Chitosan and Starch are polymers that can be obtained from renewable sources, with good film-forming
properties and many applications in food industry, such as active and smart-packaging, which can
monitor and inform consumers about food conditions in real-time. Hence, we report here a system for
pH monitoring based on Chitosan, Corn Starch and red cabbage extract, all inexpensively obtained from
renewable sources. The system was produced from medium molecular weight Chitosan, CorneStarch
and phytochemical extract from Brassica oleracea var. capitata (Red Cabbage). TG-DSC, FT-IR, Water
Vapour Transmission Rate, as well as light microscopy were used to characterize the system. The colour
variation after activation in different pH range was measured with the CIELab methodology. In order to
validate the use of this system as a fish spoilage detection sensor, application tests were conducted with
fish fillets. The results show that the system has good optical and morphological properties and is very
sensitive to pH variations. During the application test, the system visually indicated pH changes. Thus,
the system shows a clear response to pH variation of the samples. Therefore, it has potential to be used as
a visual indicator of the storage and consumption conditions of food