Electrical Impedance Variations in Banana Ripening: An Analytical Study with Electrical Impedance Spectroscopy

Fruit ripening is a very crucial event in food engineering as the fruits are very important and essential food materials for human health. Under-ripening and over-ripening both are not desirable to have all the essential and important nutrients in the fruits which are only available at their optimum-ripening state. Hence, studying the ripening process of fruits is very much essential which will not only help the people to have the best fruit quality but also will help the researcher and scientist to analyze the food quality. Chemical and biochemical analyses conducted to analyze the fruit ripening are time-consuming and destructive in nature; hence, these methods, generally, are not found suitable for routine, fast and repetitive inspections. A fast and nondestructive fruit ripening characterization method is found essential to study the ripening state and fruit nutrients levels. In this direction, the EIS studies have been conducted as a nondestructive evaluation method to study the electrical impedance variations during banana ripening. The electrical impedance of banana samples is measured by Agilent 4294A impedance analyzer at different states of ripening and the ripening states are correlated with their corresponding impedances. All the impedance parameters, Z, phase angle, real part of Z and imaginary part of Z are studied to analyze the ripening phenomena in terms of banana impedance. The results demonstrate that the complex impedance, real part and imaginary part of the impedance all increase with the progresses in the ripening process. Equivalent circuit modeling shows that the ripened banana contains constant phase elements. Statistical analysis conducted on the samples from a same bunch also shows that the electrical impedance spectroscopy technique can be applied for noninvasive characterization of banana ripening. Practical Applications EIS conducted on banana ripening characterizes the banana ripening process in terms of its impedance variation and develops the equivalent circuit. EIS studies establish the correlation between the bioimpedance variation and ripening states which can be potentially utilized to study the banana ripening noninvasively. Statistical analysis shows that the standard deviation of all the impedance parameters of different banana samples obtained from a same bunch is very low compared to the corresponding mean values. It is observed that the EIS study conducted on one banana sample can represent the ripening state of the other bananas and hence the EIS studies conducted on limited number of samples can be utilized to characterize the ripening of the entire banana stacks. Thus EIS studies on banana ripening not only help us to find the optimum ripening state but also it will help the researchers to analyze its physiological changes, taste, and nutrient levels.