tiểu luận-nhom 6

8/3/2019 tiu lun-nhom 6

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TRNG I HC BNH DNGKHOA CNG NGH SINH HC

Tiu lun:

CNG NGH SAU THU HOCHC CHUA TI

GVHD: Th.S Nguyn Cng Minh

SVTH: Lp 11SH04 nhm 6

Bnh Dng, thng 2/2012


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Mc LcM U .............................................................................................................................4

CHNG 1.........................................................................................................................5

TNG QUAN V CNG NGH SAU THU HOCH NC TA ..............................5

CHNG 2.........................................................................................................................8

C CHUA V NHNG BIN I SAU THU HOCH.................................................8

2.1. Gii thiu s lc v c chua ...................................................................................8

2.2. Nhng bin i sau thu hoch ..................................................................................92.2.1. Nhng tn thng c gii .................................................................................9

2.2.2. H hp ...............................................................................................................9

2.2.3. S sinh sn Ethylen............................................................................................ 9

2.2.4. S sinh nhit......................................................................................................9

2.2.5. S bay hi ........................................................................................................10

2.2.6. S gim khi lng qu...................................................................................10

2.2.7. S thay i thnh phn ho hc. .....................................................................10

CHNG 3.......................................................................................................................12

CNG NGH BO QUN SAU THU HOCH C CHUA TI .............................. 12

3.1. Thu hoch v x l ti rung..................................................................................12

3.1.1. chn thu hoch ........................................................................................... 12

3.1.2. Thi gian thu hoch.........................................................................................13

3.1.3. Phng php thu hoch ..................................................................................13

3.1.4. Lu tr trn ng rung..................................................................................14

3.2. Cc cng on trong nh ng gi .........................................................................16


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3.2.1. Lm sch v kim sot thi hng....................................................................16

3.2.2. Phn loi / tuyn chn .....................................................................................17

3.2.3. Kim sot s chn ............................................................................................ 19

3.2.4. Lm lnh s b ................................................................................................ 20

3.2.5. Bao gi.............................................................................................................21

3.3. Bo qun.................................................................................................................23

3.3.1. Bao gi iu bin kh quyn (MAP) ................................................................ 24

3.3.2. Bo qun lnh bng phng php bay hi (Evaporative Cooling System)...25

3.3.3. Cc phng php ko di thi gian bo qun n gin v r tin khc ........28

3.5. Vn chuyn.............................................................................................................28

3.6. Tiu th...................................................................................................................31

TI LIU THAM KHO....................................................................................................34


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M UCng vi s pht trin ca nn kinh t th gii th nhu cu v vn lng thc,

thc phm ca ngi dn ngy cng c quan tm nhiu hn c bit l vn rau quti.

Rau qu ti sau thu hoch l mt trong nhng sn phm thc phm khng ththiu c v lun gn lin vi cuc sng hng ngy. Tuy nhin, c c sn phmrau qu ti p ng c cc yu cu v cht lng thc phm th phi c cc phng

php x l bo qun chng sau thu hoch nhm gi nguyn gi tr dinh dng v thihn s dng lu di. V vy vic nghin cu v tm hiu cc yu t nh hng n sn

phm rau qu ti v cc bin php x l, bo qun chng sao cho c hiu qu l rt

cn thit. Trong s cc sn phm rau qu ti phi k n l c chua. y l loi rauva c th c dng n ti, va dng ch bin trong cc ba n hng ngy cangi dn hay ch bin cc sn phm ung, sn phm ch bin khc rt thun tincho s dng v c li cho sc kho con ngi.

C chua l loi qu rt d b hng sau qu trnh thu hi, chu nhiu tc ng cacc yu t ngoi cnh cng nh con ngi, vy cn nghin cu cc yu t nh hng tm ra c phng thc bo qun thch hp.


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CHNG 1

TNG QUAN V CNG NGH SAU THU HOCH NC TA

Nhng nm qua, sn xut nng nghip nc ta c nhng bc pht trin vtbc, nhng cn thiu tnh bn vng, khin cho nng sn xut khu b thua thit nhiu khithm nhp th trng th gii. Theo nh gi ca cc nh khoa hc, sn xut v tiu thrau qu Vit Nam vn dng quy m h gia nh, rt t trang tri sn xut rau quchuyn canh, quy m ln phc v ch bin v xut khu. Phn ln cc sn phm rau qu Vit Nam c s dng di dng ti sng. Nng lc ch bin ch khong 200.000tn/nm (2% tng sn lng), ch yu l cc loi rau qu ng hp, nc qu ng chai.

Tn tht sau thu hoch i vi nng sn Vit Nam khong hn 25% i vi ccloi qu v hn 30% i vi cc loi rau, 15-20% i vi cc loi lng thc khc... Nhvy, vi t l tn tht ny, mi nm chng ta b mt khong 3.000 t ng - mt khontin ln hn so vi tng thu ngn sch ca nhiu tnh.

C nhiu nguyn nhn dn n tnh trng trn. Th nht l, v mt nhn thc. Chvi nm gn y, cng ngh sau thu hoch mi c quan tm, nht l khi sn lngnng nghip nc ta p ng cho nhu cu trong nc v c d hng ti xutkhu.

Ngay vic hoch nh chin lc v pht trin cng ngh sau thu hoch cng chac quan tm ng mc. Bn cnh , tn tht ny cn ph thuc vo nhiu yu ttrc thu hoch nh: ging, phn bn, cch thc chm sc, v vic s dng thuc bo vthc vt... Ngay chnh nng dn, nhng ngi trc tip sn xut cng cha nhn thcc tm quan trng v bo qun nng sn sau thu hoch, khin cho mc v gi tr tntht ln hn rt nhiu so vi cc nc trong khu vc.

Cht lng nng sn ca chng ta cha th snh c so vi cc nc trong khuvc nh Thi Lan, Singapo, Malaixia, Trung Quc... n gin l, v cc khu trc vsau thu hoch ca h c chun b v trin khai rt ng b nn cht lng nng sn sau

thu hoch rt cao v tn tht sau thu hoch cng khng ng k. Vit Nam, cng nghsau thu hoch do mi c quan tm nn cn tnh trng km pht trin. C l, phi mt15 n 20 nm na, cng ngh sau thu hoch nc ta mi theo kp trnh ca ThiLan ngy nay.


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Ti sao gi tr go xut khu ca Vit Nam li lun thp hn Thi Lan? l vcng ngh sy thc go ca chng ta cha pht trin, thc thng phi trn cc sn t,

b tng hay trn ng ri nha dn n rn, gy rt cao (30-40%), bn cnh t lsn, ct u vt tiu chun cho php, nn gi go ca nc ta thng thp hn loi go

cng phm cp Thi Lan t 20-30 USD/tn, gy thit hi cho nh sn xut mi nm ti50-60 triu USD.

Tin ti hi nhp, r rng chng ta phi quan tm hng u n cht lng snphm, ch bin, bo qun v xy dng thng hiu nng sn Vit Nam. Tuy nhin, chtlng sn phm l yu t quyt nh n cc tiu ch khc. Mun c sn phm nngnghip tt th cc khu trc thu hoch l rt quan trng, n ng vi tr gn nh quytnh i vi cc khu khc. Bi l, khi sn phm m bo tt, an ton, t tiu chun,th cng ngh bo qun s rt thun li, bn cnh , cht lng nng sn tt cng l tiu

ch quan trng khch hng quc t bit n thng hiu hng Vit Nam. Mun vychng ta cn xy dng cc vng chuyn canh phc v xut khu.

Bn cnh l vic hin nay, h thng kim tra cht lng nng sn ca nc tacha thng nht, v vy cn nhanh chng xy dng cc phng kim tra cht lng nngsn hin i, nng lc phn tch cc ch tiu v thnh phn dinh dng, cht ph gia,cht kch thch, c t, thc phm chiu x v nng sn chuyn gen.

Hin trng cng ngh sau thu hoch nc ta hin nay nh sau:

- Thiu nghin cu k v ch s thu hoch tri cy: y l mt ch s quan trng,

nhng ch c mt s c quan nghin cu bc u thc hin i vi mt s tri cy trichnh.

- Cng ngh thu hoch, sau thu hoch (x l, bo qun, vn chuyn...) lc hu vthiu u t c s vt cht km theo (kho lnh chuyn dng, thit b ra, x l, bung chn, bao b, ng gi, vn chuyn...). C nc mi ch c vi c s s ch, ng gi ttiu chun xut khu.

- Tn tht trong qu trnh thu hoch v sau thu hoch cn kh ln (c khong25% v khi lng, cha k n tn tht v cht lng).

- Do din tch trng tri cy manh mn, cha c quy hoch tng th vng tp trungcha c nhiu ging mi c gii thiu p dng, nht l vic p dng quy trnh sn xuthng thc hnh nng nghip tt (GAP) cha c ph bin rng ri.

- Nng dn v cc thnh vin trong h thng cung ng cha c hun luyn vhng dn y v k thut thu hoch v x l bo qun, nn nng sn c chn


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khng ng u, d b mt nc, nhim vi sinh vt, qu nhiu d lng thuc bo vthc vt... nn vic thu mua, x l nng sn m bo s lng v cht lng ng ugp kh khn, nh hng n vic kinh doanh nht l xut khu.

- Hin nay chng ta cha c quy nh trong cht lng rau qu sau thu hoch c

ban hnh thnh nhng tiu chun bt buc. Nhng quy nh v cht lng nng sn hinnay vn ch yu c xy dng trn c s theo s tha thun gia nh vn v nh thumua tri cy.

- iu kin kim sot v sinh an ton thc phm v d lng cc cht c hi khix l tri cy cha c ch . C s vt cht cho cng ngh x l, bo qun v ch binti vng nguyn liu cn thiu thn.

- Bn cnh , h thng c s h tng nng thn (ng ni b, knh rch, innc, thng tin lin lc...) cn yu km, v ang lm hn ch kh nng pht trin, tiuth sn phm tri cy.

Vic gii quyt c tng bc nhng vn nu trn khng nhng s lm gimtn tht sau thu hoch, duy tr gi tr dinh dng cht lng tri cy, m cn lm c s

pht trin ngnh tri cy mt cch bn vng, phc v tiu dng trong nc v tham giaxut khu, c bit l lm tng thm thu nhp ca ngi nng dn, lc lng lao nghin cn chim khong trn 70% dn s Vit Nam.


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CHNG 2

C CHUA V NHNG BIN I SAU THU HOCH

2.1. Gii thiu s lc v c chuaC chua l loi rau n tri rt c a thch v phm cht ngon v ch bin cnhiu cch. C chua cn cho nng sut cao, do c trng rng ri v c canh tckhong 200 nm nay Chu u lm cy thc phm. C chua c v hi chua v l mtloi thc phm b dng, giu vitamin C v A.

Tri c chua thuc loi mng nc, c hnh dng thay i t trn, bu dc n di.V tri c th nhn hay c kha. Mu sc ca tri thay i ty ging v iu kin thi tit.Thng mu sc tri l mu phi hp gia mu v tri v tht tri

Qu trnh chn ca tri chia lm 4 thi k:

- Thi k tri xanh: Tri v ht pht trin cha hon ton, nu em dm tri khngchn, tri cha c mi v, mu sc c trng ca ging.

- Thi k chn xanh: Tri pht trin y , tri c mu xanh sng, keo xungquanh ht c hnh thnh, tri cha c mu hng hay vng nhng nu em dmtri th hin mu sc vn c.

- Thi k chn vng: Phn nh tri xut hin mu hng, xung quanh cung tri vn

cn xanh, nu sn phm cn chuyn ch i xa nn thu hoch lc nay tri chn tt khi chuyn ch.

- Thi k chn : Tri xut hin mu sc vn c ca ging, mu sc th hin honton, c th thu hoch n ti. Ht trong tri lc nay pht trin y c thlm ging.

Ht c nh, dp, nhiu lng, mu vng sng hoc hi ti. Ht nm trong bungcha nhiu dch bo kim hm s ny mm ca ht. Trung bnh c 50 - 350 ht trong tri.Trng lng 1000 ht l 2,5 - 3,5g.

Trong c chua c cha rt nhiu cht dinh dng c li cho c th nh carotene,lycopene, vitamin v kali. Tt c nhng cht ny u rt c li cho sc kho con ngi.c bit ci loi vitamin B, vitamin C v beta carotene gip c th chng li qu trnhoxy ho ca c th, gim thiu nguy c t vong do bnh tim mch v ung th.


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2.2. Nhng bin i sau thu hoch

2.2.1. Nhng tn thng c gii

L nhng tn thng trong qu trnh thu hi, vn chuyn v gi chn. C chua

b dp nt, khng nhng gy mo m xu x b ngoi m cn lm tng s mt nc, toiu kin cho ly nhim bnh, kch thch qu trnh h hp v tng hp ethylene. Nhngqu ny khng th bo qun c v chng b thi hng ch sau vi gi.

Nn gim n mc ti thiu nhng tn thng c gii l mt trong nhng conng ko di tui th v cht lng c chua, ng thi nng cao sn lng ch bin v

bo qun.

2.2.2. H hp

H hp l qu trnh sinh l quan trng ca qu sau thu hoch. S h hp lm gim

khi lng mt cch t nhin v khi h hp qu s dng cht dinh dng, thi ra nnglng dng nhit (lm nng khi qu), nc, kh CO2 v i khi c ru. Nc vnhit sinh ra lm qu b m t v d b thi, c bit l nm mc. Khi qu ang chn ccng h hp cao nht. T lc chn hn n qu chn, cng h hp gim nhanhng thi gim kh nng khng cho nn qu d b thi hng. Cc yu t nh hngn cng h hp l: nhit , m, thnh phn khng kh mi trng. Trong iukin t Oxy, nhiu kh Cacbonic, khng c cht kch thch chn Ethylenth cng hhp gim.

2.2.3. S sinhsn Ethylen

Song song vi qu trnh h hp, qu sn sinh ra kh ethylen. Khi qu gn chn hmlng cht ny t n mc cc i. Kh ethylen kch thch s phn gii cholorophyl vqu trnh chn qu.

Qu t bin h hp sinh ra nhiu ethylen trong qu trnh chn hn cc loi khc.S chn trong qu t bin h hp c bt u bi s tng dt bin trong s sinh snethylen. Mc sn sinh ra ethylen thay i nhiu theo tng loi qu.

2.2.4. S sinh nhitNhit c sinh ra trong qu trnh bo qun ti l do h hp. 2/3 lng nhit

c ti ra ngoi mi trng, 1/3 lng nhit cn li c dung vo cc qu trnh traoi cht bn trong t bo, qu trnh bay hi nc..

Trong bo qun cn duy tr cc thng s nhit , m ti u trong kho. Khinhit tng kch thch cng h hp mnh ln, t y mnh chu trnh: nhit ,


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m tng lm qu trnh h hp tng, cho s pht trin ca vi sinh vt tng, lng nhitsinh ra li tng hn na. l iu kin dn n h hng qu nhanh chng.

2.2.5. Sbay hi

Qu sau khi tch khi cy s xy ra qu trnh mt nc t nhin do bay hi, dnn qu b nhn ho, hnh thc xu. Nu qu trnh mt nc nhanh lm ri lon sinh l,lm tng h hp dn n qu b hng nhanh. Mc bay hi nc ph thuc vo tngloi qu, ging v cu to ca qu (qu v dy, v mng, dai , gin), chn ca qu,mc bm gip c hc. Mc bay hi cn ph thuc vo m v nhit mitrng, phng thc bao gi qu.

Qu non, xanh bc hi nc nhanh nn chng b ho. Qu b khuyt tt do cntrng, nm bnh, bm gip c hc cng lm tng s mt nc.

S mt nc cng thay i theo thi gian bo qun: Sau khi thu hi th mt ncmnh, sau gim ri li tng ln khi qu chn ri thi hng. m mi trng thp,nhit mi trng cao cng lm tng s mt nc.

2.2.6. S gim khi lng qu

Khi xy ra hin tng bay hi nc trong qu trnh bo qun th khi lng caqu b gim v cht lng dinh dng ca qu cng b tn hao. S tn hao cht dinhdng tn hao do qu phi s dng cht dinh dng (ch yu l ng) duy tr ssng sau khi ngt khi cy m do qu b gim hm lng cht kh sau thi gian bo

qun.

2.2.7. S thay i thnh phn ho hc.

Trong qu trnh qu chn, qu s tr nn mm (do cht protopectin chuyn thnhpctin ho tan lm qu tr nn mm ). S bin i pectin trong qu trnh bo qun qunl mt yu t quan trng cho qu trnh bo qun qu. V vy, khi thu hoch cn phi xcnh thi im qu cha chn thch hp. Nu chn qu, qu kh bo qun; nu qu cnqu xanh th cht lung qu khng tt .

Glucid (cc cht ng, tinh bt): l thnh phn thay i ln v mnh nht trongkhi bo qun. Trong thi gian bo qun qu chn, ng c s dng trong qu trnhh hp chuyn ho thnh nng lng, hm lung ng b gim theo thi gian. Cc loiqu cha chn hoc t l chn thp th tip tc chn trong qu trnh bo qun, tinh btchuyn thnh ng, mt phn uc s dng sinh nhit, phn cn li tch t trong qulm tng lng ng trong qu tng theo thi gian bo qun.


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Bin i v axt hu c: Trong qu chn c cha 0,5 1,0 % axt hu c. Cc axthu c thng gp l axt malic, axt xitrc, axt tractic...Trong qu trnh bo qun, lngaxt hu c gim r rt c v cht v lng . iu ny lm cho v chua ca qu gim i vv ngt tng ln khi qu chn .

Bin i v sc t, mu sc: mu sc ca qu do cht chlorophyl, antoxian vcarotenoit quyt nh. Tu theo mc chn ca tng loi qu m mu xanh ca qu mtdn do chlorophyl gim, mu vng, tng dn do hm lng carotenoit v antoxiantng .

Bin i cc cht gy v, gy hng: trong qu xanh thng cha hiu tanin lmcho qu c v cht. Khi qu chn, tanin bin i thnh ng glucoza ri gim dn v mthn lm cho qu c v ngt v mt v cht. Cc cht thm c to ra v tng ln trongqu trnh chn sau thu hoch nh ete, ru, aldehyt vi hm lng rt nh nhng to

cho qu c mi thm ring .

Bin i vitamin: T giai on xanh gi chuyn sang chn c nhiu loi vitaminto thnh nh vitamin B9 , B15, P , K, tin vitamin A... c bit vitamin C tng ln r rtnhng khi chn qu th hm lng ny b gim.


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CHNG 3

CNG NGH BO QUN SAU THU HOCH C CHUA TI

3.1. Thu hoch v x l ti rungBn yu t chnh c quan tm trong v ngay sau khi thu hoch c chua l

chn thu hoch, thi gian thu hoch, phng php thu hoch v x l qu thu hoch tirung. Bt k s thiu st no i vi nhng yu t ny u dn n gim cht lngqu, thm ch l tn tht hon ton.

3.1.1. chn thu hoch

C chua c th thu hoch khi qu t chn xanh ( thun thc v mt sinhl nhng cn xanh v), hoc ng mu, hoc chn hon ton, ty vo mc ch s dng,

thi gian vn chuyn, hoc khong cch t ni sn xut n ni tiu dng hoc thtrng.

i vi nhng th trng xa, hoc i hi thi gian tn tr lu, c chua c thuhoch khi cn xanh hoc hi (ang chuyn mu). L mt th qu h hp t bin, cchua thu hoch khi cn xanh nhng thun thc th c th chn tip t nhin, v c tht n cht lng ti u. Ngc li, qu non s khng t c mu sc v hng thmtt v s d dng b h hng sau thu hoch (Bautistaand Acedo, 1987).

Hnh 1. Mu c chua t chn xanh c th thu hoch

C chua chn xanh c xc nh bng v d mu c th nh nh 1. Mu i dinny c ct cho v nu nh cc ht ca mt ct khng b ct v cc qu th tng ngnhau v kch thc, hnh dng, th c coi l chn. Trong sut qu trnh vn chuyn, cchua chn xanh c th chu c iu kin b mt lu tr rp, x x tt hn, v th mvic tn tht cht lng v s lng l ti thiu. Tuy nhin, c chua chn xanh c thkhng t chn yu cu khi n thi im bn hoc tiu th, nn vic cho qu chn


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t nhin sau thu hoch hoc lm chn nhn to l cn thit. Qu c mu hng hoc chn thng c thu hoch do nhu cu ca ngi tiu dng hoc nh ch bin.

Hnh 2. Thu hoch c chua trng thi chn khc nhau da vo mu v

i vi cc th trng gn, c chua c th thu hoch khi ang ng mu, c muhng hoc chn hon ton. Cc trng thi ny c th xc nh d dng v chc chn davo mu v (Hnh 2). Hin nay, c rt nhiu ging c chua l sn phm ca cng nghsinh hc nh c chua ESL thi hn bo qun di, bin i gen hoc khng (Suslow vCantwel, 2005). Nhng ging khc nhau ny nu thu hoch qu trng thi chn xanhth qu trnh chn s b nh hng. V vy, t nht qu phi c thu hoch khi v hng.

3.1.2. Thi gian thu hoch

Nn thu hoch khi tri mt v tt nht l vo bui sng, v khi nhit thp cth gim thiu s tng nhit ca qu, ng thi tng hiu qu thu hoch. Bt u thuhoch khi sng sm tan ht hoc nu thu hoch vo lc qu sm th cn cn thn ch iu ny trnh gy hi cho nhng cy vn cn qu cho t thu hoch sau.

Khng nn thu hoch khi tri ma hoc ngay sau khi ma, v t l mc bnh cth cao hn (Bautista v Acedo, 1987). Nc ma c th tch t trn cung qu, l nixm hi chnh ca vi sinh vt, to iu kin thun li cho vi sinh vt pht trin. Tuynhin, nu khng trnh c iu ny, qu cn phi c ra sch v lm kh trc khi

bao gi. Vic ra v lm kh cng cn thit i vi qu t cc cy khng c cc hockhng c li chn t, v t l ngun cha vi sinh vt gy hi, c th bm vo qu c

bit l trong ma ma.

3.1.3. Phng php thu hoch

Phng php thu hoch thng dng l hi qu bng tay (Hnh 3)


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Hnh 3. Thu hoch c chua bng tay

Hi qu ra khi cy cn trnh gy tn thng cy v khng cn thit phi ri iphn cung nh, lm l ra phn cui cung, l ni trao i kh ch yu ca qu (v d,

y l ni thot hi nc, gy mt nc v gim khi lng; l li vo ca O2 v li raca CO2, v th lm tng cng h hp v cc hot ng trao i cht khc). Mt vickhc cn lu khi thu hoch l phi quan st trnh tn thng c gii, nh mt vtthng nh gy ra do mng tay ca ngi thu hoch. Nhng vt thng nh nh th cth khng d dng nhn thy nhng qu xanh, nhng s thy sau khi vt thng chuynsang mu en.

Hnh 4. Dng c thu hoch c chua vi b mt nhn

Dng c cha khi thu hoch, tt nht l c lm bng nha c b mt nhn (nhthng hoc khay nha nh). Dng c ny thng thun tin cho vic ng mt lngnh, v khng gy tn thng qu.

3.1.4. Lu tr trn ng rung

Cn trnh nm qu vo r thu hoch, hoc khng nn qung ko mnh cc r thuhoch. Nu khng, nhng va chm c th dn n nhng triu chng khng nhn thy


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c nh vt thm nu hoc en phn ht. Cc st ln c s dng thun tin chovic cha ng v vn chuyn sn phm t ng rung n ni ng gi. Nn s dngcc r nha, nhng cng c th s dng cc vt cha n gin nh st tre. i vi ccst tre, hoc thng g, c th lt l hoc giy bo c bo v qu trnh b mt ca vt

cha.Cc thao tc khng ng cch trong qu trnh lu gi trn ng rung bao gm:

nm qu vo thng cha, lm ri hoc ko mnh dng c cha trong qu trnh vnchuyn. Nhng thao tc ny c th dn n c cc tn thng vt l nhn thy v khngnhn thy. Cc vt thng nhn thy c th l cc vt ct, l thng hoc vt try xc.

Ngoi vic nh hng n cht lng cm quan, cc tn thng vt l cn lm tng smt nc v tc chn, v dn ng cho vi sinh vt xm hi.

Hnh 5. Qu nng ln do b phi di nh mt tri suy gim nhanh cht lng domt nc, qu nhn nheo v tng tc chn.

C chua sau thu hoch c gi tm thi di bng rm, trnh phi ra di nhnng mt tri, v iu ny gy rm nng, mt nc nhanh dn n kh nhn v tch l ynhit thc y qu trnh chn. S tng nhit ca qu thng thy khi qu b phinng mt n hai gi. Nhit tch t bn trong qu s c gii phng sau v lmtng nhit bn trong vt liu bao gi, vt chuyn ch hoc khu lu tr. ng thi n

lm tng cng h hp. loi b nhit, cn lm mt s b.Qu c thu hoch nhng chn khc nhau c th phn loi trong qu trnh

thu hoch v qu trnh lu gi trn ng, bng cch chng trong cc vt cha khcnhau hoc trong cc thng cha c ngn.


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Hnh 6. Dng c thu hoch v vn chuyn c tm ngn chia qu xanh v qu chn.

Phn loi qu ty thuc vo kch thc v ng thi c th phn loi khuyt ttnu ngi thu hi c kinh nghim. Nu khng, qu s c vn chuyn n nh bao gi

lm vic ny.

3.2. Cc cng on trong nh ng gi

Hot ng chnh trong nh bao gi l ng gi trc khi bo qun hoc vnchuyn n th trng. Mc d vy, cc cng vic khc trc khi bao gi cng cn thchin sao cho tn tht l thp nht trong sut qu trnh vn chuyn v tn tr v t cyu cu cht lng trong sut qu trnh lu thng trn th trng v tiu dng. Cc cngvic trc bao gi i vi c chua bao gm lm sch, phng nga thi hng, phn loituyn chn, x l kim sot qu trnh chn v lm mt s b.

3.2.1. Lm sch v kim sot thi hng

C th s dng vi mm lau sch qu trong qu trnh phn loi, hoc c th rabng nc sch, sau phi lm kh. Trong qu trnh ra, nc ra c th b nhim bnv cha vi sinh vt gy thi hng nu khng thng xuyn thay nc. x l phng

bnh, c th s dng cc cht thng thng c php s dng (General-Regarded-As-Safe - GRAS) nh Clo di dng cht ty ra (5.25% HypoChlorit NaOCl) v muicacbonat nh Natricacbonat. Nhng nghin cu trc y ch ra rng, phng phpx l n gin ny s lm gim thi hng mt cch c hiu qu. Tuy vy, i vi tng

ging phi s dng nng thuc thch hp.

Khi s dng mui cacbonat (v d kim cacbonat hoc ph bin l Natricacbonat),nng 3% (30g/l) th nn dng phun ln qu hoc nhng qu, sau ra vi nc(Smilanick 2002).


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Sau khi ra, cn lm kh qu v s m t bn trong vt cha s to iu kinthun li cho vi khun pht trin. Vic ny c th thc hin d dng bng cch lau qu,hoc qut bng khng kh thch hp. Trong sut qu trnh ra hoc lm kh, c th tinhnh mt s cng vic trc bao gi nh phn loi tuyn chn.

3.2.2. Phn loi / tuyn chn

C chua c cht lng tt lun l s la chn u tin ca ngi tiu dng. V th,phn loi hay tuyn chn lun l vic lm c li. Phn loi v tuyn chn c th thay thcho nhau, nhng tht ra gia chng vn c s khc bit. Khi phn loi da trn tiu chunla chn chnh thc ca cng nghip th c gi l s tuyn chn. Nhng qu trnh ngin hn gi l phn loi.

Phn loi hay tuyn chn bt u bng vic phn bit nhng qu c cht lng ttvi nhng qu km cht lng hoc b khuyt tt (nhng qu b rn nt, bin dng, thi

hng, b cn trng hi, hoc b cc vt thng vt l). Nhng qu tt sau s tip tcc phn loi theo mc cht lng, da vo kch thc v chn. Nh th, phnloi v tuyn chn s xc nh cht lng v gi thnh ca sn phm hng ha khi a rath trng. Nu thiu cc tiu chun cht lng th s l ro cn thng mi v s cntr s pht trin v tnh cnh tranh trong cng nghip. Trong thi i tng cng m rngthng mi v ton cu ho th trng, cc nc ang pht trin cn c c quan tiuchun ha v kim tra tiu chun la chn.

Phn loi v tuyn chn s trnh c s h hng sm ca qu. Nu ln cc

loi qu khc nhau v cht lng, qu b bnh hoc b tn thng vi cc qu lnh ln slm tng t l thi hng, v qu cht lng km hoc qu b tn thng rt nhy cm vis pht sinh bnh, d dng b nhim bnh t qu b bnh v c th dn n h hng cnhng qu lnh ln khc. Qu b bnh hoc b tn thng c gii thng sn sinh ranhiu ethylene, mt hoocmon thc y qu trnh chn v gi ho. Vn ny s tr nnnguy him nu qu c tiu th th trng xa, nhng ni m thi gian vn chuyn cth phi ko di 3 5 ngy, nhit s tng, to iu kin thun li cho bnh pht trin.Cng khng nn ln qu cha chn vi qu chn, c bit l trong sut thi gian divn chuyn v lu tr, v qu chn s sinh ra lng ethylene cao, gy ra s chn sm ca

nhng qu cha chn.

cc nc Lo, Vit Nam, Cambodia v nhiu nc ang pht trin khc, khngc tiu chun la chn no vi c chua. S phn loi gia ni cung cp v ni c nhu culi khc nhau. C th phn loi da trn kch thc (v d: A ln, B trung bnh, C nh, D rt nh), mu sc hoc trng thi chn v khng b khuyt tt.


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S phn loi theo ging cng quan trng v c chua c rt nhiu loi ging, khcnhau v nhy cm vi nhng tn thng c gii v tc chn. C chua c tht dythng chu c lu tr trong nhng vt dng b mt g gh tt hn so vi nhng gin

tht mng. Nu c hai ging ny c lu tr trong cng mt ni, th tn thng c gii nhng qu mng tht c th dn n thi hng hoc gim cht lng nhng qu c thtdy v lm tng tc chn. Mt s nng dn thng trng v thu hoch hai hoc viging cng mt lc. Cc qu khc ging c bao gi ln trong cng mt thng cha vnc th gi c cht lng nu ni sn xut gn ni tiu th. Tuy vy, nu mun thitlp mt ci tn cho sn phm c cht lng tt ca mnh, ngi nng dn cn phn loisn phm theo kch c hoc yu cu cht lng ca ngi tiu dng. C th dn nhnhoc ng du cho sn phm, con du phi c bo v v cao ngun cung cp cchua cht lng cao. V tiu chun la chn c chua cha c s dng cho cng nghip cc nc ang pht trin trong c Lo, Cambodia v Vit Nam nn cch phn loic ngh diy c th dng tham kho:

- Loi A, ln: C chua ca cng mt ging, c cng trng thi chn, cng hnh dng,khng khuyt tt (khuyt tt do cn trng hi, tn thng vt l, thi hng, bindng,)

- Loi A, trung bnh: Cht lng yu cu nh loi trn, nhng khc v kch c.

- Loi A, nh: Cht lng yu cu nh trn, nhng khc v kch c.

- Loi B, ln: C chua ca cng mt ging, khuyt tt trn b mt hoc khuyt ttnh (khuyt tt nh ngha l khng nh hng n cht lng qu khi n v nhhng khng ln n cht lng cm quan ca c l hng).

- Loi B, trung bnh: Cht lng yu cu nh trn, nhng khc v kch c.

- Loi B, nh: Cht lng yu cu nh trn, nhng khc v kch c.

- Loi C, a kch c: C chua ca cng mt ging, khng c phn loi theo trng

thi chn, nhng khng c qu chn hon ton, c khuyt tt nh nh loi B, nhiukch c.

Suslow v Cantwel (2005) a ra ch s cht lng tiu chun cho cc ging cchua khc nhau, trc ht l da trn s tng ng v hnh dng v khng c khuyt tt,h hng. Kch c khng phi l yu t tuyn chn cht lng nhng c l nh hungkh nhiu n cht lung v mt thng phm. Cc ch s cht lng ny nh sau:


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- Hnh dng: c cng mt kiu hnh dng (hnh trn, hnh cu, hnh cu dt)

- Mu sc tng ng (t cam n m, vng nht). Khng c muxanh.

- Biu hin bn ngoi: Trn mn, so cung nh. Khng c cc vt rn nt,rm nng, vt thng do cn trng, vt thng c gii, hoc vt bm tm.

- cng: Chu c p lc. Khng b bin dng do chn nu.

3.2.3. Kim sot s chn: S chn ca c chua c th c lm chm li hoctng cng hoc ci thin.

Lm chm qu trnh chn l mc ch chnh ca tch lu, bo qun, ko di tuith sau thu hoch. Trnh qu trnh chn sm trong khi vn chuyn cng rt quan trng.

Vic thc y qu trnh chn cng cn dng n, c bit l i vi nhng qu thuhoch trng thi chn xanh p ng nhu cu ca th trng tiu dng v thm chnhng qu c thu hoch trng thi khc nhau c th t c chn ng u theoyu cu. C chua chn thng l nhu cu ca ngi tiu dng hoc nh ch bin. Chnn lm chn nhn to nhng qu trng thnh, v qu non chn p s khng tt.

Phng php lm chn khc nhau c mt c ch chung tng tc chn l x lethylene hoc nhng cht tng t (nh axetylene) trong mt khong thi gian kch thch qu sn sinh ethylene mc cao. Vic s dng kh ethylene i hi chi ph caov my mc phc tp. C th lm chn c chua bng mt s k thut n gin nh sau:

- S dng nguyn liu thc vt sn sinh kh ethylene cao nh l cy ca Gliricidiasepium v Samanea saman hoc nhng qu chn, ang chn. Nhng nguyn liuny thng c s dng vi lng thch hp l 10% trng lng qu (c 10 kgqu, th s dng 1 kg nguyn liu thc vt ny), trn ln vi qu trong mt bungkn 2-3 ngy, sau a qu ra khi phng v chn t nhin trong iu kinthong.

- S dng dung dch Etan (ch phm thng mi l Ethrel ging vi ethylene dnglng) nng 2500-5000 ppm, nhng trong 5 pht.

- S dng t n (CaC2), cho mt lng t vo ng qu gi trong phng nh, nnnh v khi c chua phi c ph kn bng bao ti trong 2 ngy acetylene giiphng ra t t n khi n phn ng vi nc, sau bao ti chn c d i, qu chn. Trong mt vi trng hp, qu c cha trong thng cha ln, sau t n c a vo trong mt ti nh, ph kn trong 2 ngy. Khong 0.25-0.5 kgCaC2 c gi trong giy bo v trong mt st tre 80 kg. Qu xanh s chuynsang c mu sau 1 ngy t khi x l, trong khi chn t nhin th phi mt 6-7


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ngy. Cn ch rng phn ng ca CaC2 v nc s sinh ra acetylene l mt phnng to nhit, v th khng x l trong thi gian ko di v s dn n tn thngnhit ca qu v d qu chn cng ch t c mu cam hoc vng, thay v mu.

cc nc nhit i th ci thin s chn rt quan trng, v d nh Lo, Vit Namv Cambodia, ni m iu kin nhit cao l ch yu, thng dao ng t 27 320C,khng thun li cho s hnh thnh mu ca qu c chua. Nhit chn ti u chogi tr cm quan tt v cht lng dinh dng l 200C (Suslow v Cantwell 2005). Nhit ny cho mu sc tt nht v gi c nhiu vitamin C nht. Mu ca qu c chual do carotenoid, lycopene c tng hp nhit khong t 13 250C. Cao hnkhong nhit ny s cho mu vng cam hoc vng nht, v -carotene c tng hpnhiu hn, trong khi thp hn khong nhit th qu c th b tn thng lnh(khng chn c, hoc b nu ha b mt). Mu hnh thnh qu c chua khng phil mt vn nhng vng t cao, ni c nhit thp, hoc khi lu tr kho lnh

trong cc ch bn bun, bn l. nhng vng t thp hoc khi nhit cao, c th lmcho c chua chn bng cch gi qu trong khu mt hoc trong mi cht lm mt d bayhi.

3.2.4. Lm lnh s b:

Lm gim nhanh chng nhit sn phm, mt qu trnh c gi l lm lnh sb, c th gip gi c cht lng thng qua vic lm chm cc hot ng trao i cht.Lm lnh ngay sau khi thu hi c th gi cht lng rau qu mc tt nht sau thuhoch. Nu c thc hin kt hp vi bo qun lnh, n c th lm gim thi gian lmlnh. Lm lnh khng kh cng bc l c hiu qu nht nhng phng mt li ph bin

hn (theo Suslow v Cantwell, 2005). Mt phng php n gin v nhanh chng calm lnh s b l s dng nc lnh. Lm lnh nc n gin v gi thp c thcnghim ti Vin Nghin cu rau qu, H Ni, xem hnh 10. H thng ny gm mt bkhung c lm t nhng ng nc v hai loi vt liu lt u tin l nhng tm tre an,tm ct v tip theo l tm nilon ph ln trn trc khi cho nc vo. Nc c lmlnh n 100C bng cch cho . Qu c th c nhng ngp trong nc lnh n khinhit tm qu t 10-130C.


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Hnh 10. M hnh lm lnh s b n gin thc hin ti Vin NC Rau qu, H Ni

3.2.5. Bao gi

H thng bao gi khng ch c chc nng cha sn phm m quan trng hn,n cn c s dng nh mt yu t bo v sn phm hu hiu, gip sn phm trnhnhng tc ng c hc v nhng nguyn nhn lm hao tn khc. Cc chc nng khc ca

bao b l cung cp cc thng tin v sn phm bn trong nh: khi lng v nh gibn ca sn phm, xut x sn phm v.v C nhiu loi bao b khc nhau c s dng bao gi v vn chuyn c chua nhng ph bin nht l cc st tre v st g c dungtch cha thay i t 20-60 kg (Hnh11). Mt s t trng hp s dng st nha mc dchng kh t, nhng vn c gii thiu bi chng rn chc v c th ti s dng, hoctr li, chng c b mt mm v d v sinh v c th xp thnh chng cao.

Hnh 11. Vt ng c chua: A-St tre, B-St g, C-St nha

Tuy nhin khng ging nh nhng vt liu cng khc, nu khng s dng nhngbin php bo v ph hp th tc dng bo v rau qu t nhng tn thng vt l ca sttre l rt thp. St tre thng c b mt sc v gh gh, chng khng th chng ln nhaum khng lm dp nhng qu lp di nu khng s dng tm g lt hoc np y

bng g gia cc lp, v cc st trng khng th chng ln nhau tit kim khng giannu khng c thit k vi nhng cnh cho theo y nh hnh 12A. Thng g cng

bo v sn phm tt hn st tre nhng nu khng lt b mt mt cch cn thn th n c


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th l nguyn nhn gy nn nhiu tn thng rau qu. Mun tit kim khng gian khitn tr cc thng trng th c th thit k cc thng g dng c th gp li, xp li c(Hnh 12A) trong khi st nha c th lm cc cnh xin (Hnh 12B).

Hnh 12. Thng g xp c (A) v st nha c cnh xin (B).

trnh hoc hn ch thp nht cc thng tn vt l v nhng hao tn khc qu, khi bao gi cn ch thc hin nhng im sau:

a. S dng bao b sch

b. Nu ti liu bao gi c s dng ph bin, vic ng gi d c thc hinng u. Nhng bao gi cha t 40-50 kg l qu nng. Ngi ng gi thng lm rihoc nm chng hn l nhc chng ln mt cch nh nhng trong sut qu trnh ng giv vn chuyn.

c. S dng nhng vt lt v vt m hoc nhng vt liu dng lt nh giy bo,l... Vi thng g, c th dn sn nhng tm ba cc tng mng pha bn trong.

d. Khng s dng nhng vt cha qu su v s d lm tn thng qu phn y.

e. Ch ng va dung tch cha ca bao b. Khng c n qu cht hoc ngqu y dn n nhng tn thng do bm dp.

f. ng gi nhng qu c cng chn trong cng mt bao b. Nu xp ln nhngqu chn vi nhng qu cha chn c th dn n s chn p ca nhng qu cha chn v

lm tng h hng nhng qu chn t trc.g. Gi c nh qu trong bao b lm cho qu khng x dch trong sut qu trnh

ng gi v vn chuyn v hn ch thp nht h hng do va p. C th c nh qu bngcch lc nh bao b trong qu trnh ng gi lp y cc khong trng. Bao b clm y ti 1/3 dung tch cha v lc nh; sau tip tc lm y n 2/3 dung tch chav lc li bao b ln na. Tip tc qu trnh ny cho n khi bao b c lm y kht.


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h. Cn thao tc cn thn trong sut qu trnh ng gi (nh khng ri qu...)

i. Buc cht bao b bng dng c chuyn dng hoc dy buc.

j. Xp vo ni mt.

C nhng bin php bao gi c th gip lm chm s chn v ko di thi gian tntr ca c chua. Mt k thut n gin c ng dng kh ph bin mt s nc l bao

b ci bin kh quyn (MAP), mt loi bao b chuyn dng c th linh ng trong mitrng bo qun. Loi mng MAP ny nn c s dng nh l yu t b sung hn kthp vi cc vt liu bao gi khc l mt vt liu bao gi c lp v n c kh nng chngchu tc ng c hc km.

3.3. Bo qun

Khi qu c bo qun th mc ch chnh l tr hon s chn v ko di thi gian

tn tr qu. Thng thng qu c em bo qun tm thi trong khi ch vn chuyn,bc vc hoc ch n lc bn, nhng nng dn v ngi bun bn li khng mun snphm ca h b chn sm. Nh vy, qu chn sm trong sut qu trnh vn chuyn l iukhng c mong mun. Nhng cng c nhiu trng hp, c chua c gi trong mtkhong thi gian no i qu chn v lc chng c bo qun vi mc chlm tng chn nhiu hn l ko di thi gian tn tr qu.

Nhng k thut bo qun khc nhau khi em ng dng bt c ni no u phic kim nghim cho ph hp vi cc iu kin ni bng cch s dng cc ging a

phng, yu t nh hng n cc phn ng trong qu trnh bo qun. Phng php hiu

qu nht lm chm chn v ko di thi gian bo qun l bo qun nhit thp.Nu c c s bo qun lnh, nn lu cc iu kin sau y (Suslow v Canwell,

2005): Nhit : 12,5-150C vi qu xanh; 10-12,50C vi qu ng (c mu nht); 7 100C vi qu chn (c mu m). m tng i: 90-95%.

Qu c chua t chn k thut c th bo qun c n 14 ngy trc khi chn 12,50C m khng lm gim cht lng cm qun v s bin i mu sc. nhit ny, sau qu 2 tun, s thi hng s tng dn theo thi gian bo qun. Vi nhng qu t chn ti ( chn s dng, n c), c th bo qun c 8-10 ngy khongnhit thch hp. Bo qun ngn hn hoc h nhit thp hn khong nhit nu

trn i khi c p dng trong th trng nhng s d xy ra tn thng lnh sau mtvi ngy. C chua s xut hin tn thng lnh nhit di 100C nu gi qu 2 tunhoc 50C nu qu 6-8 ngy. Hu qu ca vic tn thng lnh l c chua s khngtip tc chn mt cch bnh thng, khng t c mu sc v hng v t nhin, qu bmm, b mt b lm, thm ht, v tng nguy c h hng (c bit l mc en gy ra bivi khunAlternaria spp.). Bn cnh , m tng i cao cng cn thit cho vic gicht lng c chua mc cao nht c th v chng li s mt hi nc (lm nhn v


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qu). m cao ko di cng l iu kin thun li pht trin mc trn b mt quhoc nhn cung.

nhng nc ang pht trin bao gm Cambodia, Lo, Vit Nam nhng c sbo qun lnh vn cn him. Nhng phng php bo qun khc l rt cn thit. Sau y

l nhng phng php bo qun c chua n gin v r tin.

3.3.1. Bao gi iu bin kh quyn (MAP)

MAP l mt phng php n gin v r tin lm c ch s chn ca qu bngcch to ra mi trng kh c t kh CO2 v nhiu kh O2. MAP cn to ra mi trng mlm gim s mt hi nc. MAP c to ra mt cch n gin bng cch cho qu votrong mt ti cht do (hnh13). Mng nilon cng c th c dng lm vt liu lt trongcc thng cha, hoc che ph, y cc pallet.

Hnh 13. C chua bo qun MAP v khng bo qun MAP sau 6 ngy iu kinthng (25-330C)

Nhng loi mng MAP c sn cc nc chu bao gm cc nc Lo, VitNam v Cambodia l cc loi ti LDPE v HDPE, mng polypropylene (PP) vi cc dy khc nhau.

Trong ng dng ring mng MAP vi iu kin nhit cao cc nc nhit i,bn trong ti thng xy ra hin tng ng nc v c th dn n thi hng qu (Hnh14). trnh tnh trng y, nhng loi mng ph hp vi dy thch hp phi c sdng hoc phi xc nh c thi gian ti a trong bo qun bng MAP trc khi xy racc hin tng nh vy. c l trn ti nilon cng tr nn cn thit. Cc l thng c th


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c c u n bng cch s dng cc vt dng di thng thng, inh ghim hocnhng hng l kim chm siu nh. V d, khi s dng dng LDPE 50 m th nn c 4 linh ghim cho mi 4 kg qu trong khi vi st g c kch thc 36 x 48 x 24 th cn 24 linh ghim.

Hnh 14. Nc ng bn trong mng MAP (A) v lm hng qu bo qun bng

MAP (B)

3.3.2. Bo qun lnh bng phng php bay hi (Evaporative Cooling System)

ECS bao gm s bay hi ca nc mang theo yu t lm mt. Nc c cungcp vo nhng vng ln cn ca sn phm v lm h nhit trong bung bo qun, nhitsinh ra t chnh sn phm (nhit sinh ra do h hp) v do mi trng bn ngoi. S gimnhit c th khng qu ln nhng m c th tng ln t 90% hoc cao hn, ngdng ECS rt c hiu qu trong vic hn ch s mt nc v cc qu trnh lin quan ns mt nc (nh s ho, s chn nhanh).

Cc phng php ECS khc nhau u c mt im chung s c mt ca nc vng ln cn sn phm:

- S dng mn ca m:

Mn ca c lm m vi nc t l 1:1 c th tr hon s chn ca c chua ti 2tun v qu c chua vn tip tc chn (Hnh 15) (Bautista v Acedo, 1987). Mn ca

phi c lm sch, bng cch di nc si, phi kh dit vi khun. Mt k thutkhc dit khun l s dng dung dch Hypochlorite 200ppm lm m mn ca. Quc chua nn c xp thnh tng lp mng, chng hn: mt lp mn ca dy khong 2

cm, tip theo l mt lp qu sau li ph ln mt lp mn ca v c tip tc nh th.Cch ny c th ngn khng cho bnh ly lan t lp ny sang lp khc. Phng php nyc th thc hin nhiu khng gian hoc trong cc vt cha.


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Hnh 15. S dng mn ca m trong bo qun c chua

- S dng chum, vi lm m:

Nhng ci chum, vi ln rt sn cc vng nng thn c th c s dng lmECS mc trung bnh (Hnh 16) (Bautista v Acedo, 1987). Chum c t trn mt cikhay nc v ph ln trn bng mt mnh vi m hoc bao ti lm t si ay. Phng

php ny c th gi qu c chua chm chn t 1- 2 tun.

Hnh 16. S dng chum vi m bo qun c chua

- T lm mt nh bay hi:

Mt kiu cu trc ca ECS c th gi c chua xanh trong thi gian bo qun lu

gp i so vi c chua bo qun iu kin thng (Acedo, 1997a). Kiu cu trc thnht (Hnh 17A) gm c t bo qun lm bng g v li kim loi, ton b cu trc cph bi bao ti ay c lm t bng nc trong khay t trn nh v di y. Cutrc th hai (Hnh 17B) l s ci tin ca cu trc th nht. Cc cnh hp c lm ttm Gl phng, c khong cch 5x5cm so vi cnh pha ngoi c lm bng li thptt. Khong cch 1,5cm gia hai bc vch bn trong v bn ngoi cha y tru c git bng s tip xc vi mt tm vi ngm ngp trong khay nc t trn nh hp, cth thay tru bng than ci v mn ca. Cu trc th 3 (Hnh 17C) l mt cu trc phng


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to, khong gp 4 ln kch thc ca cu trc th 2, dng bo qun s lng ln. Nkhng c phn no c lm t g v c lm t nhng vt liu bn nh cc thanh stv tm Gl dy v li thp. h nhit, ta nhit bn trong t, phn nh t c bc tngthng gi. Mng ng nc cng nh t vi h thng ng nha dn nc vo lp trudy 5 cm. Ton b cu trc ny t trn mt khay Gl cha nc.

Hnh 17. Thit b lm mt bay hi bo qun c chua

- Thit b lm mt bay hi vi qut thng gi: (hnh 18)

Cu trc ny c hai hp mng trn cc cnh i nhau c cha nhng b rm hocthan (Redulla v cng s., 1984). Nc c cho nh vo than hoc rm v gi lm quaytuabin ht hi m, kh mt c a vo lm mt sn phm bn trong t mt. Nhit

bn trong t gim t 3-50C trong khi m tng ln khong 85%.

Hnh 18. Thit b lm mt bay hi vi my ht gi


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- T mt khng cn nng lng:

y l thit b lm mt bay hi, c dng ln vi hai lp gch, khng gian giahai bc tng trong v ngoi c y ct t m nc (Hnh 19) (Roy, 1989). Cchua c t bn trong v ton b t c ph bng mt tm thm r tin gi m.

Sut thi gian nng, t bo qun c th duy tr 15-180

C v 95% m.

Hnh 19. Thit b lm mt bay hi kiu bung lm mt khng nng lng

3.3.3. Cc phng php ko di thi gian bo qun n gin v r ti n khc

Mt bin php hu hiu nhm lm chm s chn l s dng 1-methylcyclopropene

(1MCP), l cht c tc dng c ch hot ng ca ethylene v c y ban Mitrng v Cc kim nh thuc v thc phm Hoa k (US EPA v FDA) cng nhn l anton cho ngi s dng rau qu. N c th lm c chua chm chn n 2 tun theoImproved Pope vi c chua c th s dng 250ppb 1-MCP trong 24 gi (Acedo v cngs., 2004). N cng c tc dng lm chm chn tng t trn c chua bi vi liu lng sdng 110ppb (Opiyo v Ying, 2005). Tuy nhin, trong c hai trng hp, qu c chuau khng t mu mong mun khi t s chn mm. Nhng x l ng thi khc saukhi x l 1-MCP c th cn thit qu c chua chn mt cch bnh thng v mu scv. Mt x l khc cho thy cn thit s dng ethanol (Acedo v cng s., 1995).Bin php x l tt nht l 1 ml ethanol cho mi kg c chua trong 6 gi bng cch s

dng phng php bay hi v 4% ethanol trong 4 pht khi s dng phng php nhngngp.

3.5. Vn chuyn

y l mt trong nhng cng on quan trng trong x l c chua bi v bt cmt thiu st no trong h thng ny (nh iu kin vn chuyn ngho nn, thao tc cuth, nhng s chm tr) u c th dn n nhng hao ht nghim trng (Hnh 20).


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Hnh 20.iu kin vn chuyn ngho nn dn n nhng hao ht c chua nghimtrng

Nhng phng tin vn chuyn ch yu l xe bc hng, xe but v xe ti v chngthng khng c lm lnh. hn ch thp nht nhng hao tn, cn lu mt s im

sau:a. Cch thc xp hng ph hp i vi cc st tre, t cc tm g ngn nm

ngang gia cc lp trong khi hng trnh lm hng qu cc lp pha di (Hnh21A). Vi cc loi bao b nh thng g hoc st nha th khng cn thit (Hnh 21B).

Hnh 21. Cch thc xp hng i vi st tre (A) v st g hoc st nha (B)trnphng tin vn chuyn

b. Gi cht cc thng hng trong mt khi m bo cho cc thng hng trongcng mt khi gi chng khng b trt ra khi khi trong sut qu trnh vn chuyn,iu c th dn ti s h hng ln.

c. Cn che ph trnh ma, nng v gi to S dng vi bt che ph trnhma t, phi sn phm di tri nng v di tri gi mnh trong qu trnh vn chuyn.Qu b m t s to iu kin thun li cho s pht trin ca vi khun v thi hng, cn


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vic phi nng s lm qu b nng ln. Phi by qu di tc gi cao dn n s mthi nc v lm ho qu.

d. Cn m bo s thng kh thch hp trnh hin tng nng cc b hoc sym kh lm tng nhit v hm lng ethylen. Mt h thng thng kh nh v d

Hnh 22 (Pantastico, 1980). Khi vn chuyn cn che ph cn thn bng vi bt v tmngn gi c lm bng tm Gl phng t cao hn cabin.

Hnh 22. H thng thng kh trong xe ti khng lm lnh

e. Thao tc cn thn trong khi xp vo hoc ly ra Nu khng s d gy hngqu do va chm nh nt qu (Hnh 23).

Hnh 23. Nhng vt nt trn qu l biu hin ca s h hng do va chm

hn ch thp nht vic lm ri qu trong sut qu trnh tin hnh v thao tc,c th dng mt h thng bng ti nh hnh 24A (Pantastico, 1980). Bng ti gm 2rng rc v mt si dy cho chc chn. Mt rng rc c t bn trong xe ti phau thng xe, ci th hai t mt v tr di ng hoc ni c nh ca nh kho. Thnghng c th c treo trc tip hoc t vo trong mt ci r mc chuyn hng ln


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hoc xung xe ch hng. S dng thang hoc bc gip hot ng vn chuyn hng lnxung c d dng hn (Hnh 24B). Thang c th di chuyn c v mt thang lm

bng g hoc st, chn thang lm bng st.

Hnh 24. H thng bng ti (A) v cu thang (B) gip bc v d hng thun tin

f. Thc hin vn chuyn vo thi gian mt trong ngy iu ny gip bo v qukhi s tng h hp v suy gim cht lng.

g. Trnh nhng tr hon khng cn thit Nhng tr hon trong sut qu trnh vnchuyn tng mc hao tn cht lng qu.

3.6. Tiu th

y l khu quan trng cui cng ca hot ng sau thu hoch gia ngi snxut hoc ngi vn chuyn vi ngi mua hoc ngi tiu dng. Nhng hot ng x l


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th trng quyt nh cht lng cui cng ca sn phm by bn v cn cung cp chongi tiu dng cht lng tt nht c th. Sn phm phi c b ngoi hp dn nh ti,khng b khuyt tt, cht lng cao. Cn c nhng x l thch hp, khng ch quan tmn ring sn phm m cn phi ch n thao tc ca ngi x l. hnh 25, v d: sty c chua chn c th c vn chuyn an ton hn bng xe y hoc xe ch hng

chuyn dng.

Hnh 25. Vn chuyn cc st c chua bng tay ch

Mt s hot ng quan trng th trng (ngi bn bun v bn l) m bocht lng v tnh thng phm ca c chua nh sau:

- Thc hin v sinh thch hp Sn phm h hng phi c vt b, lm sch cs ng gi v bo qun, khu vc by bn phi c v sinh v lau dn sch s. C ths dng Chlorine 200ppm kh trng khu vc bn hng.

- Ti lm sch Lau qu lm cho chng hp dn ngi tiu dng hn. Ra qubng nc chlorin ha i vi nhng qu b h hng trong qu trnh vn chuyn.

- Ti la chn, phn loi iu ny l cn thit i vi lot c chua c cht lngkhng ng u, ln ln cc chn, b thng tn do bnh hoc do c hc. iu nycng rt quan trng trong vic m bo tnh ng u v cht lng ca sn phm c

by bn.

- X l chn C chua c tiu th nhiu nht khi chn, do , c th chn cchua trc khi by bn. Vic x l chn cn tun theo quy nh ca a phng v phi

c cng b rng ri.

- Bao gi li th trng bn bun, sn phm c la chn li v ng trongcc ti nh hn, ph hp hn vi phn phi l.

- Trnh h hng do ethylene C chua rt nhy cm vi ethylene sinh ra bi schn p. Mt khc, c chua chn cng sn sinh ra hm lng ln ethylene lm cho quchn khng ng lc v lm gim gi tr ca nhng qu ti khc, v thng th trng


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bn bun v bn l thng bn cc loi qu khc nhau. Nhng sn phm sinh nhiuethylen v nhng sn phm nhy cm vi ethylen khng nn chung trong mt phnghoc trn cng ngn by bn. Nhng ngun sinh ethylen khc (forklifts, phng lm chn,qu hng) phi c khng ch. S dng h thng thng hi v cht hp ph ethylen(nh KMnO4) lm gim lng ethylen trong khu vc bo qun.

- Bo qun Tt c lng c chua nhn v khng th phn phi ht trong cngmt ngy, do cn phi bo qun. Phng bo qun vi ch bo qun ph hp l cnthit. Phi n s tng thch ca cc loi qu cng c bo qun.


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TI LIU THAM KHO

1. Ti liu tp hun, Cng ngh sau thu hoch v k hoch tp hun d n Reta 6208.

2. http://agriviet.com/nd/517-cay-ca-chua/

3. http://www.vacvina.org.vn/Story/vn/home/BaigiangVAC/2010/12/396.html

4. http://vst.vista.gov.vn/home/database/an_pham_dien_tu/MagazineName.2004-04-22.2018/2005/2005_00030/MItem.2005-07-20.0434/MArticle.2005-07-20.0303/marticle_view

5. http://rausach.com.vn/forum_posts.asp?TID=3098&title=bo-qun-rau-qu-cao-cp

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