EVOH encapsulating blueberry anthocyanin dispersed in PVA nanofibers for real-time shrimp freshness monitoring based on pH-responsive colorimetric

Aiming to improve the low stability of blueberry anthocyanins (BA) and moisture absorption of the ethylene vinyl alcohol copolymer (EVOH), BA was encapsulated in EVOH and then dispersed in PVA solution to form water in water (W/W) emulsion, and further electrospun into nanofibers. The stability of the emulsion was analyzed by bio microscopy and zeta potential particle size analyzer. The successful encapsulation of BA/EVOH in the continuous phase of PVA was verified by infrared spectroscopy. The incorporation of BA significantly improved the oxidation resistance and UV resistance of the membranes, which could completely block UVB region and most of the UVA region. In addition, water vapor transmission rate and mechanical properties were effectively enhanced after thermal crosslinking. Finally, the potential application of the membrane in shrimp spoilage monitoring was explored, where the color of the indicator changed from mauve to grayish blue during indoor sealed storage. The results suggest that the membrane can monitor shrimp spoilage in real time through pH changes and the developed index membrane would be a good candidate as intelligent food package material.