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LI M ULoi ngi bit lm bnh t thi trung c, nhng chic bnh u tin c sn xut ra t nc Anh. Nhng chic bnh u tin c lm ra ch t mt s t nguyn liu nh: bt m, mui v nc. Vo thi y, lm bnh l mt cng vic nng nhc v vic n bnh cng khng d dng, bnh mun n c phi ngm vo cc loi thc ung nh tr, sa, nc, hoc sp cho mm mi dng c.Ngi Vit Nam bit n bnh biscuit khi ngi Php mang chng n nc ta trong chin tranh vo khong cui th k th 19. Ngy nay, nguyn liu dng sn xut bnh rt phong ph v bnh l mt mt hng c gi tr cao v mt dinh dng v cung cp nhiu nng lngNhng nm gn y, ngnh bnh Vit Nam pht trin rc r, khng ch nhiu v s lng m cn phong ph v mu m, gi thnh cng nh cht lng. Bnh ngy nay, c s dng nh mt loi thc n c bn trong cc ba n, bnh c xem nh mt thc phm tng cng dinh dng v c bit bnh cn c dng lm qu biu vo nhng dp L, Tt. Bnh c phn thnh nhiu loi da vo m ca bnh, da vo cc phng php to hnh hay phng php lm n.Vi nhng loi bnh nh sandwich, biscuit cng vi bnh cookie l dng bnh nng rt thng dng v tin li, chng c mi v thm ngon v hp dn. Ngoi ra cn c nhiu loi bnh nh bnh cake, waferang ngy cng c bit n nhiu hn. Hin nay th bnh c sn xut vi s lng kh ln, mi v v hnh dng bnh phong ph hn. to ra nhng chic bnh thm ngon i hi nh sn xut phi c nhng nguyn liu cht lng cao cng vi cng thc lm bnh ring cho mi loi bnh, ng thi phi c phng php lm n bnh thch hp.Chng em xin chn thnh cm n c H Xun Hng gio vin ging dy mn Cng Ngh Sn Xut ng Bnh Ko to iu kin chng em tip xc vi ti Phng php ha hc lm n bnh chng em c th hiu r v s bin i hay cc yu t nh hng n qu trnh nng cao kin thc.Sinh vin thc hin

NI DUNGI. Cc tc nhn ha hc lm n bnhNi v cc cht gip n, c l nn chia thnh hai nhm c bn, lin quan n hai loi bnh chnh l bnh m (bread) v bnh ngt (cake) (tht ra chia nh th ny khng hon ton chnh xc, nhng mc cn bn th chia theo cch ny s d hiu nht).Vi bnh m (bao gm c cc loi bnh m ngt, croissant), th c s dng gip bnh n l men n (yeast). Cn vi bnh ngt th hai loi cht gip n thng dng l bt n (baking powder) v mui n (baking soda/ bicarb). Tuy nhin, cn phi ni thm l khng phi loi bnh ngt no cng cn dng bt n hay mui n, v c ring mt dng bnh (Foam Cake) da vo bt kh trong trng hay lng trng trng nh bng n m khng cn n s h tr ca bt n.1. Baking soda Thnh phnL tn gi khc ca hp cht sodium bicarbonate (ting Vit: natri bicacbonat, natri hirocacbonat), c thnh phn ha hc l NaHCO3

(Ngun: http://hoachatjsc.com/p/6112/nahco3) c imy l mt ph gia thc phm thuc nhm INS500 (gm Natri Carbonat (i), Natri Hydro Carbonat (ii), Natri sesquicarbonat(iii)) trong INS (International Numbering System) l h thng nh ch s quc t do y ban Tiu chun Thc phm quc t Codex xc nh cho mi cht ph gia. Cht ny theo h thng "s E" ca chu u c gi l E500(ii).Baking soda c tm thy trong qung nahcolite nhng ni c hoc tng c sui khong, loi khong cht ny c to ra t hng ngn nm trc khi m cc sng h b bay hi mt cch nhanh chng bi nhit cao. Do c s dng rt rng ri trong thc phm nn n c nhiu tn gi, bread soda, cooking soda, bicarbonate of soda, trong ting Vit c bit n nhiu hn vi tn "thuc mui", "mui n". Trong ngn ng giao tip thng thng, tn ca n c rt ngn xung cn natri bicarb, bicarb soda, hoc ch n gin l bicarb.y l hp cht khi gp nhit nng hay tc dng vi cht c tnh acid s gii phng ra kh CO2(carbon dioxide/kh cacbonic). (Phuong trinh hoa hoc minh ha )V vy, baking soda c dng trong nu n, nh to xp cho nhiu loi bnh nhcookies,muffin,biscuits,quy Thm vo st c chua hay nc chanh lm gim nng acid, hoc cho vo nc ngm u hay lc nu s lm gim thi gian ch bin, u mm ngon v hn ch tnh trng b y hi khi n cc loi ht u, . Soda cng rt hiu qu khi c dng ch bin cc mn tht hm hay gn, c bp ng vt tng t nh nu u, c c iu l do kh cacbonic khi c gii phng ngm vo v lm mm cc loi thc phm. Trong y t, soda c dng trung ha acid cha au d dy; dng lm nc xc ming hay s dng trc tip ch ln rng loi b mng bm v lm trng

Hnh 1. Baking sodaBaking soda c kt cu ht nh, mn v c mu rt trng, an ton vi con ngi v thn thin vi mi trng, gi thnh r v cng dng a nng. Ngoi s dng trc tip cho con ngi, soda cn c dng lau chidng c nh bp, ty ra cc khu vc cn v sinh nh tnh nng mi mn, tc dng vi mt s cht (ng cn), rc vo cc khu vc xung quanh nh chng mt s loi cn trng.Baking soda dng trong thc phm l loi tinh khit, c th mua hiu thuc (tn l thuc mui hay natri bicacbonat), ni bn nhng dng c lm bnh vi nhng hng uy tn. Khng nn mua soda ni ca hng ha cht s dng trong nu nng v khng an ton (khng tinh khit, cha nhiu tp cht) v khng r ngun gc.(Ngun: Dr.Lakshmi J, Associate Professor,Dept of Food Chemistry, Bakery and Confectionary Products, College of Food Science and Technology, Bapatla, page 23 25) (Ngun:http://www.savourydays.com/tu-hoc-lam-banh-can-ban-cac-chat-gay-no-men-no-bot-no-muoi-no-phan-loai-va-cac-luu-y-khi-su-dung/)2. Baking powder Thnh phnBaking powder (bt ni, bt n).Thnh phn ca baking powder gm- Sodium bicarbonate (soda), l cht to bt, kh.- Cc mui acid (kh):+ Monocalcium phosphate+ Sodium acid pyrophosphate+ Sodium aluminum phosphate+ Sodium aluminum sulfatey l cc mui acid chnh c dng sn xut baking powder. Chng c thi gian phn ng khc nhau khi tc dng vi soda nhm mc ch duy tr qu trnh n trong thi gian lm chn bnh t c kt cu (texture) tt nht.- Tinh bt ng: L nguyn liu cui cng trong sn xut baking powder, n l mt cht tr, c tc dng lm kh v ti bt n, khng b ng cc; ngn cc cht ny phn ng vi nhau; ng thi gip cho vic chun ha khi lng ca baking powder, d dng trong vic cn ng khi lm bnh.Khi c mt cng thc, nu nhc n bt n/ni th l baking powder. Baking powder c nghin cu, sn xut vi mc ch duy nht l hon thin nhng chic bnh, v vy u im ca n hn hn baking soda trong vic to n v c th s dng trong nhiu loi bnh khc nhau.

Hnh 2. Cc thnh phn ca mt loi baking powder c imL cht gy n, ng thi cng l ha cht, baking powder khng gy nh hng n sc khe con ngi nhng cng ging nh mui n, dng va phi s an ton nht. Nhiu ngi hay lo lng mi khi s dng bt n cho vo bnh, cho nh cng thc th hi t, cha yn tm, s bnh khng n Cn bit rng, vi nhng loi bnh dng b, trng th lun c n nht nh, bt n nu thm vo ch h tr mt phn. c bit l nhng loi bnh cn trng nh bng nh gateau, chiffon hn hp nh, nu trng nh bng bnh s n tt, hn na cc loi bnh ny c cu trc xp, bt kh ca baking powder ln trong nn cng khng c tc dng g ngoi gii quyt yu t tm l. Nu trng cha bng th d bt n c lm bnh phng ln th khi ngui s vn xp v cu trc bt- trng khng vng, bnh khng ng c.Cc loi bnh thng s dng baking powder thng l nhng l loi c hn hp kh, chc nh cookies (cc loi) hay c v nng nhbrownies, muffin,cupcake, cc loibutter cakehaybnh baoV cng dng ca baking soda v baking powder l nh nhau nn trong trng hp ch c mt trong hai loi th c th thay th, vi cng mt lng. Cn ch , trong cc mn bnh hp, luc (dng nc lm chn) m c ch nh dng baking powder th khng nn thay bng soda v loi ny cho nhiu s c mi hi tanh, ch cc mn bnh nng vi nhit l cao mi lm ht c mi ny.

Hnh 3. Do c tinh bt ng, baking powder ging vi bt m hn, khi ha vo nc s c mu trng c; baking soda dng tinh th mu trng c mi thm nh, ha tan hon ton trong ncHm lng s dng:Ty theo xp mong mun m iu chnh hm lung. Thng thng t 3% - 5% /hm lng bt s dng(Ngun: Dr.Lakshmi J, Associate Professor,Dept of Food Chemistry, Bakery and Confectionary Products, College of Food Science and Technology, Bapatla, page 23 25)(Ngun:http://www.savourydays.com/tu-hoc-lam-banh-can-ban-cac-chat-gay-no-men-no-bot-no-muoi-no-phan-loai-va-cac-luu-y-khi-su-dung/)3. Bt khai Thnh phnC thnh phn l NH4HCO3(Ammonium bicarbonate) Thuc tnh

Cng thc phn tNH4HCO3

Phn t gam79.056 g/mol

B ngoiDng bt tinh th mu trng

T trng1.586 g/cm3

im nng chy41.9 C, 315 K, decomp.

ha tan trng nc11.9 g/100 mL (0 C)21.6 g/100 mL (20 C)36.6 g/100 mL (40 C)

(Ngun: http://www.ammoniumbicarbonate.com/products/) c imc dng lmquy, to gin v xp n. Bt khai ch c s dng trong cc mn chin do nhit ca du, m cao c kh nng lm bc hi hu ht cc thnh phn ca bt khai, trnh c mi kh ngi khi n v an ton vi sc khe. Mi ngi c th ngi c c vi trm n hng nghn phn t mi, trong khi mt du chm . ca vn bn in trn giy ln ti 1 triu, v vy chin quy khng cn mi th hon ton c th yn tm n (tr trng hp cc b m mang bu v ang cho con b, tr s sinh). Nn mua bt khai ti nhng ni c uy tn v c m bo v cht lng.(Ngun: Dr.Lakshmi J, Associate Professor,Dept of Food Chemistry, Bakery and Confectionary Products, College of Food Science and Technology, Bapatla, page 23 25)(Ngun:http://www.savourydays.com/tu-hoc-lam-banh-can-ban-cac-chat-gay-no-men-no-bot-no-muoi-no-phan-loai-va-cac-luu-y-khi-su-dung/)II. Bn cht ca phng php ha hc lm n bnh1. c im ca cc loi bnh lm n bng phng php ha hcMt s loi bnh lm n bng phng php ha hc nh biscuit vanilline, biscuit b u phng, cheese biscuit, cookies ng tin, bng lan b, bng lan l da Ph S, cookies duc im chung ca phng php ny l c th p dng rng ri trn cc loi bt nho khc nhau c dng bnh kh v dng bnh ti. Trong gn nh tt c cc loi bnh kh u dng phng php ha hc, bnh ti thng ch p dng i vi bnh bng lanc im nguyn liu: bt m c hm lng gluten t cao n thp, hm lng ng v cht bo ca bt nho tng dn t bnh Cracker n bnh Cookiesc im bt nho: khung gluten c th pht trin ti a -hard dough: dai, n hi loi bnh Cracker, gim dn (Biscuit cng) cho n s to khung gluten b hn ch do hm lng ng v cht bo cao -short dough: bt rt t dai v n hi Biscuit mm. Khi cu trc c bn ca bt nho s gm hn hp tinh bt, proteine v ng, cht bo dng ht ln gn cc ht tinh bt vi nhau, xen vo l cc bt kh. Cookies v bnh bng lan, s to khung gluten b hn ch mt cch ti a: bt rt mm do khung gluten gn nh khng pht trin.Phng php to hnh:Cracker: cn, phn tm v ctBiscuit cng: cn, ctBiscuit mm: c (p)Cookies: nn (n)Bng lan: khunCu trc sn phm: Cracker, Biscuit cng: gin, cngBiscuit mm: gin xpCookies: mm hoc mm xpBng lan: mm xp

2. Nguyn tcPhi trn thuc n vo khi bt nho. Khi nng, di tc dng ca nhit cao, thuc n s phn hy to kh lm xp bnh, hoc do phn ng gia cc cht trong thuc cng to kh. Thng s dng cc cht NaHCO3, NH4HCO3, hoc hn hp hai cht. 3. C chi vi baking soda v baking powder c cha hp cht NaHCO3 , hp cht ny l tng i r v c th t c trong cc lp kch thc ht khc nhau , v d, lp ht t do, ht tinh ch v ht mn . Mi trong s ny l ph hp nng, nhng lp th c th khng ha tan mt cch nhanh chng trong vic chun b v nng bnh ca bt nho v s cho kt qu m si bt mu nu sm trn b mt bnh . iu ny cng s l trng hp ny nu soda l sn khi thm vo bt v khng phn tn y trong qu trnh trn.S c mt ca m, soda s phn ng vi bt c thnh phn c tnh axit gii phng kh carbon dioxide. Mc ch ca s kt hp ny l to ra cc bong bng CO2 hoc l trc khi nng hoc l khi ming bt nho c gia nhit trong l nng. Cc bong bng kh ny to thnh cc vng nhn gip cho s gia tng kch thc khi kh c gia nhit v p sut hi nc tng trong sut qu trnh nng. Do , iu quan trng l phi to ra c cc bong bng kh nhiu v rt nh bnh con gu to thnh c cu trc mn, ng u.Nh nhiu thnh phn bnh bch quy, bao gm bt m, c mt phn ng c tnh axit n thng l hu ch s dng sodium bicarbonate nh mt cht iu chnh chua ca bt v do lm tng hng v ca bnh quy. Trong nhng trng hp bt n phi c phn tn ng u qua hn hp v nu cn thit soda nn c sng bng mt ci ry mn trc khi s dng loi b nhng phn b vn cc. D tha sodium bicarbonate s cung cp cho bnh quy vi mt phn ng kim v mt mnh vn v b mt vng vi mt mi v kh chu km theo.(Ngun: Duncan Manley, Biscuit, cookie and cracker manufacturing manuals, Published by Woodhead Publishing Limited, Abington Hall, Abington, Cambridge CB1 6AH, England, First published 1998, pages 70-74)Phn ng s tri qua 2 giai on:Giai on u tin: phn ng din ra khi bn thm bt n vo bt nho v n c lm m. Mt trong nhng mui axit phm ng vi NaHCO3 v to kh CO2.Ngay trong dung dch, nhit thng NaHCO3 cng phn hy chm gii phng kh CO2. Khi un nng phn ng phn hy din ra mnh lit hn.

Khi tan trong nc,NaHCO3 b thy phn cho mi trng kim rt yu c th pht hin bng qu hoc metyl da cam nhng khng th pht hin c bng phenolphtalein:

Giai on th hai: din ra khi bt t trong l. Cc phn t kh m rng lm th tch ca khi bt tng. Bi v trong hai giai on, qu trnh nng bnh c th b tr hon khong 15 20 pht m khng lm mt i kh nng dy bt ca n.NaHCO3 l mui km bn, b phn hy bi nhit 80 900C theo phn ng:

Lng kh thot ra lm xp bnh l 50%. Kh CO2 sinh ra khng mu, khng mi nn khng nh hng xu n cht lng bnh v lm cho bnh c mu vng p v v ngon c bit. y l loi thuc ni c s dng rng ri. Dng sodium bicarbonat qu mc s lm cho bnh biscuit c tnh kim, c ming hi vng vng b mt v c v kh chu. Gi tr pH cao, nh vt qua gii hn pH = 8 th cng c mi nh vy. Thng thng, mt vi loi bnh qui c bit, pH ca bnh l 7.0 0.5 v iu ny t c bng cch dng mt lng sodium bicarbonat. (Ngun: Hong Nhm, Ha hc v c, tp hai, NXB Gio Dc, nm 2005)Bt khai l cht gy n tt nht cho bnh bch-quy v n phn hy hon ton khi b t nng 600C, ph v vo kh carbon dioxide, kh amoniac v nc v do khng li d lng trong bnh nng. Tn Vol, m n thng c bit n, xut pht t " mui bay hi ' v phn ly hon ton ny. N l d dng ha tan nhng rt kim cho bt nho mm m i hi t nc hn cho mt hn hp nht nh.

Mc d mi amoniac, c th rn v trong dung dch, ch mt phn nh ca kh c sn b mt khi n c ha tan trong nc v din ra nhit bnh thng. Ngay c trong dung dch trong 24 gi hiu lc ca n s b mt.Do ammonium bicarbonate l khng ph hp nh mt cht men trong bt k sn phm ri khi l vi hn 5% m, v d nh bnh ngt v bnh xp.(Ngun: Duncan Manley, Biscuit, cookie and cracker manufacturing manuals, Published by Woodhead Publishing Limited, Abington Hall, Abington, Cambridge CB1 6AH, England, First published 1998, pages 70-74)Nhng ti sao (NH4)2CO3 t c s dng lm bt khai. l v (NH4)2CO3 khi phn hy cho lng CO2 bng NH4HCO3, nhng lng NH3 (mi khai) th nhiu hn (khong 82%) nn rt kh ngi v lm gim gi tr cm quan ca bnh.Khi phn hy (NH4)2CO3: (NH4) 2CO3 ------> 2NH3 + CO2 + H2O=> 1 mol (NH4)2CO3 cho 2 mol NH3 v 1 mol CO2.Khi phn hy NH4HCO3: NH4HCO3 ------> NH3 + CO2 + H2O=> 1 mol NH4HCO3 cho 1 mol NH3 v 1 mol CO2.Do ngi ta thng dng NH4HCO3 lm bt khai thay v dng (NH4)2CO3 v khi phn hy do tc dng ca nhit (t l nng) th cc cht trong bt khai (NH4HCO3) b phn hy sinh ra cc cht kh (NH3 v CO2), cc kh ny thot ra t trong lng chic bnh, lm cho chng n to ra, to ra cc l xp khin bnh mm, d n.III. V d kho st loi v lng bt n trong mt loi bnhDa theo s liu kho st thc t trong qu trnh thc hnh bnh ko ca nhm HTP3, em xin a ra v d v kho st loi v lng bt n no l ph hp cho mi loi bnh khc nhau. y em xin c trnh by trn bnh cookies ng tin.1. Kho st loi v lng bt n trong bnh cookies ng tinBaking powder 4%: bnh n to nhng c mu khng p, c hu v ng, hi kh chu 2.67%: mi, mu, n tt nhng vn cn cm gic kh chu. 2%: mi thm, mu p, cu trc gin xp, l kh nh khng cn cm nhn c hu v ng

Kim Nga 4%: bnh n bp ra, dy gim nhiu, bnh mng v ng knh ln, v ng, kh chu, mu sm, xu. 2%: bnh c cch tnh cht nh dng 4%, vn khng ci thin c nhiu.

NaHCO3 4%: mu bnh xu c mu vng sm, xut hin nhiu vt trn mt bnh, n nhiu lm bnh b xp, l kh b mt ln, v rt ng kh chu. 2%: vn cn trng thi nh 4% nhng t ng hn. 0.67%: bnh khng t v trng thi cm quan, b mt r, cn xut hin nhiu vt , mu vng sm, v ng kh chu.

Ta so snh gia baking powder v Alsa 2%Ta thy khi alsa th v mt cm quan vn nh khi dng baking powder, cu trc bnh vn gin xp nhng khng bng baking powder.

2. Bn lunBt n Kim Nga v NaHCO3 c bn cht l kim, khi dng vi liu lng ln s gy ra v ng, kh chu v lng CO2 sinh ra nhiu lm bnh xp xung, gim dy v tng ng knh.Bt n baking powder hiu Alsa v baking powder t phng th nghim c cng bn cht, u cha baking soda, mui axit v cht nn nh tinh bt, tuy nhin t l gia cc cht l khng ging nhau v ty thuc vo tng loi bt n m ta c cht lng khc nhau. (Ngun: Bo co thc hnh mn ng bnh ko: bnh cookies ng tin, HTP3, Vin Cng ngh sinh hc v thc phm, Trng i hc Cng nghip TP. H Ch Minh, nm 2010)IV. u im v nhc im ca phng php ha hc lm n bnh1. u imPhng php ny c u im l tn tht cht kh t, c th t ng ha, chu k sn xut ngn, d iu khin. Hiu qu lm n cao, d s dng Trong qu trnh to bt nho khng cn thit b kn v khng yu cu nghim ngt v m bt nho.Do phng php ny thch hp trong sn xut bnh ngt c hm lng ng v cht bo cao. Ngy nay ngi ta thng sn xut bnh theo phng php dng thuc n lm n v xp bnh. i vi bnh biscuit thng chn phng php lm n bt nho bng thuc n.2. Nhc imTiu tn nhiu ha cht, khng thch hp lm n bnh vi mt s loi bnh nh bnh mC th to ra mi khai kh chu. Khng s dng (NH4)2CO3 c nht cao v hm m cao v kh NH3 khng thot ra ngoi c.Khng s dng NaHCO3 > 1.5% v c tnh baz lm tng pH, gy cm gic kh chu.Loi bt n hay bt khai c s dng ty theo yu cu ca bnh v cu trc bt nho. Ta phi bit cch la chn cho thch hp. Thng s dng kt hp nhiu loi thuc n lm tng u im v lm gim khuyt im ca cc loi thuc n.V. Nhng lu khi s dng phng phpCc lai cht to xp, lm n khc nhau: +Lm bnh n nhng giai an khc nhau ca qu trnh nng+C nhng tc dng ph khc nhau. V d : NaHCO3 c th nh hng n mu sc v lm tng pH sn phm, (NH4)2CO3 c th lm bnh c mi khai nu m bt nho v m bnh cao. V vy cn s dng phi hp cc lai cht to xp, lm n khc nhau t hiu qu cao v gim tc dng phS dng lai v hm lng cht to xp, lm n phi ph thuc vo :+ pH, mi v sn phm + Yu cu v tnh cht bt nho+ Chiu cao, ng knh bnh + Cng ngh nng bnh

KT LUNPhng php lm n bnh no cng c nhng u v nhc im ring v i vi mi loi bnh li c yu cu v n v cht lng bnh khc nhau. Do trong sn xut ngi to ra sn phm phi bit to ra sn phm bnh no th s dng phng php lm n no l tt nht.Do s dng tt nht bt n hay bt khai bn cn phi hiu r c im v tnh cht ca chng cng nh cch s dng v cch bo qun chng.

TI LIU THAM KHO1. Duncan Manley, Biscuit, cookie and cracker manufacturing manuals, Published by Woodhead Publishing Limited, Abington Hall, Abington, Cambridge CB1 6AH, England, First published 1998, pages 70-742. Dr.Lakshmi J, Associate Professor,Dept of Food Chemistry, Bakery and Confectionary Products, College of Food Science and Technology, Bapatla, page 23 253. Hong Nhm, Ha hc v c, tp hai, NXB Gio Dc, nm 20054. Bo co thc hnh mn ng bnh ko: bnh cookies ng tin, HTP3, Vin Cng ngh sinh hc v thc phm, Trng i hc Cng nghip TP. H Ch Minh, nm 20105. Ths. Trng Th Minh Hnh, Gio trnh cng ngh sn xut ng, bnh ko, Trng i hc Bch Khoa Nng nm 20106. H Xun Hng, Slide bi ging Cng ngh sn xut ng bnh ko, Trng i hc Cng nghip TP. H Ch Minh, nm 20137. Trn Th Thu Tr, Bi ging mn Cng ngh sn xut ng Bnh Ko, HBK TP HCM, nm 20108. Link: http://hoachatjsc.com/p/6112/nahco39. Link: http://www.ammoniumbicarbonate.com/products/10. Link: http://www.savourydays.com/tu-hoc-lam-banh-can-ban-cac-chat-gay-no-men-no-bot-no-muoi-no-phan-loai-va-cac-luu-y-khi-su-dung/

PH LC

Hnh 1. Baking soda

Hnh 2. Cc thnh phn ca mt loi baking powder

Hnh 3. Do c tinh bt ng, baking powder ging vi bt m hn, khi ha vo nc s c mu trng c; baking soda dng tinh th mu trng c mi thm nh, ha tan hon ton trong nc

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