Browning cc loi thc phm c th l khng-enzyme (caramen ha hoc maillard phn ng) hoc enzyme. KHNG-enzyme BROWNING Caramen ha l mt phn ng enzym khng xy ra khi carbohydrate hay cc loi ng trong thc n c un nng . N l qu trnh loi b nc t mt ng tip theo l ng phn v cc bc polyme

.

Phn ng Maillard l mt phn ng ha hc gia mt axit amin v ng mt gim, thng l yu cu b sung nhit . Ging nh caramen ha, l mt hnh thc khng-enzyme nu. Nhm cacbonyl phn ng ca ng tng tc vi nhm i nhn ca amino axit amin, v th v nhng cha c m t mi v hng v kt qu phn t . Qu trnh ny lm tng tc trong mi trng kim bi v cc nhm amin khng v hiu ha . Phn ng ny l c s ca ngnh cng nghip hng liu, t cc loi axit amin xc nh cc hng v kt qu. Trong qu trnh ny, hng trm cc hp cht hng v khc nhau c to ra . Nhng hp cht ny ln lt ph v hnh thnh cc hp cht hng v mi, v nh vy. Mi loi thc phm c mt b rt khc bit ca cc hp cht hng v c hnh thnh trong phn ng Maillard. l nhng hp cht hng v cc nh khoa hc s dng trong nhiu nm to ra hng v nhn to .

-Enzyme nu - kt qu ca phn ng Maillard v caramen ha ca c rt.

Enzyme browing Cc ch phm enzim dng mu nu din ra khi cc enzyme polyphenol oxidase hay cc enzyme khc xc tc qu trnh oxy ha ca phenol trong tri cy hnh thnh cc hp cht c gi l quinon. Quinon sau c th polymerize hnh thnh melanins, gy ra cc sc t nu Cc ch phm enzim dng mu nu ca tri cy v rau thng khng mong mun v to ra tn tht nng n v kinh t cho ngi trng. Cc ch phm enzim dng mu nu l c li cho: Xy dng hng v trong tr ( y phn ng l khng chnh xc c gi l qu Pht trin cc mu sc v hng v tri cy sy kh nh qu sung v nho kh . Cc ch phm enzim dng mu nu l bt li cho: Tri cy ti v rau qu, c bit l trong to v Hi sn nh tm

trnh ln men)

khoai ty

Kim sot ca mu

nu

Ch phm enzim dng mu nu thng l kim sot ha cht, hoc bng cch ph hy cc ha cht c trch nhim vi nhit, phng php chn ph hy cc enzym thng c s dng bo qun mu sc trong cc loi rau. Nc chanh v axit khc c s dng bo qun mu sc trong tri cy, c bit l to, bng cch lm gim pH v loi b cc trang web ng cn thit cho cc enzyme hot ng.

Sau khi ch c 5 pht sunchokes tip xc vi khng kh bt u mu nu . (Hnh nh di) iu ny c th c kim sot bng cch p dng mt axit nh nc chanh (trn hnh nh)

Acid ascorbic c th c ch cc phn ng ha nu bng cch gim cc quinon tr li vi cc hp cht phenol ban u . Trong s hin din ca oxy hoc metalions, phenol c th d dng chuyn i cho cc

quinon.Maiya;

Nguyn tco o

Maillard phn ng Cc ch phm enzim (oxy ha) Browning

Maillard phn ngGii thiuPhn ng Maillard l mt mu nu khng enzyme phn ng, gy ra bi s ngng t ca mt nhm amino v mt hp cht lm gim, dn n thay i phc tp trong h thng sinh hc v thc phm. Phn ng ny c m t ln u tin bi Louis Maillard vo nm 1912. Maillard phn ng xy ra khi hu nh tt c cc thc phm c un nng, v

cng c th xy ra trong qu trnh lu tr. Hu ht cc tc dng ca phn ng Maillard, bao gm c cc mi hng caramel v mu nu vng, l mong mun. Tuy nhin, mt s tc dng ca phn ng Maillard, bao gm c cc loi thc phm bng ti v pht trin off-hng v, khng c a chung.

Maillard phn ng* Aroma v hng v Maillard c ngun gc t hng liu l v cng phc tp v nhiu thnh phn c hnh thnh vi s lng du vt bng cch phn ng ph v con ng ti ngha. Deoxyosones c coi l ngun chnh ca cc hp cht mi thm d bay hi. Deoxyosones tri qua to vng / mt nc sn xut cc cht dn xut hng v furan quan trng v cc loi khc nhau ca furans c hnh thnh ty thuc trong cu trc osone. H s hng v cng thay i theo nhit v thi gian lm nng. Ti bt k s kt hp nhit -thi gian nht nh, hng thm c o, khng c kh nng sinh sn ti bt k s kt hp khc ca cc iu kin nng, c sn xut. S hnh thnh ca mt hng v c trng c th yu cu cc th h ng thi ca 100 hoc 200 ha cht c nhn trong nng thch hp v cn bng tinh t. Mt s lng ln v nhiu loi hng v v mi thm hp cht c hnh thnh thng qua phn ng Maillard. Hn na, thnh phn cht phn ng, mi trng v ch bin c th nh hng n phn ng. * Mu S pht trin ca mu sc l mt tnh nng cc k quan trng ca phn ng Maillard nhng tng i t c bit n v bn cht ha hc ca cc hp cht chu trch nhim. C c hai bn tt v xu ca cc phn ng Maillard cho s pht trin mu. Mu pht trin trong tht v bnh m nng l mong mun trong khi mu nu sa kh hoc cc sn phm b mt nc l khng mong mun.

Kim sot cc yu t ca cc sn phm phn ng Maillard* Nc hot ng (w) Nc l sn xut trong phn ng Maillard, do phn ng xy ra d dng trong thc phm vi mt gi tr cao w trong khi, ti thp w, linh ng ca cht phn ng c hn ch, bt chp s hin din ca h nng tng ln.

Khi con s hin th, trong thc t phn ng Maillard xy ra nhanh nht trung gian mt gi tr w (0,5-0,8), v w l c ngha nht phn ng trong thc phm kh v m trung (IMFs), trong c mt gi tr w trong phm vi ny. Tuy nhin, mt gi tr w ti a mu nu l b nh hng bi cc thnh phn khc ca h thng: cht gi m, chng hn nh glycerol, c th thp hn mt gi tr w ti a mu nu . * PH K t khi phn ng chnh n c mt nh hng mnh m trn pH rt kh nh gi nh hng ca pH. Tuy nhin, phn ng xy ra bi tt c cc con ng, vi pH ca h thng nh hng n t l sn phm c hnh thnh v t l hnh thnh mu sc c th c gim bng cch gim pH. Hng thm tht v ni rang hp dn nht thu c pH 4.7, nhng pH c mt t tc dng rt ln n hng v so vi nhit , thi gian, hm lng nc.

Cc con s cn li l "nh hng ca pH trn Maillard mu nu ca L-lysine, L-alanine, v Larginine un nng vi glucose-D 121C trong 10 pht". Theo iu kin kim yu, v vi mt mnh m cc thnh phn c bn th amino, ng 2,3enolization c a chung.

Ti sao hp th ca cc sn phm c sn xut t L-lysine l mt trong nhng cao nht? * Nhit S ph thuc nhit ca phn ng ha hc thng c biu din nh nng lng kch hot (Ea). D liu nhit kch hot cho cc phn ng Maillard c bo co trong mt phm vi rng 10-160KJ/mole, ty thuc vo hiu qu ca phn ng c o. Nng lng kch hot cng ph thuc nhiu vo pH. S ph thuc nhit ca phn ng Maillard cng b nh hng bi cc cht phn ng tham gia. V vy, rt kh c lp cc tc ng ca nhit nh l mt bin duy nht.

Cc ch phm enzim (oxy ha) BrowningGii thiuC bn loi phn ng ha nu trong thc phm: Maillard, caramen ha, axit ascorbic qu trnh oxy ha v phenolase mu nu. Cu ba khng phi l enzyme trong t nhin, v phenolase hoc enzyme, xc tc qu trnh oxy ha mu nu l ngha thng mi, c bit trong tri cy v rau ni phenolase l rt ph bin. Cc ch phm enzim dng mu nu l him m nguyn vn, k t khi nn phenolic v phenolase c tch ra. Cc ch phm enzim dng mu nu l rt ph bin b mt ct ca tri cy v rau qu c mu sng. B mt ct nhanh chng c th thay i mu nu do qu trnh oxy ha ca phenol orthoquines, m ln lt polymerize hnh thnh sc t mu nu hoc melanins nhanh chng. Enzyme xc tc qu trnh oxy ha phenol c th c phn loi nh phenolase, oligomers trong thc phm v c cha mt nhm b phn gi ng mi tiu n v.

Phn ngHai loi phn ng lin quan n phn ng phenolase xc tc, v d nh. hyroxylation v qu trnh oxy ha (theo hnh). Hydroxyl monophenols bc i chm v xc nh tc phn ng. Bn cnh tyrosine, nn chnh phenolases trong nh my bao gm axit caffeic, acid v axit chlorogenic protocatechuic phong ph trong cc nh my. Nhng tyrosine v chlorogenic acid l hai cht nn ph bin nht cho phenolase do tc phn ng tng i cao ca h. Phenolase ang hot ng trong pH5-7, v c th khng th phc hi bt hot pH thp hn pH 3.

Lm th no kim sot phn ng khng mong mun enzyme nu trong tri cy v ch bin rau ?

X l nhit bt hot phenolase p dng dioxide lu hunh hay sulfite iu chnh pH n 3 hoc thp hn bng cch s dng axit citric axit malic axit photphoric Ngm trong nc mui hoc siro