Ohmic Cooking of Processed Meats and its Effects on Product Quality

Innovative Processing Technologies to Develop a New Segment of Functional Citrus-Based Beverages: Current and Future Trends

The food industries are interested in developing functional products due to their popularity within nutritional and healthy circles. Functional fruit-based beverages represent one of the fast-growing markets due to the high concentrations of bioactive compounds (BCs), which can be health promoters. Hence, functional beverages based on citrus fruits are a potential way to take advantage of their nutritional and bioactive properties that could attract the interest of consumers. In order to ensure microbial and quality stability, the beverages are subjected to preservation treatment; however, the application of high temperatures leads to the loss of thermolabile BCs. Nowadays, innovative processing technologies (IPT) such as pulsed electric field (PEF), high-pressure processing (HPP), ultrasound processing (US), ohmic heating (OH), and microwave (MW) are a promising alternative due to their efficiency and low impact on juice BCs. The available literature concerning the effects of these technologies in functional fruit-based beverages is scarce; thus, this review gathers the most relevant information about the main positive and negative aspects of the IPT in functional properties, safety, and consumer acceptance of functional citrus-based beverages, as well as the use of citrus by-products to promote the circular economy in citrus processing.

Use of ohmic heating as an alternative method for cooking pasta

BACKGROUND

In this study, the alternative method of ohmic heating (OH) was applied to investigate its potential usage in the cooking process for pasta and its comparison with the conventional method. For this purpose, OH was operated at four different voltage gradients (10, 20, 30, 40 V cm^-1 ). The electrical conductivity of pasta σ (S m^-1 ) was calculated for the temperature range 22-95 °C and a three-phase linear relation between σ and temperature was determined.

RESULTS

According to the results, the energy consumption of the OH system and cooking time were lower than the conventional method. Energy conservation was about 73.7% at 40 V cm^-1 and increased up to 90.4% (at 10 V cm^-1 ) with lower voltage gradients. Total cooking time, cooking loss, water absorption, degree of gelatinization, volume uptake, energy consumption and sensorial properties were investigated. No significant differences between the results of samples cooked with the conventional method and OH at 30-40 V cm^-1 were found in terms of starch gelatinization degree, volume change, water absorption, and sensorial analysis (P > 0.05).

CONCLUSION

These results revealed that OH did not cause any negative effects on the quality parameters of pasta samples, and positive effects were observed on energy and time saving. © 2021 Society of Chemical Industry.

Inactivation Kinetics and Membrane Potential of Pathogens in Soybean Curd Subjected to Pulsed Ohmic Heating Depending on Applied Voltage and Duty Ratio

The aim of this research was to investigate the efficacy of the duty ratio and applied voltage in the inactivation of pathogens in soybean curd by pulsed ohmic heating (POH). The heating rate of soybean curd increased rapidly as the applied voltage increased, although the duty ratio did not affect the temperature profile. We supported this result by verifying that electrical conductivity increased with the applied voltage. Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in soybean curd were significantly (P < 0.05) inactivated by more than 1 log unit at 80 Vrms (root mean square voltage). To elucidate the mechanism underlying these results, the membrane potential of the pathogens was examined using DiBAC4(3) [bis-(1,3-dibutylbarbituric acid)trimethine oxonol] on the basis of a previous study showing that the electric field generated by ohmic heating affected the membrane potential of cells. The values of DiBAC4(3) accumulation increased under increasing applied voltage, and they were significantly (P < 0.05) higher at 80 Vrms, while the duty ratio had no effect. In addition, morphological analysis via transmission electron microscopy showed that electroporation and expulsion of intracellular materials were predominant at 80 Vrms Moreover, electrode corrosion was overcome by the POH technique, and the textural and color properties of soybean curd were preserved. These results substantiate the idea that the applied voltage has a profound effect on the microbial inactivation of POH as a consequence of not only the thermal effect, but also the nonthermal effect, of the electric field, whereas the duty ratio does not have such an effect.IMPORTANCE High-water-activity food products, such as soybean curd, are vulnerable to microbial contamination, which causes fatal foodborne diseases and food spoilage. Inactivating microorganisms inside food is difficult because the transfer of thermal energy is slower inside than it is outside the food. POH is an adequate sterilization technique because of its rapid and uniform heating without causing electrode corrosion. To elucidate the electrical factors associated with POH performance in the inactivation of pathogens, the effects of the applied voltage and duty ratio on POH were investigated. In this study, we verified that a high applied voltage (80 Vrms) at a duty ratio of 0.1 caused thermal and nonthermal effects on pathogens that led to an approximately 4-log-unit reduction in a significantly short time. Therefore, the results of this research corroborate database predictions of the inactivation efficiency of POH based on pathogen control strategy modeling.