The Effect of Formalin Addition on the Electrical Impedance of White Shrimp

Shrimp is one of the important protein sources for diet. Shrimp has high water content, causing quick spoilage of the product and degradation of its quality from post-harvesting to end-consumers. The use of formalin to prolong the shelf life of shrimp has become a raised issue in the food safety field as formalin could have negative impacts on human health. Therefore, its use in food products is prohibited. The electrical impedance spectroscopy could be used to detect the food additives such as formalin in shrimp. This paper discusses the impedance of the shrimp after soaked in formalin solution. The shrimp samples were soaked in the different concentrations of formalin solution and stored for five days. The shrimp without formalin was used as a control sample. The electrical properties of the shrimp samples were measured using the electrical impedance spectroscopy method using frequency from 1 Hz to 1 MHz each day. The results show that the impedance of the shrimp decrease with an increase of the storage time. The shrimp with formalin experience a slower degradation compared to the shrimp without formalin. Higher the formalin concentrations (10% - 40%) added to the shrimp causes a slower texture change on the shrimp compared to lower formation concentrations (1%-5%). The impedance of the shrimp decrease with the increase of injected signal frequency. The electrical impedance spectroscopy has the potential to be developed as a tool in food safety field to detect food additives contained in the food to ensure the safety of the food products to the consumers.