Evaporation kinetics and quality attributes of grape juice concentrate as affected by microwave and vacuum processing

Figures & data

Figure 1. Microwave assisted vacuum concentrator.

Table 1. Processing conditions to prepare juice concentrate.

SR. NO.	Time (min)	Power (W)	Pressure (InHg)
Control	0	0	0
1.	5 (−1)	30 (−1)	50 (0)
2.	5 (−1)	80 (1)	50(0)
3.	15 (1)	30 (−1)	50 (0)
4.	15 (1)	80 (1)	50 (0)
5.	5 (−1)	50 (0)	35 (−1)
6.	5 (−1)	50 (0)	70 (1)
7.	15 (1)	50 (0)	35 (−1)
8.	15 (1)	50 (0)	70 (1)
9.	10 (0)	30 (−1)	35 (−1)
10.	10 (0)	30 (−1)	70 (1)
11.	10 (0)	80 (1)	35 (−1)
12.	10 (0)	80 (1)	70 (1)
13.	10 (0)	50 (0)	50 (0)
14.	10 (0)	50 (0)	50 (0)
15.	10 (0)	50 (0)	50 (0)

Figure 2. Graphical representation of evaporation rate affected by power and time (a), pressure and time (b), power and pressure (c) and power, pressure and time (d). 35 KPa (▲), 70 KPa (■), and 70 KPa (●).

Figure 3. Graphical representation of moisture ratio affected by power and time (a), pressure and time (b), power and pressure (c) and power, pressure and time (d). Moroever, ▲, ■, and ● represent pressure values of 35, 50, and 70 KPa, respectively.

Table 2. Evaluation of different statistical models for moisture ratio at different powers and pressures.

Model	Power (W)	Pressure (KPa)	n	a	b	c	R^2	RSME	SSE	Chi^2	RPD (%)
Henderson	30	35			1.22×10^−2		0.964	1.93×10^−2	3.73×10^−4	4.48×10^−3	1.697
	30	50			1.07×10^−2		0.956	1.93×10^−2	3.72×10^−4	4.47×10^−4	1.867
	30	70			6.78×10^−3		0.965	1.12×10^−2	1.26×10^−4	1.52×10^−4	1.009
	50	35			4.02×10^−2		0.936	6.61×10^−2	4.37×10^−3	5.25×10^−3	9.631
	50	50			5.20×10^−2		0.929	8.05×10^−2	6.48×10^−3	7.77×10^−3	19.903
	50	70			3.07×10^−2		0.918	6.46×10^−2	4.18×10^−3	5.01×10^−3	9.227
	80	35			7.61×10^−2		0.967	5.64×10^−2	3.18×10^−3	3.97×10^−3	13.453
	80	50			7.15×10^−2		0.963	5.80×10^−2	3.63×10^−3	4.20×10^−3	11.386
	80	70			8.54×10^−2		0.974	5.08×10^−2	2.58×10^−3	3.22×10^−3	10.158
Wang and Singh	30	35		−1.34×10^−4	−8.15×10^−3		0.988	1.13×10^−2	1.29×10^−4	1.93×10^−4	0.968
	30	50		−1.88×10^−4	−5.84×10^−3		0.997	4.85×10^−3	2.35×10^−5	3.53×10^−5	0.414
	30	70		−1.18×10^−4	−3.96×10^−3		0.998	2.94×10^−3	8.64×10^−6	1.30×10^−5	0.269
	50	35		−2.08×10^−4	−2.42×10^−2		0.987	2.94×10^−2	8.67×10^−4	1.30×10^−3	3.186
	50	50		−1.35×10^−4	−3.11×10^−2		0.991	2.84×10^−2	8.10×10^−4	1.21×10^−3	5.378
	50	70		−4.40×10^−4	−1.46×10^−4		0.992	1.97×10^−2	3.88×10^−4	5.81×10^−4	2.595
	80	35		8.28×10^−4	−5.87×10^−4		0.986	3.62×10^−2	1.31×10^−3	2.19×10^−3	9.691
	80	50		7.80×10^−4	−5.63×10^−2		0.980	4.20×10^−2	1.77×10^−3	2.94×10^−3	9.599
	80	70		1.43×10^−3	−7.10×10^−2		0.986	3.74×10^−2	1.40×10^−3	2.34×10^−3	10.085
Page	30	35	1.359		4.24×10^−3		0.993	8.23×10^−3	6.78×10^−5	1.02×10^−4	0.732
	30	50	1.468		2.67×10^−3		0.999	2.31×10^−3	5.34×10^−6	8.00×10^−6	0.203
	30	70	1.404		2.04×10^−3		0.999	1.10×10^−3	1.22×10^−6	1.83×10^−6	0.102
	50	35	1.604		7.30×10^−3		0.995	1.71×10^−2	2.91×10^−4	4.37×10^−4	2.552
	50	50	1.705		7.37×10^−3		0.999	9.42×10^−3	8.87×10^−5	1.33×10^−4	2.014
	50	70	1.745		3.58×10^−3		0.999	6.11×10^−3	3.74×10^−5	5.60×10^−5	0.900
	80	35	1.412		2.72×10^−2		0.994	2.48×10^−2	6.13×10^−4	1.02×10^−3	7.581
	80	50	1.407		2.57×10^−2		0.990	2.96×10^−2	8.75×10^−4	1.46×10^−3	8.043
	80	70	1.310		4.02×10^−2		0.989	3.18×10^−2	1.01×10^−3	1.69×10^−3	10.918
Two term exponentials	30	35		1.895		0.0272	0.992	8.98×10^−3	8.07×10^−5	1.21×10^−4	0.838
	30	50		1.935		0.0264	0.999	2.58×10^−3	6.65×10^−6	9.97×10^−6	0.220
	30	70		1.917		0.01858	0.999	1.71×10^−3	2.92×10^−6	4.38×10^−6	0.150
	50	35		2.062		0.0757	0.997	1.45×10^−2	2.11×10^−4	3.16×10^−4	2.594
	50	50		2.118		0.0945	0.996	1.76×10^−2	3.10×10^−4	4.64×10^−4	4.470
	50	70		2.082		0.0633	0.998	8.99×10^−3	8.097×10^−5	1.21×10^−4	1.148
	80	35		1.967		0.123	0.994	2.34×10^−2	5.48×10^−4	9.13×10^−4	7.011
	80	50		1.982		0.118	0.992	2.65×10^−2	7.02×10^−4	1.17×10^−3	7.289
	80	70		1.911		0.132	0.991	2.96×10^−2	8.74×10^−4	1.46×10^−3	10.041
logarithmic	30	35		−0.737	−1.35×10^−2	1.749	0.990	1.04×10^−2	1.09×10^−4	2.18×10^−4	0.963
	30	50		−0.239	−3.01×10^−2	1.244	0.997	5.02×10^−3	2.52×10^−5	5.05×10^−5	0.447
	30	70		−0.167	−2.87×10^−2	1.170	0.997	3.08×10^−3	9.51×10^−6	1.90×10^−5	0.313
	50	35		−4.661	−6.03×10^−3	5.687	0.989	2.72×10^−2	7.42×10^−4	1.48×10^−3	3.203
	50	50		−33.610	−1.04×10^−3	34.637	0.993	2.58×10^−2	6.68×10^−4	1.34×10^−3	4.899
	50	70		−0.736	−2.55×10^−2	1.756	0.993	1.94×10^−2	3.75×10^−4	7.49×10^−4	2.606
	80	35		1.578	3.98×10^−2	−0.5604	0.985	3.74×10^−2	1.40×10^−3	3.49×10^−3	10.559
	80	50		1.545	3.94×10^−2	−0.523	0.979	4.27×10^−2	1.82×10^−3	4.55×10^−3	10.384
	80	70		1.213	6.46×10^−2	−0.193	0.982	4.27×10^−2	1.82×10^−3	4.56×10^−3	13.223
Midilli	30	35	1.402	1.001	9.26×10^−3	0.0116	0.998	3.94×10^−3	1.56×10^−5	4.67×10^−5	0.377
	30	50	1.419	1.000	4.00×10^−3	0.0024	0.999	2.02×10^−3	4.10×10^−6	1.23×10^−5	0.171
	30	70	1.314	0.999	4.49×10^−3	0.00382	0.999	1.40×10^−4	1.97×10^−8	5.92×10^−8	0.012
	50	35	1.628	1.006	7.68×10^−3	0.00199	0.996	1.62×10^−2	2.64×10^−4	7.91×10^−4	2.873
	50	50	1.646	1.004	8.09×10^−3	−0.00144	0.999	8.67×10^−3	7.52×10^−5	2.25×10^−4	1.292
	50	70	1.761	1.000	3.86×10^−3	0.00204	0.999	5.33×10^−3	2.84×10^−5	8.52×10^−5	0.674
	80	35	1.627	0.996	1.97×10^−2	0.00494	0.996	1.96×10^−2	3.83×10^−4	1.92×10^−3	5.042
	80	50	1.752	0.996	1.52×10^−2	0.00767	0.997	1.63×10^−2	2.64×10^−4	1.32×10^−3	3.901
	80	70	1.664	0.997	2.30×10^−2	0.00686	0.997	1.55×10^−2	2.40×10^−4	1.20×10^−3	4.773

Figure 4. Influence of pressure and power on DPPH a), TPC b), TFC c) and solubility index d) of grape pomace.

Table 3. Effect of microwave power and vacuum pressure on color parameters.

Power (W)	Pressure (InHg)	WI	C	ΔE
30	35	95.49 ± 0.028^c	30.82 ± 0.040^a	33.28 ± 0.033^a
	50	99.48 ± 0.045^b	34.05 ± 0.030^a	35.99 ± 0.020^a
	70	99.76 ± 0.052^a	1.64 ± 0.015^c	15.52 ± 0.030^c
50	35	99.49 ± 0.037^c	3.44 ± 0.029^c	15.92 ± 0.040^c
	50	99.92 ± 0.055^a	0.13 ± 0.004^c	15.32 ± 0.035^c
	70	98.86 ± 0.065^a	11.31 ± 0.041^b	19.61 ± 0.064^b
80	35	99.32 ± 0.032^b	4.90 ± 0.028^b	16.43 ± 0.069^b
	50	99.26 ± 0.049^c	26.0 ± 0.050^b	30.87 ± 0.038^b
	70	99.57 ± 0.046^b	31.3 ± 0.033^a	35.31 ± 0.035^a

Figure 5. Influence of power and pressure on specific energy consumption (a) and extraction yield (b).

Figure 6. Effect of power and pressur on effective diffusivity (a) and activation energy (b).