Hat CA Cao Thuong Pham

Quy trnh sx ht cacao thng phm

GVHD: PGS.TS L VN VIT MN

CHNG 1. TNG QUAN V CY CACAO1.1 Ngun gc v s pht trin ca cy Cacao 1.1.1 Ngun gc v s pht trin ca cy cacao trn th gii Cy cacao (Theobroma cacao Linnaeus) c ngun gc t vng rng rm nhit i Amazon v trung tm chu M c bit l Mexico. Christopher Columbus l ngi u tin mang ht cacao v chu u vo nm 1502. Nm 1828, Van Houten - ngi H Lan - pht minh ra k thut p cacao cho php tch b t cacao thu c bt cacao c khong 23% cht bo. Mt pht minh quan trng khc l vic ch to thnh cng chocolate sa vo nm 1876 bi Daniel Peter - ngi Thy S. Cc mnh nhn cacao c phi trn vi ng, sa v ch bin thnh chocolate sa sn phm chnh ca ngnh cng ngh chocolate ngy nay. Mc d cacao c pht hin v s dng t rt sm nhng mi n th k 19 th ngh trng cacao mi pht trin v t c nhng tin b ng k v t gip cho cng ngh sn xut chocolate chu u pht trin mnh. Cy cacao pht trin mt cch nhanh chng cc nc Ty Ban Nha, B o Nha, H Lan, Cuba, n , Sri LanKa, nam M, ty Phi, Philippines v Indonesia. Nam M v n l nhng nh cung cp cacao nhn ch yu cho th gii n nhng nm 1900. Ngy nay, cc quc gia ty Phi ang l nhng nh cung cp cacao nhn ln nht th gii. 1.1.2 S pht trin ca cy cacao Vit Nam Vit Nam, cy cacao c du nhp t rt sm theo chn cc nh truyn gio phng Ty nhng pht trin rt chm cho n thi gian gn y. Hin ti, cacao c trng rng ri nhiu ni: Ty Nguyn, mt s tnh vng ng bng sng Cu Long, B Ra Vng Tu, Bnh Phc. Trong , vng Ty Nguyn vn c nh gi l c iu kin l tng nht cho s pht1



trin ca cy cacao. y, theo nghin cu thng k th cy ra hoa cho qu quanh nm, sn lng bnh qun t 3 kg ht kh/1 cy 5 nm tui. Nm 2009, sn lng cacao ca Vit Nam t 1000 tn ht kh. Trong , klk chim 33%, Bn Tre: 25%, B Ra Vng Tu: 17%, Tin Giang: 5% v Bnh Phc: 2%. V nh hng pht trin cy cacao nc ta trong thi gian ti, theo mc tiu ca B Nng nghip v Pht trin Nng thn l pht trin bn vng cy ca cao Vit Nam nhm tng khi lng sn phm hng ho, tng hiu qu kinh t trn n v din tch t, nng cao thu nhp cho ngi dn v bo v mi trng. C th, n nm 2015, d kin din tch trng cy ca cao t 60.000 ha, trong c 35.000 ha kinh doanh, nng sut bnh qun 15 t/ha, sn lng ht kh t 52.000 tn, kim ngch xut khu t 50 - 60 triu USD. n nm 2020, d kin din tch t 80.000 ha, trong c 60.000 ha kinh doanh, nng sut bnh qun 18 t/ha, sn lng ht kh 108.000 tn, kim ngch xut khu t 100 - 120 triu USD. 1.2 c im ca cy cacao Cy cacao (Theobroma cacao) thuc: H: Sterculiaceae Th: Theobroma cacao, gm 22 loi nhng trong ch c loi Theobroma cacao l c gi tr kinh t nn c trng rng ri, cn cc loi khc hoc mc hoang di hoc rt c t trng. Hnh 1.1: Cy cacao Hin nay c rt nhiu chng cacao c trng, tuy nhin, c th phn thnh 3 nhm chnh: Criollo, Forastero v Trinitario. Criollo: Dng qu: di, c kch thc ln. Sng qu: nhn, rnh su, mang 10 kha u nhau.2



V qu: mng, mm, t cht g, qu c mu i khi cng xut hin mu xanh nhng rt t. Hoa: nhy c mu hng nht. Ht: c khong 20 40 ht trong mt qu, mu ca phi nh ht c mu trng, trng ng hoc ta rt nht. Cc chng loi bao gm: Criollo Mexico, Criollo Nicaragua, Criollo Hnh 1.2 Cacao Criollo Colombia, Criollo Calabacillo. Cy cacao ny c ngun gc t vng Trung M. Criollo l dng cacao cho cht lng hng v ca cc sn phm ch bin tt nht. Tuy nhin, Criollo rt kh trng do kh nng khng bnh km v nng sut thp. Hin nay, cacao thuc dng ny ch chim 5% tng sn lng cacao ca th gii. Forastero: Dng qu: qu trn hoc hnh bu dc. Sng qu: trn, khng c rnh su. V qu: cng, dy, nhiu cht g, qu c mu xanh l cy khi chn th c mu vng. Hoa: nhy c mu tm. Ht: c khong 30 60 ht c khi nhiu hn, mu phi nh ht c mu ta nht n m, tm m nh np than hay m. Hnh 1.3 Cacao Forastero Cc chng loi bao gm: Amelonado, Angoleta, Cundeamor, Calabacillo. Cy cacao ny trc y sng vng Nam M v vng h lu sng Amazon. Cacao Forastero chim hn 80% tng sn lng cacao ton th gii. Cacao thuc dng Forastero cho nng sut cao, kh nng khng bnh cao nhng cht lng ht trung bnh.3



Trinitario:

y l dng cacao c xc nh l do lai gia dng Criollo v Forastero. Dng qu: qu di. Sng qu: khng r nt. V qu: cng, mu qu khng nht nh thng l mu xanh c mt phn ging mu . Ht: thng l nhiu hn 40 ht i khi nhiu hn, mu ca phi nh c mu tm rt nht.

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CHNG 2. TIU CHUN LA CHN NGUYN LIU2.1 M t qu v ht cacaoTri cacao c th t chiu di 1520 cm, khi lng khong 200 g hoc hn ty ging. Ty theo tng loi m hnh dng tri c khc nhau (di, trn hoc bu dc). Mu sc tri kh a dng: , xanh hay vng. Hnh 2.1 Qu v ht cacao Qu cacao c cha t 25 n 80 ht. Ht cacao c hnh trng, t nhiu dt v thng c mu tm hoa c hi nht. V ht gm c phn v ngoi, mng v d v cng c gi l v cng v phn v la trong rt mng c mu trng m bc ly li ht v n c vo phn li ht, chia li ra thnh nhng gc cnh. Ht cacao l ht khng c nhn, mp, di 2 3 cm, c lp nhy mu trng, c v ngt hi chua bao quanh. Dng mt ca xt cho sch ci, ht s xut hin v nm trong mt ci bao mng nhng chc, mu hng, c nhiu ng gn. Hai phi nh ca phi mu sc c th thay i t trng ca Criollo sang tm m ca Forastero qua cc mu trung gian ca cc ging lai Trinitario chim ton b th tch ca ht. Phi nh c nhiu np nhn v gm nhiu thu chng ln nhau, quanh chng c mng mng trong, bng bao bc. Chng c ni lin v pha gc v bng mt ci r con di 6 7 mm v mt ci mm th s cp vo gia c thu bao quanh to thnh mm ca ht cacao. 2.2 Thnh phn ha hc ca qu v ht Thnh phn ha hc ca ht cacao ti c th hin trong bng 2.1.5



Bng 2.1 Thnh phn ha hc ca ht cacao ti, tnh theo % KL [3]Thnh phn Nc Cht bo (b cacao) Cacbonhydrats Cellulose Tinh bt Pentosans Sucrose Glucose + Fructose Nitrogen Protein Theobromine Enzyme Polyphenols Acid hu c Citric, Acetic, Oxalic Mui khong 0,7 0,8 _ 8,2 0,6 2,6 0,6 _ _ _ 18,0 _ _ 0,8 8.4 2,4 0,8 5,2 _ _ 2,7 0,7 10,0 13,8 46,0 _ _ _ 3,2 4,5 4,9 _ 1,1 Cht nhy (Muccilage) 84,5 _ V ht (Shell/ Testa) 9,4 3,8 Phi nh (Cotyledon/ Kernel) 35 31,3

Phi nh c hm lng b cacao kh cao, v ht c mt t v khng c cht nhy. B cacao chim khong 31.3 % khi lng phi nh. B cacao ch yu cha cc triglyceride ca glycerol v cc acid bo no. Thnh phn cc glyceride trong b cacao c th hin trong bng 2.2. Bng 2.2 Thnh phn cc glyceride trong b cacao [6]Tn glyceride Oleopanmetostearin Oleodistearin Oleodipanmitin Dipanmitostearin Dioleopanmitostearin Dioleostearin Oleolioleopanmitin Oleolioleostearin Cc acid bo t do6

T l (%) 52 57 18 22 46 23 78 6 12 0.5 4.5 1.1

Tnc (0C) 34.5 43.3 29 63 68 Nhit thng Nhit thng Nhit thng Nhit thng Nhit thng



B cacao nng chy nhit 16 - 370C, ty thuc vo dng tinh th ca cht bo to thnh trong qu trnh kt tinh. B cacao chit t ht cacao c dng tinh th nh mu trng v c mi thm c trng. B cacao gp phn to mi v cho cacao. Cht nhy c cha mt hm lng ng (glucose, fructose, sucrose) v nc kh cao. Ngoi ra, cn c mt lng acid citric lm cho pH ca cht nhy lun n nh 3,5. Protein trong v qu chim 18%, trong ci: 0.6% v trong phi nh: 8.4%. Thnh phn protein chim nhiu nht trong qu cacao l albumin v globulin. Mt thnh phn quan trng khc trong cacao l cc alkaloid. Alkaloic in hnh trong cacao l theobromine (3, 7 dimethylxanthine). N l cht kch thch nh, to cm gic hng phn cho c th ngi. cng kch thch ca theobromine thp hn caffein rt nhiu. Trong cacao, hm lng theobromine dao ng trong khong 1- 4% (w/w). Trong cacao cng c cha caffein nhng hm lng rt thp (0 2%) so vi trong c ph. 2.3 Chn ging cacao sn xut Hin nay ti Vit Nam, B Nng nghip v Pht trin Nng thn ph duyt b ging ca cao c php s dng rng ri trn c nc. l cc dng v tnh TD1, TD2, TD3, TD5, TD6, TD8, TD10, TD14 do trng i hc Nng Lm thnh ph H Ch Minh tuyn chn. y l nhng dng v tnh c tim nng nng sut t 2 n 5 tn/ha. Nguyn liu dng sn xut ht cacao thng phm l tri cacao ti thu hoch t cy cacao Theobroma cacao thuc dng TD5. Hnh 2.2 Ging cacao TD5

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Ging TD5 Do H Nng Lm TP. HCM nhp ni t Malaysia - Thuc b ging (8 ging) duy nht c B Nng nghip cho php trng ti Vit Nam Tn Malaysia: KKM 22. Ging TD5 : V tri xanh, tm lt, khi chn mu vng, b mt v nhn bng, chiu su rnh cn, dng tri t, nng sut 2,8 tn ht/ha. Khng bnh vt sc en, nhim nm Phytopthora, nm hng. Ht c khi lng 1.29 g/ ht, 42 ht trong 1 qu , b cacao chim 53% khi lng cht kh (i vi ht). 2.4 Tiu chun la chn nguyn liu Tri cacao ti a vo sn xut phi m bo ng chn k thut tc l t chn ti thiu 75% (qu c mu vng). Khng s dng cc qu cha chn v ht trong qu kh bc ra, ht kh ln men, t l ht tm v xm cao, hiu sut thu hi gim. Tuy nhin, cng nn trnh tri qu chn v lc ny ht c th ny mm t trong qu, d b su bnh, nh hng n cht lng ca nhn cacao. Ngoi ra, tri cacao ti phi m bo khng b thi ra, dp nt, v hoc b cn trng cn. Ti ni thu mua cacao nguyn liu, tri cacao c phn ring theo chn thun li cho qu trnh sn xut. Tri cacao sau khi thu mua c bo qun nhit thng khong 4 n 7 ngy ri mi a vo sn xut. Qu c tr ni kh ro, trnh tip xc trc tip vi nng, ma v ngun nc.

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CHNG 3. QUY TRNH CNG NGH SN XUT HT CACAO THNG PHM3.1 S quy trnh - S khi Nguyn liu

Bc v, tch ht

V, ht h

Sy s b

Ln men

Dch nhy

Nc

Ra

Nc thi

Sy

Phn loi, tch tp cht

Tp cht

Ht cacao thng phm

Bao gi

Hnh 3.1 S khi quy trnh sn xut ht cacao thng phm9



3.2 S thit b 3.3 Gii thch quy trnh 3.3.1 Bc v, tch ht a. Mc ch cng ngh: chun b Trong qu trnh ny, v cng bn ngoi ca tri cacao ti c loi b, phn ht bn trong c ly ra chun b cho qu trnh ln men tip theo. b. Cc bin i ca nguyn liu Bin i vt l: Sau qu trnh tch v, khi lng ca khi nguyn liu gim i do ton b lp v cng ca tri b tch ra. Bin i ha l: c th xy ra s bc hi nc t lp cht nhy ra mi trng. Bin i ha hc: do v cng b tch ra nn mt s cht cng b mt theo (nc, cht bo, cellulose, tinh bt, protein, polyphenol, mui khong). Bin i sinh hc: sau khi bc v, phn dch nhy bn trong qu l ra ngoi, tip xc vi khng kh. Do dch nhy cha nhiu ng v c pH thp nn rt d b nhim vi sinh vt gy ra cc bin i khng kim sot c. c. Phng php thc hin Tri c p bng vt dng cn, n gin nht l dng mt thanh g p vo tri lm v v theo chiu thng ng trnh lm tn thng ht. Tt nht nn trnh dng dao ct tri, bi v ht c th b ct t v s lm nh hng n cht lng ca chng sau khi ln men v sy. Tri sau khi b p th v ra, dng hai ngn tay lch theo chiu di v c hai bn x ci tr, ht s tch ra d dng. Tri khng nn c p di tri ma bi v nc ma s lm tri lp cm nhy bao quanh ht v nh vy s nh hng n qu trnh ln men. Ht c mu en hoc c r hoc ht lp s khng c ln men hon ton nn c loi b.

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Hnh 3.2 Bc v qu ca cao bng tay 3.3.2 Sy s b a. Mc ch cng ngh: chun b Qu trnh sy s b gip gim bt lng nc trong lp nhy, lm b mt lp cht nhy se li gip cho qu trnh ln men tt hn. Ngoi ra, khi s dng khng kh m thi qua lp ht, vi sinh vt c trong khng kh s ri vo lp ht, lm tng lng vi sinh vt ln men cng gip qu trnh ln men c tt hn. b. Cc bin i xy ra: Bin i vt l: nhit ht tng, khi lng ht gim Bin i ha hc: hm lng nc gim Bin i ha l: nc b bc hi Bin i sinh hc: cc vi sinh vt trong khng kh nhim vo ht c. Thit b s dng: dng my sy bng ti Cu to thit b: c th hin trn hnh 3.3. Nguyn tc hot ng: Thit b gm mt bung sy hnh ch nht, trong c cc bng ti chuyn ng chm nh tang quay. Cc bng ti ny ta trn cc con ln khi b vng xung, bng ti ny c lm bng li kim loi v chuyn ng vi tc khong 0.3 0.6 m/s. Ht t phu nhp liu ri6

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xung cc bng ti v chuyn ng theo bng ti, khng kh nng thi t di ln trm qua cc bng ti c ht ly mt phn nc v thot ra ngoi.

Hnh 3.3 Thit b sy i lu dng bng ti 1. Phu nhp liu 2. Trc ln dn vt liu sy 3. Phng sy hnh ch nht 4. Con ln 5. Bng ti Thng s cng ngh Chiu cao lp nguyn liu Tng thi gian sy Nhit tc nhn sy Lu lng tc nhn sy 3.3.3 Ln men ht cacao a. Mc ch cng ngh Qu trnh ln men ht cacao c hai mc ch cng ngh ch yu l chun b v ch bin. 3 cm 45 pht 35 380C 0.5 1 m3/s 6. Caloriphe 7. Thng cha sn phm 8. Qut ht 9. Tm chn tc nhn sy 10. ng tc nhn sy ra

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Qu trnh ln men gy ra nhng bin i sinh ha trong lp nhy, ha lng lp cht nhy, tch chng ra khi phn ht bn trong gip cho qu trnh sy nhanh hn. Qu trnh ln men cng gy ra nhng bin i sinh ha trong phi nh lm gim v ng v cht trong ht cacao. ng thi, qu trnh ny cng lm khi mo cho s pht trin ca cc hng, v v mu sc trong qu trnh rang ht v sau. b. Cc bin i xy ra trong qu trnh ln men Bin i sinh hc: - Ln men cacao l qu trnh ln men t nhin, trong qu trnh ln men c s pht trin ca rt nhiu cc loi vi sinh vt khc nhau, nhng ch yu l cc loi sau: Nm men (yeasts) ch yu l nm men Saccharomyces cerevisiae v Kluyveromysses. Trong khi cacao ln men thy s c mt ca nhiu loi nm men (loi to cn v hng thm). Cc loi nm men c hu ht cc lp ht cacao t y n b mt khi ln men. Thng thy hai ging Kluyveromysses v Saccharomyces vi s lng rt ln. Ngoi ra cn thy mt s ging nm men khc nh: Hansenula, Kloeckera, Torulopsis, Candina, Pichia, Shizo saccharomyces, Saccharromycopsis, Rhodotorula, Debaryomyces, Hanseniospora. Vi khun (bacteria) ch yu l: Vi khun lactic Trong khi ln men ngi ta thy rt nhiu loi vi khun lactic khc nhau nh: Lactobacillus lactic, Lactobacillus mali, Lactobacillus plantarum, L.fermentum, L.collinoides, Betabacterium, Streptobacterium, Streptococcus. Cc loi vi khun lactic chuyn ho ng thnh acid lactic v mt s acid hu c khc. Vi khun acetic13



Cc vi khun acetic pht trin sau nm men, chng chuyn ha ethanol thnh acid acetic. Thng thy trong ng ln men cc ging vi khun acetic sau: Acetobacter rancens, Acetobacter aceti, Acetobacter oxydan, Scetobacter raneer, A. ascendens, A. suboxydans, A. xylinoides, A. orleanense. Cc vi khun khc Ngoi hai ging vi sinh vt trn trong ng cacao ln men cn thy s c mt c a B.Coagulans, B.Pumidus, B.sterothermophilus, Micrococus, Pediococcus, Streptococus, Propionibacterium, Zymomonas, Flavobacterium Achromobacter v Proteus. Trong ng cacao ln men ngi ta cn pht hin thy nhiu ging nm si nh: Aspergillus, Mucor, Penicillium, Rihzopus. - Nhng bin i sinh hc quan trng xy ra l s trao i cht v s sinh trng ca h vi sinh vt trn. Bin i ha sinh: - Cc bin i ha sinh u tin l s ln men ru, ln men lactic lp cht nhy bn ngoi v s ln men acetic trong giai on tip theo sau . Lp cht nhy bao quanh ht cacao mi ly ra t qu c mt tr lng ng kh cao, pH thp do s c mt ca cc acid hu c l mi trng rt thch hp cho s pht trin ca nm men. Trong giai on u ca qu trnh ln men, s hin din ca lp cht nhy lm gim lng oxy khuch tn vo bn trong khi ht to nn iu kin k kh. Trong giai on ny, nm men v cc vi khun lactic chuyn ha ng v acid hu c trong cht nhy thnh ethanol, acid lactic, CO2. C6H12O6 2C2H5OH + 2CO2 + 93.3 kJ C6H12O6 2CH3-CHOH-COOH + 94 Kcal C ch ca qu trnh ln men gm 2 giai on c bn: u tin ng s c chuyn ha thnh pyruvate theo qu trnh ng phn EM, sau pyruvate s c chuyn ha thnh ethanol hoc acid lactic.14



Acid pyruvic CH3-CO-CH3Alcohol decarboxylase

Acetaldehyde HCHOdehydrogenase

Ru ehanol C2H5OH Acid pyruvic CH3-CO-CH3Lactate dehydrogenase

Acid lactic CH3-CHOH-COOH

Hnh 3.4. Qu trnh ng phn EM Sau khong 48 gi ln men, nh vo hot tnh phn gii pectin ca h vi sinh vt m lp cht nhy b phn hy lm mi trng thng thong hn, h vi khun acetic pht trin mnh oxi ha ethanol thnh acid acetic.15



C2H5OH + O2 CH3COOH + H2O + 496 kJ Ngoi ra, do s c mt ca h vi sinh vt bao gm nhiu loi nn qu trnh ln men cn sinh ra nhiu sn phm ph khc. - Bin i ha sinh quan trng tip theo l cc bin i xy ra trong phi nh. Khi nhit khi ht tng ln, acid acetic v ethanol sinh ra khuch tn vo bn trong phi nh lm cho ht cht khng cn kh nng ny mm. Khi ht cht, phi nh s ht m lm cho vch t bo ca n tr nn thm nc v ni cht ca t bo c th khuch tn qua cc m. Nhng enzyme ca t bo d tr (protease, polyphenol oxydase) nh th c tip xc vi cc c cht (anthocyanins, flavanols, phenol v cc protein d tr) m trc kia hon ton b ngn cch, tng tc v phn ng vi nhau. Trong cc polyphenol, nhng sc t anthocyanin b thy phn cho ra cyanidin v hai ng kh l nhng cht khng mu m sau ny khi b oxy ha s cho ra mu nu c bit (mu nu cacao). Nhng polyphenol khc s tn i mt phn qua v ca ht hoc chu nhng bin i ha hc khc, c hai qu trnh u gp phn gim v ng v cht. Cc qu trnh bin i ny s xy ra cho ti cui t ln men v s tip tc trong qu trnh lm kh. Cc protein trong phi nh b phn gii thnh cc amino acid v chuyn thnh cc dng khng ha tan do cc phn ng vi cc polyphenol cc bin i ny s to ra cc hng v, mu sc cho ht. S xut hin nhng tin cht ca hng chocolate, nhng cht ny c hnh thnh khi ht mi b cht, cng lc y anthocyan cng nhanh chng b mt. Ch c nhng tin cht mi truyn cho ht cacao khi rang hng v c bit cn thit cho sn phm ny. Nhng t bo cha sc t cng nh nhng t bo d tr ca phi nh ht ti khng cha cht c hng chocolate. Nu ht khng ln men th s khng c mi hng ny, ngay c khi rang. V vy, ngi ta khng nh nhng cht hng ca cacao ch sinh ra trong qu trnh ln men. Nhng ng kh tm thy trong ht ln men l mt thnh phn16



ca nhng tin cht. Trong qu trnh rang, chng tham gia vo nhng phn ng phc tp vi nhng acid amin t protein b phn gii thot ra to nhng cht aldehyde bc hi sinh ra nhng mi hng c bit ca mi loi cacao. Thng thng cc purin c th khng tham gia vo s to thnh nhng mi hng ny. S thay i hng v ca ht cacao trc v sau ln men c th hin trn hnh 3.5.

Hnh 3.5 S thay i hng v ca ht cacao trc v sau ln men C th tm tt cc bin i sinh ha trong qu trnh ln men nh sau: Lp cht nhy: CO2 H2OH hp Hiu kh

ng Acid hu cVi khun lactic

Nm men Ln men

Ethanol CO2

Acid lactic Phi nh:enzyme

Vi khun acetobacter

Acid acetic polyphenolenzyme

Protein

enzyme

ng a ng n

Amino acid

Cc cht tin hng v chocolate17



Bin i ha hc: Hm lng ng, acid hu c ban u gim do nm men v cc vi khun lactic s dng chng nh ngun cung cp carbon. Hm lng protein gim do b phn gii thnh acid amin tham gia phn ng to cc hp cht mu v do theobromine b mt i. Hm lng ethanol, acid acetic, acid lactic v CO2 tng ln. Trong 24 48 gi u hm lng ethanol trong phn cm nhy c th tng ln ti 6 %. Kt thc qu trnh ln men, lng acid acetic c th t c 2 % v lng acid lactic tng t 0,01 0,22 %. Hm lng polyphenol gim. Bin i vt l: - Nhit khi ht tng do qu trnh ln men sinh nhit. Nhit tng mnh t ngy th hai tr i. Nhit khi ht trong qu trnh ln men c th tng ln n khong 500C, nhng phi khng ch nhit lun thp hn 600C trnh s ln men qu mc. S thay i nhit trong qu trnh ln men c th hin trn hnh 3.6. - Khi lng gim do qu trnh ln men phn gii lp nhy bn ngoi thnh dch lng thot ra ngoi.

Hnh 3.6 S thay i nhit trong qu trnh ln men18



Bin i ha l: pH cht nhy tng do cc acid hu c trong cht nhy b s dng nh ngun cung carbon cho cc vi sinh vt trong qu trnh ln men. pH ca cht nhy trc khi ln men l khong 3,5 v tng ln 4,6 4,9 sau khi kt thc ln men. pH phi nh gim t 6,3 6,5 xung 4,5 5,1 do mt phn acid acetic v acid lactic to ra t s ln men lp cht nhy bn ngoi di chuyn vo trong phi nh. c. Thit b s dng Quy trnh 1: s dng thit b ln men dng khay (cuvet) Khay c dng hnh hp ch nht lm bng inox, chiu cao 23 cm, bn trong cch y 3 cm l mt v lt inox c c nhng l nh thot dch ln men. Chiu cao ca lp ht ln men l 15cm. Cc khay c xp ln mt gi c nhiu k, sau c t vo trong t ln men. T c h thng qut ht, h thng thi kh. Sau 2 ngy tin hnh o trn bng tay v sc kh vo.3 1 5

2 4

Hnh 3.7: Thit b ln men dng khay (cuvet)19



1- Bung ln men 3 B phn gia nhit khng kh 5 Ca thot kh Thng s cng ngh: Lng nguyn liu u vo Chiu cao lp nguyn liu

2 Khay ln men 4- Qut ht

250 kg ht ti/m 15 cm Sau 48 v 96 h ln men, lu lng 1000 lt/pht 30 pht 5 ngy 50C

Thi im v lu lng khng kh c cp vo t ln men Thi gian cung cp khng kh Thi gian ln men Nhit ln men Cu to

Quy trnh 2: s dng thit b ln men hin i c dng hnh tr ng thc hin qu trnh ln men ht cacao s dng thit b ln men hnh tr ng y cn, hai lp v lm bng inox, c np y. Bn trong thit b cn c b phn sc kh, cnh khuy v cc h thng cm bin o nhit . Pha di y thng l tm v chn c c nhng l nh tch phn dch ln men (ng knh l khong 1 2 mm)

20

Quy trnh sx ht cacao thng phm 12 11 1


2 3 9 8

10 7 5 6 4

Hnh 3.8: Thit b ln men dng hnh tr ng 1- ng c cnh khuy 2- Cnh khuy 3- Bung cha 4- Lp v lt c c l 5- Ca thot dch ln men 6- Ca np kh Nguyn tc hot ng: Cho cacao vo cc thng ln men, cacao ln men t nhin. Khi ng b phn iu khin theo di nhit . Khi cacao ln men sinh ra nhit lm tng nhit trong thng. Tuy nhin mc tng nhit ny cn c kim sot khng b ln men qu mc. Sau mi hai ngy ln men tin hnh khuy trn cung cp khng kh qu trnh ln men c tt hn. Khng kh s c thi t di ln qua lp v chn i xuyn qua lp ht cung cp oxy cho s pht trin ca vi sinh vt. Thng s cng ngh:21

7- Ca tho sn phm 8- ng c bm nc 9- B phn gia nhit nc 10- Ca nc vo 11- Ca nc ra 12- Np y



Lng nguyn liu u vo Chiu cao lp nguyn liu Thi im v tn s khuy trn Thi im v lu lng khng kh c cp vo bnh ln men Thi gian cung cp khng kh Thi gian ln men Nhit ln men 3.3.4 Ra a. Mc ch cng ngh: chun b v hon thin.

250 kg ht ti/m 150 cm Sau 48 v 96 h, 10 - 15 pht/ln Sau 48 v 96 h ln men, lu lng 500 lt/pht 30 pht 5 ngy 50C

Ht sau ln men vn cn mt lng nh cht nhy bm quanh ht. Qu trnh ra gip loi b cc cht nhy ny, lm cho qu trnh sy nhanh hn. ng thi ht qua ra sau khi sy s c sng bng hn. b. Cc bin i ca nguyn liu Bin i vt l: khi lng thay i. Bin i ha l: hm m ca ht tng ln. Bin i vi sinh: c th nhim cc vi sinh vt t nc ra. c. Thit b s dng: s dng thit b ra gin on c cnh khuy.1 2 3 5 4

6

Hnh 3.9: Thit b ra c cnh khuy22



1- ng c cnh khuy 2- Cnh khuy 3- Bung ra

4- Gi li 5- Nc vo 6- Nc ra

Cu to: thit b gm mt gi li t bn trong mt bn ra bng inox. Cacao c cho vo gi li, t vo bn ra. Nc chy lin tc vo bn. tng cng hiu qu qu trnh ra s dng thm cnh khuy. Nc ra mang cc cht b nhy thot ra ngoi. Thng s cng ngh: Nhit nc ra Thi gian ra Tc khuy trn 3.3.5 Lm kh ht sy a. Mc ch cng ngh Bo qun: ht sau khi ln men xong phi a i sy ngay m ca ht gim xung cn khong 7% thun li cho qu trnh bo qun. Nu m ca ht cao hn 8% th nm mc d pht trin lm gim cht lng ht. Hon thin: trong qu trnh sy, dc tc dng ca nhit cao ht cacao ln men s hnh thnh mt s hp cht mu v mi, ch yu l s oxi ha cc polyphenol di tc dng ca cc polyphenoloxydase. Cc hp cht quinon cng c hnh thnh. Nhng cht ny sau tc dng vi cc acid amin t do hoc cc protein lm thay i mu sc ca ht. b. Cc bin i xy ra Bin i vt l: Trong qu trnh sy s xut hin gradient nhit trong ht cacao. Nhit s tng cao ti vng b mt ht v gim dn ti vng tm. S khuch tn m s xy ra do s chnh lch m ti cc vng khc nhau bn trong ht. Cc tnh cht vt l ca ht s thay i: ht gim th tch, co li, tr nn gin hn.23



Bin i ha hc: Cc phn ng oxi ha cc hp cht polyphenol xy ra nhanh hn di tc dng ca nhit cao trong qu trnh sy hnh thnh cc hp cht mu. Phn ng Maillard gia ng kh v cc gc NH2 t do. Bin i ha l: S chuyn pha ca nc t lng thnh hi. B cacao b ha lng. Bin i ha sinh: Di tc dng ca nhit cao, cc enzyme b v hot, protein b ng t. Bin i ha sinh: Vi sinh vt tham gia qu trnh ln men b c ch hot tiu dit t chm dt hn qu trnh ln men ht cacao. Ngoi ra, cc vi sinh vt b c ch hoc tiu dit mt phn cn l do hot nc trong ht cacao gim. c. Thit b v nguyn tc hot ng thc hin qu trnh sy s dng thit b i lu dng sy khay. Cu to v nguyn tc hot ng

1 - Qut, 2 - caloriphe, 3 - bung sy

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Hnh 3.10 Thit b sy i lu dng khay Thit b gm ba b phn chnh: mt qut ht, mt caloriphe v bung sy, bn trong bung sy c nhiu khay c c l. Vt liu sy c cho vo cc khay ri xp vo bung sy. Qut ht s ht khng kh ngoi tri y qua caloriphe c nung nng thnh tc nhn sy ri i vo bung sy, chy trm qua cc khay, ly m t vt liu sy ri thot ra ngoi. Trong qu trnh sy, c sau 3 gi sy th ngng li 1.5 gi m t bn trong ht di chuyn ra ngoi gip qu trnh sy tip theo c d dng. Qu trnh sy ko di n khi t c m cn thit. Thng s cng ngh m nguyn liu vo Chiu cao lp nguyn liu Tng thi gian gia nhit sy Nhit sy Lu lng tc nhn sy m sn phm 60 65% 5 cm 20 24 h 50 - 600C 1 3 m3/s 6.5 7%

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3.3.6 Phn loi tch tp cht a. Mc ch cng ngh: hon thin. Ht cacao sau khi sy c a qua h thng sng phn loi, ng thi tch cc tp cht cn st trong ht. b. Cc bin i xy ra: ch yu l bin i vt l do tp cht c tch ra khi ht cacao. c. Thit b s dng: h thng sng phng, mt sng chuyn ng rung Cu to v nguyn l hot ng: mt sng l mt hnh ch nht, c c cc l trn, ng knh 5 mm. Mt sng c t nghing khong 150 so vi mt phng ngang v c ni vi mt ng c bng c cu truyn ng. Khi ng c hot ng lm sng rung, ht di chuyn theo mt phng nghing, cc tp cht c kch thc nh hn l sng s i qua l sng, ri xung di v c tch ra ngoi. Cacao sau di vo thit b ng gi. 3.3.7 Bao gi a. Mc ch cng ngh: bo qun. Ht cacao sau khi lm sch c cn nh lng, ng vo bao b ph hp bo qun. S dng bao b gm bao PE bn trong v bao ay bn ngoi. b. Cc bin i xy ra: hu nh khng c bin i g xy ra giai on ny. c. Thit b v nguyn tc hot ng: Nguyn tc hot ng: Khi thit b hot ng, nguyn liu c cp vo phu cp liu v i vo bng ti liu n cn nh lng t ng. Bao c a vo ming phu ti ca thot, c cu kp bao s tc ng, bao c kp cht, cc van iu khin bt u m, ht chy vo bao. Ty theo trng lng yu cu c ng bao, ngi thao tc t gi tr nh lng yu cu mc cn th v cn tinh phn iu khin (cho c lot sn phm). Khi t yu cu v trng lng, cc van iu khin ln lt ng, dng vic cp liu vo bao, c cu kp bao ngng tc ng, bao ng trn bng ti v c a n v tr may ming bao.26



Phu cp liu

Bng ti liu

Cn nh lng t ng Ca ra ca cp nh lng Thng liu cn V tr gn bao

ng c H thng ng m cn Ca thot li u

ng c

H thng bng ti

Hnh 3.11: Thit b ng bao 3.4 So snh hai quy trnh Quy trnh 2 Thit b s dng u im Thit b ln men hnh tr ng - C th o trn t ng - Ph hp vi quy m sn xut ln - t tn nhn cng - Cht lng ht tt hn Nhc im - Chi ph u t thit b cao - Chi ph v nng lng. - i hi nhiu nhn cng. - Cht lng ht thp hn. Quy trnh 1 Thit b ln men dng khay (cuvet) - Thit b n gin, chi ph u t thp, d vn hnh.

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CHNG 4. CHT LNG SN PHM HT CACAO THNG PHM4.1 M t sn phm Ht cacao thng phm l ht cacao c ln men, lm kh n m an ton cho bo qun. Ht cacao khng c mi khi, khng c bt c mi v l v bt thng no ngoi mi cacao. Khng c cn trng trong ht. Ht phi ng u v kch thc, trong khi ht khng c cc mnh v ca v ht v cc tp cht. 4.2 Tiu chun cht lng sn phm 4.2.1 Thut ng v nh ngha (TCVN 7518: 2005) Ht cacao (cocoa beans): ht ca cy (Theobroma cacao Linnaeus), cn nguyn vn c ln men v lm kh. Ht cacao kh (dry cocoa beans): ht cacao c lm kh n m quy nh (khng vt qu 7,5 %). Ht khuyt tt (defective beans): ht cacao b mc bn trong, b xm mu, b h hi do cn trng/ b nhim cn trng hoc b ny mm. Ht mc (mouldy beans): ht cacao c phn bn trong b mc m khng th nhn thy bng mt thng. Ht chai xm (slaty beans): ht cacao b xm mu trn mt na b mt hoc ln hn, khi c kim tra bng phng php quy nh trong TCVN 7522 : 2005. Ht cacao Xc nh cc dng khuyt tt sau khi ct. Ht b h do cn trng/ nhim cn trng (insect damaged/ infested beans): ht cacao c cc phn bn trong cha cn trng bt k giai on pht trin no hoc b cn trng lm h hng m c th nhn thy bng mt thng. Ht ny mm (geminated beans): ht cacao c v b m thng, nt hoc v do mm ht pht trin.

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Ht m khi (smoky beans): ht cacao c mi, v hoc c biu hin bn ngoi b nhim khi. Ht lp (flat beans): ht cacao c hai l mm qu mng, khi ct kh c th c c nguyn chiu di l mm. Ht v (broken beans): ht cacao b mt mt mnh nh hn hoc bng mt na ht. Mnh v (fragment): mt phn ca ht cacao nh hn mt na ht. V ht (piece of shell): phn v m khng c nhn. Ht cacao ln men hon ton (fully fermented beans): ht cacao c mu sc ca l mm c chuyn t mu ta v mu nu tng phn sang mu nu hon ton. S pha ln (adulteration): s bin i thnh phn ca ht cacao phn loi bng bt k cch no hoc ln loi quy nh, hoc cht lng hoc mi b nh hng, hoc khi lng b thay i. S m ht/s ht c trong 100 g (bean count): tng s ht cacao m c (khng k ht lp v v) c trong 100 g. Tp cht l (foreign matter): bt k cht no khng c ngun gc t cacao. Rc thi cacao (cocoa waste): ht lp, mnh v, mnh v v mnh ht, bi, mng qu kh, tht qu kh v cung chm. Ht kt dnh (bean cluster): chm ht cacao khng th tch ri m khng lm v ht. 4.2.2 Yu cu k thut 4.2.2.1 Yu cu chung Khng c c tp cht l. Khng c c mi khi, khng c mi hoc v l. Khng c cha cn trng sng. ng u v kch thc. Khng c cc ht dnh i, dnh ba. Kh u. c ln men hon ton.29



4.2.2.2 Yu cu c th Ht cacao c phn thnh ba loi; 1A, 1B, 1C v c c quy nh c th trong bng 3.1 Bng 4.1 Yu cu i vi ht cacao Loi Ch tiu 1. S ht c trong 100 g (s m ht), khng ln hn 2. m (%), khng ln hn 3. Ht chai xm (%), khng ln hn 4. Ht mc (%), khng ln hn 5. Ht b h do cn trng, ht ny mm (%), khng ln hn 6. Tp cht rc thi cacao (%), khng ln hn nng nht theo th t gim dn nh sau: Ht mc Ht chai xm Ht h hi/ b nhim cn trng v ht ny mm. 4.2.2.3 D lng thuc bo v thc vt Theo quy nh hin hnh 4.2.2.4 Bao gi, ghi nhn, bo qun v vn chuyn Bao gi: Bao b phi sch, nguyn vn, chc chn v khu ng cch. Bao b v lp lt, nu s dng, phi c lm bng vt liu an ton cho thc phm. Ghi nhn: Mi bao gi ng ht cacao phi c nim phong chc chn. Trn bao b hoc du nim phong t nht c cc thng s sau: Cp loi;30

1A 100 7,5 3,0 3,0 2,5 1,0

1B 110 7,5 3,0 3,0 2,5 1,0

1C 120 7,5 3,0 3,0 2,5 1,0

Khi mt ht c nhiu hn mt loi khuyt tt, th ch tnh loi khuyt tt



Tn nh sn xut/ xut khu v giy php c lin quan (nu c); Tn nc xut x v a danh; Chuyn hng hoc l hng hoc s hp ng (nu cn); Khi lng tnh, tnh theo kilogam. Ch c s dng mc in hoc sn khng c ghi nhn v khng c tip xc vi ht cacao. Bo qun: L hng cacao c trong cc kho c xy dng v s dng sao cho gi c m thp. Bao gi ht cacao phi c bo qun trn cc bc hoc k cch sn t nht l 7 cm lu thng khng kh. Phi c bin php bo v sn phm khi cn trng gy hi, loi gm nhm v cc ng vt gy hi khc. Cc bao gi ng ht cacao phi c sp xp theo cch sau: Cc cp loi phi ring bit, gia cc li i rng t nht l 60 cm v cc bao sn phm cng phi cch tng ca kho t nht l 60 cm; C th tin hnh kh trng bng phng php xng hi hoc phun bng thuc dit cn trng thch hp, nu cn; Khng sn phm b nhim bn mi hoc hng, hoc bi t cc sn phm khc; m ca mi l phi c kim tra nh k trong sut qu trnh bo qun v ngay trc khi chuyn ln tu. Vn chuyn: Ht cacao c vn chuyn bng phng tin kh ro, sch s, bo v c sn phm. 4.2.3 Ly mu (TCVN 7521: 2005) 4.2.3.1 Phm vi p dng Tiu chun ny quy nh cc iu kin chung lin quan n vic ly mu nh gi cht lng ca ht cacao.

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Tiu chun ny cp n vic ly mu ht cacao ng bao nh quy nh trong TCVN 7519: 2005 ; ng thi cng a ra quy nh ly mu ht cacao ri. 4.2.3.2 nh ngha Trong tiu chun ny p dng cc nh cc nh ngha sau: Chuyn hng (consigment): lng ht c gi i hoc vn chuyn cng mt thi im v c khng ch bi hp ng c th hoc chng t gi hng. L hng (lot): mt lng hng ha c tha nhn c cc c im ng u, c ly t mt chuyn hng v c dng nh gi cht lng ca l hng . Cc l hng khng c vt qu c quy nh v mi mt mu cui ch c th i din cho mt l hng. Mu ban u (primary sample): mt lng nh ht cacao c ly t mt v tr trong l hng. Mu chung (bulk sample): mt lng ht cacao c to thnh bng cch tp hp v trn cc mu ban u t cc v tr khc trong l. Mu rt gn (reduced sample): mt lng ht cacao thu c bng vic gim mu chung, nu cn v t mu cui cng c ly ra. Mu cui cng - mu phng th nghim (laboratory sample): mt mu nh i din cho cht lng l hng, thu c t mu chung hoc mu rt gn v c dng kim tra trong phng th nghim. 4.2.3.3 Yu cu chung Vic ly mu phi do cc chuyn gia ly mu thc hin hoc c s ng ca cc bn c lin quan. Chuyn hng hon thin phi c kim theo cc l khng qu 25 tn khi chuyn i v khng qu 200 tn khi chuyn n. Cc mu phi i din cho cc l hng xc nh v do thnh phn ca cc l hng chng mc no thng khng ng nht, nn mu chung phi c ly bng cch t mi l hng rt mt s lng nht nh mu ban u v32



trn u. Mu dng kim tra trong phng th nghim phi thu c bng vic rt gn lin tip mu chung ny. Vic ly mu cc ht h hng do i bin hoc trong khi vn chuyn, hoc trong iu kin xu, cng nh do ri vi hoc do b loi ra, phi c tin hnh ring bit vi vic ly mu cc ht tt. Cc sn phm ny khng c trn ln vi ht tt v c nh gi ring. c bit ch m bo rng tt c cc dng c ly mu phi sch, kh v khng c mi l. Vic ly mu phi c thc hin sao cho bo v c cc mu ht cacao, dng c ly mu v vt cha mu trnh khi nhim bn ngu nhin nh ma, bi Cht bm dnh bn ngoi dng c ly mu phi c loi b trc khi mu ra. 4.2.3.4 Thit b, dng c Ly mu t bao: ng thm mu (xin mu) c thit k c bit ly mu trong cc bao. Ly mu ri: dng c xc mu bng tay, ng thm hoc cc dng c thch hp khc dng rt cc mu nh nh k t dng chy ca ht cacao. Trn v chia mu: dng c chia mu c hnh nn hoc khng c loi ny th dng dng c chia bn bng st hoc dng c chia mu thch hp khc. 4.2.3.5 Phng php ly mu a. Mu ban u: ty theo tng trng hp m mu ban u c ly ra, t mu trong bao gi hay t mu ri. T 1 tn hay mt phn ca tn ly ti thiu 300 ht. i vi hng bao gi: cc mu ban u phi c ly t t nht mt phn ba s bao trong mi l, cc bao c rt ngu nhin t l hng. Dng ng xin ly ngu nhin t pha trn, v tr gia v di y ca cc bao trong iu kin tt. i vi hng ri: T 1 tn hoc mt phn ca tn ly t nht nm mu ban u.

33



Nu vic ly mu c thc hin trong khi ang mu th cc mu ban u c ly trong khi ht ang ri ti cc khong thi gian c xc nh bi tc dng chy. Khi ly mu ht c ri nm trn b mt sch, th mu ban u phi c rt t pha trn, gia v pha di ca ng sau khi ht trong l c trn k. b. Mu chung: thu c mu chung, gp cc mu ban u li v trn k. c. Mu rt gn Mu cui cng: Dng dng c chia mu, rt gn mu chung bng cch chia nh mu chung cho n khi thu c mu rt gn c c ph thuc vo s lng yu cu v mu cui cng v khi lng ca chng. S lng mu cui cng cn kim tra v phn x cn c quy nh trong hp ng hoc theo tha thun gia ngi mua v ngi bn, cng c th quy nh bi c quan kim tra. Thng thng, mt mu cui cng c khi lng 2 kg l . Trong cc trng hp c th, c th cn n mu ln hoc nh ph thuc vo cc php th nghim cn thc hin. 4.2.3.6 Bao gi v dn nhn cc mu cui cng Bao gi: Vt cha mu v h thng kn ng mu phi sch v kh. Chng phi c lm t vt liu khng nh hng n mi, v hoc thnh phn ca sn phm. Mu dng xc nh m, hoc phn tch s thay i m ca mu phi c bao gi kn bng cc vt cha khng thm nc. Cc vt cha phi c in y v c gn kn trnh lm thay i m ban u. Cc bao gi mu phi do mt ngi ly mu c ch nh tin hnh nim phong hoc c cc bn lin quan cng nhn. Dn nhn cho cc mu:

34



Nu s dng nhn giy cho ht cacao, th nhn phi c kch c thch hp v c cht lng tt thch hp cho mc ch nh. L xu dy trn nhn phi c gia c. Nhn phi c gn vo vt ng mu v phi do ngi ly mu ch nh nim phong hoc c cc bn c lin quan cng nhn. Ti thiu cc thng tin sau phi c ghi ln nhn: Tu, xe hoc kho hng; T (trong trng hp vn chuyn bng tu hoc xe); n. n. S lng; Hng ri / ng bao (s lng); Hng ha; Du nhn bit hoc s l hng; S vn n hoc ngy vn n hoc ca hp ng; Ngy ly mu; V tr v im ly mu (c bit, trong trng hp sn phm ri th nu r vic ly mu c thc hin thi im bt u hay sau cng ca h thng vn chuyn); Mu c ly bi. Thng tin trn nhn th phi r rng v kh ty xa. 4.2.3.7 Gi mu Mu cui cng phi c gi i ngay sau khi kt thc vic ly mu. 4.2.3.8 Bo co ly mu Trong bo co ly mu phi ch ra c k thut s dng, nu khc vi m t trong tiu chun ny, phng php rt gn mu s dng v mi tnh hung c th nh hng n vic ly mu. Bo co cng phi ch ra tnh trng ca l hng v cc yu t do ngi ly mu quan st c m c th nh hng n mu sau ny (v d nh s nhim cn trng).35



4.2.4 Phng php kim tra mt s ch tiu 4.2.4.1 Xc nh s ht c trong 100 g T mu c ly theo TCVN 7521 : 2005 trn k v chia bn, ly hai phn cho gc hoc bng dng c chia mu thch hp, sao cho mt phn ch va khong 300 ht nguyn thc t sau khi loi b cc ht lp v ht v. Cn s ht nguyn chnh xc n 0,05 g. S ht c trong 100 g c tnh nh sau: S m ht = S lng ht nguyn Khi lng ht nguyn 100 %

Kt qu c ly n s nguyn theo quy tc lm trn s. 4.2.4.2 Xc nh m (TCVN 7520: 2005) nh ngha: m ca ht cacao (moisture content of cocoa beans) l s hao ht khi lng c xc nh theo phng php quy nh trong tiu chun ny v c biu th bng phn trm khi lng. Nguyn tc: Ht cacao sau khi nghin, c lm kh 16 gi trong t sy c kim sot 1030 C. Thit b v dng c Chy v ci gi, nghin ht m khng b gia nhit. T sy thng gi, tt nht l c lp qut, kim sot c nhit 1030 C 20 C. a c np y, bng kim loi chng n mn di cc iu kin th nghim, hoc bng thy tinh, c din tch b mt tin ch, t nht 35 cm2 (v d ng knh ti thiu 70 mm) v c chiu su t 20 mm n 25 mm. Bnh ht m, c cht lm kh hiu qu. Cn phn tch. Cc thit b thng thng ca phng th nghim. Cch tin hnh Chun b mu th: trn k mu phng th nghim (mu cui cng) thu c theo TCVN 7521 : 2005. Bng cch rt gn lin tip mu trn k, ly36



khong 10g ht cacao, nghin dp s b trong ci gi khong 1 pht, sao cho kch thc ln nht ca cc ht khng qu 5 mm, trnh to thnh bt nho. Tt nht l nghin ring tng ht v vo trong ci gi ln lt tng ht mt. Cc ht c ly phi i din cho mu th nghim. Phn mu th: cn a rng v np c sy kh trc, cho ngay phn mu th c chun b trn vo a. y np v cn chnh xc n 1 mg. Xc nh: t a ng phn mu th ln trn np y vo trong t sy c kim sot nhit 1030 C 20 C. yn 16 gi 1 gi v khng m t sy. Ht gi, ly a ra, y ngay np li v t vo bnh ht m. ngui n nhit mi trng (khong t 30 40 pht sau khi t vo bnh ht m), gi nguyn np y v cn chnh xc n 1 mg. S ln xc nh: tin hnh hai php xc nh, mi ln thc hin trn mt lng ht c x l ring l, nghin, ly phn mu th v sy kh. Ch khi tin hnh: Cc thao tc nghin v cn i vi mi ln xc nh phi c tin hnh cng nhanh cng tt, trong bt k trng hp no cng khng qu 5 pht. Sau khi cn phn mu th, ring a cn, v d nh khi cn hng lot. Biu th kt qu Phng php tnh v cng thc: m ca mu, biu th theo phn trm khi lng, c tnh bng cng thc: (m1 Trong : m0: l khi lng ca a rng v np, tnh bng gam. m1: l khi lng ca a v np cng vi phn mu th trc khi sy kh, tnh bng gam. m2: l khi lng ca a v np cng vi phn mu th sau khi sy kh, tnh bng gam.37100 m1 m0

m2)



Ly kt qu s hc ca hai php xc nh, tha mn yu cu v lp li. Nu khng, lp li php xc nh. Bo co kt qu n mt ch s thp phn. lp li: chnh lch gia cc kt qu ca hai php xc nh trn cng mt php phn tch, c tin hnh ng thi hoc lin tc nhanh, khi lng hao ht khng c vt qu 0,3 g trn 100 g mu. Bo co th nghim Bo co th nghim phi ch ra c phng php s dng v kt qu thu c. Bo co cng cp n mt s iu kin thao tc khng quy nh trong tiu chun ny, hoc vic ty la chn cng nh mt s cc trng hp khc c th nh hng n kt qu. Bo co th nghim phi bao gm tt c thng tin cn thit nhn y v mu. 4.2.4.3 Xc nh tp cht T mu c ly theo TCVN 7521: 2005 trn k v chia bn hoc s dng dng c chia thch hp. Cn phn mu chia bn. Tch ring phn tp cht v cn. Lng tp cht c tnh nh sau: Rc thi cacao (%) = Khi lng tp cht Khi lng mu 100 %

4.2.4.4 Xc nh cc dng khuyt tt sau khi ct (TCVN 7522: 2005) Chun b mu th: trn k mu cui cng ca l hng (mu phng th nghim) thu c bng phng php quy nh trong TCVN 7521: 2005. Rt gn mu phng th nghim bng cch chia thnh bn phn hoc bng dng c chia thch hp, n khong trn 300 ht. Phn mu th: t mu th nghim ly ra 300 ht nguyn vn.

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Xc nh: tch hoc ct 300 ht dc theo gia ht, sao cho l ra mt ct ln nht ca l mm. Kim tra bng mt thng c hai na ca ht di nh sng ban ngy hoc nh sng nhn to tng ng. m ring tng loi khuyt tt ca ht, v d nh b mc, chai xm, b hng do cn trng gy hi, ny mm, lp hoc cc dng khuyt tt khc. Khi mt ht c nhiu hn mt loi khuyt tt, th ch tnh loi khuyt tt nng nht theo th t gim dn nh trong TCVN 7519: 2005. Biu th kt qu cho tng loi khuyt tt theo phn trm ca 300 ht c k i m t ra. Bo co th nghim: Bo co th nghim phi nu r phng php s dng v kt qu thu c. Bo co cng phi cp n bt k chi tit thao tc no ca cch tin hnh m khng c quy nh trong tiu chun ny, hoc nhng la chn ty v bt k trng hp no khc c th nh hng n kt qu. Bo co cng bao gm mi chi tit c yu cu nhn bit y v mu.

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TI LIU THAM KHO1. L Vn Vit Mn (ch bin). Cng ngh Ch bin Thc phm. Nh xut bn H Quc gia TP.HCM, 2010. 2. Nguyn c Lng. Cng ngh vi sinh (tp 1,3). NXB i hc quc gia TP. H Ch Minh, 2008. 3. Phm Tr Thng. Bi ging bo qun v ch bin cacao. Trng H Nng Lm TP.HCM, 1999. 4. Nguyn Vn Thng. K thut ln men v phi sy cacao p dng ti Wasi v Ty Nguyn. Vin Khoa hc K thut Nng lm nghip Ty Nguyn, 2009. 5. Chales W. Bamforth. Food, fermentation and Micro organisms. Blackwell publishing. (p 198 p200) 6. Stephen T. Beckett. The Science of chocolate. The Royal Society of Chemical publisting, 2008. (p11-p22) 7. P J Fellows. Food processing technology - principles and practice (second edition). Woodhead publishing limited. (p 180) 8. Bernard W. Minifie. Chocolate, cocoa and confectionery science and technology (third edition). An Aspen publication. (p 3 p35) 9. Micheal P.Dole, Larry R. Beuchat, Thomas J.Montville. Food Microbiology. ASM press Washington, D.C

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