Ryszard Żywica

Possibilities of Using Electrical Parameters of Milk for Assessing its Adulteration with Water

This manuscript presents results of a research aimed at conducting a statistical analysis of correlation between the percentage addition of water to milk and its electrical parameters, which are used to determine the degree of milk dilution and the level of milk adulteration with water. The results of milk conductivity parameters analysed in the study showed admittance and conductance to decrease systematically with water addition from ca. 10.8 to 7.8 mS. In contrast, impedance and resistance values were observed to increase from ca. 91 to 128 Ω. Results of the measurements of capacitance parameters showed that with an increasing content of distilled water in milk the value of equivalent parallel capacitance was decreasing from 1.4 to 0.65 μF. In turn, along with water content increasing to 15%, the value of equivalent series capacitance was increased from 212 to 237 μF. Still, at water content of milk exceeding 15%, the value of that parameter remained unchanged. The statistical analysis demonstrated a close linear correlation (0.989 ≤ r ≤ 0.998) between the percentage of water added to the milk and electrical parameters of impedance, resistance, admittance, conductance, as well as equivalent parallel capacitance of milk.

Influence of Variety, Moisture Content, Kernel Size and Applied Current Frequency on the Electric Properties of Wheat Grain

The work aimed at determination of electric properties of wheat grain in dependence on its variety, moisture, geometrical features of kernels and applied current frequency. Wheat grain of 4 Polish winter varieties: Korweta, Juma, Mikon and Kobra from harvest 2001 were used as the material for study. Grain was sized into 3 fractions: (1) > 2,8mm, (2) 2,5–2,8mm, and (3) 2,2–2,5mm. Basic geometrical features were determined for not sorted grain (control sample) and its three fractions by the use of digital image analysis. Electric properties of grain (at 11% and 15% moisture content) have been performed with the Hewlett Packard 4263B meter. Measurements of impedance, resistance, admittance, conductance, as well as equivalent parallel capacitance and equivalent series capacitance were made. Obtained results were subjected to statistical analysis with the use of Statistica™ programme. Changes in electric properties of grain significantly depended on all of studied factors. Most of all significant correlations appeared between geometrical features and studied electric properties of grain of 15% moisture. Statistical analysis of the results proved significant linear correlations between electric properties of kernels and their length, perimeter and circularity coefficient RC2 at higher measurement frequencies.

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

ABSTRACT The aim of the present study was to determine mathematical relationships between pH changes in beef 24 h post-slaughter and changes in the intensity of electrical current flowing through bull and heifer carcasses during high-voltage electrical stimulation. The electrical stimulation was applied 40 min postmortem for 120 s. The pH values of m. longissimus thoracis et lumborum were analyzed in the function of electrical current intensity changes and its change during electrical stimulation. Mathematical linear correlations of the y = ax ± b type were demonstrated between pH values at 2, 6, and 24 h postmortem and the initial (Ii) and ultimate (Iu) electrical current intensity values, the difference between them and the initial pH values determined before electrical stimulation. High multiple correlation coefficients (R2 = 0.416, α ≤ 0.001) between Iu and pH values 24 h post-slaughter enabled concluding that there is a possibility to predict a pH value of stimulated carcass with high accuracy, and thus also beef quality, based merely on the ultimate electrical current intensity values.