Plant phytochemicals as bio-responsive compounds in smart packaging for food spoilage detection: a comprehensive review

With growing consumer concern for eating fresh and nutritious food, there arises a demand for freshness indicators to build consumer trust and brand value. An active and intelligent packaging system helps extend the shelf life of a product and facilitates visual communication of the dynamic shelf life, respectively. These methods thereby may improve food safety and reduce food wastage at household and retail level by eliminating the confusing use-by and best-before labels printed on packaging. This review on smart packaging has more emphasis on freshness indicators, a segment of intelligent packaging. In the past few decades, the trend of using natural coloring compounds, flavonoids, as pH indicators has been booming. The complex process of food spoilage and its association with color change of flavonoids is elaborated. These compounds can be extracted efficiently from fruit and vegetable peels and flowers using several techniques. They can be employed as pH indicators after immobilizing them in a base matrix, usually biopolymers owing to their biodegradability.