Colorimetric Biocomposite Sensor Using Polyvinyl Alcohol/Sodium Alginate Film for Visual Detection of Edible Oil Deterioration

Routine analytical techniques for assessing lipid oxidation frequently require expensive, complex equipment or intricate procedures, which restrict their use in day-to-day situations. Also, ordinary consumers could not follow up on the deterioration of household edible oils as they lack proficiency. An effective way to determine the freshness of edible oil is to look for a visual detection procedure. Aldehydes, which are significant chemicals created during the oxidation of lipids, could be employed to follow up on oil deterioration during storage. Here, a colorimetric composite sensor for aldehydes made of polyvinyl alcohol and sodium alginate was created and used to visually detect the oxidation of edible oil. Congo red and either hydroxylamine sulfate or hydroxylamine chloride were used to manufacture the sensor. The unique reaction between hydroxylamine sulfate or hydroxylamine chloride and aldehydes releases mineral acid and lowers pH, causing Congo’s color to change from red to blue, an easy visual way to detect the aging of stored oils. The response of the hydroxylamine sulfate sensor film was more pronounced visually than that of hydroxylamine chloride. Additionally, the relationship between the sensor films’ efficacy and the concentration of hexanal or peroxide value was examined. The sensor films strongly correlated to the two major oil oxidation markers, namely, hexanal and PV of both soybean and olive oils, indicating the reliability of the colorimetric sensor with considerable potential for visual detection of edible oil oxidation.