Non-destructive and Rapid Method for Monitoring Fish Freshness of Grass Carp Based on Printable Colorimetric Paper Sensor in Modified Atmosphere Packaging

Xanthan gum ink based on Lycium ruthenicum anthocyanin as an indicator of color change for monitoring freshness of cold fresh meat

The continuous development of intelligent food packaging has led to an increased focus on using freshness-indicating inks, which could provide a high level of quality control and consumer experience. This study aimed to further promote the application of xanthan gum ink in food freshness indication by optimizing its performance in screen printing. A novel freshness-indicating ink was prepared using Lycium ruthenicum anthocyanin (LRA) as the core indicator, glucose as the pigment carrier, soybean oil as the linker, and xanthan gum (XG) as the thickener. Scanning electron microscopy (SEM) demonstrated that the ink was uniformly distributed on paper using screen printing. Rheological and particle size analyses revealed that the incorporation of XG significantly enhanced the interaction force between droplets in the ink system. Further tests on viscosity, fineness, and initial dryness indicated that XG, a natural microbial polysaccharide with excellent stability, could effectively improve the flowability of the ink. Specifically, at a 0.3 % XG content, the ink exhibited a unimodal particle size distribution with an average particle size of 851.02 nm and a zeta potential of -27 mV. This indicated the ink system was stable and uniform, with optimal rheological properties and printing suitability. Furthermore, the printed freshness indication labels exhibited a significant change in color as the freshness of the refrigerated meat changed. This study develops a natural and safe method for monitoring the freshness of refrigerated meat and provides an optimized idea for applying indicator inks.

Recent advances in carboxymethyl cellulose-based active and intelligent packaging materials: A comprehensive review

Researchers have concentrated on innovative approaches to increase the shelf life of perishable food products and monitor their quality during storage and transportation as consumer demand for safe, environmentally friendly, and effective packaging develops. This comprehensive review aims to provide an overview of recent developments in carboxymethyl cellulose (CMC) chemical synthesis and its applications in active and intelligent packaging materials. It explores various methods for modifying cellulose to produce CMC and highlights the unique properties that make it suitable for addressing packaging industry challenges. The integration of CMC into active packaging systems, which helps reduce food waste and enhance food preservation, is discussed in depth. Furthermore, the integration of CMC in smart sensors and indicators for real-time monitoring and quality assurance in intelligent packaging is examined. The chemical synthesis of CMC and strategies to optimise its properties were studied, and the review concluded by examining the challenges and prospects of CMC-based packaging in the industry. This review is intended to serve as a valuable resource for researchers, industry professionals, and policymakers interested in the evolving landscape of CMC and its role in shaping the future of packaging materials.

Cellulose acetate/MOF film-based colorimetric ammonia sensor for non-destructive remote monitoring of meat product spoilage

Herein, we designed an on-site and portable colorimetric assay using cellulose acetate polymeric films incorporated with HKUST-1 metal-organic framework while immersed in a solution of methyl red and brilliant cresyl blue organic dyes as an indicator for monitoring ammonia levels. Ammonia serves as a significant biomarker of food spoilage which falls under the category of volatile organic compounds (VOCs). The designed colorimetric solid-state sensor was comprehensively characterized using FE-SEM, EDS-mapping, XRD, FTIR, and contact angle analyses. The results confirmed the superior stability, water permeability, good crystallinity and desirable morphology of the prepared sensor platform. Additionally, customized smartphone was developed and applied for online signaling and colorimetric analysis. The findings demonstrated two linear ranges: 1-100 ppb and 0.1-1340 ppm with a detection limit of 0.02 ppm. The solid-state sensor exhibited high selectivity in the presence of other VOCs such as methanol, ethanol, acetone, 2-propanol, toluene, humidity, and hexane. It displayed acceptable repeatability in both inter-day (RSD = 3.38 %) and intraday (RSD = 3.86 %), long-term stability over 4 days as well as reusability over 3 cycles. We successfully applied this sensing platform for ammonia monitoring in spoiled meat foods including veal, fish and chicken. The results indicated favorable percentage recovery and repeatability, confirming the feasibility and potential applicability of this intelligent packaging system for monitoring freshness. The platform allows for real-time monitoring and data analysis via smartphone-based online signaling, providing a convenient and effective method for ensuring food quality.

Recent advances on natural colorants-based intelligent colorimetric food freshness indicators: fabrication, multifunctional applications and optimization strategies

With the increasing concerns of food safety and public health, tremendous efforts have been concentrated on the development of effective, reliable, nondestructive methods to evaluate the freshness level of different kinds of food. Natural colorants-based intelligent colorimetric indicators which are typically constructed with natural colorants and polymer matrices has been regarded as an innovative approach to notify the customers and retailers of the food quality during the storage and transportation procedure in real-time. This review briefly elucidates the mechanism of natural colorants used for intelligent colorimetric indicators and fabrication methodologies of natural colorants-based food freshness indicators. Subsequently, their multifunctional applications in intelligent food packaging systems like antioxidant packaging, antimicrobial packaging, biodegradable packaging, UV-blocking packaging and inkless packaging are well introduced. This paper also summarizes several optimizing strategies for the practical application of this advanced technology from different perspectives. Strategies like adopting a hydrophobic matrix, constructing double-layer film and encapsulation have been developed to improve the stability of the indicators. Co-pigmentation, metal ion complexation, pigment-mixing and using substrates with high surface area are proved to be effective to enhance the sensitivity of the indicators. Approaches include multi-index evaluation, machine learning and smartphone-assisted evaluation have been proven to improve the accuracy of the intelligent food freshness indicators. Finally, future research opportunities and challenges are proposed. Based on the fundamental understanding of natural colorants-based intelligent colorimetric food freshness indicators, and the latest research and findings from literature, this review article will help to develop better, lower cost and more reliable food freshness evaluation technique for modern food industry.

A novel anthocyanin electrospun film by caffeic acid co-pigmentation for real-time fish freshness monitoring

In recent years, the use of intelligent and efficient food freshness indicators (FFIs) for monitoring food freshness has been studied widely. In this work, we employed polyacrylonitrile as polymer, blueberry anthocyanins as an indicator, and caffeic acid as a co-pigment and fabricated a novel colorimetric sensing film for real-time monitoring the freshness of fish. The total volatile basic nitrogen (TVB-N) level is one of the potential indicators to evaluate meat freshness. Visual observation confirmed that the polyacrylonitrile-anthocyanin-caffeic acid film changed from pink to light purple, and then to dark purple providing a good indication of spoilage, which correlated well with the TVB-N content and pH values in fish. It is because the volatile ammonia combined with water to form NH₃·H₂O, and then NH₃·H₂O is hydrolyzed to form OH^- and NH₄⁺. The change of the polyacrylonitrile-anthocyanin film was caused by OH^-. Compared with the polyacrylonitrile-anthocyanin film without caffeic acid, the addition of the caffeic acid film had enhanced significantly ammonia responsiveness with a total color difference value of 29.897. And it was also observed that caffeic acid obviously improved the storage stability of the film. This study provided a reference for detecting food freshness using co-pigmentation and electrospinning encapsulation technology in combination.

Nanoporous Graphene Oxide-Based Quartz Crystal Microbalance Gas Sensor with Dual-Signal Responses for Trimethylamine Detection

This paper presents a straightforward method to develop a nanoporous graphene oxide (NGO)-functionalized quartz crystal microbalance (QCM) gas sensor for the detection of trimethylamine (TMA), aiming to form a reliable monitoring mechanism strategy for low-concentration TMA that can still cause serious odor nuisance. The synthesized NGO material was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to verify its structure and morphology. Compared with the bare and GO-based QCM sensors, the NGO-based QCM sensor exhibited ultra-high sensitivity (65.23 Hz/μL), excellent linearity (R² = 0.98), high response/recovery capability (3 s/20 s) and excellent repeatability (RSD = 0.02, n = 3) toward TMA with frequency shift and resistance. Furthermore, the selectivity of the proposed NGO-based sensor to TMA was verified by analysis of the dual-signal responses. It is also proved that increasing the conductivity did not improve the resistance signal. This work confirms that the proposed NGO-based sensor with dual signals provides a new avenue for TMA sensing, and the sensor is expected to become a potential candidate for gas detection.

Paving the Way for a Green Transition in the Design of Sensors and Biosensors for the Detection of Volatile Organic Compounds (VOCs)

The efficient and selective detection of volatile organic compounds (VOCs) provides key information for various purposes ranging from the toxicological analysis of indoor/outdoor environments to the diagnosis of diseases or to the investigation of biological processes. In the last decade, different sensors and biosensors providing reliable, rapid, and economic responses in the detection of VOCs have been successfully conceived and applied in numerous practical cases; however, the global necessity of a sustainable development, has driven the design of devices for the detection of VOCs to greener methods. In this review, the most recent and innovative VOC sensors and biosensors with sustainable features are presented. The sensors are grouped into three of the main industrial sectors of daily life, including environmental analysis, highly important for toxicity issues, food packaging tools, especially aimed at avoiding the spoilage of meat and fish, and the diagnosis of diseases, crucial for the early detection of relevant pathological conditions such as cancer and diabetes. The research outcomes presented in the review underly the necessity of preparing sensors with higher efficiency, lower detection limits, improved selectivity, and enhanced sustainable characteristics to fully address the sustainable manufacturing of VOC sensors and biosensors.