87
,,,
jÎ
l’_,'_"
E 150
'
,
-
.
3
.
.Ë 100
,
,
-
,
,
'
.
% 0
.
»
_
..
_
a.
0
5
10
15
Mean pressure 55 (Torr)
FIGURE 5. Typical perméabiÏyèpressuref‘plot for freeze—dried foods
The slope and the interæptcüto" on the
by
line to=the
linear part of the curve yield specicinforrnation concerning the sttuCtürèf—bf » the pr0‘duCt,
especially the average pore si‘Ze'idterms
eqüiÿalenÏ
also the °di‘ùsibn
ratio,
e/ (f) . Some typical yalues of these
tabulatedf”, n;
‘
TABLE 3. POROSITYÂNÙ‘PERLŒÂÏBILÏTŸ DATÀ FoR° A_ RANGEOF FREEZE—DRŒDFOODS
Î'
,
Equiv.
,
…
_
_.
.
…
D1'.
.
Slope
Porc
,
.
,
.
Tortuosüy
Product
X 108
Radius
Porosrty
Factor
(cm3/seclg)
(°m ’Sæ)
»
r
——2
8
(Le/LF -
,
)
(Le/L)
'
,
(L
.
__
_
_
Beef
.
.
.
.
.
.
.
.
1.5
21
-
58
0.18
.
0.75
4.2
.
'
Cooked meat product .
2.7
22
-
.
0.16
0.58
3.7
Apple
.
.
.
.
.
.
.
4.3
32
.
87
‘
0.87_
_
4.4
,
»
‘
Strawberry. . . . . .
5.9
,,43
'
88e
'
”
026
'
,
3.2
Onion
.
.
.
.
.
.
.
1.1
10 '
96"
“
'
Tomato concentrate
.
5.8
30
.
126
.,
,;,6‘.3=—
.—
,_
’
Sugar cane juice . . .
9.0
49
119
0.21
.
-
_
0.95
4.5,
_
Equations for the slope and intercept in
Of, au equivalent cylindrical model for
& porous product can be deriVed from Kinetic
«
are :
_
_
. —
“
‘
—
.“ “°°?
‘
.
L
2
.
,
[191