Linear correlation between pH value of stimulated beef and electrical current intensity

Figures & data

Table 1. Regression analysis of pH value after a slaughter (pH_{h(2, 6, 24)}) as a function of pH₀ value measured directly before ES and the initial (I_i) and the ultimate (I_u) values and the changes of intensity (ΔI) of electric current passing through carcasses of young bulls and heifers during electrical stimulation (n = 109).

T (h)	R^2	P	Regression equation
pH in a function of Iu (Eq. (1))
2	0.213	0.000***	pH2 = 5.393 + 0.486 Iu
6	0.292	0.000***	pH6 = 4.848 + 0.731 Iu
24	0.416	0.000***	pH24 = 4.353 + 0.968 Iu
pH in a function of pH0 and Iu (Eq. (2))
2	0.519	0.000***	pH2 = 21.937 − 2.310 pH0 + 0.131 Iu
6	0.575	0.000***	pH6 = 25.372 − 2.866 pH0 + 0.291 Iu
24	0.769	0.000***	pH24 = 29.732 − 3.543 pH0 + 0.423 Iu
pH in a function of pH0, Ii, and Iu (Eq. (3))
2	0.520	0.000***	pH2 = 21.928 − 2.308 pH0 − 0.040 Ii + 0.169 Iu
6	0.575	0.000***	pH6 = 25.381 − 2.868 pH0 + 0.040 Ii + 0.252 Iu
24	0.770	0.000***	pH24 = 29.741 − 3.545 pH0 + 0.038 Ii + 0.387 Iu
pH in a function of pH0, Ii, Iu, and ΔI (Eq. (4))
2	0.509	0.000***	pH2 = 23.719 − 2.535 pH0 + 0.044 ΔI
6	0.542	0.000***	pH6 = 29.444 − 3.383 pH0 − 0.030 ΔI
24	0.711	0.000***	pH24 = 35.640 − 4.294 pH0 − 0.025 ΔI

T: time after a slaughter; P: significance level – calculated; ***: significant differences (α ≤ 0.001) ; R²: multiple correlation coefficient.

Table 2. Results of calculations of expected pH values after a slaughter (pH_{h(2, 6, 24)}) based on regression functions in case of the highest pH₀ value and the lowest values of electrical current parameters (Table 1).

Measured values		Source of the regression functions
pH0	7.00	Iu (Eq. (1))	pH0, Iu (Eq. (2))	pH0, Ii, Iu (Eq. (3))	pH0, ΔI (Eq. (4))
Ii (A)	1.30
Iu (A)	1.30
ΔI (A)	0.00
		Calculated pHh(2, 6, 24) values
pH2		6.025	5.937	5.940	5.974
pH6		5.798	5.688	5.685	5.763
pH24		5.611	5.481	5.478	5.582

pH₀: value measured directly before electrical stimulation; I_i and I_u: initial and ultimate values of intensity of electrical current; ΔI: changes of intensity of electrical current flowing through carcasses of young bulls and heifers during electrical stimulation.

Table 3. Results of calculations of expected pH values after slaughter (pH_{h(2, 6, 24)}) based on regression functions in case of the mean pH₀ value and the mean values of electrical current parameters (Table 1).

Measured values		Source of the regression functions
pH0	6.896	Iu (Eq. (1))	pH0, Iu (Eq. (2))	pH0, Ii, Iu (Eq. (3))	pH0, ΔI (Eq. (4))
Ii (A)	1.786
Iu (A)	1.731
ΔI (A)	0.055
		Calculated pHh(2, 6, 24) values
pH2		6.234	6.234	6.233	6.240
pH6		6.113	6.112	6.111	6.113
pH24		6.029	6.032	6.032	6.028

pH₀: value measured directly before electrical stimulation; I_i and I_u: initial and ultimate values of intensity of electrical current; ΔI: changes of intensity of electrical current flowing through carcasses of young bulls and heifers during electrical stimulation.

Table 4. Results of calculations of expected pH values after slaughter (pH_{h(2, 6, 24)}) based on regression functions in case of the lowest pH₀ value and the highest values of electrical current parameters (Table 1).

Measured values		Source of the regression functions
pH0	6.80	Iu (Eq. (1))	pH0, Iu (Eq. (2))	pH0, Ii, Iu (Eq. (3))	pH0, ΔI (Eq. (4))
Ii (A)	2.30
Iu (A)	1.90
ΔI	0.40
		Calculated pHh(2, 6, 24) values
pH2		6.316	6.478	6.463	6.499
pH6		6.237	6.436	6.449	6.428
pH24		6.192	6.443	6.458	6.431

pH₀: value measured directly before electrical stimulation; I_i and I_u: initial and ultimate values of intensity of electrical current; ΔI: changes of intensity of electrical current flowing through carcasses of young bulls and heifers during electrical stimulation.