui phia Bic. Nhi xuat ban Ndng nghidp H i Ndi.
3. Chen WenPin, Zi WenXiang . Yang LiuXia.
Nghien ciru dieu tra hidn trang thi trudng vi trien vpng phit trien eua nganh edng nghidp sin xuat che Phd Nhr. Tuyen tap cie nghidn cuu khoa hpc ky thuat vi phit tridn ben viing quoc te nim 2005, 2005, 11, HangZhou.
4. Chan Ying Can, 2006. Thao luin vd co ehd ldn men che Phd Nhi, Tap chi Thdng tin Kinh te Che (1), 36 - 37.
5. Yuerong Dang, lingyun Zhang, Jianliang Lu.
A study on chemical estimation of Pu'er tea quality [J]. Sci. Food Agric. 2005(85): 381 - 390.
6. Wang Han Sheng, 2006. Quy tiinh ldn men ddng ehd Phd Nhi. Tap ehi Che Quang Ddng (1): 3 - 4.
STUDY THE FERMENTATION PROCESS FROM THE YELLOW TEA SHAN TUYET Dao Thi Viet Ha, Khuat Huu Thanh, Nguyen Duy Thinh
Summary
The yellow tea from the Shan tuyet (Ha Giang) tea variety can be used to process by fermentaUon to get Pho Nhi tea with good quality. In the process of researching on fermentation, the results were showed that initial moisture of tea in the fermentation should be achieved at about 35%. In the fermentation process, humidity decreases graduaDy to about 25.2% at the 8* week. Temperature increases gradually from the first week to the 6* week, reaching 52.1 to 54.5° C and maximum at about SS.S'C at tiie 3"* week , at this ttme microbial activity is powerful. At tiie experimental scale, the suitable incubation time for the Shan tuyet (Ha Giang) tea is 42 days.
Key word: Tea, fermentation.
Ngudi phin bi^n: PGS.TS. Trjnh Vin Loan
