# Ohmic Heating in the Food Industry: Developments in Concepts and Applications during 2013-2020
## 8 Effects of Ohmic Heating on Inactivation Microorganisms in Food
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Foods** & **Electrical Properties** & **Effect of Ohmic Heating** & **References** \\ \hline \multirow{3}{*}{Colored potato} & \multirow{3}{*}{15 V/cm and 30 V/cm} & Extraction of anthocyanins and phenolic compounds in & \multirow{3}{*}{[30]} \\  & & large quantities, treatment time and energy & \\  & & consumption were low. & \\ \hline \multirow{3}{*}{Sesame oil} & 600, 750 and & The oil extraction rate was higher than mechanical & \multirow{3}{*}{[73]} \\  & 900 V/m & recovery. Free fatty acids (oleic acid) and peroxide value & & \\  & 900 V/m & were within acceptable limits. & \\ \hline \multirow{3}{*}{Mango juice} & \multirow{3}{*}{40 V/cm, 80 \({}^{\circ}\)C and holding time for 60 s} & Polyphenol oxidase inhibition 96\%, pectin methyl & \multirow{3}{*}{[74]} \\  & 40 V/cm, 80 \({}^{\circ}\)C and & esterase 90\%, decrease in the value of ascorbic acid & \\  & & (11.3\%), total phenol content 8\% higher compared to & \\  & & conventional heating and improve the functional & \\  & & properties of juice. & \\ \hline \multirow{3}{*}{Corn flour} & \multirow{3}{*}{120 V, 60 Hz.} & Maintaining the insoluble fiber content, the percentage & \multirow{3}{*}{[75]} \\  & & of soluble fibers increased by 65\%, maintaining the & \\ \cline{1-1}  & & composition of both phenols and antioxidants, greatly & \\ \cline{1-1}  & & reducing water loss. & \\ \hline \multirow{3}{*}{Polyphenolic extracts} & \multirow{3}{*}{496.0–840.0 V/cm} & An increase in the concentration of phenolic & \multirow{3}{*}{[31]} \\  & & compounds, antioxidant activity, antimicrobial activity, & \\ \cline{1-1}  & & and inhibitory activity of cancer cell growth. The & \\ \cline{1-1}  & & extracts had advantages in the food, pharmaceutical, or & \\ \cline{1-1}  & & cosmetic industries compared to other extraction & \\ \cline{1-1}  & & methods in which toxic solvents should be removed. & \\ \hline \multirow{3}{*}{Pasteurized orange juice} & 32–36 V/cm, 60–90 \({}^{\circ}\)C, & The pectin esterase inhibition was higher compared to & \\ \cline{1-1}  & & holding times 0–200 s & the conventional method. & [7] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Cont. Moreover, ref. [78] studied the effect of ohmic heating on the spores of _Bacillus subtilis_ in an aqueous solution of sodium chloride at 101 \({}^{\circ}\)C (i.e., boiling point) and the effect of the intensity and frequency of the electric field during the treatment. The microbial inactivation effects of ohmic heating for all conditions of the electric field (5, 10, 20 V/cm at 20-60 kHz) and treatment times of 8, 10, 12, 14, and 16 min was better than those of samples treated by traditional method. The efficiency of eliminating bacteria increased with increasing intensity of the electric field. _B. subtilis_ was almost completely eliminated at 14-16 min and 60 kHz, while the spores remained alive at 20 and 40 kHz for the same period. These results proved that ohmic heating inhibited _B. subtilis_ more effectively than the traditional method [78]. [PERSON] et al. [17] studied the optimum ohmic heating conditions and investigated the effect of voltage gradients and corresponding sugar concentrations (\({}^{\circ}\)Bx) of apple juice to inactivate _Escherichia coli_ O157: H7, _Salmonella enterica serovar Typhimuriumium_, and _Listeria monocytogenes_. The lowest heating rate was at a concentration of 72 \({}^{\circ}\)Bx in all voltage gradients used in the study and a similar pattern of temperature increase was shown in 18-48 \({}^{\circ}\)Bx juice samples. System performance coefficients (SPC) were comparatively higher under two treatment conditions (30 V/cm in 36 \({}^{\circ}\)Bx or 60 V/cm in 48 \({}^{\circ}\)Bx juice). Meanwhile, after treatment for 60 s in 36 \({}^{\circ}\)Bx at 30 V/cm, 5-log reductions of the three foodborne pathogens were achieved. A treatment of 8 \({}^{\circ}\)Bx juice at 60 V/cm for 20 s was sufficient to achieve 5-log reduction without affecting product quality [17].