Determination of Electrical Parameters of Liquid Foods for Predicting Waveforms of High‐Voltage Low‐Energy Pulses

Figures & data

Figure 1. Block diagram of the batch pulsed power treatment system.

Figure 2. Voltage waveform with 7.42 Ω load resistance and 20 kV voltage applied (o: observed data, – predicted data).

Figure 3. Voltage waveform with 2.47 Ω load resistance and 20 kV voltage applied (o: observed data, – predicted data).

Figure 4. Voltage waveform with 1.09 Ω load resistance and 20 kV voltage applied (o: observed data, – predicted data).

Table 1. Circuit parameters of test solutions using (Eq. 1)

Solution	Electrical conductivity, mS/cm	Electrode gap, cm	Resistance, Ω	α × 10^6 1/s	ω × 10^6 rad
Tap water	0.735	0.9	7.421	1.855	0.852
Tap water	0.735	0.3	2.474	0.619	1.945
0.235% NaCl	5	0.9	1.091	0.273	2.023
0.47% NaCl	10	0.9	0.545	0.135	2.037
0.235% NaCl	5	0.3	0.364	0.091	2.039
0.47% NaCl	10	0.3	0.182	0.0455	2.041

Table 2. Overall shaping function parameters of test solutions using (Eq. 1)

Parameters	1st Function term	2nd Function term
Q	258.529	−2.805
q (S)	−3.285	0.142
U (10^6, 1/s)	13.932	0.347
u (10^6, S/s)	−1.791	0.196

Table 3. Shaping function parameters of test solutions, expressed in terms of load resistance, using (Eq. 1)

R, Ω	P 10	p 1 (10^6, 1/s)	P 20	p 2 (10^6, 1/s)
7.421	0	0.641	−8.046	1.802
2.474	0.076	9.501	−3.989	0.832
1.091	7.780	11.978	−3.275	0.561
0.545	43.15	12.956	−3.031	0.454
0.364	78.20	13.28	−2.954	0.480
0.182	142.186	13.606	−2.878	0.383

Table 4. Statistical analyses on the parameters using (Eq. 1)

	P 10	p 1 (10^6, 1/s)	P 20	p 2 (10^6, 1/s)
r ^2	0.980	0.949	0.921	0.981
Standard error of estimate	10.753	2.771	1.427	0.134
Mean sum of squares (regression)	28265.83	711.28	117.91	4.76
Mean sum of squares (error)	115.618	7.680	2.036	0.018
DF (error)	5	5	5	5
p < T	< 0.05	< 0.01	< 0.01	< 0.01

Note:  r ², coefficient of determination; DF, degree of freedom.

Table 5. Voltage pulse waveform distribution of the test solutions at 10 kV voltage applied

R, Ω	Peak voltage, 1st portion, −ve, kV	Pulse width, 1st portion, µs	Peak voltage, 2nd portion, +ve, kV	Pulse width, 2nd portion, µs
7.421	8.6	3.5
2.474	5.2	1.9	1	0.35
1.091	4.4	1.7	1.4	0.55
0.545	4	1.4	1.95	0.85
0.364	4	1.3	1.95	0.92
0.182	4.1	1.2	2.1	1

Table 6. Voltage pulse waveform distribution of the test solutions at 20 kV voltage applied

R, Ω	Peak voltage, 1st portion, −ve, kV	Pulse width, 1st portion, µs	Peak voltage, 2nd portion, +ve, kV	Pulse width, 2nd portion, µs
7.421	15.5	3.5
2.474	9.6	1.9	1.9	0.40
1.091	8.4	1.65	2.6	0.65
0.545	7.8	1.4	3.4	0.70
0.364	7.8	1.3	3.6	1
0.182	8.4	1.15	3.8	1.15

Figure 5. Voltage waveform with whole milk as load resistance and 15 kV voltage applied (o: observed data, – predicted data).

Figure 6. Voltage waveform with whole milk as load resistance and 15 kV voltage applied (o: observed data, – predicted data).

Figure 7. Voltage waveform with whole milk as load resistance and 15 kV voltage applied (o: observed data, – predicted data).

Table 7. Electrical parameters of food products, water, and salt solution

Products	Electrical conductivity, mS/cm	Electrode gap, cm	Resistance, Ω	α × 10^6, 1/s	ω × 10^6, rad
Tap water	0.735	0.3	2.474	0.619	1.945
0.235% NaCl	5	0.3	0.364	0.091	2.039
Milk	4.75 ± 0.25	0.3	0.3828	0.0957	2.039
Skim milk	5.25 ± 0.25	0.3	0.3463	0.0866	2.039
Orange juice	3.5 ± 0.1	0.3	0.5195	0.1299	2.037
Apple cider	2.5 ± 0.1	0.3	0.7273	0.1818	2.033

Table 8. Voltage pulse waveform distribution of the products at 15 kV voltage applied

Solution	Resistance, Ω	Peak voltage, 1st portion, −ve, kV	Pulse width, 1st portion, µs	Peak voltage, 2nd portion, +ve, kV	Pulse width, 2nd portion, µs
Tap water	2.474	−7	2	1.1	0.3
0.235% NaCl	0.364	−5.8	1.3	2.8	0.95
Milk	0.3828	−6	1.3	2.8	0.95
Skim milk	0.3464	−5.8	1.3	2.8	0.95
Orange juice	0.5195	−6.2	1.4	2.8	0.85
Apple cider	0.7273	−6.2	1.5	2.4	0.75