Agriculture Reference
In-Depth Information
Table 1. Analysis of variance (ANOVA) of the responses in sucrose solutions
Rezidual
Model
Response
SS
DF
MS
SS
DF
MS
F
p-value
R
2
WL 1/k
1
0.109
3
0.036
23.566
6
3.923
107.682
0.00134
0.958
WL 1/k
2
16.990
3
5.656
8678.769
6
1446.437
255.384
0.00038
0.986
SG 1/k
1
0.002
3
0.001
0.081
6
0.014
23.143
0.01312
0.955
SG 1/k
2
173.040
3
57.678
16717.525 6
2786.246
48.305
0.00448
0.978
The results of the statistical analysis according to the experimental plan are presented in
Table 2. The significance of each coefficient was determined by Student‟s t-test. The larger
the magnitude of the t-value the more significant is the corresponding coefficient. As for
significance of the polynomial coefficients, its t-values suggest that the most important factor
influencing initial water loss rate is sucrose concentration, both linear and quadratic effects.
The quadratic effect of osmotic solution temperature is also significant, while the interaction
of sucrose concentration and temperature is less significant. On the other side when
equilibrium water loss is analyzed it can be seen that again sucrose concentration, both linear
and quadratic effects, are significant. The linear effects of temperature has significant
influence at the equilibrium water loss, as well as its interaction with sucrose concentration,
which can be attributed to prolonged time needed to achieve equilibrium values, i.e., the end
of the osmotic dehydration process. As for solid gain initial rate the most influence is
arbitrated to the linear and quadratic effect of the temperature, while the effect of sucrose
concentration is less important. The same results are obtained for the equilibrium values of
solid gain.
Table 2. Regression equation coefficients for responses in sucrose solutions
Response
WL 1/k
1
(1/min)
WL 1/k
2
(g/g)
SG 1/k
1
(1/min)
SG 1/k
2
(g/g)
Effects
coefficient t-value
coefficient t-value
coefficient t-value
coefficient t-value
Intercept
b
0
-7.6773
-3.1592
-138.2717
-4.5652
-1.8055
-5.8642
395.7323
4.0943
Linear
b
1
0.1270
3.2585
3.7122
7.6413
-0.0035
-0.7025
-1.2292
-0.7929
b
2
0.3104
2.7987
4.6240
3.3454
0.1039
7.3968
-20.9500
-4.7497
Quadratic
b
11
-0.0013
-3.9427
-0.0291
-5.1715
0.00002
0.6036
-0.0049
-0.3546
b
22
-0.0044
-3.2906
-0.0218
-3.0287
-0.0013
-7.6128
0.2700
5.0279
Interaction
b
12
0.0008
1.6007
-0.0510
-4.8961
-0.000005
-0.0736
0.0492
2.5894
Plotting responses as a function of two factors drew response surface plot. In this
manner graphical representation of process parameters on the selected responses can be
represented. The effects of sucrose concentration and temperature on water loss initial rate are
given in Figure 1. As it was noticed initial rate of water loss is increased with the increase of
sucrose concentration to the value of about concentration of 50% w/w. Increase in sucrose
concentrations, above 50% w/w, had smaller influence on the initial water loss and it can be
neglected. Increase in temperature values showed a positive effect on the water loss initial
rate. At the temperatures higher than 45
o
C decrease of water loss initial rate was observed
