Osmotic Dehydration: Dynamics of Equilibrium and Pseudo-Equilibrium Kinetics

Figures & data

Figure 1 Schematic explanation of large size sample sectioning.

Table 1 Relation of the experimental data and Azuara's model predicted equilibrium value of osmotic dehydration during dynamic period

Var.	Conditions (°C °B)	Time interval	Exp.	Calc.	Time interval	Exp.	Calc.	Time interval	Exp.	Calc.
ML∞	40C30B	3	10.9	12.3	12	17.2	19.6	24	24.6	26.3
SG∞			2.79	2.94		6.34	7.06		12.5	14.1
ML∞	40C40B	3	18.2	20.3	12	36.0	37.9	24	50.4	54.0
SG∞			3.45	4.20		7.37	8.14		11.4	12.7
ML∞	40C50B	3	26.0	29.3	12	45.2	50.3	24	59.5	62.9
SG∞			3.68	4.00		5.69	6.31		6.57	6.96
ML∞	40C60B	3	35.2	37.5	12	61.8	66.7	24	73.0	78.7
SG∞			5.55	6.25		5.48	5.81		6.10	6.21
ML∞	50C30B	3	16.2	18.5	12	33.9	41.2	24	36.5	41.7
SG∞			5.08	5.64		8.02	8.82		14.0	14.5
ML∞	50C40B	3	31.6	36.2	12	45.0	48.8	24	52.6	55.3
SG∞			4.42	5.13		8.30	9.30		12.1	13.0
ML∞	50C50B	3	36.6	41.3	12	53.6	60.2	24	65.2	69.4
SG∞			3.49	3.72		5.39	5.97		7.73	8.03
ML∞	50C60B	3	35.1	39.1	12	68.4	76.3	24	73.8	80.6
SG∞			4.37	5.01		6.20	6.52		7.39	7.63
ML∞	60C30B	3	19.0	21.6	12	36.2	41.3	24	37.4	41.0
SG∞			5.88	6.93		9.66	10.8		16.0	16.8
ML∞	60C40B	3	31.2	36.6	12	50.7	55.0	24	52.7	56.2
SG∞			6.20	7.07		10.0	10.9		12.4	13.8
ML∞	60C50B	3	41.0	46.5	12	58.7	62.5	24	68.0	70.4
SG∞			6.05	6.94		7.75	8.08		8.65	8.89
ML∞	60C60B	3	48.8	54.6	12	72.8	77.5	24	76.3	80.6
SG∞			5.77	6.91		7.62	7.87		8.43	8.65

Figure 2 Moisture loss, solids gain and weight reduction of apple cylinders as a function of time at 50°C 50°Brix.

Figure 3 Plot of t/ML / t/SG / t/WR vs t for osmotic dehydration of apple cylinders at 50°C 50°Brix.

Table 2 Relation of Azuara's model predicted equilibrium moisture loss, weight reduction and solid gain with 24-h period experiment data

Variables	Conditions	R.M.S. %	Time (h) interval used for prediction	Exp.	Calc.	Constant related to velocity (h^−1)
ML	40°C 30°Brix	1.52	24	24.6	26.3 (0.96)	0.28
SG		2.84		12.4	14.5 (0.81)	0.13
WR		2.33		12.2	12.9 (0.98)	0.48
ML	40°C 40°Brix	2.46	24	50.4	54.0 (0.90)	0.24
SG		9.41		11.4	12.7 (0.84)	0.46
WR		2.68		39.0	41.7 (0.92)	0.26
ML	40°C 50°Brix	1.92	24	59.5	62.9 (0.96)	0.35
SG		1.53		6.57	6.96 (0.99)	0.50
WR		2.00		52.9	56.2 (0.96)	0.33
ML	40°C 60°Brix	1.94	24	73.0	78.7 (0.96)	0.34
SG		1.23		6.10	6.22 (0.99)	1.17
WR		2.18		66.9	73.0 (0.95)	0.30
ML	50°C 30°Brix	2.72	24	37.3	41.7 (0.97)	0.28
SG		3.17		14.0	14.5 (0.89)	0.25
WR		2.94		23.2	27.3 (0.95)	0.30
ML	50°C 40°Brix	1.50	24	52.6	55.2 (0.99)	0.52
SG		1.98		12.1	13.0 (0.93)	0.25
WR		1.58		40.5	42.4 (0.99)	0.63
ML	50°C 50°Brix	1.42	24	65.2	69.4 (0.98)	0.41
SG		2.33		7.73	8.03 (0.95)	0.35
WR		1.32		57.4	61.3 (0.98)	0.42
ML	50°C 60°Brix	1.87	24	73.8	80.6 (0.98)	0.41
SG		1.69		7.39	7.63(0.98)	0.58
WR		1.96		66.4	73.0 (0.97)	0.39
ML	60°C 30°Brix	2.49	24	37.4	41.0 (0.98)	0.44
SG		2.92		15.9	16.8 (0.91)	0.25
WR		2.42		21.4	23.7 (0.97)	0.66
ML	60°C 40°Brix	1.55	24	52.6	56.2 (0.99)	0.60
SG		2.02		12.4	13.8 (0.96)	0.33
WR		1.48		40.2	42.7 (0.99)	0.71
ML	60°C 50°Brix	1.13	24	68.0	70.4 (0.99)	0.62
SG		6.91		8.65	8.90 (0.99)	0.80
WR		1.26		59.4	61.7 (0.99)	0.59
ML	60°C 60°Brix	0.98	24	76.3	80.6 (0.99)	0.67
SG		1.00		8.43	8.65 (0.99)	0.84
WR		1.12		67.8	71.9 (0.99)	0.65
Numbers in the bracket are the experimental data regression coefficient use Azuara's model.

Figure 4 Plot of equilibrium ML% vs temperature for osmotic dehydration of apple cylinders at different concentration.

Figure 5 Plot of equilibrium ML% vs concentration for osmotic dehydration of apple cylinders at different temperatures.

Table 3 Mean values and 95% confidence limits for moisture loss (%) during osmotic treatment of apple cylinders in sugar solution at different concentrations and different temperatures

Concentration (°Brix)	ML%
	40°C	50°C	60°C
30	25.5 ± 0.86^a1 *	38.3 ± 2.98^a2	37.8 ± 2.99^a2
40	51.9 ± 1.89^b2	53.8 ± 1.34^b2	54.0 ± 1.90^b2
50	60.2 ± 2.40^c2	67.0 ± 2.22^c2	68.7 ± 1.48^c2
60	76.0 ± 2.90^d2	76.6 ± 3.56^d2	78.2 ± 2.18^d2
*Means in columns followed by the same letter or rows followed by same number are not significantly different at the 5% level.

Figure 6 Plot of equilibrium SG% vs temperature for osmotic dehydration of apple cylinders at different concentrations.

Figure 7 Plot of equilibrium SG% vs concentration for osmotic dehydration of apple cylinders at different temperatures.

Table 4 Mean values and 95% confidence limits for solids gain (%) during osmotic treatment of apple cylinders in sugar solution at different concentrations and different temperatures

Concentration (°Brix)	SG%
	40°C	50°C	60°C
30	13.2 ± 0.82^ad *	14.4 ± 0.39^ae	15.9 ± 0.99^af
40	11.9 ± 0.69^bd	12.0 ± 1.12^be	12.5 ± 1.22^bf
50	6.68 ± 0.25^cd	7.70 ± 0.46^ce	8.50 ± 0.48^cf
60	6.13 ± 0.08^cd	7.47 ± 0.14^ce	8.36 ± 0.33^cf
*Means followed by the same letter are not significantly different at the 5% level.

Figure 8 Plot of equilibrium ratio of ML/SG vs temperature for osmotic dehydration of apple cylinders at different concentrations.

Figure 9 Plot of equilibrium ratio of ML/SG vs concentration for osmotic dehydration of apple cylinders at different temperatures.

Figure 10 Plot of equilibrium (a) ML and (b) SG vs concentration for osmotic dehydration of apple cylinders at 50°C 50°Brix 24 h for three-size sample.

Figure 11 Plot of %MC (a) and %SC (b) vs sample section number for osmotic dehydration of apple cylinders at 50°C 50°Brix for large-size sample at different time.