Διατήρηση τροφών
-
Upload
manduceriano -
Category
Documents
-
view
217 -
download
3
description
Transcript of Διατήρηση τροφών
-
15C
. , , ... . .
, .
()
( )
, . , , . ,
, . , , .
, , , . , . , . .
-
. , , , . , . , , . , , .. . 6 , .
, , . , . . . ,
. , , (climacteric), . , . , , , ,
-
, , , , , .., , , , , , , , , . , , ,
. . (2.1) , , .
2.1. . . (, 1996)
. . .
-
ppm. , , , .
, , . () , pH 7 5.1 6.5. 1-36 h . pH . ATP . ATP pH . pH
. . (2C 2 3 ) . (, ...)
.
-
. . , - . , .
: Gram- : Pseudomonas ( ), Acinetobacter, Aeromonas, Alcaligenes, Alteromonas, Flavobacterium, Moraxella, Shewenella, Vibrio. , , , .
-
0 -3C 5-10C. , pH (
-
. : Candida, Debaryomyces, Hansenula, Kluveromyces, Rhodotorula, Saccharomyces, Torula, Zygosaccharomyces (), Aspergilus, Cladosporium, Geotrichum, Mucor, Penicillium, Rhizopus, Thamnidium (). . . 0C . pH , . , , ( -).
( ) ( ). 3-10C, 3C. , 12C. 2.1.
2.1. .
< 0C Listeria monocytogenes (inf)a Yersinia enterolytica (inf) 0- 5C Vibrio parahemolyticus (inf) Clostridium botulinum type E,
(tox)a Aeromonas hydrophilia (inf) Bacillus cereus (tox) 5-10C Salmonella (inf) Bacillus subtilis (tox) Escherichia coli 0157 (inf) Clostridium perfringens (inf) Staphylococcus aureus (tox) 10-15C Campylobacter jejeuni (inf) Clostridium botulinum type A & (tox) a inf: , tox: : Brown and Gould, 1992 Walker and Stringer, 1992
-
, Staphylococcus aureus 2.1, , . , Clostridium botulinum type E Bacillus cereus 5C. , .
. . .. 13C, 14C, . 4C, , . . ,
. .
.
. 3-10C, 3C.
-
, , .
, . (chilling injury). - , , , . . 0-5C . .
, . . 2.2. , 1-2C . 1C . , , , . , 7C.
. . ,
-
, . 2.2. , . (C) . (%)
7-9 90-95 10-14 0-8 65-75 8-12 -1-0 85-95 6-7 -1-0 90-95 2-7 -1-0 90-95 2-3 0 85-90 1-2 0-2 80-85 2 0 90-95 3-7 0-9 85-90 4-6 -1-0 90-95 2-4 7-10 85-90 4-6 0 90-95 4-5 2-4 85-90 2-3 0-8 65-75 8-12 -1-0 90-95 2-3 0 85-90 2-3 0-1 88-92 1-6 0-1 85-90 5-12 0-1 85-90 3-7 0 90-95 3-4 0-4 85-90 3-6 0-1 85-90 3-5 0-2 60-70 1 0 90-95 2-3 7-9 85-90 9-11 -1-0 88-90 3-8 14-16 85-95 7-11 -1-0 85-90 2-4 7-9 85-90 1-2 0-9 85-90 6-12 -1-0 85-90 2-4 0-2 90 2-3 -1-0 85-90 3-6 -1-0 85-90 8-10 6-8 85-90 8-10 0 85-90 7-9 0 50-60 9-12 0 65-75 6-12 0-2 90-95 5-15 : , 1996
-
90-95%. 85-90%. , , 85%. , 85%. 2.2 .
. 0-1C .
. (, ...) .
, . . , (, ...) , , . .
. . . () ().
. .
-
, . (Modified Atmosphere, MA) (Controlled Atmosphere, CA).
. , . . 2 10% CO2. 2 CO2. CO2 10% . 2
. , . 2 ( 2 ), . 2 1.8% 3.5C, 2.3% 1.2% 20 10C, 4% 20C. CO2
, , . . 2 CO2
. CO2 10% . ( ), , . CO2 2
, .
-
.
, , , , ... . , .
(.. , ), , , .
() . , . .
2.3. . (m3)
500 2 5000 3 20000 4 50000 5 85000 6
: Woolfe, 1992.
, . . 500 m3 . 2.3. .
-
1-2C. .
, , (). (Chromel-Alumel) (Copper-Constantan). , (-184 1600C). , ( ) .., . (0.8C) (1.8C). (-270 850C) (0.4C), . . (0.3C), (-40 140C) . (chart recorders) (data logging systems) , .
H . (temperature indicators), (time-temperature indicators or integrators). , . , , .
-
(, CA)
, , , . , .
2.4.
(C) 2 (%)
CO2 (%)
() 7/12 2-3 3-10 2 12 1-4 0 0.7 0/1 2-4 2-3 0.7 0 2 4-5 7 -1.5/0 1-5 0.5-8 3-8 0 2 5 1.5 0 3 10 3 0 3-10 10-12 1 0 3-4 5-7 1.3-1.7 0 1-2 0-1 9 0 2-3 4-5 3-4 0 10-14 8-10 0.3-0.7 0/4.5 1.5-4 1-6 4-8 0 2-3 5-10 0.3 -0.5/0 2 5 1.7 0 3-4 4-5 1-1.3 -0.5/0 2 4-5 1.3 -1 3 5 7 1/3 10-16 10-14 0.3-0.5 2 3-4 2-3 1-1.3
7 3-4 4-5 0.3
:Gorini et al, 1990
. . . 2 3% 2-3% , CO2 2
-
7% 0.5 2% . , .
, , , , , (1-2 ) 20% CO2. CO2 . SO2 . .
(, , , ) 5-50% CO2 1-7 , . . 2.4. .
. O2 CO2, . . 2.5. . . 10 20C.
CO2, . 10% CO2 -1 -1.5C. , 50% . .
CO2, 15%.
-
2.5. 5C
(mL CO2/kg h)
60 , , , ,
: OBeirne, 1990
CO2>20%. 50-100% CO2 .
/ . , . . 25 mm . 5 mm . 0.2% 12.5 mm . 30 mm 30 min (15 mm ).
, . .
.
-
. H :
C6H12O6 + 6O2 6CO2 +6H2O O CO2 O2
1. CO2/ O2 1. , CO2 (10.7 J/mg CO2). CO2 2 .
, , . . .
. , , ( , ). , .
(scrubbers). Ca(OH)2, NaOH . , . . .
,
-
, CO2 / N2.
. : 1. ,
, . .
2. , .
, . , , . :
m cdTdta a
a =( )-( ) (2.1)
:
mdWdta
a = ( )-( ) (2.2)
ma (kg) ca (J/kgC) Ta (C) Wa (kg /kg )
/ : ) / ) , , . ) , (), . ) ) /
-
(). , , . .
: ) ) ) ,
/
, . , . . . , .
p1 p2 (C) :
Q m c T Tp p p p= ( 1 2 ) (2.3)
mp (kg) cp p1 p2 (J/kgC).
. . 4
-
, , . 837.36 J/kgC, 1647.72 J/kgC 4186 J/kgC .
, :
[m c dTdt hA T T T T T T hA t m cp pp
p a p p a pIT a p p p= = + ( ) ( ) exp / ]
a
(2.4)
q hA T Tp p p= ( ) (2.5)
Bi0.1 . h, (hAp) (2.4) (2.5), .
, :
N k A p pp g p a s= ( ) (2.6)
q Nevap p= L (2.7)
:
m cdTdt
q q hA T T qp pp
p evap p a p evap= + = +( ) (2.8)
.
() :
q aerbT= (2.9)
b .
-
2.6. , qr mW/kg C. q aer
bT=
b 12.1 0.173 11.7 0.092 29.1 0.083 6.9 0.099 16.8 0.074 59.1 0.074 19.4 0.108 111.0 0.106 97.7 0.121 33.4 0.072 13.4 0.106 14.8 0.133 20.3 0.104 65.6 0.131 173.0 0.086 38.1 0.056 13.2 0.103 86.1 0.115 50.1 0.106 : Toledo, 1980.
b 2.6. t (2.9):
Q aerbT t
t
= ( )0
dt (2.10)
, . (2.10) .
. :
-
m cdTdt
hA T T q qp pp
p a p evap r= + +( ) (2.11)
, ,
. , , . , . . :
q UA T Tw ext= ( )a (2.12)
qw (W) U (W/m2 C) A (m2) ext (C)
24 . (Text-Ta) Text. qw (2.1) Ta .
. . . , , . , , .
, ,
1025 J/s(hp). .
-
. , , 300 J/s .
(2.2) . , (.. ). (Nt) (2.2)
, , ( ) . 22 66C :
q W e Hd dT
d= 21260 0484 1 71. .
T )
)
(2.13)
qd (W) Wd (m) Hd (m) (C)
, :
q Av c Td a a a ext a= 05. ( (2.14)
(m2) va (m/s) a (kg/m3) ca (J/kgC) ext (C)
: N Av W Wd a a ext a= 05. ( (2.15)
Wext (kg /kg ) Wa (kg /kg )
-
, . , :
m cdTdt
hA T Tb bb
b a b= ( ) (2.16)
q hA T Tb b b= ( )a (2.17)
mb (kg) cb (J/kg C) Tb (C) Ab (m2)
(h) . . 1. 32.2C 4.4C 4h.
, .
(Q) : Q = (Qs)+ (Qr) 90% Siebel: cp=33.49x90+837.36=3851 J/kg C : Q c Ts p= = = 3851 32 2 4 4 107 07. ( . . ) . kJ/kg (tc) (2.11):
Q aerbT t
tc
= ( )0
dt
: T T
tT T
tT T
T Tt
tc c
1 1 21
1 2 =
=
-
[ ]
Q a e e dt ae e dtae
b T T te
t aeb T T
e
rbT
tb
T Tt
tbT
tb
T Tt
t bT
c
bT T
tt
cbT
b T T
c
c
c
c cc
= = =
=
1
1 2
1
1 2 1 1 2
1
1 2
0 0 1 2
1 2
1
1
( ) /
( )( )
b 2.6 16.8 0.074, . 1=32.2, 2=4.4, tc=4 h=14400 s Qr=1112 J/kg Q=Qs+Qr=107.07+1.11=108.18 kJ/kg . 2. (1 kg) 2 L
50% . 4C 1 atm 2.5%. CO2 / 2 = 1.
CO2 10.7 J/mg CO2 . 2.6 : =65.6 b=0.131 qr=ebT=65.6xe0.131x4=110.78 mW/kg 1 kg 110.78 mW. (110.78x10-3 W) / (10.7 J/mg CO2) = 10.35x10-3 mg CO2/s = 37.3 mg CO2/h = 37.3x10-3/44 = 0.85x10-3 mole CO2/h. CO2 / 2 = 1 0.85x10-3 mole O2/h. mole O2 , 50%, :
n nPVRTIT
= = =
= 0 21 0 21 0 21
1 05 20 08206 277
0 21 0 044. . ..
.. . mole
2 2.5% n nFin = = 0 025 0 025 0 044. . . mole 2 , :
t =
=
( . . ) ..
.0 21 0 025 0 044
085 109 63 h
1. 0.08x0.04x0.065 mxmxm
27C 2C. 8C.
-
h=40 W/m2 C, =1030 kg/m3.
2. 21C 4C
1.5C. 4C 50 W/m2 C, 0.035 m, =975 kg/m3 k=0.52 W/m C. 14.6%, 0.4%, 0.3%, 0.5%, 84.2%.
3. 2 C, 100 m3
50% . 2C 1atm. N CO2 5%, 2=2% CO2 =5%. CO2 / 2 = 1, 840 kg/m3.
(2.10) (m2) w b (2.10) i Biot: hR/k c (J/kg K) f
(s) Fo Fourier kt/(cpR2) t/R2 h (W/m2 C) Hd (m) j k (W/m K) kg (s/m) L (J/kg) m (kg) (% ) N (kg/s) Nt (kg/s) pa (Pa) ps (Pa)
-
q (W) Q (J) T (C) U (W/m2C) va (m/s) V (m) W (kg /kg ) Wd (m) Y=(T-Tm)/(TIT-Tm) ( ) av b c d ext IT m p r rad s w Brown M.H. and Gould G.W. (1992) Processing in Chilled Foods A Comrehensive Guide, ed. C. Dennis and M. Stringer, Ellis Horwood, N.Y., pp.111-146. Cleland A.C. (1990) Food Refrigeration Processes Analysis, Design and Simulation,
Elsevier Applied Science, London-N.Y., pp. 1-32, 79-94. Fennema O. (1975) Preservation of food by storage at chilling temperatures in
Physical Principles of Food Preservation, ed. O. Fennema, Marcel Dekker Ink., N.Y., pp. 133-171.
Gorini F.L., Eccher Zerbini P. and Testoni A. (1990) The contolled atmosphere storage of fruit and vegetables in Chilled Foods The State of the Art, ed. T.R.Gormley, Elsevier Applied Science, London-N.Y., pp. 201-224.
Heldman D.R. and Singh R.P. (1981) Food Process Engineering, 2nd ed., The AVI Publishing Co. Inc., Westport, Connecticut, pp.87-157, 385-408.
-
James S.J. and Bailey C. (1990) Chilling systems for foods in Chilled Foods The State of the Art, ed. T.R.Gormley, Elsevier Applied Science, London-N.Y., pp. 1-35.
.. (1981) , , , . 201-219.
. (1996) , , , . 87-92.
OBeirne D. (1990) Modified atmosphere packaging of fruits and vegetables in Chilled Foods The State of the Art, ed. T.R.Gormley, Elsevier Applied Science, London-N.Y., pp. 183-199.
Rahman S. (1995) Food Properties Handbook, CRC Press, Boca Raton, pp. 416-417. Singh R.P. and Mannapperuma J.D. (1990) Developments in food freezing in
Biotechnology and Food Process Engineering, ed. H.G. Schwartzberg aand M.A. Rao, Marcel Dekker, N.Y., pp. 309-358.
Toledo R.T. (1991) Fundamentals of Food Process Engineering, 2nd ed, The AVI Publishing Co. Inc., Westport, Connecticut, pp. 398-436.
Walker S.J. (1992) Chilled foods microbiology in Chilled Foods A Comrehensive Guide, ed. C. Dennis and M. Stringer, Ellis Horwood, N.Y., pp. 165-195.
Woolfe M.L. (1992) Temperature monotoring and measurement in Chilled Foods A Comrehensive Guide, ed. C. Dennis and M. Stringer, Ellis Horwood, N.Y., pp.77-109.