NLN'108-11/2012 M l
MO HINH HO HAP - BAY HOfI CUA RAU QUA TU^OI TRONG MOI TRU^OfNG BAO GOI KHI CAI BIEN
H 6 HLfU P H U N G , N G U Y E N VIET DUNG, Wen KH & CN Nhiet - Lanh. Dai hgc Bach khoa Ha Npi Tren ca sa md hinh hda qui trinh hd hip-bay hai cua rau qua trong qui trinh bao quan lanh trong dieu kien moi truxyng khi cai bien cOa bao gdi xiy dwng thuit toin xic dfnh sw thay doi theo thai gian, nhiet dp, dp am, Iwo-ng nwdc ngwng tu trong bao gdi vi dp hao hut tw nhien cua x o a / Mpc Chiu trong bao gdi theo phwang trinh can bing ning Iwang va vit chat. Ket qui tinh toin bing mo hinh dwgn: kiem chOug bdi cic so lieu thi nghiem khac nhau cho thay tinh chinh xic hem hin cua md hinh so vai cic md hinh twang tw hien cd.
KY HIEU
X - thanh phin khi khong ngung x, x ( N2, O2, CO2, Ar,...);
Mo, [x] - tuung ling la nong dp khi x trong va ngoai bao goi;
V I - the tich rieng phan cua khi x, (m^, A • dren tich bao goi (m^), L - b§ day bao goi (|im).
Palm - Ap sucit khi quyen (atm),
Px' h? so tham khi x qua mang bao goi (ml m'^ h"' atm"^);
T- thoi gian;
H-am dung cua h6n hp'p khi (kg/kg);
RH - do ^m tuong doi cua hSn hpp khi,
Qrt ,Qs - l^n lypt la ngu6n nhiet trong va nhipt do ho hip (kJ);
hE,hp - lan lifpt la hp so trao <j6i nhipt doi lu'u tgi be mat rau qua va be mat bao goi v6i moi tru'O'ng;
To, T,, Ts- nhi^t 60 moi inrong bao quan, nhipt 3p trung binh cua hon hpp khi trong bao goi IVIAP;
Cs - nhipt dung rieng ciia qua I. DAT V A N Dt
Hi$n nay van de k6o d^i th6'i gian bao quan hoa qua t u a l sau thu hoach giam Ion that ti> 20% xuong c6n 10%, \ii van dh Ccip thiet nh3m dam bao nhu cau tiSu thu trong nu'dc ngSy cSng gia tang cung nhu- de xu^t khau. Trong ITnh v y c niy cong ngh? bao quan b^ng nhi6t 6d thSp ket hg'p vd\ bao g6i khi dieu bien (MAP) to ra nhiSu u'u diem, nhu- han che t6i da SLH dung h6a chat trong bao quan, chi phi thap vS c6 mCpc tieu hao nang lu'ong khdng cao Tuy nhien a nu'6'c ta c6ng ngh& MAP mdi chf du'O'c nghien cu-u b^ng thu'c nghifim trong thd'i gian gan diy nen phgm vi ip dung c6n r i t h§p Do dd rat cSn phai co nhUng nghiSn cCru tiep theo de phat tnen cong ngh6 nSy.
Yeu to quyet djnh de co the mg dung du-ac c6ng ngh0 MAP \i phai kiem socit c^c th6ng so vi khi hau cua m6i tru'dng khi bao quanh rau qua trong bao goi Cac thfing so niy gom c6' (1) nong dp khi trong bao goi, (2) nhi^t dO trung binh cua hon hap khi trong bao g6i v^ (3) Cp I m tyong doi va lu'p'ng nu'dc ngu-ng ty trong bao goi xult hi0n trong thdi gian bao quan. Trong do c^c thong s6 (1), (2) dCing d^ thi^t ke, lira chon bao goi vi kiem sodt nhifit do bao quan, thong so (3) cho phep du- dodn dO I m tuong doi, lu'p'ng nu'dc ngu'ng trong bao g6i, \i nhSn to thuc d i y sy phdt tnen cua vi smh vat lam hong rau qua, gidn tiep danh gid chat lipp-ng vd d y doan thdi gian t)ao quan cua rau qua Trong thdi qian gan diy d3 cd mOt so nghien CLCU lien quan tdi van de nay. Cdc
nghifen ciru nay c6 the chia ra ldm hai tru-dng phdi chinh:
(i) mo ta qud trinh bay hoi nu'dc tLr be mat qua b i n g Phu'O'ng trinh khuech tdn dgng Dalton ket hp'p vdi h6 h i p cua rau qua trong bao goi MAP [2]. Dang m6 phong nay co han chi la khong phan dnh day diJ ban c h i t vat ly cua hifin tu'gng bay hai nu'dc .•:. ai mat qua c6 hen he chat che vdi nhiSt thai ra trong qua trinh ho h i p , xay ra ngay ca khi dp am tu'ong doi RH trong bao gdi dgt tdi trang thdi bao hda Tru'dng phai thif' hai (ii) mo ta qua trinh bay hoi tiy bi mdt qua thong qua viec xdc djnh lu'ong nhifit an hoa hai trfin be mat qua tLF phu'ang trinh can bdng nhifit hoge ethalpy theo dinh luat nhifit dpng I ket hp'p vdi mo hinh ho hap cua rau qua trong I\/1AP [1,2]
Trong khu6n kho bdi bdo ndy tac gia de xuat phat t r i l n md hinh ho hap-bay hoi theo tru'dng phdi (ii) trfin CO s d ket hap hfi phu'ang trinh vi phan n6ng dp khi vd cdc phu'ang trinh vi phdn can bdng nhiet vd cdn b i n g chat.
II. XAY DVNG MO HINH 2.1. Cac gia thifit cua m o hinh
Mo hinh md phong qua trinh h6 h i p -bay hoi cua rau qua t u o i trong bao goi cd kich thu'dc hinh chi>
nhdt, vdi cdc gia thiet sau:
- San pham, khong khi trong bao goi v^nnoi tnjdng co nhipt do ban dau bing nhau.
- Lop khong khi trong bao goi co the tich nho, can bing nhipt giiJa san pham va Idp khong khi nay dgi du'p'c trong khoang thdi gian ngan
- Khoang (70-100)% nang lifpng giai phong trorg qua trinh ho hip la nang liK^ng nhipt
- Nhipt ho hap la nguon nhipt trong va co the xac <^nh tir phii-ong trinh ho hip cho mgt moi chat phan irng [1,2,3] nhtf sau
C6H12O5 + 6 O2 -> 6 CO2 + 6 H2O + 2816 kJ (1) - Cu'dng dp ho hap cua rau qua tuoi I3 ham cua nong dp O2 va CO2, va tuan theo mo hinh Michaelis-IVIenten.
- Sy thay doi nhipt dp ben InDng Idp khong khi la rat nho, nen co the bo qua anh hifdng den cac thong so mo hinh ho hip va dp tham cua mang bao goi
2.2. Mo liinh cua qua t r i n h h d hdp-bay ho'i Khdng khi trong bao gdi MAP cd chda rau qua tu'oi cd t h l coi Id hdn hop gom ndm thdnh phan chinh sau N2, O2, CO2, Ar, vd hoi nifdc. Nong dp cua b6n thdnh phan khi khdng ngirng difdc hinh thdnh bdi hai con du'dng" s y tham khi qua mdng bao
12'NLN-108 Ml/2012
gdi va qud trinh trao doi khi gi&a rau qua va mdi tru'dng khi cai bien do qud trinh hd h i p Dp tham khi qua mdng bao goi du'ae bieu difin thdng qua djnh luat khuech tan Pick [2,3] du'di dang:
dV, dr
P.-A-P,..
Uoo 100.
(2)K i t hp'p cdng thdc (2) bieu difin dd t h l m khi qua thdnh bao goi vdi cu'dng do hd hap, chiing ta thu du'ae edc phu'ang trinh edn b i n g c h i t cho cac thdnh phan khi khdng ngu'ng trong bao gdi MAP [2]:
4 ^ ^ 1 0 0 \A^-P<n-P..„ ([o^.l-lOdi J.
dz V \ L { ' " " ' •' •
]-f^s-'?<,2}.
(3)[ 100
Pj^({Ar]^-{Arl^
(4)
(5)
(6) Trong cdc phu'ang trinh (2 -r6) ap s u i t bao gdi b i n g s u i t khi quyen vd du'p'e coi Id khong doi, cdn nhi^t dd, I m dung hoac do am tu'ong doi, t h l tich V, khoi lypng khi trong bao gdi MAP, lyp'ng nu'dc ngu'ng, nong dp the tich eua cac khi trong bao gdi Id eae b i l n theo thdi gian. Ngoai ra tai thdi diem ban dau (T = 0), hdn hp'p khdng khi trong bao gdi cd nong dO [O2], = 20 9 vd [COa], = 0.03 va b i n g gia tn nong dp cua Idp khdng khi bfin ngoai bao gdi [02]o = 20.9 vd [C02]o = 0.03 tai mpi thdi diem.
Doi vdi ndng dp hoi nu'dc trong khdng khi Id thdnh p h i n khi I h d 5, du'p'c dac tryng bdi am dung H, chiing ta se xdc dinh thdng qua cae phyong trinh cdn b i n g nhiet eu the n h y sau.
Nguon nhifit bfin trong (Q,r,t) ehinh la nhifit thai ra khi hd h i p cua rau qua d y o e tinh nhy sau:
Qint = Qs W s (7) 6" diy. Qs la nhi#t hd h i p d y o e xdc djnh t d
phyong trinh (2) va gia thiet r i n g c y d n g do hd hap Id gid trj trung binh cua c y d n g dd \\iu thu O2 vd phdt thai CO2 thi Qs d y a c tinh n h y sau'
Hr]{'^v
(8)Phu'O'ng trinh trSn dup'c thi^t lap bo'i Kang v^
Lee, h6 s6 a du'O'c xem nhu' la he so chuyen aoi nSng lu'ong ho h i p thanh nhiet lu'ong a = 0.7 -^
1[2,3]
Trong d6 cac he so R02 v^ Rcos la lan luot IS cutl^ng do h i p thu O2 Vci phat thai CO2 (ml/kg.h) vS aiK?c tinh theo [2+6]
CO,
x O , (10)
--[<:]
Nhifit doi l y u trao doi giu'a b l mdt rau qua vd Idp khdng khi trong bao gdi d y d c bieu dien nhy sau:
Q „ , = h 3 A , ( T , - T j ' ( 1 1 )
P h y o n g trinh can bdng nhiet doi vdi rau quad y o e xdy d y n g theo cac thdnh phdn nhiet sau, nhi^t ben trong (nhifit ho hap), nhiet doi l y u be mSt, nhifit an hda hoi cua am thoat ra trfin b l mdt vd nhifit hi0n lam tang nhifit dd qua [3]:
Q s W - + h - A , ( T i - T , ) = m | ? . + W , a ^ ' (''2) dx
d day, mi la toe dp bay hoi n y d e tiF b l mdt rau qua t y o i dfin Idp khdng khi t y do trong bao gdi, A Id nhifit an hda hoi vd Cs Id nhifit dung nfing cua rau qua.
Trong qud trinh bao quan cd the coi x i p xi T, = Ts, khi do phyang trinh (11) cd the viet lai don gian han:
Q , W , = m , ? . + W x / ^ ' (13) dx
T d dd xde dinh d y o e lyp'ng n y d c bay hai:
. Q s W , - W , C , ' d T
m, = dT (14) Bien thien dd t h l m hai n y d e cua bao gdi dypc
bieu d l i n nhy sau [2,3].
d m , ^ r P H , o S p ( P i - P j l r o . 0 1 8 P , ( ^ / dT L ' RT,
(15)
qud trinh tham nay xay ra Id do dd chenh ap suit gida Idp khdng khi trong bao gdi vd mdi trydng bfin ngodi Tgi nhifit dd khdng doi, cd hai trydng hpp xay (i) khi P, nhd hon hode bdng phdn dp s u i t bdo hda Psp, dd tham hoi n y d c d y o e tinh n h y sau-
P H , o S p ( P i - P o ) T a 0 1 8 P , „ L RT
m , = (16)
(ii) khi Pj cao hon Psp, p h y o n g trinh (16) v i n giU nguyen Tuy nhifin, hoi n y d c qud bdo hda se ngyng ty trdn be mdt rau qua hode trfin be mat mdng bao gdi vd nhifit an ngyng ty se Idm nhiet dd rau qua vd Idp khdng khi trong bao gdi tdng Ifin.
Biin thiin dd im twang ddi trong bao gdi Toe dp tich tu am trong bao gdi dyp'c viet dydi dgng p h y o n g trinh edn bdng c h i t [6] n h y sau'
NLN'108-11/2012*13
dH, _ m i - m 2
di ~ W,
(17)
d ddy, H| Id am dung cua hdn hp'p khi trong bao gdi Khi T = 0 thi RH, = RH,,„
Xdc dinh lugng nuoc ngung
Lypng n y d c ngyng cd t h l cd trong bao gdi d y a c xdc djnh bdng cdch so sdnh H{T) vdi H (T) d cuoi mdi byde tich phdn phyang trinh (16) theo difiu kifin
AH = H(T)'H'\T)>0. (18) Khi dd H(T + A r ) = H ( r ) , cdn lyp'ng n y d c
ngyng tyang irng d y a c xde dmh nhy sau [2]:
m{T)
\ + H - A / / = Am„,
(19)Lypng n y d c ngyng ndy d y o e cdng don vdi lypng n y d c ngyng da d y p c xdc dinh d euoi byde tich phdn tryde dd mcond(T + AT) = m«,nd(T) + Am^^^j
Biin thiin nhiit dd trong bao gdi
Phyong trinh cdn b i n g nang lyp'ng bfin trong bao gdi [3]:
IV. K E T Q U A V A T H A O L U A N 4 . 1 . T h o n g s d m o h i n h h o hip
Nong dd khi theo thdi gian, khdi lyp'ng qua, t h l tich t y do cua bao gdi xoai Mdc Chdu trong he kin dyp'c xac dinh theo cdc thi nghifim d nhifit dd 11°C vd 27°C Cdc gid tri ndy iJypc s d dung nhdn dang md hinh hd hap theo phyong trinh (8) vd (9) Gid tri d y doan cua cac tham so trong md hinh hd hap d y a c the hifin trong Bang 2 Phyong trinh hdi quy nhdn dang t d cdc tham sd ndy cho gid tn r i t tdt vdi he s6 t y a n g quan R^ > 0,98. Vdi eae tham sd dd d y dodn nay, c y d n g dd hd h i p lai cde gid tri ndng dd O2 vd CO2 khde cd the d y a c d y dodn tir phyang trinh (8) va (9).
4.2. Kiem chu>ng m o hinh ho h i p - bay ho'i trong binh t h i n g h i d m
Cae tham sd m d hinh c y d n g dd hd h i p trong Bang 2 dd d y a c kiem chdng b i n g cdch so sdnh ndng dd khi d y a c d y dodn t d md hinh ho hap vd gid tn thyc nghifim bao quan xodi trong hfi kin t?i nhifit dp 11°C va 27°C. Nong do khi d y dodn nhdn dang t d edc phyang trinh (3 ^ 6) theo phyong phap Runge-Kutta, dyoe md phong trong cdc do thi htnh 1.
dT , dT
aif, + h„A(T„ -T,) = m^A + iV,C^ ^ ^ + IV^C^ ^ ^ (20)
dr dT Dieu kifin ban d I u ' T, = T,., tai T = O.Td phyong trinh (19) , b i l n thifin nhifit dd khdng khi trong bao
dl
QJV.-m^X-h^Afi,-T„)
wc,+wc^ (21)
— q,(MH)
• oo,(m) I CQ,(l*Hli
d diy, hp Id h0 so trao doi nhifit doi lyu cua be mdt bao gdi vd d y d c xde djnh theo [3],
Tdm Igi, md hinh hd hap - bay hai bao gom hfi bon phyong trinh vi phdn phi tuyen (8), (9), (16) va (20). Hfi ndy dypc giai d y a theo phyang phdp sd Runge-Kutta bdc 4 b i n g cdch ldp trinh trfin phan m I m Matlab
III. 061 TU'ONG VA PHl/aNG PHAP 3.1. Odi t y f f n g t h i nghiem
Thl nghidm d y p c tien hdnh vdi xoai Mpc Chdu (Son La) chya x y ly hda chat, thdi gian t d khi thu hogch den khi thl nghifim < 24h. Cac m i u thi nghidm dypc thl nghifim d dd chin 2 (50%), Moi thi nghifim dyp'c Idm 3 l l n , Thi nghifim dyoe tien hdnh d 2 nhigt dd' 11 ± 1°C vd 27 ± 1°C Nong dp O2 vd CO; dyoe xac djnh thdng qua mdy phdn tich s i c ky khi TRACE GC Thermo Electron. Nhifit dd vd dd I m cua mdi trydng khi dypc do vd lyu gid bdi data logger HIOKI S6 diem thi nghifim Idn han 200
3.2. P h y a n g phap nghien CLPU
Phyang phdp nghien edu tien hdnh thi nghifim xdc djnh md hinh hd h i p , xdc dinh bien thifin nhifit dd, dp I m trong binh thi nghiem, xdc dmh dp hyt t y do. So sdnh ket qua thl nghifim vd tinh todn b i n g md hinh.
• ofm
— cywfl
» cq,rTN)
Tirm (/J) Hinh 1-Ndng ddOiVdCOi
(a) nhifit dp 11^C, khoi lyong 0 407 kg, the lich t y do 2610 ml; (b) nhifit dd 27°C, khoi !y(?ng 0.332 kg, the tich t y do 2650 ml.
Hinh 1 (a) vd (b) deu the hifin s y xap xi l y o n g d6i tot giya nong dd d y dodn vd gid tri thyc nghifim trong hfi kin cua xodi Mpc Chdu. Sai so tyong doi gida gid trj d y dodn t d md hinh vd thyc nghifim <
2%, hfi so t y o n g quan linh todn dydC R^ > 0.95. 0 d6 thj ndy the hifin rd rdng anh hydng cua nhifit dO d i n c y d n g dO hd h i p cua xodr d nhi^t dO cao nhi$t
1 4 ' N L N - 1 0 8 ' 1 1 / 2 0 1 2
dd cao (27°C), xodi hd hap manh hon nfin so vdi d nhifit do ttilp (11°C) B d thi hinh 3 vd 4 md phong tnj-dng nhifit dd vd do am t y a n g doi cua khdng khi trong h0 kin. K i t qua nhdn dang t d md hinh cho kfil qua xdp xi vdi cdc sd lifiu thyc nghifim T y dd cho I h l y kha nang dng dung md hinh hd h i p cho xodi Mdc Chdu da dyp'c kiem chirng thdnh cdng trong hfi kin.
4.3. Du> doan do hao hut tu' nhien cua qua trong S y dung md hinh neu tren d y dodn dd hao hut t y nhifin cua qua cho kfil qua trong bang 2
So vdi k i t qua thf nghifim k i t qua tinh todn b i n g md hinh cho sai sd Idn nhat 15 67% Id kfil qua cd the c h i p nhdn d y o e
fling 1. CAc tham s6 md hinh hd hip theo phucmg trinh Michaelis-Menten
Hinh 2- Nhiet do vii dg im khdng khi trong binh lo'n (l^ = 11°C)
/••
'•']/
Nhiet do 11''C
27°C M d h i n h
ho h i p Oi C O i
02 C O ,
Vm 55.5351 90 7669 55 7457 78 0150
Km 15 2466
0 0007 3 5124 0 0001
Kl 11 9915 0,9153 46.7680 4.2807
R* 0 99452 0.99698 0 99985 0 96986 Bang 2. Dd hao hyt ti/ nhi§n Nhiet d o
I I ^ C 2 / C
D o h u t t h e o t h i nghifim (g)
0 3 1 5
D $ h u t t h e o tinh t o a n (g)
0 347 1.517
Sai sd % M 5 67
•1.15 . K ^ T L U A N
Md hinh hd hap- bay hoi d y o e xdy dyng trfin ca sd edng thdc Michaelis-Menten ket hap vdi cdc phyang trinh vi phdn bieu difin qua trinh cdn bdng nang lyong cho sai s6 nho, trfin CO s d dd k i t qua d y dodn nong dd khi, nhifit dO vd dp am tyong doi trong bao gdi cd dd chinh xdc cao, giai thieh dyac qud trinh thyc tfi. Vific xdc dinh dypc luong nydc ngyng trong bao gdi cho phep xac (Jnh dyoe lyong c h i t hilt I m can thilt dat vao trong bao bi.
Tdm lai vdi md hinh d y p c trinh bdy trong bdi bdo, cho phep lya chpn vd thiet ke bao gdi MAP thich hpp vdi ddc tinh cua tdng logi qua theo mtia vu, hydng tdi muc tieu tang chat lyong vd keo ddi Ihdi gian bao quan cua rau qua trfin thyc te san x u l t
ABSTRACT
The modelling relations within the scope of the elementary model of respiration and transpiration processes at refrigerated storage of fresh fruit-and-vegetable prodi/ct/on in MAP (modified atmosphere packages) are obtained. A calculated algonthm is constructed: approbation of a energy and mass balance equation is earned out (transpiration) Approbation is earned out on an example of mangoes. The received results testify about much best descnption of changes in time of temperature, relative humidity of MAP.
condensate mass, mass losses of a product in comparison with models of other researches.
T A I L I E U T H A M K H A O
1 ChinsinkulW/Vi/(20Q6}, "EMA Pa<d<aging techndogy kir tropical frBSt\
produce", Bilec, Thailand.
2 NVDOng, Tmmac I.G., Onhishenl(oV P. CV Hung (2011), "Xiy dijng md hinh ho hip-bay hoi cua xoai Cam Ranh bio qvan Irong md hinti khi cai biin" Tgp Oil khoa hQC congr ngh$ cA: tnrimg d^i hqc kj^ Ihu^.
No 80/2011
3 Song Y, Varsa N. Yam KL (2002). TAjdeSmg lesfxrabon- tran^iration in a modified atmosphere padding system containing blueberry", Journal of Food Engineenng 53 {2002). pp 103-109
4 Uu Y. Wang ft, u Y. Tian P (2003). TMlxb/ for gas exdwnge dynamics in modilied atmosphere padoges contaii^ fresh pmdux'.
ICRQ546. Wasinglon D C USA
6 PeppelenbosHW.LevenJ (199S). "Evaluation of for types inMbot\
hr modelling fte influence ofcartxx} doxide on oxygen consumpbon of/Ms and vegetables". ATO Agrolechnological Reseach. Wagenngen.
Hinh 3 Nhi$t ddva0im khdng khi bong binh kin (t„t = 2fC)
7 CV Hung (2006). "t^hiin cOv cJd thim khi Oi vd COj aJs mW s i plastic Him Vi$t Nam trong cdng ngh$ bao gdt Ifhi Oiu bien (IMP) bio quSn rauqui" T^ i^i^Jdngnghi^v^ phat tn4n Ndng thdn (21-^X6). tr 59^
8. C. V Hung. •TJghien cCnj ung dung cdng ngh^ bao gdi Oiu biSn hhl (ModiHed atmosphere padtagmg - MAP) nh§m n^g cao giA tq m(it s6 logi rau qua xuit khiu vdb§u dung trong nudc; B^c^lSng Pastil dp HM nudcKC062mN(2006)tr I^I.HaNfyJ
