Blanching is extremely important for further processing of carrots and to
improve the product quality and shelf life. In this study, various blanching
TABLE 7.
COMPUTED COEFFICIENTS OF THE WEIBULL DISTRIBUTION FUNCTION (EQ. 8) FOR
PEROXIDASE INACTIVATION
Temperature (C) bnR2 SE
80 0.739 0.855 0.992 0.006
85 0.641 1.117 0.976 0.022
90 1.802 0.568 0.981 0.013
95 1.695 1.043 0.981 0.178
100 2.669 0.804 0.991 0.007
b, scale factor; n, shape factor; R2
, coefficient of determination.
0.0
0.2
0.4
0.6
0.8
1.0
Time (min)
Residual activity (A/Ao)
80C
85C
90C
95C
100C
model (equation 8)
0 1 0.5 1.5 2 2.5 3 3.5 4 4.5
FIG. 7. THE ACTIVITY CURVE OF PEROXIDASE IN CARROT EXTRACT FITTED WITH
THE WEIBULL DISTRIBUTION AT 80–100C
A, enzyme activity at time (t) min; Ao, initial enzyme activity at zero time.
OPTIMIZATION OF BLANCHING PROCESS FOR CARROTS 601
treatments were considered based on the inactivation time of POD and catalase
and the process was optimized on the basis of the maximum yield of carrot
juice and minimum loss of vitamin C and b-carotene. The best blanching
treatment for carrots based on these process parameters was 95C for 5 min in
water. At this time–temperature combination, both POD and catalase enzyme
were inactivated and 8.192 mg/100 g vitamin C, 55% yield of carrot juice and
3.18 mg/100 g b-carotene content were observed. The Weibull distribution
model provided a good description of the kinetics of inactivation of POD in
-0.05
-0.04
-0.03
-0.02
-0.01
0
0.01
0.02
0.03
0.04
0
Time (min)
Residuals
1 345 2
FIG. 8. RESIDUAL DISTRIBUTION PLOT OF PEROXIDASE ACTIVITY AT 80C BASED ON
THE WEIBULL DISTRIBUTION FUNCTION
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0
Experimental value
Predicted value
80C
85C
90C
95C
100C
0.2 0.4 0.6 1 0.8
FIG. 9. PARITY BETWEEN EXPERIMENTAL DATA AND PREDICTED
(USING EQ. 8) VALUES
602 U.S. SHIVHARE ET AL.
carrot extract in the experimental range of temperatures and, therefore, was
inferred to be appropriate for predictive modeling purposes. The Weibull
function can therefore be recommended to describe the heat inactivation kinetics
of POD, provided it satisfies the statistical and physical criteria.
Blanching is extremely important for further processing of carrots and toimprove the product quality and shelf life. In this study, various blanchingTABLE 7.COMPUTED COEFFICIENTS OF THE WEIBULL DISTRIBUTION FUNCTION (EQ. 8) FORPEROXIDASE INACTIVATIONTemperature (C) bnR2 SE80 0.739 0.855 0.992 0.00685 0.641 1.117 0.976 0.02290 1.802 0.568 0.981 0.01395 1.695 1.043 0.981 0.178100 2.669 0.804 0.991 0.007b, scale factor; n, shape factor; R2, coefficient of determination.0.00.20.40.60.81.0Time (min)Residual activity (A/Ao)80C85C90C95C100Cmodel (equation 8)0 1 0.5 1.5 2 2.5 3 3.5 4 4.5FIG. 7. THE ACTIVITY CURVE OF PEROXIDASE IN CARROT EXTRACT FITTED WITHTHE WEIBULL DISTRIBUTION AT 80–100CA, enzyme activity at time (t) min; Ao, initial enzyme activity at zero time.OPTIMIZATION OF BLANCHING PROCESS FOR CARROTS 601treatments were considered based on the inactivation time of POD and catalaseand the process was optimized on the basis of the maximum yield of carrotjuice and minimum loss of vitamin C and b-carotene. The best blanchingtreatment for carrots based on these process parameters was 95C for 5 min inwater. At this time–temperature combination, both POD and catalase enzymewere inactivated and 8.192 mg/100 g vitamin C, 55% yield of carrot juice and3.18 mg/100 g b-carotene content were observed. The Weibull distributionmodel provided a good description of the kinetics of inactivation of POD in-0.05-0.04-0.03-0.02-0.0100.010.020.030.040Time (min)Residuals1 345 2FIG. 8. RESIDUAL DISTRIBUTION PLOT OF PEROXIDASE ACTIVITY AT 80C BASED ONTHE WEIBULL DISTRIBUTION FUNCTION00.10.20.30.40.50.60.70.80.910Experimental valuePredicted value80C85C90C95C100C0.2 0.4 0.6 1 0.8FIG. 9. PARITY BETWEEN EXPERIMENTAL DATA AND PREDICTED(USING EQ. 8) VALUES602 U.S. SHIVHARE ET AL.carrot extract in the experimental range of temperatures and, therefore, wasinferred to be appropriate for predictive modeling purposes. The Weibullfunction can therefore be recommended to describe the heat inactivation kineticsof POD, provided it satisfies the statistical and physical criteria.
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