Smart packaging films based on locust bean gum, polyvinyl alcohol, the crude extract of Loropetalum chinense var. rubrum petals and its purified fractions

Development of Shrimp Freshness Indicating Films by Embedding Anthocyanins-Rich Rhododendron simsii Flower Extract in Locust Bean Gum/Polyvinyl Alcohol Matrix

“…Recently, Yao et al [ 31 ] also found that the cross-sectional microstructure of LP film was unchanged by the natural pigment of pitaya betacyanins. However, Yun et al [ 24 ] documented that the nodular cross-section of LP film was remarkably altered by Loropetalum chinense flower anthocyanins. The results indicated that the microstructure of the films was related to the source of pigment.…”

“…The extract solution was combined and centrifuged at 8000 rpm for 15 min, and the supernatant was collected and concentrated by a rotary evaporator at 45 °C. The concentrate was loaded on an AB-8 resin column (50 cm × 2.6 cm), which was first eluted with distilled water to remove impurities, and then eluted with 25% ethanol containing 0.5% HCl [ 24 ]. The eluate was collected, dried under vacuum, and named as RA.…”

“…Each film sample (2 mg) was heated from room temperature to 700 °C by an HTG-1 analyzer (Henven Corp., Beijing, China) under high-purity nitrogen gas with a flow rate of 20 mL/min [ 24 ].…”

“…The pH sensitivity of each film sample (1 cm × 1 cm) was determined in 50 mL of pH 3−12 buffers for 2 min. The ammonia sensitivity of each film sample (1 cm × 1 cm) was determined in ammonia gas (1 mol/L ammonia solution) for 10−90 min [ 24 ].…”

“…The Petri dish was sealed and the shrimp were stored at 4 °C for 6 days. The color of the film sample and the total volatile basic nitrogen (TVB-N) level of the shrimp were measured every 24 h [ 24 ]. Three replications were performed for each kind of film.…”