Freshness Indicating Substance Sensor in Meat Using Molecularly Imprinted Carbon Paste Electrode

Abstract

Fresh fish and meat are rich in adenosine-triphosphate (ATP), which over time is converted via adenosine-diphosphate (ADP) and adenosine-monophosphate (AMP) into the flavor component inosinate, which, with more time, is converted into the unpleasant-tasting components inosine and hypoxanthine . These six substances are indicators to measure the freshness and maturity of meat and fish. If these substances can be easily measured at the distribution site, fair trade based on objective judgments of freshness and ripeness will become possible.We are attempting a simple disposable sensor using molecularly imprinted polymer-immobilized carbon paste (MIP-CP). Graphite particles immobilized with a radical polymerization initiator were immersed in a solution of the target materials, inosine, methacrylamidophenylboronic acid, methacrylic acid, and methylenebisacrylamide, and graft polymerized by photoirradiation. The particles were washed with hydrochloric acid to remove the inosine to obtain graphite covered with an MIP layer. This was mixed with ferrocene-containing silicone oil to form a paste and applied to a commercial carbon screen-printed electrode (Zensor, Taipei) to obtain disposable electrodes. Differential pulse voltammetry was performed in buffer solutions containing inosine or sodium inosinate; the current at 0.9 V vs. Ag/AgCl increased with increasing inosine concentration, but there was little sensitivity to sodium inosinate concentration as shown in the Figure. These results indicate that a sensor has been created that shows a highly selective response to inosine, which is the template for MIP. The measurement takes about 30 seconds. We will continue to improve the reproducibility and develop a sensor that can detect the other five indicator substances in the same way.This work is partially supported by Small-Business Innovation Research (SBIR) Program of Bio-oriented Technology Research Advancement Institution (BRAIN), in Japan (SU23A03). Figure 1