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Electrical Impedance Spectroscopy (EIS) technique is found to be an excellent candidate for bio-sensing and food quality monitoring applications due to its rapid, robust, cost-effective and point-of-care approach. The present research work investigates the implementation of EIS technique supported by several optical spectroscopic techniques such as Ultraviolet-Visible (UV-Vis) and Fourier Transform Mid Infrared (FT-MIR) to detect and quantify several toxic adulterants in foods and bio-consumables. A comprehensive understanding on the background theory related to the study has been developed to analyze the overall polarization of the system and the effect of frequency on complex permittivity of such system have been observed. In the current work, the technique is applied to adulterated saccharides, honey and turmeric samples through a prototype sensing device. All the corresponding measurements have been performed by dipping a custom-made parallel plate conductivity cell with unity cell constant inside the solution under test. EIS study exhibited a steady variation of electrical parameters such as impedance, capacitance, conductance and current values with increasing adulterant percentage in the solution. Variation in such properties due to adulteration provides a systematic sensor plot through which one can determine their percentage of adulteration in unknown adulterated samples. Co-efficient of sensitivity has been extracted from the EIS data for adulteration study in terms of one of the measured parameters. The results of UV-Vis and FT-MIR studies have been used for comparative analyses which corroborate with the EIS results, wherever applicable., Comment: This is my PhD thesis, around 164 pages