Development and optimization of dynamic gelatin/chitosan nanoparticles incorporated with blueberry anthocyanins for milk freshness monitoring.

In this study, we prepared gelatin and chitosan as wall materials, and composites with a controlled release capability in a weak acidic environment were synthesized for loading and protecting anthocyanins. Fourier-transform infrared spectroscopy and scanning electron microscopy were used to assess the properties of the nanoparticles. The loading efficiencies and oxidation resistances of the proposed substances were measured. Under optimal conditions, the anthocyanins exhibited a loading efficiency of 83.81 %, and suitable long-term storage capacity at room temperature with a retention rate of ∼50 % after 15 d. When the nanoparticles were used for detecting the milk freshness, spoiled milk exhibited a reddish color, whereas the color of fresh milk did not change. Moreover, these nanoparticles exhibited a stable chroma in milk for 0-16 h. Therefore, the proposed pH responsive nanoparticles can provide a possibility for the dynamic monitoring of milk quality changes, or provide some reference value for future related research.