Colorimetric Freshness Indicator Based on Cellulose Nanocrystal–Silver Nanoparticle Composite for Intelligent Food Packaging

Abstract

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 (H2S), 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.

Nanofillers in Novel Food Packaging Systems and Their Toxicity Issues

“…This gas sensor could analyse H2S with a detection limit of 0.18 µM at pH 7 and showed excellent selectivity for H2S against other volatile components produced from chicken breast and silver carp during spoilage, showing a visible color change from yellow to colorless [188]. Consistently, Kwon and Ko [189] also developed CNC-AgNP composites as efficient colourimetric freshness indicators for poultry products or broccoli.…”

Antibacterial nanocomposite of chitosan/silver nanocrystals/graphene oxide (ChAgG) development for its potential use in bioactive wound dressings

“…The XRD pattern of AgNCs presented earlier in Figure- S2 , revealed 2 major peaks corresponding to (111) and (200) planes of fcc structure, corresponding to Ag (111) and Ag (200) 27 (AgCl as chlorargyrite (PDF 00–001-1238). The d-spacing values of the derived diffraction planes from d 111 Ag = 0.2428 nm and d 200 Ag = 0.2126 nm, are in good agreement with XRD diffraction pattern of AgNCs 39 .…”

“…The graph shows signs which are assigned to A1 and A5 experiments in which more nanocrystals were obtained. In the garlic samples, the presence in the diffraction peaks at 2θ = 38.2° and 44.2° mainly represent crystal planes of Ag, corresponding to (111) and (200) 26 , in another reference, 2θ = 38.1◦ and 44.3◦ corresponding to Ag (111) and Ag (200) 27 .…”

Efficient Cellulose/Nano‐silver Composite Sheet Derived from Pineapple Leaves for Hydrogen Sulfide Detection

“…Our material (RC/0.1AgNPs‐F) detected H 2 S at a superior low concentration of 20 ppm. Some materials (see Table 6), such as cellulose nanocrystals with AgNPs, [29] Au/Ag nanorods, [30] and AgNPs films, [31] detected H 2 S gas concentrations below 20 ppm. However, other materials, such as microplate cover coated with Nafion doped with Ag ions [32] and gellan gum with AgNPs, [8] had LOD values of over 27 ppm.…”