Direct evaluation of meat spoilage and the progress of aging using biosensors

A direct sensing method for monitoring meat quality was developed. The sensor is composed of an AgAgCl electrode and a platinum electrode on which putrescine oxidase or xanthine oxidase were immobilized to estimate bacterial spoilage or the progress of aging, respectively. A potential-step chronoamperometric method was applied in which the potential was stepped from 300 mV to 600 mV. A linear relationship was obtained between 5 and 60 nmol g−1 for putrescine (Put) and 0.05 and 1.0 μmol g−1 for hypoxanthine (Hx). The coefficient of variation was 0.75% for 20 nmol ml−1 Put solution and 2.2 for a meat sample using the putrescine sensor, and 1.09% for 0.25 μmol ml−1 Hx solution and 2.6% for a meat sample using the xanthine sensor. The pH requirements and substrate selectivity were suitable for the direct measurement of substrates on the surface of meat. From the results of practical experiments, the direct sensing method was indicated to be useful with some modifications for the estimation of meat quality during aging.