基于黑果枸杞花青素的智能标签:新鲜度指示性能和机理

Intelligent Label of Anthocyanins Based on Lycium Ruthenicum Murray:Freshness Indicator Property and Mechanism

黑果枸杞富含天然花青素,pH的变化可引起花青素响应性变色,通过简便易行的方法,在滤纸基底上构筑智能标签,实现包装中肉类食品新鲜度的快速、无损检测,可有效保护消费者的身体健康。鉴于此,本研究以黑果枸杞为原料,采用超声波-溶剂法提取黑果枸杞花青素(LMa);随后,以多孔的滤纸为载体,将LMa锚定于滤纸上,组装后获得黑果枸杞花青素纸基(LMa-p)智能标签。紫外-可见光光谱(UV-Vis)、傅里叶红外光谱(FTIR)、光学显微镜等仪器的表征结果表明:LMa具有典型的花青素结构,已在多孔滤纸上成功负载,其指示机理为:随着pH值的增大,LMa的分子构型从黄烊盐阳离子向醌式碱结构转变,进而引起颜色变化。以快速滤纸为载体,当LMa的浸泡浓度为10.0 mg/mL时,制备的LMa-p智能标签具有疏松多孔的表面结构,可同时兼顾响应速度和灵敏度,且能多次循环使用,响应时间、总色差(ΔE)分别为(0.94±0.18)s和11.27±0.12。此外,在鱼肉的保鲜实验中,LMa-p标签能够实时且准确地反馈新鲜度信息,在腐败时(11 h)的ΔE达到了9.29±0.06,具有较大的实际应用潜力。

Lycium ruthenicum Murray(LM) is rich in natural anthocyanins, and the variation of pH can cause responsive discolouration. Through the simple and easy method, the smart label is constructed on the filter paper to realize the rapid and non-destructive detection of the freshness of the packaging meat, which can effectively protect the health of consumers. Hence, this study employed LM as raw material to extract anthoc-yanins(LMa) by an ultrasonic-solvent method. Then, the porous filter paper was selected as the carrier, and the paper-based LMa(LMa-p) smart label was obtained via the soaked method followed by assembling. The results of UV-Vis, FTIR, optical microscopy and other instruments show that LMa has a typical anthocyanin structure, which has been successfully loaded on porous filter paper. The indicator mechanism attributes the molecular configuration of LMa changes from yellow last cation to quinone base with the increase of pH, resulting in the color change. In addition, the LMa-p label is based on a 10.0 mg/mL soak solution and the fast filter paper has a loose and porous surface structure, which can balance response and sensitivity well. The response time and total color difference(ΔE) are about(0.94±0.18) s and 11.27±0.12, respectively, and the label can be reused many times. Furthermore, in the preservation experiment of fish, LMa-p label can feedback on the freshness information in time and accurately, and the ΔE value reaches 9.29±0.06 at the time of corruption(11 h), indicating great application potential.