Development of electrospun nanofiber films based on pullulan/polyvinyl alcohol incorporating bayberry pomace anthocyanin extract for aquatic products freshness monitoring

Aquatic products were susceptible to spoilage during storage due to microorganisms and enzymes, which could cause food safety problems. The electrospun nanofiber films, based on pullulan (PUL) and polyvinyl alcohol (PVA) incorporating bayberry pomace anthocyanin extract (BAE), were developed to monitor the freshness states of aquatic products in this study. The SEM results revealed that the electrospun nanofiber films exhibited a smooth surface, and the average diameter decreased from 481.56 nm to 237.68 nm as anthocyanin content increased from 0 to 20%. The FTIR and XRD results showed that there were no new characteristic peaks, confirming the successful loading of BAE. The incorporation of BAE decreased the water content (from 13.58% to 7.84%), swelling ratio (from 146.75% to 114.24%), water vapor permeability (from 3.38 g<middle dot>mm<middle dot>m(-2)<middle dot>Pa-1<middle dot>s(-1)<middle dot>10(-5) to 2.00 g<middle dot>mm<middle dot>m(-2)<middle dot>Pa-1<middle dot>s(-1)<middle dot>10(-5)), and elongation at break (from 24.67% to 14.90%), but increased water solubility (from 74.99% to 85.74%) and water contact angle (from 51.84 degrees to 63.73 degrees). The electrospun nanofiber films presented obvious color changes in buffer solutions (pH 2.0 to 12.0) or volatile ammonia and showed good reversibility. Besides, the electrospun nanofiber films were stable during storage at 4 degrees C or 25 degrees C for 20 days. Furthermore, PUL-PVA-A15 effectively distinguished the freshness states (fresh, sub-fresh and spoiled) of Penaeus vannamei during storage at 4 degrees C by showing different colors (from pink to grayish purple to green). Therefore, the electrospun nanofiber films showed great potential to real-time monitor the quality of aquatic foods as intelligent packaging.