Optical method for detecting oxygen via the chromogenic reaction catalyzed by polyphenol oxidase

The present work describes a method for detecting the ingress of gas phase oxygen into packed food. It uses the enzyme polyphenol oxidase (PPO)from Mushroom and Mediterranean dwarf palm. The PPO is incorporated into an indubiose film along with a non-toxic polyphenol such as gallic acid or chlorogenic acid. If exposed to oxygen, the test spot undergoes an irreversible and visible color change from pale to deep brown due to the PPO catalyzed oxidation of the respective polyphenol by oxygen. The color change can be detected visually or by spectrophotometry at 470 nm. The effect of the amount of oxygen or substrate, type of enzyme substrate, enzyme source, temperature and duration of storage on the response were studied. Air oxygen can be detected within 30 min under optimized condition. The smallest amount of oxygen that can be detected with acceptable response time (120 min) is 5%. The test is highly selective for oxygen and the detector is stable over time. The detector may be used in any application as long as the presence or absence of oxygen in a sealed space is determined prior to the application using the detector.