Evaluation of the application effect of visual indicator coatings based on H2S for predicting the shelf-life of eggs

Eggs coated with visual indicator coatings were stored at 5, 15, 25, and 35 degrees C. The effects of storage time and temperature on changes in quality were studied using physicochemical indices. The results showed that the albumen pH and the diameter of the air space of coated eggs increased with storage time and temperature but the weight, Haugh unit, yolk index and L* value decreased. During the entire trial, the weight loss of coated eggs stored at 5 celcius was less than 5% with the other quality indicators being better than those of coated eggs stored at higher temperatures. The hydrogen sulfide (H2S) produced by the breakdown of sulfur-containing proteins can be considered a reliable indicator for evaluating the freshness of coated eggs. A visual indicator coating based on H2S was prepared and used to predict the shelf-life of eggs. Subsequently, a shelf-life prediction model was developed using a kinetic model of changes in the L* value of the visual indicator coatings on the eggshell. The results showed that the prepared visual indicator coatings provided the expected L* response toward H2S. The L* value was highly correlated with various indices, indicating that the L* value could be used as a critical quality index to establish the shelf-life prediction model. Verification based on the L* value indicated that the relative errors between the predicted and experiment values were less than 10%. Overall, the visual indicator coatings can provide valuable information on egg quality to assure their freshness.