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Trng i hc M tp. H Ch Minh

TRNG I HC M TP.HCMKHOA CNG NGH SINH HC

ti

CC THUT NG NH GI CM QUAN SN PHM BIAGVHD:Nguyn Th Thu H Nhm thc hin: Nguyn B Qunh 0953010573 Lng Th M 0953010399 Hong Th Phng 0953010543 ng Th Dim Linh 0953010332 L M Kiu 0953012306 Mai Hong Phng 0953010531 H i Hi 0953012165 Nguyn nh Huy 0953012511 Trng Anh Phi 0953012265 ng Hong M Trn 0953012776 Nguyn Trng An 0953012003

Chuyn ngnh: CNG NGH THC PHM

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Mc LcI. II. Khi nim v nh gi cm quan Cc khi nim trong nh gi cm quan bia 1. Hu v(after-flavor; after-taste) 2. Mu phiu nh gi(answer form) 3. Thnh vin nh gi(Assessor) 4. S cn bng xut hin mu(Balanced presentation) 5. Thnh kin (Bias) 6. Mi l (Off-flavor) Khu gic v vai tr ca khu gic trong qu trnh cm nhn cht lng 1. Khu gic v vai tr ca khu gic trong qu trnh cm nhn cht lng 2. Cc tiu chun dng trong cm quan bia Gii thiu vng trn hng bia 1. Vng trn hng bia 2. Cc thnh phn hng trong bia

III.

IV.

3. Cc thnh phn hng ch yu : (>2 FU) (FU : Flavour unit) 4. Cc thnh phn hng quan trng th hai (0,5-2 FU) 5. Cc thnh phn hng quan trng th ba (0,1-0,5 FU) 6. Cc thnh phn hng nn (,0,1 FU)

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I. Khi nim v nh gi cm quanC rt nhiu nh ngha v cch m t khc nhau v khi nim nh gi cm quan sn phm: Phng php khoa hc c s dng gi ln, o c, phn tch v gii thch cm gic i vi cc sn phm vn c nhn bit thng qua cc gic quan: th gic, khu gic, xc gic, v gic v thnh gic. (Stone & Sidel, 1993). Hoc Phn tch cm quan l k thut s dng cc c quan cm gic ca con ngi tm hiu, m t v nh lng cc tnh cht cm gic ca mt sn phm thc phm nh: mu sc, hnh thi, mi v v cu trc

II. Cc thut ng trong cm quan biaChuyn ngnh: CNG NGH THC PHM Trang3

Trng i hc M tp. H Ch Minh

1. Hu v (after-flavor; after-taste): cm nhn v mi hoc v c c sau khi s dng sn phm v c cm nhn khc khi sn phm vn ang cn trong ming. 2. Mu phiu nh gi (answer form): L cc cu hi v cc biu cho im c pht cho mi thnh vin nh gi ghi chp. 3. Thnh vin nh gi (Assessor): L ngi bt k c tham gia vo qu trnh nh gi cm quan v c cung cp s liu. Cc t ng ngha: ngi th, ngi tham gia nh gi cm quan. 4. S cn bng xut hin mu (Balanced presentation): S ln mi mu xut hin tng v tr trong ton b bui th cm quan phi bng nha. 5. Thnh kin(Bias): Mt h thng li c th gy nh hng n cc kt qu hoc c nh hng i vi s nh gi. 6. Mi l (Off-flavor):Mi hng khng in hnh (mi hng do thc phm b h hng hoc nhim tp. III. Khu gic v vai tr ca khu gic trong qu trnh cm nhn cht lng Ngng cm nhn C ch cm nhn cc tnh cht cm quan ca sn phm l thng qua cc gic quan vi nguyn l nh sau: Ngun kch thch l cc hp cht (mi, v), nh sng, m thanh, nhit , s tip xc vi cc c quan th cm ca c gic quan (ch yu l c t bi b mt). Sau , nng lng ban u ca cc kch thch s tc ng vo mt phn t c trng gi l im nhn. Ti im nhn thng tin s c khuych i v truyn i n no. Cc t bo cm nhn cn c nhim v nhn din bn cht kch thch (v, mi hng, .) v cng ca kch thch. i vi sn phm bia, vic nh gi cm quan c rt nhiu yu t nh: hng, v... Tuy nhin trong bi vit ny ti ch cp n nh gi cm quan hng bia.

1. Khu gic v vai tr ca khu gic trong qu trnh cm nhn cht lngnh ngha

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Trng i hc M tp. H Ch Minh

Khu gic l mt c quan rt quan trng trong vic nh gi cm quan cht lng sn phm c s dng nh gi hng, mi ca sn phm.

Ngun kch thch: cc hp cht ho hc C hai l thuyt v ngun kch thch to ra mi hng Thuyt ha hc cho rng: cc loi cc phn t bay hi hu c hoc v c l ngunkch thch s tc ng ln cc t bo thn kinh ca mng nhy mi da trn hnh dng, cu trc phn t ca chng. Trong hai triu cht hu c, th 400.000 cht c mi nhiu hoc t. Theo nh ha hc hu c Amoore (1962), ca trng i hc Oxford nghin cu hng trm loi hng v a ti kt lun c 7 mi s cp: 1. Mi bng phin (long no) 2. Mi x hng (pentadecanolacton) 3. Mi hoa thm (phenylmetyletylcacbinol) 4. Mi bc h (mentol) 5. Mi ete (dicloetylen) 6. Mi cay hng (axit formic) 7. Mi thi (butylmecarptan) T by mi c bn ny trn theo cc t l nht nh c th thu c hng thm bt k. Theo thuyt ny, cc cht c mi bng phin u c hnh cu hoc gn cu. Mi te c hnh gy, mi bc h c hnh ci chm.

Thuyt l hc cho rng: nguyn nhn mi khng phi do hnh dng ca phn t mdo kh nng pht sng in t ca chng. Theo thuyt ny th cm gic c mi khng nht thit phn t c mi phi tip xc vi cc b phn cm bin ca t bo. Cc phn t khi dao ng s pht ra sng in t ging nh mt my pht tia hng ngoi. Cc t bo thn kinh s l my thu v no s phn tch a ra thng tin. L thuyt ha hc v l hc v mi b sung ln nhau. C th coi cc phn t c hnh dng ging nhau (tng t v cu to) s c dao ng nh nhau.

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C quan cm th v c ch: mi. Mi c kh nng cm nhn mi ca cc cht bay hic nng rt thp 107 n 1017 phn t/ml khng kh. Cc phn t cht bay hi sau khi vo mi c ha tan trong cc cht lng ca nim dch mi. Sau tc ng ln nhng c quan th cm nm trn cc lng mao ca mng nhy khu gic.

- Mt s nguyn tc khi cm nhn mi v hng:Trong qu trnh nh gi cm quan cm gic nhn c bng ng ngi trc tip gi l mi, nu cc cht mi c truyn qua ming ri mi ln mi (cm nhn c sau khi n v ung) c gi l hng. + Khi th bnh thng, tc dng kh qua mi khong 1m/s vi lu lng khong 100 m/s. Khi th mnh tc 10 m/s s gip cho nhn bit mi tt hn. Cn ch khi nh gi cm quan v mi, mu th cn c cha trong dng c c cng hnh dng, kch thc. Th tch khng kh trn b mt thong phi nh nhau.

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+ Khi ngi mi phi cch sn phm mt khong cch nht nh v nh nhau i vi cc mu + Trong khi nh gi i khi nh gi chung cm gic mi v.

2. Cc tiu chun dng trong cm quan bia1. bt: Nh, u, trng, xp. Bt bn, thi gian tn ti di 2. trong, mu sc: Trong sut, mu sc t vng rm n vng nht 3. Hng (mi): D chu, khng c cc mi l 4. V: Hi ho, d chu, khng c v l

IV. Gii thiu vng trn hng biaCc loi hng trong bia bao gm 800 trm mi hng chia lm mi bn nhm. Da trn danh sch hng ny, ngi ta xy dng nn mt vng trn hng c phn b v chi tit cc mi hng cu thnh nn hng sn phm bia.

1. Vng trn hng biaNm 1970, vng trn hng bia c chp nhn bi Hip hi ung Chu u (EBC), Hip hi nh Ho hc ung M (ASBC), Hi lin hip ung ca M (MBAA). Vng trn hng a ra s phn loi hng da vo s m t tn gi v cc nhm tng t vi 14 hng.(VD v s m t tn cc ng ng phenol th gm c 5 nhn din sau: tarry (ging nh nha), bakelit (nha tng hp, carbolic (phenol ), clophenol (C6H5ClO), iodoform (CHI3). Cc tn hng ca chng u ph hp vi t in ca Hip hi ung Chu u. Vng trn hng bao gm tng s 46 bc hng u tin- chng hn nh mi hoa qu, mi dung mi, mi kim loi. Mt loi bc th hai ph v bc loi bc th nht s m t 76 hng c trng c tm thy trong bia. Mt i to c o to v vic th hng bia nn c th xc nh xp x 100 cc loi hng. Hn mt na loi hng y c tm thy trong bia; cn li thng m t cc loi hng tm ra qu trnh b hng hoc nhng c im c trng trong bia.

2. Cc thnh phn hng trong bia

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Hng v c bit ca bia phn ln l t hoa hublng (phin m t tng Php). Hoa hublng thuc h Gai mo Cannabinaceae, cy Humulus lupulus L. trc kia l mt loi dy leo hoang di, dn dn c trng cc nc n i m thp u chu, chu cng nh M chu. nc ta nhng nm sau ny, v nhu cu trnh nhp cng, cng c th trng th nghim Mc Chu, H Bc, Lt. Ch c hoa ci c dng v tng i thm hn hoa c. Ngoi nhng thnh phn chnh (%) : protein (55), nha (19), cellulot (13), hoa cn cha tannin (3), tinh du (0,4), tro (7,5) v nc (12,5). Lc u hoa c dng ch thm hng v cho bia. Dn dn, ngi ta nhn thy hoa hublng cn c tnh cht n nh nc hm ng thi n cn c tc dng gi nng v lp bt. V ng ca bia l do nhng ha cht humulon, lupulon trong hoa hublng m ra. Humulon thm hn cht lupulon, ngoi ra n cn c tnh cht tr khun, c bit khun ht k (sarcine) trong bia. u chu, hoa hublng c xem nh cy thuc a tr : b dng, khai v, st trng. V c tc dng tt ln cc ng tiu ha , n c dng cha tr cc bnh bing n, rut mt trng lc, thn kinh d dy (1). Cy sn st H. japonicus Sieb. et Zucc. cng h vi H. lupulus, mc hoang di khp ni nc ta, cng c ly l ti hay l kh sc ung kht nc hay cha l, st, nhng khng c lng tit thm nn khng c dng ch bin ru bia, thng ch cho tru b

Cy Hublong mc hoang

Nh thy, nhng cht humulon, lupilon trong hoa bng c nh hng ln ln hng v ru bia. Kho cu su rng hn, ngi ta khm ph ra ra c mt lot cht Chuyn ngnh: CNG NGH THC PHM Trang8

Trng i hc M tp. H Ch Minh

xeton sp thnh hai nhm : nhm a-acid (85-95% tng s) gm c humulon, cohumulon, adhumulon, em un nng th bin cht thnh iso-a-acid cid tng ng, ngha l isohumulon, isocohumulon, v nhm b-acid gm c lupulon, colupulon, adlumulon. Iso-aacid l cht ng quan trng nht. Bia cn cha nhiu ha cht khc, t nhiu u c ng gp vo hng v chung : humulol, humulenol, humuladienon, humulen oxid, humulen, myrcen, caryophyllen, farnesen, linalool, geraniol, geranylisobutyrat nng ln trong cc loi bia Cluster, Cascade. Ngi thnh mi c th ngi thy trong ru bia mi hnh, nguyn do t cc ho cht c lu hunh : dimethyl sulfid, methional, methyl ethyl thiiran, methyl mercaptaptobutanal, -pentanon t phn ng ca hydrosulfid vi mesityloxid m ra ; mt lot methyl thio- propanol, -propanal, -propylacetat, -propionic acid cng ester tng ng v methyl tetrahydro thio phenol. Mt cng trnh kho cu khm ph cc vi khun Flavobacterium to ra ethyl mercaptan v dimethyl sulfid d bc hi, cn nm men S. diastaticus th em li hai dixeton : diacetyl v pentadienon, trong khi vi khun Pediococcus cerevisiae sn xut diacetyl, axetolactat cn Clostridium tertium th cng hin butyric acid c mi pho mt. Hng v bia cn chu nh hng mt s ha cht loi khc nh furan, pyridin pyrazin, thiazol, guanosin, catechin, quercetin, tryptophol, tyrosol, phenyl ethanol hay cc hydrocarbua thm a nhn nh benzathrancen, benzopyren, benzoperlen, dibenzopyren. Cyanidin, delphinidin xut pht t cht leuco anthocyanin c tm ra trong bia cng vi nhiu flavonoid nh kaempferol, myricetin v cafeic, coumaric, ferulic, chlorogenic acid. T nc hm qua ru bia, cc flavonoid ny bin chuyn rt nhiu. Cng c mt trong mt, tr, c ph, ch khong vi g/kg, cht lng b-damascenon gp phn ln vo hng v bia