Natural Biomaterial-Based Edible and pH-Sensitive Films Combined with Electrochemical Writing for Intelligent Food Packaging

An edible and pH-sensitive
film combined with electrochemical writing
was developed by using gelatin, gellan gum, and red radish anthocyanins
extract for intelligent food packaging. The composite film showed
an orange red-to-yellow color change in the pH range of 2–12.
The tensile strength, ductility, and barrier abilities to ultraviolet
(UV) light and oxygen of the films were improved as the concentration
of red radish anthocyanins increased. Multicolor patterns were successfully
drawn on the films by using the electrochemical writing method. The
composite films, which acted as gas sensors, presented visible color
changes in the presence of milk and fish spoilage, while the written
patterns were well-preserved. Accordingly, this composite film with
written patterns could be an easy-to-use indicator with great potential
for monitoring food spoilage as a part of an intelligent packaging
system.