TRNG I HC NNG LM HU

KHOA C KH CNG NGH

----------

ti:

NG DNG CNG NGH SINH HC

TRONG QU TRNH BO QUN RAU QU

Hc vin: V Th Bch Nhn Nguyn Quc Khnh Lp: Cao hc CNTP K20 Mn: Cng ngh sau thu hoch Gio vin: Nguyn Vn Ton

Hu, 6/2015

MC LC PHN 1: LI M U

PHN 2: NI DUNG CHNH

1. Nguyn liu rau qu

1.1. Nguyn liu tri cy

1.2. Nguyn liu rau c

2. Bo qun nguyn liu rau qu

2.1. Mc ch nguyn tc vic bo qun rau qu

2.2. Tnh hnh bo qun rau qu hin nay s dng ha cht v s

dng ch phm sinh hc

3. Cc phng php bo qun theo cng ngh sinh hc

3.1. Phng php Modified atmosphere packaging (MAP):

3.2. S dng ch phm mng sinh hc

PHN 3: KT LUN

TI LIU THAM KHO

Phn 1

LI M U Nng sn ni chung v rau qu ni ring l mt thnh phn quan trng trong

h thng thc phm ca con ngi. Do , vic tm cch nng cao sn lng, nng

sut l mt yu cu v cng cp thit. Th nhng nu ch tp trung vo vic gia tng

sn xut thi th vn cha . c im ca rau qu l loi thc phm rt d b tn

thng v nhiu kha cnh v dn n h hng. Hn na, rau qu cn l loi thc

phm theo ma, vic c tri cy tri ma i khi cng phc v cho con ngi v mt

th hiu v gp phn lm tng tnh a dng trong khu phn n ca con ngi. V

th, song song vi vic tm cch nng cao sn lng n mc ti a cng khng th

khng quan tm n vn bo qun nng sn sau thu hoch. lm c iu

cn phi nghin cu tt c cc qu trnh xy ra trong bn thn cc loi rau qu khi

bo qun t tm mi bin php nhm phng, ngn chn hoc hn ch nhng

hin tng h hi c th xy ra.

Bo qun nng sn ni chung tht s cng cn tn ti nhiu vn li bt cp

hi. Vic s dng ha cht bo qun tri cy t nhiu lm gim kh nng t

khng chng bnh tt ca qu v nh hng n cht lng tri cy, mt khc c khi

lm nh hng n sc khe ca ngi tiu dng. Chnh v hu qu tim n ca cc

ha cht bo v ny m hin nay chng ta phi d chng khi s dng chng.

Xu th mi ca con ngi hin nay hng n vi cc hp cht t nhin, hn

ch ti a vic a cc ngun c hi vo c th qua ng n ung. Bi l , hin

nay trn th gii ng dng cng ngh sinh hc vo cng on bo qun rt nhiu.

Cc loi sn phm c bo qun bng cng ngh sinh hc tht s an ton hn, lnh

tnh hn i vi ngi tiu dng v qu trnh bo qun da trn cc ch phm c

ngun gc hon ton t nhin. Do vy, trong khun kh bi tiu lun ny, chng ti

xin trnh by ni dung: ng dng cng ngh sinh hc trong qu trnh bo qun rau

c qu

Phn 2

NI DUNG CHNH 1. Nguyn liu rau qu:

1.1. Nguyn liu tri cy:

Cc loi tri cy thng phm c hnh thnh a dng do kt hp cc phn

m t bo ca bu nhy, ht, v cc phn khc ca cy nh hoa (nh to, du

ty), l bc v cung hoa (nh da). S kt hp cc phn to nn tri cy v c t

in Oxford nh ngha l sn phm n c ca cy, c ch ht v v, c bit l

cc phn khc khi chn v mng nc. Ngi tiu dng nh ngha tri cy l sn

phm cy trng c mi thm, c v ngt t nhin hoc c x l qu t ngt

trc khi n. Tuy nhin, ty mc ch s dng ph bin m mt s qu cha chn

(nh da chut, u) hay chn (nh c chua, t) c s dng lm rau. Nhng

sn phm ny c gi l rau dng qu v c s dng n ti hay nu chn,

dng lm thc n ring bit hay trn thnh salad. Qu thng thng bt ngun t

bu nhy v cc m bao quanh.

Ngun gc hnh thnh: (A) cung hoa; (B) hoa; (C) o ht; (D) ni b; (E) v

ngoi; (F) vch ngn; (G) gi non; (H) v gia; (I) v trong; (J) l non; (K) m

ph; (L) cung (Wills et al., 1998)

Phn ln s pht trin ln ln ca mt phn no sau ny tr thnh qu l

do tng trng t nhin, nhng cng c th do con ngi tc ng thm thng qua

cc hat ng lai to v chn ging nhm to ra kch thc ti a phn s dng c

v hn ch s pht trin ca cc phn khng cn thit. C th thy nhiu ging tri

cy khng c ht 1 cch t nhin (nh chui, nho, cam navel) hay do lai to (nh

da hu, i) hay do k thut canh tc (nh hng).

Tri cy l ngun cung cp ng, khong, vitamin,...cho nhu cu dinh dng

ngi v cng l nguyn liu quan trng trong cng ngh thc phm.

1.2. Nguyn liu rau c:

Khc vi qu, rau khng i din cho nhm cu trc thc vt no m l nhng

phn a dng khc nhau ca cy trng. Tuy vy, c th nhm rau thnh 3 loi nh

sau: ht v qu (u); c (hnh ti, khoai sn, khoai ty); hoa, chi, thn, l. Trong

nhiu trng hp, b phn c s dng thng c bin i rt nhiu so vi

cu trc nguyn s. B phn s dng lm rau thng rt d nhn ra khi quan st.

Mt s kh nh loi hn, c bit l nhng nng sn loi c pht trin di mt t.

V d nh c khoai ty l dng cu trc d tr ca thn bin i, nhng dng

khc nh khoai lang li do r phnh ra thnh c.

Ngun gic hnh thnh rau v c t thc vt: (A) chi hoa; (B) chi thn;

(C) ht; (D) chi nch; (E) cung l; (F) c (chi ngm); (G) thn c; (H) r; (I) r

c; (J) tr di l mm; (K) gc l; (L) phin l; (M) qu; (N) hoa; (O) chi chnh

(Wills et al., 1998)

Ngun gc cu to ca rau v qu l c s quan trng quyt nh k thut bo

qun. Ni chung, nng sn trn mt t c xu hng pht trin lp sp b mt gip

hn ch h hp v thot hi nc khi chn, cn cc loi r c li khng pht trin lp

v ngoi nn cn c bo qun iu kin c m tng i cao hn ch mt

nc. Cc loi r c c kh nng t hn gn vt thng do cn trng gy hi. c

tnh ny cng gip lm tng tnh an ton cho nng sn nu c nhng vt thng c

hc trong qu trnh thu hoch.

Rau l ngun cung cp vitamin, khong cht, ng v cht x cho nhu cu

dinh dng ngi.

2. Bo qun nguyn liu rau qu:

2.1. Mc ch nguyn tc ca vic bo qun rau qu:

2.1.1. Mc ch:

Hng nm Vit Nam sn xut ra hng triu tn rau qu ti nhng vic tiu

th cha n nh do cng tc bo qun, ch bin m bo cht lng ban u

cha c tt. nng cao cht lng qu ti, ngoi vic ci to v thay i ging

mi, p dng khoa hc k thut vo vic chm bn, x l trc thu hoch, cn ch

n k thut sau thu hoch nhm ko di thi gian bo qun, gim cc tn tht do

h hng nhm mc ch:

Ci thin cht lng dinh dng, cm quan, cht lng v sinh nhm

cung cp cho ngi tiu dng nhng sn phm c cht lng cao.

Gp phn nng cao gi tr thng mi v gi tr kinh t cho ngi sn

xut.

Ko di tui th bo qun, to iu kin cho tiu th sn phm trong

nc v phc v xut khu qu ti.

2.1.2. Nguyn tc:

Nguyn tc bo qun rau, hoa qu ti l gi cho rau, hoa qu ti lun

trng thi ng ngh, gim cng hot ng sng, trnh s xm nhim ca vi sinh

vt, gi c cht lng ban u ca rau, hoa, qu ti.

thc phm c thi gian s dng di hn v m bo cht lng tt hn,

cc phng php bo qun t n gin nh p mui, phi khn cc phng

php hin i nh chiu x, thanh trng, tit trngu c s dng. Chng u

da trn mt s nguyn l bo qun rau qu nh sau:

Kch thch hot ng ca cc vi sinh vt v enzyme c bit.

Loi b bt cc vi sinh vt v cc cht gy nhim bn c bit.

c ch hot ng ca cc enzyme v cc vi sinh vt gy h hng thc

phm.

Tiu dit cc vi sinh vt v lm mt hot tnh ca enzyme.

2.2. Tnh hnh bo qun rau qu hin nay s dng ha cht v s dng ch phm

sinh hc:

T nm 2005 n 2009, thng tin v hin trng lm dng ha cht trong sn

xut, bo qun thc phm tr nn nhc nhi i vi ngi dn Vit Nam trong vic

bo v sc khe v tnh mng. Trong phn tm hiu v tnh hnh bo qun rau qu

hin nay, lng thng tin c thu nhn t trn cc trang web c ngun gc ng

tin cy t nm 2004 n cui nm 2010, qua nhm chng mnh a ra s khc

bit v tnh hiu qu cng nh an ton i vi sc khe gia s dng ha cht

n thun v p dng phng php k thut tin tin v cc ch phm sinh hc.

Nhng phng php bo qun rau qu truyn thng nc ta nh dm dm,

ln men chua, ln men ru cng chnh l nhng cch bo qun bng ha cht, tuy

nhin, y xin cp n cc loi ha cht c kim nghim l mang tnh

nguy hi cho c th.

Trc tin l cc cht chng dit nm mc nh kh SO2, cc mui sulfit, cn

hn ch c s oxy ha rau qu; th nhng, vi liu lng khng kim sot

nghim ngt SO2 s ph hy Vitamin B1 ng cc, gy cc triu chng ng c,

tn thng kh qun do ht phi SO2.

Vi cc cht dit vi khun in hnh l acid benzoic, cc mui benzoate, lun

phi ch n liu lng do gc phenol gy nguy c ung th cao ngi.

i vi sn phm acid ascorbic l cht dit vi khun an ton v c sn

xut bng con ng s dung vi khun sinh ra acid ny.

Ring cc ha cht khng chnh phi nh cht 2,4 D (thuc dit c hay cht

c mu da cam) - cng c dng kh ph bin trong c hai khu tng sn v bo

qun sau thu hoch. Trong canh tc, n c dng lm cht kch thch cc mnh

khin cho c qu tng kch thc nhanh . bt thng. Trong bo qun n c gii

kinh doanh s dng dit cn trng, vi khun... v lm chm qu trnh lo ha gi

cho hoa qu ti lu, mu sc khng i.

i vi cc ch phm sinh hc nh mng Chitosan, mng bn thm BOQ_15,

mng MA mang li hiu qu kinh t cao: Gim c t l h hao, tng thi gian bo

qun nhm ko di thi gian thu hoch v tiu th. Hu ht cc ch phm ny u

c ngun gc sinh hc, n gin, d s dng, sn phm c bo qun bng cc ch

phm ny hon ton khng c hi, an ton cho ngi sn xut ln ngi s dng.

Mng bn thm BOQ-15; sn phm do b mn Bo qun sau thu hoch ( Vin

c in Nng nghip v Cng ngh sau thu hoch) nghin cu, sn xut; dng

bo qun cc loi qu thuc h Citrus ( cam, chanh, qut, bi) c trn 2 thng,

nh gi ca nng dn nhiu ni khi s dng ch phm POQ 15 l cng ngh n

gin, d lm, chi ph thp ( 200-300 ng/kg cam bo qun). Mng Chitosan, sn

phm v quy trnh cng ngh do cc cn b khoa hc ca Vin nghin cu cy n

qu min Nam v Vin nghin cu v Pht trin Cng ngh Sinh hc ( Trng i

hc Cn Th) nghin cu thnh cng trong vic bo qun cc loi qu ti sau thu

hoch; ngn chn s mt nc v xm nhp ca nm bnh, xoi ngn nga bnh

thn th v rui c tri, bo qun tri bng cch bao mng Chitosan nng

0,25% kt hp vi bao Polyethylene (PE) c c 5 l vi ng knh 1 mm c

ghp m bng my p v bo qun nhit lnh 120 C c th bo qun c ti 8

tun.

Tuy nhn thy s u th ca ch phm sinh hc so vi cc ha cht thng

dung nhng mc p dng li rt hn ch, c th hiu do quy m sn xut cc ch

phm ny khng cung ng cho cc nh vn c nc, ng thi cn phi cnh

tranh vi hng lot ha cht c nhp khu t Trung Quc mt cch v ti v.

ng thi vi phng php bo qun bng chiu x hay dung dung dch ozon

cng gp nhiu kin chp nhn v phn i t nh sn xut, n cc nh khoa hc

v ngi tiu dng. Nhng lo ngi v bin i ca bn thn thc phm c chiu

x sau khi hp thu vo c th ngi s gy bnh, ri n nhn nh ca Tin s Brian

Wild - chuyn gia ngnh sau thu hoch ca Vin Nghin cu rau hoa qu Gosford,

B Nng nghip New South Wales, c - tin hnh th nghim tc dng ca ozon.

Kt qu cho thy vi cam, chanh th mt s loi thuc b phn hy khong 60% sau

mt gi, 80% sau ba gi v 100% sau su gi. Trong thc t, thng khng ai ra

rau qu bng ozon qu 10-15 pht. Hn na, ozon khng phn bit c cht c

hi hay cht b dng. Ngha l c gp ha cht trong thc phm l n phn hy,

do mt phn cht hu ch b mt i do tc dng ca ozon.

Trong tng lai,chng ta hy vng cn tm c cc phng php bo qun

khc tin b hn v mt m bo an ton v hiu qu s dng nh dung dch st

khun Anolyte v bc tri cy bng mng MA. Mng MA , cc chuyn gia Vit Nam

v Hn Quc hp tc nghin cu, ng dng thnh cng mt loi mng c bit

bo qun mt s loi qu Vit Nam.

Tuy nhin, Vit Nam, mng MA cha c nghin cu c h thng, k cng

v cha a vo s dng. Mng MA thc cht l mng polyethylen (PE) cha mt

loi khong cht sn c nc ta, khng c hi c s dng bc cc khay qu,

s tng tc gia mng v qu lm cho kh quyn trong khay c nng kh CO2

v O2 thch hp cho tng loi qu, kt hp vi bo qun qu nhit lnh thch

hp. Mng MA trong bo qun xoi v vi, ko di thi gian bo qun n 3-4 tun

v qu vn gi c mu sc, cht lng tt. Hin vn cha c tnh c gi thnh

ca mng MA.

ng Nguyn Hoi Chu, Gim c Trung tm pht trin cng ngh cao thuc

Vin khoa hc Vt liu, cho bit, Anolyte thc cht l dung dch in phn ca mui

n (cn gi dn d l nc ozon). Trong ngoi cc ion Na+, Cl- cn c nhiu

nguyn t oxy, ozon, clo... l thnh phn c tnh st khun rt mnh, c th tiu dit

nhiu loi vi khun, k c nhng loi c sc khng cao nh nha bo, vi trng bnh

lao, E.Coli, cc lin cu khun, nm mc, x khunDo nhng c tnh ny, anolyte

t lu c cc nc tin tin s dng trong vic bo qun hoa qu, trong ch

bin thy sn, v khun bnh vin, kh trng ging... Vit Nam, cng ngh bo

qun s dng anolyte cng c p dng mt s ni (trong bo qun hoa qu,

phng dch cm g, v trng bnh vin...) nhng cn mang tnh t pht, cha c h

thng.

3. Cc phng php bo qun rau qu bng mng cng ngh sinh hc:

3.1. Phng php Modified atmosphere packaging (MAP):

y l phng php bo qun rau qu bng cch s dng cc loi mng

polymer c ngun gc t du m kt hp vi vic iu chnh kh quyn nhm khng

ch c mc h hp ca tng loi rau qu, hn ch s chn nhanh v do bo

qun c lu hn.

K thut MAP tng i n gin, r, d p dng, c th bao gi nhng sn

phm ln nh khc nhau, bo qun ngay c lc by bn v c th qung co ngay

trn bao b.

3.1.1. c tnh ca mng MAP:

Ko di ti lu ca sn phm v gim tc lo ha ca sn phm m

khng cn tr qu trnh h hp hiu kh. Khng ging nh kiu ng gi st kht vo

sn phm, MAP c kh nng khim sot lung kh lu chuyn vo v ra, n c th

ko di ng k thi gian c bo qun an ton cho rau qu. Khng phi tt c cc

loi mng MAP u c ch to c c tnh ging nhau, ty theo loi sn phm m

n bao gi, MAP s c c tnh thch hp vi loi sn phm . Cc loi rau qu

khc nhau th c cng h hp khc nhau, do khi ch to MAP ngi ta phi

nm r mc h hp ca tng loi rau qu cn bo qun.

Hnh1: Vi c bo qun lnh nhit thch hp, c dng mng MA (tri) v khng

s dng mng MA (phi)

3.1.2. Mng MAP ci tin:

Mng c thnh phn ch yu tham gia vo cu trc to mng: tinh bt chui,

metylcellulose, gelatin, paraffin v mt s ph gia gip mng tan c trong nc,

tng tnh bm dnh v kh nng gi m. Vi c tnh thnh phn nh vy, mng c

kh nng c c di dng rn v c th ha tan tt trong nc to thnh dung dch

huyn ph s dng, kh nng kh nhanh nhit mi trng.

Hnh trn cho thy thanh long sau 5 ngy bo qun nhit phng th mu

i chng v mu c bc mng ci tin khng khc nhau l my v hnh dng

ngoi. Nhng cht lng bn trong cho thy mu i chng c chc gim nhanh,

t gi tr ban u 0.85 kg/cm2 xung 0.56 kg/cm2, trong khi mu bc mng ci tin

l 0.65 kg/cm2

3.2. S dng ch phm mng sinh hc:

Trong bi cnh ngy cng tng cc vn v v sinh an ton thc phm c

bit l vic s dng nhng ha cht khng c php v khng r ngun gc ko

di thi gian thng mi ca nng sn v ang lm tng ln nhng bt an trong

x hi th vic nghin cu v s dng nhng vt liu c ngun gc thc phm v

cng ngh s dng l ht sc cn thit v cn c quan tm.

Hin nay ngi ta thng s dng phng php bo qun rau qu bng mng.

l nhng ch phm c nghin cu thnh cng vi nguyn liu trong nc,

c th s dng quy m cng nghip ln quy m gia nh, khng gy c hi v

khng gy nhim mi trng, c th gip bo qun rau, hoa, qu ti lu hn m

vn gi c nhng c trng ban u.

K thut to mng ph sinh hc l phng php to ra mt dch lng dng

composite, colloid hoc nh tng ri ph ln b mt qu tng qu ring r bng

cch phun, nhng hoc xoa. Khi dch lng kh s to ra mt lp mng mng gn

nh trong sut trn b mt qu. Nh tnh bn thm iu chnh s trao i kh v hi

nc ca mng m qu c gi ti lu hn. Qu s dng mng ph ln b mt s

hn ch hao ht khi lng t nhin v gim qu trnh thot hi nc. Do mng ph

to ra vng vi kh quyn iu chnh xung quanh qu do lm thay i s trao i

kh vi mi trng xung quanh. Nh vy, v bn cht k thut mng bn thm cng

l mt dng ci tin ca phng php MAP.

* Mc ch ca vic s dng mng ph:

- Lm gim tn tht khi lng v gim bin dng do s mt hi nc trong

qu trnh bo qun. Thay th mng sp t nhin trn mt qu.

- Lm gim trao i kh, (gim kh oxy v tng kh cacbonic) dn ti lm chm

qu trnh chn hay gi ho.

- Ci thin hnh thc bn ngoi.

- Tng ti ca qu.

- Phng nga tn thng c hc v nhim bnh trong vn chuyn

- Duy tr cht lng qu.

* Mt s loi mng c s dng trong thc t bao gm:

- Mng thc phm t cc vt liu nh cc polysaccarit. Cc polysaccharit c

th dng lm mng bn thm l cellulose, tinh bt, dn xut ca tinh bt, pectin,

chitin v gum.

- Mng sp gm sp paraffin, sp ong, polyethylene, du khong. Hin cn

c c paraffin tng hp c lm t xc tc polymer ha ethylene. Mng sp cho

php chng bay hi nc tt v cho b ngoi qu bng p.

- Mng to thnh t cc cht hu c phn t lng ln nh chitosan trong

mi trng acid khng nhng c kh nng bo qun m cn chng bin mu v qu.

- Mng vi nh t dung dch nh tng c kh nng ngn cn mt nc tt tuy

nhin sn phm bng km. Nhiu cht nh ha s dng trong dung dch mng

sp u c ngun gc t glycerol v acid bo. Cht nh tng c thng mi

ha l polyglycerols-polystearate.

3.2.1. Mng Chitosan:

CHITOSAN l mt loi polyme sinh hc c nhiu nh khoa hc trn th

gii quan tam v c tc dng tt trn bnh nhn b ung th. Hai nc nghin cu

nhiu v chitosan hin nay l Trung Quc v Nht Bn.Mi y nht cc nh khoa

hc thuc H Nng Lm thnh cng trong vic to mng Chitosan l v bo qun

thc phm ti sng d h hng nh tht, c ,rau qu m khng lm mt mu, mi

v ca sn phm.

* Ngun gc:

Chitin l thnh phn cu trc chnh trong v (b xng ngoi) ca ng vt

khng xng sng trong c loi gip xc(tm, cua), cha t 5-10% cht chitin.

Chitin l mt polyme sinh hc c nhiu trong thin nhin ch ng sau

xenluloza.Cu trc ha hc ca chitin gn ging vi xenluloza. Chitosan l mt

loi chitin kh acetyl, c th tan trong dung dch acid.

* c tnh ca Chitosan:

L polysaccharide c m, khng c hi, c khi lng phn t ln.

L mt cht rn, xp, nh, hnh vy, c th xay nh theo cc kch c khc

nhau.

Chitosan c mu trng hay vng nh, khng mi v.

Khng tan trong nc, dung dch kim v acid m c nhng tan trong dung

dch acid long (pH=6) to dung dch keo trong, c kh nng to mng tt, nhit

nng chy 309-3110C.

* Tc dng ca chitosan:

Phn hy sinh hc d hn chitin.

C kh nng khng khun v c tc dng tt trong bo qun cc loi rau qu

c v cng bn ngoi.

D dng iu chnh m, thong khng kh cho thc phm.

Mng kh dai, kh x rch, c bn tng ng vi cc loi cht do vn

c dng lm bao gi.

Mng lm chm li qu trnh b thm ca rau qu. Rau qu b thm l do qu

trnh ln men to ra cc sn phm oxy ha ca oquinon. Mng chitosan l c ch

hot tnh oxy ha ca cc polyphenol, lm thnh phn ca anthoxyanin, flavornoid

v tng lng cc hp cht ca phenol t b bin i, gi cho rau qu ti lu hn.

* Cc bc tin hnh s dng mng chitosan:

Tri cy c chn lc ng kch c, tiu chun, loi b nhng tri b

xy st, nm bnh, ngm tht sch bng nc l.

Sau nhng vo dung dch topsin M 50 PW (mt loi thuc tr nm)

vi nng 0.1% trong nc.

Pha 1 lt gel chitosan vi 3 lt nc l, khuy tan u ri nhng hoa qu

ra sch vo, sau vt ra.

Dng qut thi kh v ng gi bao b.

Bo qun nhit lnh 10-120 C th s lu gi c qu trong 4 tun,

thm ch ti 6 tun c th vn chuyn i xa an ton.

Hnh trn cho thy bo qun bi bng mng chitosan trong vng 3 thng,

bi vn ti, khng b ng v. Nghin cu ca mt nhm sinh vin trng H

Nng Lm TP.HCM.

Ngi ta dng chitosan to mng khng thm bao cc loi tri cy bo

qun lu hn

* u im ca mng chitosan:

D phn hy sinh hc.

V tm l ngun ph liu t nhin di do, r tin, c sn quanh nm, nn rt

thun tin cho vic cung cp chitin v chitosan.

Tn dng ph thi trong ch bin thy sn bo qun thc phm, gp phn

gii quyt tnh trng nhim mi trng do cc cht thi t v tm gy ra.

3.2.2. Mng tinh bt:

* Nguyn tc:

Ging cc cht cao phn t khc, tinh bt c kh nng to mng tt. to

mng cc phn t tinh bt (Amylo v Amylopectin) s dn phng ra, sp xp li v

tng tc trc tip vi nhau bng lin kt hydro v gin tip qua phn t nc. C

th thu c mng t dung dch phn tn trong nc. Mng thu c t th phn tn

thng d dng tan ra trong nc.

* Phng php to mng:

S cc bc to mng:

Tinh Bt

Nc

H ha

Khuy

Rt dch

Mng

Cho tinh bt phn tn trong nc n mt nng nht nh, khng qu c

hay khng qu long, h ha s b to ra mt nht nht nh. Khuy tht k.

Rt dung dch tinh bt thnh lp mng ln b mt kim loi phng v nhn c gia

nhit thch hp. mng khng b dnh li sau khi kh c th pht mt lp mng

parafin tr ha b mt kim loi. Nc t b mt tinh bt s bc hi ln lm tng

nng tinh bt, cc phn t s dch li gn nhau, hng t bin vo tm di tc

dng ca dng mi trng phn tn sp xp li thnh lp n ht c.

3.2.3. Mng bn thm BOQ -15:

y l sn phm do b mn Bo qun sau thu hoch (Vin c in Nng

nghip v Cng ngh sau thu hoch) nghin cu, SX. BOQ 15 l hn hp dung mi

hu c v thuc chng nm c kt hp vi nhau di dng mt dung dch lng

dng bo qun cc loi qu thuc h Citrus (cam, chanh, qut, bi) v mt s

loi rau n qu nh c chua.

Sau khi thu hi, nng dn ch cn ra sch, lau kh ri nhng hoc dng khn

sch tm dung dch lau mt lp mng trn b mt qu, kh 3-5 pht ri xp vo

thng carton em bo qun ni kh ro, thong mt. Lp mng mng bng Parafine

hu c c tc dng va lm bng mt qu, tng thm hp dn ca m qu, va

c tc dng ngn s bc hi nc gim s hao ht khi lng trong sut qu trnh

bo qun. Thuc chng nm c phi trn vi parafine c tc dng ngn nga s

xm nhim v gy hi ca nm bnh nhng hon ton khng c hi vi con ngi

khi s dng.

3.2.4. SH - Cht bo qun rau, hoa qu:

Phn vin Cng nghip thc phm TPHCM nghin cu, ch to v ng

dng thnh cng mt cht bo qun rau, hoa qu c tn l SH. Cht c dng

lng, mu nu nht, hi c mi chanh. y l loi sn phm thun sinh hc,

c thnh phn ch yu mang bn cht thin nhin, c kh nng tiu dit v hn ch

s pht trin ca nhiu loi vi sinh vt c hi cho rau, hoa qu trc v sau thu hoch.

SH c nhng u im chnh l:

Khng hi mi sinh, tan vo trong t.

Vn pht huy hiu qu khi ln ln vo cc cht hu c khc.

Hiu nghim lu di m khng c hiu ng ph.

Khng bin cht, cho d trong nc c nhiu cht vi.

Khng c, an ton cho ngi v cc ng vt.

Khng lm thay i mi v ca rau, hoa qu: khoai ty, c chua, t ty, bp

ci cc loi, da chut, hnh cc loi, c rt, cc loi tri cy (xoi, chui,

nho, vi, cam, qut, nhn, chm chm, thanh long), cc loi hoa (cc, lan,

hng), cc loi cy king nhiu l trang tr

3.2.5. Mng bn thm c ngun gc protein:

Mng bn thm n c c th c lm t nhiu ngun protein khc nhau.

Protein cng a nc v nhy cm vi s hp th nc v th m tng

i v nhit c th nh hng n tnh cht ca chng. Cc ngun protein c

dng lm mng bn thm n c gm c zein ca ng, gluten ca la m, protein

u tng, protein sa v cc protein c ngun gc ng vt nh collagen, keratin

v gelatin. Bao bc rau qu vi mng thun ty protein hin khng c s dng do

hn ch ca chng chng li vic thot hi nc tuy nhin mng hn hp hoc mng

kp gia protein v mt vi vt liu k nc khc c kh nng tng h ln nhau lm

tng tnh hu ch ca chng.

3.2.6. Mng bn thm lm t cht bo:

Mng bn thm lm t cht bo c s dng t hn 800 nm. Mng bn

thm lipid c s dng bi chng c tnh k nc cao v th c tc dng nh l mt

bc ngn chn s mt nc. Ngoi kh nng hn ch mt nc mng lipid cn c

lm gim h hp nh ko di thi gian bo qun cng nh ci thin cht lng

cm quan bn ngoi cho rau qu bng cch to mt lp v sng bng. Mng lipid c

th c lm t nhiu loi lipid khc nhau bao gm acetyl monoglycerides, wax v

cht b mt.

Phn 3

KT LUN Vi nhng phng php bo qun k trn c th gip gim phn no nhng

hao tn kinh t trong qu trnh bo qun do rau qu b h hng, gip rau qu c c

cht lng gn nh khng i sau mt thi gian di bo qun khi kt hp vi nhng

phng php bo qun ph hp. Tuy nhin, mi phng php c nhng u nhc

im ring ca chng. Chnh v vy, hiu qu p dng ca tng phng php cn

ph thuc rt nhiu vo cc yu t sau:

+ Ph thuc vo tng loi nguyn liu: mi loi nguyn liu rau qu u c

mc nhy cm vi ha cht, cng nh vi nhit , m , v thch hp vi tng

loi bao b khc nhau. Do , c th phng php ny rt hiu qu cho loi tri ny,

nhng li gy h hng hoc km hiu qu nhng loi tri cy khc.

+ iu kin bo qun: m bo nhng iu kin ti nh v c s vt cht, thi

gian bo qun, h thng qun l cht lng cng gp phn nng cao hiu nng

ca qu trnh bo qun.

+ Hiu qu kinh t: bo qun nh th no t hiu qu kinh t l iu rt

quan trng. Do cn c s so snh, tnh ton hiu qu ca tng phng php nhm

mang li hiu qu kinh t cao nht m vn gi c cht lng ca sn phm.

+ Kh nng gy c cho sn phm, con ngi v mi trng: y l vn

v cng bc xc hin nay. Hu ht tng li nhun, cc c s cha c s quan tm

ng mc v nng , d lng, mc c hi ca nhng loi ha cht cm s

dng. V vy, cn phi quan tm n sc khe ca con ngi, la chn cc phng

thc bo qun hp l, khng c tnh cht gy nguy hi.

Khng th no ph nhn c tc dng tch cc ca cng ngh sinh hc vo

cng ngh bo qun sau thu hoch. N p ng hu nh y cc yu cu kht khe

v vic bo tn cht lng rau qu, gim thit hi sau thu hoch, ko di hn s dng

v iu c bit quan trng l vn an ton sc khe i vi ngi tiu dng, an

ton vi mi trng. Bi vy, cng ngh sinh hc vn c nghin cu v p dng

vo trong lnh vc thc phm v vi xu th mi hin nay, y tht s l mt mng

khoa hc c trin vng trong tng lai.

TI LIU THAM KHO

1. Bo qun v ch bin nng sn sau thu hoch PGS Trn Minh Tm- NXB

Nng nghip

2. Gio trnh Bo qun nng sn- H Nng Nghip 1

3. Cng ngh sinh hc trong bo qun Rau c qu - Vin sinh hc v Thc

phm, H Cng nghip TP.HCM

4. Chuyn Cng ngh sau thu hoch TS Nguyn Vn Ton Khoa

CKCN, H Nng Lm Hu