Lynne Wong's PhD thesis

Table 5.1. Some commonly used isotherm models to predict equilibrium moisture content
(m) from the known water activity (a w ) of agricultural products.
Bradley (Bradley, 1936)
Caurie I (Caurie, 1981)
Caurie II (Caurie, 1970)
Halsey (Halsey, 1948)
Model
Henderson (Henderson, 1952)
Kuhn (Kuhn, 1964)
⎛ 1 ⎞
n ⎜ =
a
⎟
⎝ w ⎠
bc
Equation*
m
1 1
n
= − n
m bm
m =
m =
e
( b+
)
ca w
⎛ c ⎞
⎜
n a ⎟
⎝ w ⎠
⎡ 1 ⎤
n ⎢ n
⎥ = n b +
⎣ 1 − aw
⎦
⎛ b ⎞
m =
⎜
+ c
n a
⎟
⎝
w ⎠
m = b n
1 − aw +
Smith (Smith, 1947) [ ( )] c
GAB (Guggenheim, 1966; Anderson, 1946 and de
1
b
o
+
2b
⎛ 1 − a
n
⎜
mo
⎝ aw
c n
m
Boer, 1953) ( 1 − c aw
) ( 1 − c aw
+ b c aw
)
m =
m =
m
o
b c a
BET (Brunauer et al, 1938) ( 1 − a ) ( 1 − a + ba )
m =
Modified BET (Aguerre et al., 1938)
( 1 − a ) [ 1 − bn
( 1 − a )]
c
Day-Nelson (Day and Nelson, 1965) ( − b / m
1 − a
)
w
= e
w
Hailwood-Horrobin (Hailwood and Horrobin, 1946) ( ) 2
a
m
w
w
m
= b + c a
⎛ aw
Iglesias-Chirife (Iglesias and Chirife, 1981) m = b
⎜
⎝ 1 − a
Mizrahi (Mizrahi et al., 1970; Ayranci and Duman, a b + m
= w
2005) c + m
Oswin (Oswin, 1946)
Harkins-Jura (Erbas et al., 2005)
Peleg (Peleg, 1993)
o
ba
m
w
w
o
+
⎞
⎟
⎠
c
+
w
w
ba
d
c
w
a
⎡ aw
⎤
m = b ⎢ ⎥
⎣ 1 − aw
⎦
1 c 1
= − n a
2 w
m b b
d
m = b ( a ) + c ( a )
* where m o is the moisture content of the sample on a dry basis when each sorption site
contains one water molecule (monolayer), a w is the water activity, and b, c, d, f are
constants in the sorption models.
w
w
w
f
w
w
w
w
⎟ ⎞
⎠
176