Kwon Seongyoung, Ko Seonghyuk
Department of Packaging, Yonsei University, Wonju 26493, Korea.
Polymers (Basel). 2022 Sep 5;14(17):3695. doi: 10.3390/polym14173695.
In this study, a colorimetric freshness indicator based on cellulose nanocrystal-silver nanoparticles (CNC-AgNPs) was successfully fabricated to offer a convenient approach for monitoring the quality of packaged food. AgNPs were directly synthesized and embedded in CNC via a one-pot hydrothermal green synthesis, and CNC-AgNP composited indicator films were prepared using a simple casting method. The AgNPs obtained were confirmed by UV-Vis diffuse reflectance spectroscopy and X-ray diffraction. The ability of the as-prepared CNC-AgNP film to indicate food quality was assessed in terms of the intensity of its color change when in contact with spoilage gases from chicken breast. The CNC-AgNP films initially exhibited a yellowish to dark wine-red color depending on the amount of AgNPs involved. They gradually turned colorless and subsequently to metallic grey. This transition is attributed to the reaction of AgNPs and hydrogen sulfide (HS), which alters the surface plasmon resonance of AgNPs. Consequently, the color change was suitably discernible to the human eye, implying that the CNC-AgNP composite is a highly effective colorimetric freshness indicator. It can potentially serve as an accurate and irreversible food quality indicator in intelligent packaging during distribution or storage of products that emit hydrogen sulfide when deteriorating, such as poultry products or broccoli.
在本研究中，一种基于纤维素纳米晶体-银纳米颗粒（CNC-AgNPs）的比色新鲜度指示剂被成功制备出来，为监测包装食品的质量提供了一种便捷的方法。通过一锅水热绿色合成法直接合成AgNPs并将其嵌入CNC中，然后采用简单的流延法制备了CNC-AgNP复合指示膜。通过紫外-可见漫反射光谱和X射线衍射对所得的AgNPs进行了表征。根据制备的CNC-AgNP膜与鸡胸肉腐败气体接触时颜色变化的强度，评估了其指示食品质量的能力。CNC-AgNP膜最初根据所涉及的AgNPs的量呈现出淡黄色至深酒红色。它们逐渐变为无色，随后变为金属灰色。这种转变归因于AgNPs与硫化氢（HS）的反应，该反应改变了AgNPs的表面等离子体共振。因此，颜色变化肉眼易于辨别，这意味着CNC-AgNP复合材料是一种高效的比色新鲜度指示剂。在诸如家禽产品或西兰花等变质时会释放硫化氢的产品的分销或储存过程中，它有可能作为智能包装中准确且不可逆的食品质量指示剂。
