Читать книгу Thermal Food Engineering Operations - NITIN KUMAR - Страница 50

In the electromagnetic spectrum, radiofrequency waves fall in a frequency range of 30–300 MHz. This method works depends upon the dielectric properties of the edible sample, where with help of an indirect mode of heating they treat the target product initially with electrical energy which is then converted to radiation mildly releasing the heat [67]. Radiation from radiofrequency are non-ionizing so therefore the food molecules are not disoriented, which is the main bonus point in the process of microbial inactivation. The advantages of this process are the time consumption which is reduced remarkably, making it a feasible application in food industries for different unit operation.

Some of the chief factors on which efficacy is highly dependent for the treatment of microbial decontaminations are moisture content of the sample, temperature a frequency, targeted microorganism, and sample depth. The current study suggested that the frequency of the microwave makes the condition favorable for microbial decontamination even if it exists in food with lower moisture content. This method favors all types of food material as it works as electrothermal pasteurization which is chemical-free [68].

The principle involved in inactivating microbes by heating through radiofrequency is that the cells of the microbes get thermally injured even at a reduced heating rate as the heat develops within the cells of the microbes causing eventual destruction of the microbes [69]. RF energy combining with other different thermal methods shows synergistic effects, notably making the RF pasteurization efficient particularly for agricultural materials having less moisture content [70]. Due to the radiation mode of heating DNA of the microbial cells absorbs directly fluctuating the structure of the cell and its functionality. Radiofrequency is used for uniform heating of food products even for power products as the treatment usually depends upon the cell structure of the focused organisms.