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. The core-shell structure of nanofibers through W/W emulsion electrospinning avoided anthocyanin decomposition.The nanofibrous membranes monitored the quality of fresh shrimp through color changes.EVOH encapsulated BA could maintain the function and stability of blueberry anthocyanin, and then dispersed in PVA nanofibers to maintain barrier properties. The core-shell structure of nanofibers through W/W emulsion electrospinning avoided anthocyanin decomposition. The nanofibrous membranes monitored the quality of fresh shrimp through color changes. EVOH encapsulated BA could maintain the function and stability of blueberry anthocyanin, and then dispersed in PVA nanofibers to maintain barrier properties.

为改善蓝莓花青素（blueberry anthocyanins, BA）稳定性欠佳、乙烯-乙烯醇共聚物（ethylene vinyl alcohol copolymer, EVOH）吸湿性过强的问题，本研究将BA封装于EVOH中，随后将其分散于聚乙烯醇（polyvinyl alcohol, PVA）溶液中制备水包水（W/W）乳液，进一步通过静电纺丝工艺制备纳米纤维膜。采用生物显微镜与Zeta电位粒径分析仪对该乳液的稳定性进行表征；通过红外光谱（infrared spectroscopy）验证了BA/EVOH成功负载于PVA连续相体系中。BA的掺入显著提升了膜材的抗氧化与抗紫外性能，该膜可完全阻断紫外线B（UVB）波段，并阻挡大部分紫外线A（UVA）波段。经热交联（thermal crosslinking）处理后，膜材的水蒸气透过率（water vapor transmission rate）与机械性能均得到有效提升。本研究探索了该膜在虾类变质监测中的应用潜力：在室内密闭储存环境中，指示膜的颜色由淡紫红色渐变为灰蓝色。研究结果表明，该膜可通过pH变化实时监测虾类变质，所制备的智能指示膜有望成为性能优良的智能食品包装材料。通过水包水乳液静电纺丝制备的纳米纤维具有核壳结构（core-shell structure），可有效避免花青素降解。该纳米纤维膜可通过颜色变化实时监测新鲜虾类的品质。经EVOH封装的BA可维持蓝莓花青素的功能与稳定性，并分散于PVA纳米纤维体系中以保留其阻隔性能。通过水包水乳液静电纺丝制备的纳米纤维具有核壳结构，可有效避免花青素降解。该纳米纤维膜可通过颜色变化实时监测新鲜虾类的品质。经EVOH封装的BA可维持蓝莓花青素的功能与稳定性，并分散于PVA纳米纤维体系中以保留其阻隔性能。