基于聚乙烯醇和大黄素的比色水凝胶用于虾类新鲜度监测

Colorimetric Hydrogel Based on Polyvinyl Alcohol and Emodin for Monitoring Shrimp Freshness

将植物染料大黄素(EMO)和聚乙烯醇结合,制得双交联pH响应水凝胶(EEP),并将其用作pH响应智能包装材料。采用傅里叶红外光谱、紫外-可见光谱等表征手段,研究了EEP内部的交联作用和EMO的迁移性,同时表征了EEP凝胶的颜色变化性能、氨气响应性能和抗菌性能等。结果表明:EEP不仅具有优异的抗EMO迁移性和抗菌性能,其对氨气也具备快速响应性,在经过挥发性盐酸处理后可以多次重复使用,并应用于虾类新鲜度的可视化检测。

Intelligent food packaging has gained significant attention as people become increasingly concerned about food safety and quality.One particular aspect of this field,visualized intelligent packaging materials,has become particularly popular among researchers.However,it should be noted that traditional indicators used in such packaging have proven to be toxic and prone to leakage,posing potential risks to human health as they alter the composition of the food.To address this issue,biopolymers and natural plant dyes are becoming more vital in the field of visualized intelligent packaging due to their biocompatibility,non-toxicity,and lack of pollution.Consequently,this study focuses on the preparation of a double crosslinked pH-responsive hydrogel(EEP),which uses the plant dye emodin(EMO)and polyvinyl alcohol.EEP is intended to serve as gel-like pH-responsive intelligent packaging material.The study examines the internal crosslinking of EEP through Fourier transforms infrared spectroscopy and evaluates the release of EMO within EEP.Additionally,the study assesses the EEP's color change,mechanical properties,swelling behavior,ammonia response,and antibacterial capabilities.The double crosslinking of EEP resulted in a more compact structure compared to the physical crosslinked polyvinyl alcohol hydrogel. Consequently, the equilibrium swelling rate of EEP and the mobility rate of EMO decreased by approximately 70% and 45%, respectively. The high bactericidal rate of EEP against staphylococcus aureus, attributed to the biopharmaceutical properties of EMO, was observed to be as high as 94.6%. Moreover, the prepared EEP exhibited an intriguing color transition from yellow to red in the pH range of 7-12, along with a rapid response to ammonia vapor. It was also observed that after being treated with volatile hydrochloric acid, EEP could be reused multiple times. EEP was successfully employed in a shrimp spoilage experiment, where it facilitated visual monitoring of the freshness of the shrimp. The color change from yellow to red served as an indication of shrimp spoilage. Consequently, the nontoxic and antibacterial double crosslinked pH- responsive hydrogel, demonstrates a promising potential for applications in visual food intelligent packaging and gas-sensitive labels.