Intelligent packaging: Trends and applications in food systems

Biocomposites and Poly(lactic acid) in Active Packaging: A Review of Current Research and Future Directions

The alarming rise in environmental pollution, depletion of global resources, and increasing health consciousness have placed significant pressure on the development of eco-friendly, sustainable materials. Consequently, green, environmentally friendly materials made from biobased and/or biodegradable sources are gaining recognition and political support as sustainable alternatives to petroleum-based, non-biodegradable materials. Bio-based packaging materials, in particular, are widely used across all industrial sectors, with a growing demand for solutions that preserve food quality and extend shelf life. Within this context, the concept of "active packaging" (AP) is attracting considerable interest. While the traditional view of packaging materials is that they should be basically inert, active packaging involves intentional interactions with the packaged product or surrounding atmosphere, providing enhanced protection against degradation caused by human actions and environmental factors. This work aims to highlight the significant impact of biocomposites in the active packaging sector, driven by the synergistic integration of nanofillers and active agents, while providing an in-depth analysis of the key mechanisms and strategies underlying their functionality. Particular emphasis is placed on poly(lactic acid)(PLA), presenting a comprehensive review of innovative approaches to enhance the performance of PLA-based packaging, with a focus on improving antioxidant and antimicrobial properties to meet the demands of sustainable and efficient packaging solutions.

Smart pH-sensitive indicators based on rice starch/pectin/alginate loading Lambrusco pomace extract and curcumin to track the freshness of pink shrimps

This research is focused on the formulation and testing of green visual pH-sensitive indicators based on natural extracts from Curcuma Longa (CUR) and Lambrusco wine pomace (LAM), an Italian wine variety, incorporated into rice starch/pectin/alginate matrixes for non-destructively detecting shrimps freshness in real-time. The effect of the mixed indicators and their synergic combination on the properties and performances of indicators was investigated. Both the extracts and their combination showed pronounced pH responsiveness. Films were widely characterized in terms of morphological, barrier, spectroscopic, thermal and mechanical properties. The presence of extracts slightly reduced the transparency of the films while the film with both the extracts exhibited the highest Young's modulus (14.17 MPa), lowest moisture content (27.67 %) and a WVP value (0.79 g m m-2 s-1 Pa-1) intermediate between the Lambrusco extract loaded film and the curcumin based one. Moreover, the pH-sensitive systems showed a noticeable antioxidant activity (96 % for LAM/CUR film) and enhanced antibacterial activity toward E. coli and S. aureus compared to pristine films. Besides, the mixed indicator-based film showed high sensitivity to ammonia (68 %) determining an ΔE value easily detectable by the human eye. Finally, the films were applied as cheap visual indicators for monitoring the freshness of packaged fresh shrimps over time stored at T = 4 °C and T = 25 °C through the colourimetric variation induced by pH changes. The TVB-N value, which was correlated to the microbial count for shrimps over time, reached the rejection limit at 33 h for T = 25 °C and 54 h for T = 4 °C. The colour changes were recorded simultaneously and the turning to deeper colours indicated the decomposition of proteins to organic amines and the spoilage of food. Results show that the produced films provide easily detectable colour changes during food spoilage proving that, being fabricated from natural sources, they represent novel and sustainable tools for multi-purpose intelligent food packaging applications.

Polymers in Physics, Chemistry and Biology: Behavior of Linear Polymers in Fractal Structures

We start presenting an overview on recent applications of linear polymers and networks in condensed matter physics, chemistry and biology by briefly discussing selected papers (published within 2022-2024) in some detail. They are organized into three main subsections: polymers in physics (further subdivided into simulations of coarse-grained models and structural properties of materials), chemistry (quantum mechanical calculations, environmental issues and rheological properties of viscoelastic composites) and biology (macromolecules, proteins and biomedical applications). The core of the work is devoted to a review of theoretical aspects of linear polymers, with emphasis on self-avoiding walk (SAW) chains, in regular lattices and in both deterministic and random fractal structures. Values of critical exponents describing the structure of SAWs in different environments are updated whenever available. The case of random fractal structures is modeled by percolation clusters at criticality, and the issue of multifractality, which is typical of these complex systems, is illustrated. Applications of these models are suggested, and references to known results in the literature are provided. A detailed discussion of the reptation method and its many interesting applications are provided. The problem of protein folding and protein evolution are also considered, and the key issues and open questions are highlighted. We include an experimental section on polymers which introduces the most relevant aspects of linear polymers relevant to this work. The last two sections are dedicated to applications, one in materials science, such as fractal features of plasma-treated polymeric materials surfaces and the growth of polymer thin films, and a second one in biology, by considering among others long linear polymers, such as DNA, confined within a finite domain.

Recent advances in sustainable biopolymer-based nanocomposites for smart food packaging: A review

The main goal of emerging food-packaging technologies is to address environmental issues and minimize their impact, while also guaranteeing food quality and safety for consumers. Bio-based polymers have drawn significant interest as a means to reduce the usage and environmental impact of petroleum-derived polymeric products. Therefore, this current review highlights on the biopolymer blends, various biodegradable bio-nanocomposites materials, and their synthesis and characterization techniques recently used in the smart food packaging industry. In addition, some insights on potential challenges as well as possibilities in future smart food packaging applications are thoroughly explored. Nanocomposite packaging materials derived from biopolymers have the highest potential for use in improved smart food packaging that possesses bio-functional properties. Nanomaterials are utilized for improving the thermal, mechanical, and gas barrier attributes of bio-based polymers while maintaining their biodegradable and non-toxic qualities. The packaging films that were developed exhibited enhanced barrier qualities against carbon dioxide, oxygen, and water vapour. Additionally, they demonstrated better mechanical strength, thermal stability, and antibacterial activity. More research is needed to develop and use smart food packaging materials based on bio-nanocomposites on a worldwide scale, while removing plastic packaging.

Locust Bean Gum/κ-Carrageenan Film Containing Blueberry or Beetroot Extracts as Intelligent Films to Monitoring Hake (Merluccius merluccius) Freshness

The main goal of this work was to develop bio-based and ecofriendly intelligent films as freshness indicators to monitor European hake (Merluccius merluccius) quality during storage by using a visual, non-destructive, and real-time technique. Locust bean gum (LBG)/κ-carrageenan (Car) films incorporating blueberry extract (BLE) or beetroot extract (BEE) were developed and their effectiveness to detect hake deterioration during 7 days of storage at 4 °C was evaluated. A visible color response from pink to blue was observed on the BLE films at the end of hake storage, which correlated with the hake deterioration profile, namely an increase in pH values (from 6.60 ± 0.04 to 8.02 ± 0.03), total viable count (TVC, from 4.61 ± 0.36 to 8.61 ± 0.21 log CFU/g), and total volatile basic nitrogen content (TVB-N, from 10.21 ± 1.97 to 66.78 ± 4.81 mg/100 g) beyond the spoilage threshold. The results of this study are very promising, since it was possible to develop a new effective intelligent bio-based responsive indicator film incorporating natural dye BLE, which has the potential to contribute to food waste reduction and improve food safety by detecting the hake freshness status.

A Review on Gas Indicators and Sensors for Smart Food Packaging

Real-time monitoring of changes in packaged food is crucial to ensure safety and alleviate environmental issues. Accordingly, the development of indicators and sensors for smart packaging has long been anticipated, especially for gases related to food deterioration and microbial growth. However, the characteristics of indicators and sensors used in food packaging cannot be adjusted according to the specific food type, making it essential to select and apply suitable indicators and sensors for each type of food. In this review, the principles and characteristics of gas indicators and sensors for oxygen, carbon dioxide, and ammonia that are commercialized or in the development phase were summarized, and their application status and prospects were assessed. Indicators and sensors for smart packaging are applied in forms such as films, labels, sachets, and devices. Their detection methods include redox reactions, analyte binding, enzyme reactions, pH changes, electron transfer, conformational changes, and electrode reactions. In this work, 9 types of indicators and sensors for oxygen, carbon dioxide, and ammonia were evaluated based on their detection and indication methods, materials, sensitivity, detection range, limit of detection, and advantages and disadvantages in food applications. We anticipate our review will propose criteria for selecting the optimal indicators and sensors for specific foods. Furthermore, this review examines the current application status and future prospects of these indicators and sensors.

Effect of metal cation crosslinking on the mechanical properties and shrimp freshness monitoring sensitivity of pectin/carboxymethyl cellulose sodium/anthocyanin intelligent films

Although many preparation methods have been reported so far, it is still a great challenge for intelligent packaging films with both excellent mechanical properties and very high sensitivity. Herein, we report a facile method to prepare performance-enhanced pectin (PC)/carboxymethyl cellulose sodium (CMC)/anthocyanins (ACNs)/metal ion films by crosslinking with metal ions (Zn2+, Mg2+ and Ca2+). Cross-linking reaction between PC/CMC and metal ions significantly improved water resistance and mechanical properties of composite films (P < 0.05). Even at high relative humidity (RH = 84 %), cross-linking of Ca2+, Mg2+, and Zn2+ significantly increased the tensile index of the films by 1.37, 1.41, and 1.52 times (P < 0.05), respectively. Moreover, the complexation of metal ions/polysaccharides with ACNs reduced the decomposition rate of ACNs, improved the storage stability and antioxidant capacity of ACNs, and also increased the sensitivity of the colorimetric response of the indicator films in monitoring shrimp freshness. Thus, with this high sensitivity, the Red, Green and Blue (RGB) values of the films can be determined using a mobile phone application to monitor shrimp safety in real time. These results suggest that ACNs-metal cation-polysaccharide composite films have great potential for smart packaging applications.

Biopolymer-based solutions for enhanced safety and quality assurance: A review

The improper disposal of petroleum-based plastics has been associated with detrimental environmental consequences, such as the proliferation of microplastic pollution and increased emissions of greenhouse gases (GHGs). Consequently, biopolymers have emerged as a highly regarded alternative due to their environmental-friendly attributes and versatile range of applications. In response to consumer demands for safer food options, sustainable packaging, and escalating environmental concerns, the food sector is increasingly adopting biopolymers. Further, in the recent decade, the usage of active or functional biopolymers has evolved into smart biopolymers that can transmit real-time data to consumers. This review covers key topics such as antimicrobial and biodegradable packaging, edible coatings and films, incorporation of scavengers and bioactive substances that prolong the shelf life and guard against moisture and microbial contamination. The paper also discusses the development of edible cutlery as a sustainable substitute for plastic, the encapsulation of bioactive substances within biopolymers, 3-D food printing for regulated nutrition delivery and thickening and gelling agents that improve food texture and stability. It also discusses the integration of smart polymer functions, demonstrating their importance in guaranteeing food safety and quality, such as biosensing, pH and gas detection, antibacterial characteristics, and time-temperature monitoring. By shedding light on market trends, future scope, and potentialities, this review aims to elucidate the prospects of utilizing biopolymers to address sustainability and quality concerns within the food industry effectively.

Towards Reducing Food Wastage: Analysis of Degradation Products Formed during Meat Spoilage under Different Conditions

Foodstuffs, particularly perishable ones such as meat, are frequently discarded once the best-before date has been reached, despite the possibility of their continued suitability for human consumption. The implementation of intelligent packaging has the potential to contribute to a reduction in food wastage by enabling the monitoring of meat freshness during storage time independently of the best-before date. The process of meat spoilage is associated with the formation of specific degradation products, some of which can be potentially utilized as spoilage indicators in intelligent packaging. The aim of the review is to identify degradation products whose concentration correlates with meat shelf life and to evaluate their potential use as spoilage indicators in intelligent packaging. To this end, a comprehensive literature research was conducted to identify the factors influencing meat spoilage and the eight key degradation products (carboxylic acids, biogenic amines, total volatile basic nitrogen, aldehydes, alcohols, ketones, sulfur compounds, and esters) associated with this process. These degradation products were analyzed for their correlation with meat shelf life at different temperatures, atmospheres, and meat types and for their applicability in intelligent packaging. The review provides an overview of these degradation products, comparing their potential to indicate spoilage across different meat types and storage conditions. The findings suggest that while no single degradation product universally indicates spoilage across all meat types and conditions, compounds like carboxylic acids, biogenic amines, and volatile basic nitrogen warrant further investigation. The review elucidates the intricacies inherent in identifying a singular spoilage indicator but underscores the potential of combining specific degradation products to expand the scope of applications in intelligent packaging. Further research (e.g., storage tests in which the concentrations of these substances are specifically examined or research on which indicator substance responds to these degradation products) is recommended to explore these combinations with a view to broadening their applicability.

Smart nano-inks based on natural food colorant for screen-printing of dynamic shelf life of shrimp

Intelligent packaging embedded with food freshness indicators can monitor food quality and be deployed for food safety and cutting food waste. The innovative nano-inks for dynamic shelf-life printing based on natural food colorant with application in real-time monitoring of shrimp freshness were prepared. Co-assembly of saffron petal anthocyanin (SPA) with hydrophobic curcumin (Cur) into chitin nano-scaffold (particle sizes around 26 ± 8 nm) could deliver hindering SPA leaching, confirmed by FT-IR, FE-SEM, AFM, and color stability test. The best response to pH-sensitivity was found in a ratio of (1:4) Cur/SPA (30% (v/w) in ChNFs that was correlated with the chemical and microbial changes of shrimp during shrimp freshness. However, smart screen-printed inks signified higher responsiveness to pH changes than FFI films. Therefore, smart-printed indicators introduced the excellent potential for a short response time, easy, cost-effective, eco-friendly, co-assembly, great color stabilities, and lifetime for nondestructively freshness monitoring foods and supplements.

Development of a Freshness Indicator for Assessing the Quality of Packaged Pork Products during Refrigerated Storage

A pH-sensitive dye-based freshness indicator has been developed to monitor the quality status of pork neck through distinct color transitions, addressing a crucial need for improved food safety and real-time monitoring within the food industry. This system aims to boost consumer confidence and improve shelf-life estimates by offering transparent and immediate quality indicators. Aerobically packaged pork neck samples underwent accelerated testing at 25 °C for 36 h, followed by refrigeration experiments at typical distribution temperatures of 4 and 8 °C over 10 days. Measured pork neck quality parameters included total bacterial count (TBC), total volatile basic nitrogen (TVB-N), and pH levels. Visual observation and colorimetric analysis were used to assess the chromatic variations of the freshness indicator, which showed a significant shift from orange to green in response to the presence of TVB-N in the headspace of the pork packaging. The chromatic parameters of the freshness indicator exhibited a significant correlation with the pork quality values throughout the storage periods. The results highlight the ability of the freshness indicator to effectively convey quality information about pork through noticeable colorimetric changes.

Critical review and recent advances of emerging real-time and non-destructive strategies for meat spoilage monitoring

Monitoring and evaluating food quality, especially meat quality, has received a growing interest to ensure human health and decrease waste of raw materials. Standard analytical approaches used for meat spoilage assessment suffer from time consumption, being labor-intensive, operation complexity, and destructiveness. To overcome shortfalls of these traditional methods and monitor spoilage microorganisms or related metabolites of meat products across the supply chain, emerging analysis devices/systems with higher sensitivity, better portability, on-line/in-line, non-destructive and cost-effective property are urgently needed. Herein, we first overview the basic concepts, causes, and critical monitoring indicators associated with meat spoilage. Then, the conventional detection methods for meat spoilage are outlined objectively in their strengths and weaknesses. In addition, we place the focus on the recent research advances of emerging non-destructive devices and systems for assessing meat spoilage. These novel strategies demonstrate their powerful potential in the real-time evaluation of meat spoilage.

A review on improving the sensitivity and color stability of naturally sourced pH-sensitive indicator films

Naturally sourced pH-sensitive indicator films are of interest for real-time monitoring of food freshness through color changes because of their safety. Therefore, natural pigments for indicator films are required. However, pigment stability is affected by environmental factors, which can in turn affect the sensitivity and color stability of the pH-sensitive indicator film. First, natural pigments (anthocyanin, betalain, curcumin, alizarin, and shikonin) commonly used in pH-sensitive indicator films are presented. Subsequently, the mechanisms behind the change in pigment color under different pH environments and their applications in monitoring food freshness are also described. Third, influence factors, such as the sources, types, and pH sensitivity of pigments, as well as environmental parameters (light, temperature, humidity, and oxygen) of sensitivity and color stability, are analyzed. Finally, methods for improving the pH-sensitive indicator film are explored, encapsulation of natural pigments, incorporation of a hydrophobic film-forming matrix or function material, and protective layer have been shown to enhance the color stability of indicator films, the addition of copigments or mental ions, blending of different natural pigments, and the utilization of electrospinning have been proved to increase the color sensitivity of indicator films. This review could provide theoretical support for the development of naturally sourced pH-sensitive indicator films with high stability and sensitivity and facilitate the development in the field of monitoring food freshness.

Nanofillers in Novel Food Packaging Systems and Their Toxicity Issues

Background: Environmental concerns about petroleum-based plastic packaging materials and the growing demand for food have inspired researchers and the food industry to develop food packaging with better food preservation and biodegradability. Nanocomposites consisting of nanofillers, and synthetic/biopolymers can be applied to improve the physiochemical and antimicrobial properties and sustainability of food packaging. Scope and approach: This review summarized the recent advances in nanofiller and their applications in improved food packaging systems (e.g., nanoclay, carbon nanotubes), active food packaging (e.g., silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs)), intelligent food packaging, and degradable packaging (e.g., titanium dioxide nanoparticles (e.g., TiO2 NPs)). Additionally, the migration processes and related assessment methods for nanofillers were considered, as well as the use of nanofillers to reduce migration. The potential cytotoxicity and ecotoxicity of nanofillers were also reviewed. Key findings: The incorporation of nanofillers may increase Young's modulus (YM) while decreasing the elongation at break (EAB) (y = -1.55x + 1.38, R2 = 0.128, r = -0.358, p = 0.018) and decreasing the water vapor (WVP) and oxygen permeability (OP) (y = 0.30x - 0.57, R2 = 0.039, r = 0.197, p = 0.065). Meanwhile, the addition of metal-based NPs could also extend the shelf-life of food products by lowering lipid oxidation by an average of approx. 350.74% and weight loss by approx. 28.39% during the longest storage period, and significantly increasing antibacterial efficacy against S. aureus compared to the neat polymer films (p = 0.034). Moreover, the migration process of nanofillers may be negligible but still requires further research. Additionally, the ecotoxicity of nanofillers is unclear, as the final distribution of nanocomposites in the environment is unknown. Conclusions: Nanotechnology helps to overcome the challenges associated with traditional packaging materials. Strong regulatory frameworks and safety standards are needed to ensure the appropriate use of nanocomposites. There is also a need to explore how to realize the economic and technical requirements for large-scale implementation of nanocomposite technologies.

Sponge-like porous polyvinyl alcohol/chitosan-based hydrogel with integrated cushioning, pH-indicating and antibacterial functions

Developing a packaging material with integrated cushioning, intelligent and active functions is highly desired but remains challenging in the food industry. Here we show that a sponge-like porous hydrogel with pH-indicating and antibacterial additives can meet this requirement. We use polyvinyl alcohol and chitosan as the primary polymers to construct a hydrogel with hierarchical structures through a freeze-casting method in combination with salting-out treatment. The synergy of aggregated polymer chains and the sponge-like porous structure makes the hydrogel resilient and efficient in energy absorption. It also enables rapid movement of molecules/particles and fast reaction due to the large specific surface area of the pore structures and the large amount of free water in it, leading to a sensitive pH-indicating function. The hydrogel shows an obvious color variation within a wide pH range in 3 min. The silver nanoparticles are fixed in the dense polymer networks, enabling a lasting release of silver ions. The porous structure makes the silver ion reach the protected item in a short time, achieving an antibacterial effect against S. aureus and E. coli with little cytotoxicity. This work paves the way for fabricating multifunctional hydrogels for diverse advanced packaging systems.

Ammonia-responsive chitosan/polymethacrylamide double network hydrogels with high-stretchability, fatigue resistance and anti-freezing for real-time chicken breast spoilage monitoring

Hydrogels are a promising option for detecting food spoilage in humid conditions, but current indicators are prone to mechanical flaws, posing a concern for packaging systems that require strong mechanical properties. Herein, a double network hydrogel was prepared by polymerizing methacrylamide in a chitosan system with aluminum chloride and glycerol. The resulting hydrogel demonstrated high stretchability (strain >1500 %), notch insensitivity, excellent fatigue resistance, and exceptional anti-freezing capabilities even at -21 °C. When incorporating bromothymol blue (BB) or methyl red (MR), or mixtures of these dyes into the hydrogels as indicators, they exhibited sensitive colorimetric responses to pH and NH3 levels at different temperatures. Hydrogels immobilizing BB to MR ratios of 1:1 and 1:2 displayed clearer and more sensitive color responses when packed into chicken breast, with a sensitivity level of 1.5 ppm of total volatile basic nitrogen (TVB-N). This color response correlated positively with the accumulation of TVB-N on the packaging during storage at both 25 °C and 4 °C, providing sensitive indications of chicken breast deterioration. Overall, the developed hydrogels and indicators demonstrate enhanced performance characteristics, including excellent mechanical strength and highly NH3-sensitive color responses, making significant contributions to the food spoilage detection and intelligent packaging systems field.

Recent Progress of Carrageenan-Based Composite Films in Active and Intelligent Food Packaging Applications

Recently, as concerns about petrochemical-derived polymers increase, interest in biopolymer-based materials is increasing. Undoubtedly, biopolymers are a better alternative to solve the problem of synthetic polymer-based plastics for packaging purposes. There are various types of biopolymers in nature, and mostly polysaccharides are used in this regard. Carrageenan is a hydrophilic polysaccharide extracted from red algae and has recently attracted great interest in the development of food packaging films. Carrageenan is known for its excellent film-forming properties, high compatibility and good carrier properties. Carrageenan is readily available and low cost, making it a good candidate as a polymer matrix base material for active and intelligent food packaging films. The carrageenan-based packaging film lacks mechanical, barrier, and functional properties. Thus, the physical and functional properties of carrageenan-based films can be enhanced by blending this biopolymer with functional compounds and nanofillers. Various types of bioactive ingredients, such as nanoparticles, natural extracts, colorants, and essential oils, have been incorporated into the carrageenan-based film. Carrageenan-based functional packaging film was found to be useful for extending the shelf life of packaged foods and tracking spoilage. Recently, there has been plenty of research work published on the potential of carrageenan-based packaging film. Therefore, this review discusses recent advances in carrageenan-based films for applications in food packaging. The preparation and properties of carrageenan-based packaging films were discussed, as well as their application in real-time food packaging. The latest discussion on the potential of carrageenan as an alternative to traditionally used synthetic plastics may be helpful for further research in this field.

Intelligent carboxymethyl cellulose composite films containing Garcinia mangostana shell anthocyanin with improved antioxidant and antibacterial properties

In this study, anthocyanin from Garcinia mangostana shell extract (Mse) was used as pH indicator to prepare intelligent carboxymethyl cellulose (CMC) based composite films. The structure and properties of the CMC-based composite films were characterized and discussed in detail. Results showed that the CMC-based composite films with Mse had excellent mechanical, antibacterial and antioxidant abilities. Especially, the carboxymethyl cellulose/corn starch/Garcinia mangostana shell extract (CMC/Cst/Mse) composite film had best mechanical properties (20.62 MPa, 4.06 % EB), lowest water vapor permeability (1.80 × 10-12 g·cm/(cm2·s·Pa)), excellent ultraviolet (UV) blocking performance, and the best antibacterial and antioxidant abilities. The pH sensitivity of composite films which had Mse obviously changed with time when the fish freshness was monitored at 25 °C. Given the good pH sensitivity of the composite films, it had significant potential for application of intelligent packaging film as a food packaging material to indicate the freshness of fish.

Study on preservation and monitoring effect of sodium alginate-konjac glucomannan films loaded with tea polyphenols and Lycium ruthenicum anthocyanins

To investigate the efficacy of sodium alginate-konjac glucomannan (SA-KGM) films with anthocyanins (LRA) and tea polyphenols (TP) in meat, beef and grass carp were selected as representative meat products for preservation and freshness monitoring experiments at 4 °C. Concurrently, storage experiments of the films were conducted in this controlled environment. The results of the storage experiment showed that the films delayed meat spoilage by 2-4 days, nearly doubling the preservation time compared to the blank control. Additionally, the film exhibited significant capability to monitor the spoilage process of beef and grass carp. It was revealed by curve fitting analysis that there was a significant correlation between the color change of the film and the spoilage index of the meat. Throughout the storage experiment with the film, it was observed that moisture significantly influenced the microstructure and bonding situation of the films, thereby impacting their mechanical and barrier properties. However, the films were still able to maintain satisfactory physicochemical properties in general. The above findings were crucial in guiding the promotion of the film within the food preservation industry.

An analysis of conventional and modern packaging approaches for cut flowers: a review article

Fresh-cut flowers are considered to be one of the most delicate and challenging commercial crops. It is important to take into consideration how to minimize loss during storage and transportation when preserving cut flowers. Many impinging (bad effect) forces can interact to shorten the flowers' vase life. In the flower industry, effective methods need to be developed to extend freshly cut flowers' life. Fresh-cut flowers' vase life can be shortened by a variety of interlocking causes. The flower industry must develop new techniques to extend the flowers' vase lifespan. This review provides comprehensive, up-to-date information on classical, modified atmosphere packaging (MAP), and controlled atmosphere packaging (CAP) displays. According to this review, a promising packaging technique for fresh flowers can be achieved through smart packaging. A smart package is one that incorporates new technology to increase its functionality. This combines active packaging, nanotechnology, and intelligence. This technology makes it easier to keep an eye on the environmental variables that exist around the packaged flowers to enhance their quality. This article offers a comprehensive overview of creative flower-saving packaging ideas that reduce flower losses and assist growers in handling more effectively their flower inventory. To guarantee the quality of flowers throughout the marketing chain, innovative packaging techniques and advanced packaging technologies should be adopted to understand various package performances. This will provide the consumer with cut flowers of standard quality. Furthermore, sustainable packaging is achieved with circular packaging. We can significantly reduce packaging waste's environmental impact by designing reused or recyclable packaging.

Revolution of nanotechnology in food packaging: Harnessing electrospun zein nanofibers for improved preservation - A review

Zein, a protein-based biopolymer derived from corn, has garnered attention as a promising and eco-friendly choice for packaging food due to its favorable physical attributes. The introduction of electrospinning technology has significantly advanced the production of zein-based nanomaterials. This cutting-edge technique enables the creation of nanofibers with customizable structures, offering high surface area and adjustable mechanical and thermal attributes. Moreover, the electrospinning process allows for integrating various additives, such as antioxidants, antimicrobial agents, and flavoring compounds, into the zein nanofibers, enhancing their functionalities for food preservation. In this comprehensive review, the various electrospinning techniques employed for crafting zein-based nanofibers, and we delve into their enhanced properties. Furthermore, the review illuminates the potential applications of zein nanofibers in active and intelligent packaging materials by incorporating diverse constituents. Altogether, this review highlights the considerable prospects of zein-based nanocomposites in the realm of food packaging, offering sustainable and innovative solutions for food industry.

Nanocellulose-based antimicrobial aerogels with humidity-triggered release of cinnamaldehyde

Active food packaging with controlled release behavior of volatile antimicrobials is highly desirable for enhancing the quality of fresh produce. In this study, humidity-responsive antimicrobial aerogels were developed using chitosan and dialdehyde nanocellulose, loading with cyclodextrin-cinnamaldehyde inclusion complexes (ICs) for achieving humidity-triggered release of the encapsulated antimicrobial agent. Results showed that the prepared aerogels had capable water absorption ability, which could be served as absorbent pads to take in excessive exudate from packaged fresh produce. More importantly, the accumulative release rate of cinnamaldehyde from the antimicrobial aerogels was significantly improved at RH 98 % compared to that at RH 70 %, which accordingly inactivated all the inoculated Escherichia coli, Staphylococcus aureus and Botrytis cinerea. Additionally, strawberries packaged with the antimicrobial aerogels remained in good conditions after 5 d of storage at 22 ± 1 °C. The prepared composite aerogels had the potential to extend the shelf life of fresh strawberries.

Advanced technologies in biodegradable packaging using intelligent sensing to fight food waste

The limitation of conventional packaging in demonstrating accurate and real-time food expiration dates leads to food waste and foodborne diseases. Real-time food quality monitoring via intelligent packaging could be an effective solution to reduce food waste and foodborne illnesses. This review focuses on recent technological advances incorporated into food packaging for monitoring food spoilage, with a major focus on paper-based sensors and their combination with smartphone. This review paper offers a comprehensive exploration of advanced macromolecular technologies in biodegradable packaging, a general overview of paper-based probes and their incorporation into food packaging coupled with intelligent sensing mechanisms for monitoring food freshness. Given the escalating global concerns surrounding food waste, our manuscript serves as a pivotal resource, consolidating current research findings and highlighting the transformative potential of these innovative packaging solutions. We also highlight the current intelligent paper-based food freshness sensors and their various advantages and limitations. Examples of implementation of paper-based sensors/probes for food storage and their accuracy are presented. Finally, we examined how intelligent packaging can be an alternative to reduce food waste. Several technologies discussed here have good potential to be used in food packaging for real-time food monitoring, especially when combined with smartphone diagnosis.

Fluorescence and pectinase double-triggered chitosan/pectin/calcium propionate/curcumin-β-cyclodextrin complex film for pork freshness monitoring and maintenance

An intelligent and active food packaging film based on chitosan (CS), pectin (P), calcium propionate (CP), and curcumin-β-cyclodextrin complex (Cur-β-CD) was prepared. The CS/P/CP/Cur-β-CD film exhibited improved hydrophobicity (74.78 ± 0.53°), water vapor (4.55 ± 0.16 × 10-11 g·(m·s·Pa)-1), and oxygen (1.50 ± 0.06 × 10-12 g·(m·s·Pa)-1) barrier properties, as well as antioxidant (72.34 ± 3.79 % for DPPH and 86.05 ± 0.14 % for ABTS) and antibacterial (79.41 ± 2.89 % for E. coli and 83.82 ± 3.96 % for S. aureus) activities. The release of CP and Cur could be triggered by pectinase, with their cumulative release reaching 92.62 ± 1.20 % and 42.24 ± 1.15 %, respectively. The CS/P/CP/Cur-β-CD film showed delayed alterations in surface color, pH value, total volatile bases nitrogen, total viable counts, thiobarbituric acid reactive substance, hardness, and springiness of pork. Additionally, the fluorescence intensity of the film gradually decreased. In conclusion, we have developed a pH-responsive film with pectinase-triggered release function, providing a new concept for the design of multi-signal responsive intelligent food packaging.

Nanomaterials based sensors for analysis of food safety

The freshnessof the food is a major issue because spoiled food lacks critical nutrients for growth and could be harmful to human health if consumed directly. Nanomaterials are captivating due to their unique properties like large surface area, high selectivity, small dimension, great biocompatibility and conductivity, real-time onsite analysis, etc. which give them an advantage over conventional evaluation techniques. Despite these advantages of nanomaterials used in food safety and their preservation, food products can still get affected by various environmental factors (like pH, temperature, etc.), making the use of time-temperature indicators more condescending. This review is a comprehensive study on food safety, its causes, the responsible analytes, their remedies by various nanomaterials, the development of various nanosensors, and the various challenges faced in maintaining food safety standards to reduce the risk of contaminants.

A shadow enabled non-invasive probe for multi-feature intelligent liquid surveillance system

Liquid detection probes used to identify the features of liquids show great promise in a variety of important applications. However, some challenges, such as sample contamination by direct contact with the liquid, the requirement of additional signal emitters, and complex fabrication, hindered the development of liquid detection probes. Here, we developed a non-invasive shadow probe (SP) for a multi-feature intelligent liquid surveillance system (ILSS). The self-powered SP with the working mechanism of the shadow effect can detect the features of liquids by analyzing the variations of liquid shadows such as the area, wavelength, and brightness. The exact resolution (5 different colors, 6 different concentrations, 6 different levels, 100% accuracy) and fast response time (0.2 ms) are shown by the SP under ambient light conditions (even in 0.003 sun). The ILSS, which integrated the SPs with signal processing circuits and applied the artificial intelligence (AI) technique, successfully detects and synoptically learns about liquids simultaneously. The in-real time ILSS reaches a test accuracy of 99.3% for 10 types of liquids with multiple features. This work showcases a promising solution for non-invasive multi-feature liquid detection, displaying great potential for future applications.

Biodegradable cellulose/curcumin films with Janus structure for food packaging and freshness monitoring

The development of renewable, hydrophobic, and biodegradable intelligent packaging materials as an alternative to petroleum-based plastic products has become a new research focus in recent years, but remains a challenge. Herein, regenerated cellulose/curcumin composite films were fabricated by dispersing hydrophobic curcumin uniformly in a hydrophilic cellulose matrix using an aqueous alkali/urea solvent based on the pH-driven principle of curcumin. In addition, a unilateral hydrophobic modification was carried out using chemical vapor deposition of methyltrichlorosilane to obtain Janus structure. The composite films exhibited high transparency in the visible light spectrum, excellent antioxidation, thermal stability, mechanical strength, gas barrier properties, and antibacterial activity. Furthermore, the films demonstrated the capability to lower the overall levels of volatile basic nitrogen in stored fish. The color of the films shifted from a pale yellow to a reddish-brown over time during storage. The composite films can be completely degraded after approximately 98 days in soil with an average environmental temperature of 29 °C. This work provided a facile strategy to prepare biodegradable cellulose/curcumin films with Janus structure as packaging materials which could preserve the freshness of food products while offering visual monitor of their freshness in real-time.

Preparation and characterization of gelatin/chitosan nanocomposite reinforced by NiO nanoparticles as an active food packaging

Food packaging with antibacterial properties has attracted much attention recently. In this study, nickel oxide nanoparticles (NiONPs) were synthesized by co-precipitation and then gelatin/chitosan polymer films (GEL/CS) with different percentages of NiONPs, bio-nanocomposites, were prepared by casting. Morphology, crystal microstructure, molecular interactions and thermal stabilities of the NPs and the composite films were characterized by FESEM, XRD, FTIR and TGA, respectively. The bio-nanocomposite films exhibited excellent barrier, thermal and mechanical properties by addition of an optimized content of NPs. For example, the tensile strength (TS) of the GEL/CS film without NPs was 23.83 MPa and increased to 30.13 MPa by incorporation of 1% NPs. The antibacterial properties and toxicity of the films were investigated. These films show good antibacterial behavior against Gram-positive (Staphylococcus aureus) bacteria compared to Gram-negative (Escherichia coli) bacteria. Furthermore, the films were found to be non-toxic to fibroblast cells that came into contact with the films, with a survival rate of more than 88%. Therefore, these films can be applied for food packaging due to their excellent mechanical, barrier, and antibacterial properties.

Recent advances in biomacromolecule-based nanocomposite films for intelligent food packaging- A review

In food packaging, biopolymer films are biodegradable films made from biomacromolecule-based natural materials, while biocomposite films are hybrids of two or more materials, with at least one being biodegradable. Bionanocomposites are different than the earlier ones, as they consist of various nanofillers (both natural and inorganic) in combination with biomacromolecule-based biodegradable materials to make good compostable bionanocomposites. In this regard, a new type of material known as bionanocomposite has been recently introduced to improve the properties and performance of biocomposite films. Bionanocomposites are primarily developed for active packaging, but their use in intelligent packaging is also noteworthy. For example, bionanocomposites developed using a hybrid of anthocyanin and carbon dots as intelligent materials have shown their high pH-sensing properties. The natural nanofillers (like nanocellulose, nanochitosan, nanoliposome, cellulose nanocrystals, cellulose nanofibers, etc.) are being employed to promote the sustainability, degradability and safety of bionanocomposites. Overall, this article comprehensively reviews the latest innovations in bionanocomposite films for intelligent food packaging over the past five years. In addition to packaging aspects, the role of nanofillers, the importance of life cycle assessment (LCA) and risk assessment, associated challenges, and future perspectives of bionanocomposite intelligent films are also discussed.

Multi-functional nanocellulose based nanocomposites for biodegradable food packaging: Hybridization, fabrication, key properties and application

Nowadays, non-degradable plastic packaging materials have caused serious environmental pollution, posing a threat to human health and development. Renewable eco-friendly nanocellulose hybrid (NCs-hybrid) composites as an ideal alternative to petroleum-based plastic food packaging have been extensively reported in recent years. NCs-hybrids include metal, metal oxides, organic frameworks (MOFs), plants, and active compounds. However, no review systematically summarizes the preparation, processing, and multi-functional applications of NCs-hybrid composites. In this review, the design and hybridization of various NCs-hybrids, the processing of multi-scale nanocomposites, and their key properties in food packaging applications were systematically explored for the first time. Moreover, the synergistic effects of various NCs-hybrids on several properties of composites, including mechanical, thermal, UV shielding, waterproofing, barrier, antimicrobial, antioxidant, biodegradation and sensing were reviewed in detailed. Then, the problems and advances in research on renewable NCs-hybrid composites are suggested for biodegradable food packaging applications. Finally, a future packaging material is proposed by using NCs-hybrids as nanofillers and endowing them with various properties, which are denoted as "PACKAGE" and characterized by "Property, Application, Cellulose, Keen, Antipollution, Green, Easy."

Development of smart packaging halochromic films embedded with anthocyanin pigments; recent advances

Nowadays, innovative biodegradable packaging based on pH-sensitive natural dyes is being developed. These smart systems quickly inform the food quality to the consumer and monitor fresh foods in real-time. Smart packaging protects food against ambiance risks and simultaneously sends information to users for variations and alterations in the packaging settings. Anthocyanin (ACY), among the natural dyes used as indicators serves as water-soluble flavonoid pigments which made reflection in light in the red-blue range and can detect chemical and microbial alterations in foods based on their pH-susceptible conditions; on the other hand, they have considerable antimicrobial and antioxidant functions that result in the longer shelf life of food products. They also have beneficial properties including anti-cancer and anti-inflammatory functions, avoidance of heart diseases, overweight, and diabetes. Hence, this paper deals with the characteristics of smart packaging films based on anthocyanins, as well as their application in various food industries.

Application of Taro (Colocasia esculenta) Mucilage as a Promising Antimicrobial Agent to Extend the Shelf Life of Fresh-Cut Brinjals (Eggplants)

Taro rhizomes are a rich source of polysaccharides, including starch and mucilage. However, mucilage has excellent anti-microbial efficacy, and unique gel-forming and techno-functional properties. Therefore, this study aimed to extract and utilize taro mucilage (TM), which is viscous and has a gel-like texture, for the shelf-life enhancement of fresh-cut brinjals (eggplants). Mucilage was extracted using hot-water extraction and the yield was calculated to be 6.25 ± 0.87% on a dry basis. Different formulations of coating gel solutions were prepared: 1, 2, 3, 4, 5, 6, and 7%. The selection of the coating gel solution was carried out based on particle size. The smallest particle size was observed in treatment T5 (154 ± 0.81 nm) and zeta potential -27.22 ± 0.75 mV. Furthermore, cut brinjals were coated with the prepared mucilage gel solution and this showed a significant effect on the overall physicochemical properties of cut brinjals. Maximum weight loss occurred on the 10th day (12.67 ± 0.24%), as compared with coated brinjals (8.99 ± 0.42%). Minor changes were observed in pH, for the control sample significantly decreased from 4.58 ± 0.45 to 2.99 ± 0.75 on the 0th day to the 10th day, respectively. Titrable acidity of coated and uncoated cut brinjals was found to be at 0.31 ± 0.44% on the 0th day, which increased up to 0.66 ± 0.20% for the control and 0.55 ± 0.68% for coated brinjals on the 10th day. The taro mucilage coating gel (TMCG) solution showed pseudo-plastic behavior or shear-thinning fluid behavior. FTIR data confirmed the existence of several functional groups including various sugars, proteins, and hydroxylic groups. Antioxidant activity of coated and uncoated cut brinjals was found to be 22.33 ± 0.37% and 22.15 ± 0.49%, respectively. The TMCG solution showed effective results towards the various food pathogenic microorganisms. Overall, it is a natural, renewable resource that is biodegradable. This makes it an environmentally friendly alternative to synthetic additives or thickeners. It is cost effective, easily available, eco-friendly, and non-toxic. This can be an attractive feature for consumers looking for sustainable and eco-friendly options.

Recent Advances in the Carotenoids Added to Food Packaging Films: A Review

Food spoilage is one of the key concerns in the food industry. One approach is the improvement of the shelf life of the food by introducing active packaging, and another is intelligent packaging. Detecting packed food spoilage in real-time is key to stopping outbreaks caused by food-borne diseases. Using active materials in packaging can improve shelf life, while the nonharmful color indicator can be useful to trace the quality of the food through simple color detection. Recently, bio-derived active and intelligent packaging has gained a lot of interest from researchers and consumers. For this, the biopolymers and the bioactive natural ingredient are used as indicators to fabricate active packaging material and color-changing sensors that can improve the shelf life and detect the freshness of food in real-time, respectively. Among natural bioactive components, carotenoids are known for their good antimicrobial, antioxidant, and pH-responsive color-indicating properties. Carotenoids are rich in fruits and vegetables and fat-soluble pigments. Including carotenoids in the packaging system improves the film's physical and functional performance. The recent progress on carotenoid pigment-based packaging (active and intelligent) is discussed in this review. The sources and biological activity of the carotenoids are briefly discussed, and then the fabrication and application of carotenoid-activated packaging film are reviewed. The carotenoids-based packaging film can enhance packaged food's shelf life and indicate the freshness of meat and vegetables in real-time. Therefore, incorporating carotenoid-based pigment into the polymer matrix could be promising for developing novel packaging materials.

pH-responsive double-layer film based on chitosan/curcumin-β-cyclodextrin complex/cinnamaldehyde and zein/alizarin for pork freshness monitoring and maintaining

A pH-responsive double-layer film comprising chitosan (CS), zein (Z), curcumin-β-cyclodextrin complex (Cur- β-CD), alizarin (AL) and cinnamaldehyde (CIN) was developed to detect spoilage and prolong the shelf life of pork. The outer Z/AL is the colorimetric responsive and highly protective outer layer, while the CS/Cur- β-CD/CIN is the fluorescence responsive and functional layer. The CS/Cur- β-CD/CIN-Z/AL film demonstrated excellent barrier properties against oxygen (8.48 × 10-13 g (m s Pa)-1) and water (2.42 × 10-11 g (m s Pa)-1) primarily due to the polar interactions in the Z structure and its hydrophobic nature. The addition of AL and Cur provided the CS/Cur- β-CD/CIN-Z/AL film with pH colorimetric and fluorescence response capabilities, respectively. Furthermore, the inclusion of Cur- β-CD, CIN and AL significantly enhanced the film's antioxidant and antibacterial properties, with radical scavenging rates of 79.29 % (DPPH) and 89.84 % (ABTS), as well as antibacterial efficiencies of 96.2 % (S. aureus) and 85.78 % (E. coli). To test the effectiveness of the double-layer film, a freshness monitoring and maintenance experiment was conducted on pork stored at 4 °C for 8 days. Various parameters of pork, including surface color, pH value, total volatile bases nitrogen (TVB-N), total viable counts (TVC), thiobarbituric acid reactive substance (TBARS), hardness and springiness, were measured, along with the color and fluorescence intensity (FL) of the film. The shelf life of the pork was extended by at least 2 days compared to the control group, and the pork was considered inedible if ΔE ≥ 12 or FL intensity ≤ 2160. Overall, this food packaging film shows promise in simultaneously monitoring and maintaining the freshness of pork.

Approach to an answer to "How dangerous microplastics are to the human body": A systematic review of the quantification of MPs and simultaneously exposed chemicals

This review aims to facilitate future research on microplastics (MPs) in the environment using systematic and analytical protocols, ultimately contributing to assessment of the risk to human health due to continuous daily exposure to MPs. Despite extensive studies on MP abundance in environment, identification, and treatment, their negative effects on human health remain unknown due to the lack of proof from clinical studies and limited technology on the MP identification. To assess the risk of MPs to human health, the first step is to estimate MP intake via ingestion, inhalation, and dermal contact under standardized exposure conditions in daily life. Furthermore, rather than focusing on the sole MPs, migrating chemicals from plastic products should be quantified and their health risk be assessed concurrently with MP release. The critical factors influencing MP release and simultaneously exposed chemicals (SECs) must be investigated using a standardized identification method. This review summarises release sources, factors, and possible routes of MPs from the environment to the human body, and the quantification methods used in risk assessment. We also discussed the issues encountered in MP release and SEC migration. Consequently, this review provides directions for future MP studies that can answer questions about MP toxicity to human health.

Fabrication, performance, and potential environmental impacts of polysaccharide-based food packaging materials incorporated with phytochemicals: A review

Although food packaging preserves food's quality, it unfortunately contributes to global climate change since the considerable carbon emissions associated with its entire life cycle. Polysaccharide-based packaging materials (PPMs) are promising options to preserve foods, potentially helping the food industry reduce its carbon footprint. PPMs incorporated with phytochemicals hold promise to address this critical issue, keep food fresh and prolong the shelf life. However, phytochemicals' health benefits are impacted by their distinct chemical structures thus the phytochemicals-incorporated PPMs generally exhibit differential performances. PPMs must be thoughtfully formulated to possess adequate physicochemical properties to meet commercial standards. Given this, this review first-time provides a comprehensive review of recent advances in the fabrication of phytochemicals incorporated PPMs. The application performances of phytochemicals-incorporated PPMs for preserving foods, as well as the intelligent monitoring of food quality, are thoroughly introduced. The possible associated environmental impacts and scalability challenges for the commercial application of these PPMs are also methodically assessed. This review seeks to provide comprehensive insights into exploring new avenues to achieve a greener and safer food industry via innovative food packaging materials. This is paramount to preserve not only food shelf life but also the environment, facilitating the eco-friendly development of the food industry.

Photonic Crystal Sensor Evaluating the Effectiveness of Medical Products under Different Storage Conditions

The effectiveness of time- and temperature-sensitive medical products (TTSMPs) (vaccines, medicines, and biological agents) is generally evaluated by sporadically checking the storage conditions recorded in electronic thermometers. However, electronic thermometers do not achieve all-time and all-regional record, resulting in the wrong evaluation of a single TTSMP and seriously endangering public health. Herein, we report a photonic crystal sensor for evaluating the effectiveness of a single TTSMP processing storage environment. The photonic crystal sensor assembled by colloidal microspheres (WO3-x nanospheres were added into the microsphere gap) generates a fascinating composite color of angle-dependent structural color (maximum reflectivity = 45%) and durative color (WO3-x coloration). Effectiveness evaluation principle reveals that the pattern on the sensor, which was printed by the composite color, fades sensitively to time and temperature, thus having different visible periods (0-21 days affected by temperature). The visible periods of the patterns can be used to evaluate a single TTSMP's effectiveness stored under different temperatures. Furthermore, the photonic crystal sensor shows outstanding flexibility and slight adhesion, offering a promising application toward the effectiveness evaluation of TTSMPs throughout storage, transportation, and sales processes.

Recent advances in pH-sensitive indicator films based on natural colorants for smart monitoring of food freshness: a review

As a new type of packaging method, natural pigment-based pH-sensitive indicator film packaging can be used to intelligently monitor food freshness, provide consumers with intuitive food freshness information, and own the advantages of small size, low cost and intuitive accuracy. Based on the introduction of the principle of natural pigment in pH-sensitive indicator film intelligent packaging, this paper reviews the types of natural pigment indicators (such as anthocyanins, curcumin) and film-forming matrix materials, and systematically discusses the research progress of their application in freshness monitoring in various foods, and points out the limitations of this intelligent packaging in practical applications. In order to provide natural pigment in the application and promotion of pH-sensitive indicator film packaging for monitoring food freshness, further research and development works are required to overcome the current limitations. The needs for further research and developments are outlined.

Electrospun Nanofibers for Functional Food Packaging Application

With the strengthening of the public awareness of food safety and environmental protection, functional food packaging materials have received widespread attention. Nanofibers are considered as promising packaging materials due to their unique one-dimensional structure (high aspect ratio, large specific surface area) and functional advantages. Electrospinning, as a commonly used simple and efficient method for preparing nanofibers, can obtain nanofibers with different structures such as aligned, core-shell, and porous structures by modifying the devices and adjusting the process parameters. The selection of raw materials and structural design of nanofibers can endow food packaging with different functions, including antimicrobial activity, antioxidation, ultraviolet protection, and response to pH. This paper aims to provide a comprehensive review of the application of electrospun nanofibers in functional food packaging. Advances in electrospinning technology and electrospun materials used for food packaging are introduced. Moreover, the progress and development prospects of electrospun nanofibers in functional food packaging are highlighted. Meanwhile, the application of functional packaging based on nanofibers in different foods is discussed in detail.

Recent Advance of Intelligent Packaging Aided by Artificial Intelligence for Monitoring Food Freshness

Food safety is a pressing concern for human society, as it directly impacts people's lives, while food freshness serves as one of the most crucial indicators in ensuring food safety. There exist diverse techniques for monitoring food freshness, among which intelligent packaging based on artificial intelligence technology boasts the advantages of low cost, high efficiency, fast speed and wide applicability; however, it is currently underutilized. By analyzing the current research status of intelligent packaging both domestically and internationally, this paper provides a clear classification of intelligent packaging technology. Additionally, it outlines the advantages and disadvantages of using intelligent packaging technology for food freshness detection methods, while summarizing the latest research progress in applying artificial intelligence-based technologies to food freshness detection through intelligent packaging. Finally, the author points out the limitations of the current research, and anticipates future developments in artificial intelligence technology for assisting freshness detection in intelligent packaging. This will provide valuable insights for the future development of intelligent packaging in the field of food freshness detection.

The potential of anthocyanin-loaded alginate hydrogel beads for intelligent packaging applications: Stability and sensitivity to volatile amines

pH indicators have emerged as promising tools for real-time monitoring of product freshness and quality in intelligent food packaging applications. However, ensuring the stability of these indicators is critical for practical use. This study aims to evaluate the stability of anthocyanins-loaded alginate hydrogel beads of varying sizes at different temperatures under accelerated light conditions and relative humidity (RH) levels of 53% and 97% during 21 days of storage. Moreover, their sensitivity to the principal spoilage volatiles of muscle food products such as ammonia (NH3), dimethylamine (DMA) and trimethylamine (TMA) was investigated. The half-life of cyanidin-3-glucoside in small hydrogel beads was roughly twice as long as that of the larger beads under accelerated light exposure at 4 °C and they were less likely to undergo noticeable color changes over time. Both sizes of hydrogel beads stored at 97% RH and 4 °C showed color stability over the 21-day period with minimal color variation (|ΔE| ≤ 3). The UV-vis spectra of the purple corn extract exhibited changes across pH 2 to 12, as evidenced by the visible color variations, ranging from pink to green. The limit of detection (LOD) for NH3 was 25 ppm for small beads and 15 ppm for large ones. Both types of beads exhibited similar LOD for DMA and TMA, around 48 ppm. This research showed that alginate hydrogel beads containing anthocyanins from purple corn are a viable option for developing intelligent packaging of muscle foods. Furthermore, the use of hydrogel beads of different sizes can be customized to specific muscle foods based on the primary spoilage compound generated during spoilage.

Facile Fabrication of Anthocyanin-Nanocellulose Hydrogel Indicator Label for Intelligent Evaluation of Minced Pork Freshness

In order to develop a reliable and rapid method for meat freshness detection, nanocellulose (TOCNF) prepared via the TEMPO (2,2,6,6-tetramethylpiperidine oxidation) oxidation method was used as raw material to prepare hydrogels using Zn²⁺ coordination and binding. Physicochemical properties such as water absorption and porosity were analyzed. It was further used to select suitable hydrogels for the preparation of indication labels after anthocyanin adsorption, and it was applied in the freshness detection of fresh minced pork. Five percent TOCNF (w/w) aqueous solution was homogenized by high shear for 4 min, and 20% (w/w) zinc chloride solution was added to it, so that the concentration of zinc ions could reach 0.25 mol/L. After standing for 24 h, the hydrogel was obtained with good water absorption and a porous three-dimensional network structure. The activation energies of volatile base nitrogen (TVBN) and anthocyanin indicating label color changes were 59.231 kJ/mol and 69.453 kJ/mol, respectively. The difference between the two is within 25 kJ/mol, so the prepared indicator label can accurately visualize the shelf life of fresh pork.

Peptide hydrogels: Synthesis, properties, and applications in food science

Due to the unique and excellent biological, physical, and chemical properties of peptide hydrogels, their application in the biomedical field is extremely wide. The applications of peptide hydrogels are closely related to their unique responsiveness and excellent properties. However, its defects in mechanical properties, stability, and toxicity limit its application in the food field. In this review, we focus on the fabrication methods of peptide hydrogels through the physical, chemical, and biological stimulations. In addition, the functional design of peptide hydrogels by the incorporation with materials is discussed. Meanwhile, the excellent properties of peptide hydrogels such as the stimulus responsiveness, biocompatibility, antimicrobial properties, rheology, and stability are reviewed. Finally, the application of peptide hydrogel in the food field is summarized and prospected.

A pH-sensitive intelligent packaging film harnessing Dioscorea zingiberensis starch and anthocyanin for meat freshness monitoring

Abundant starch was isolated from Dioscorea zingiberensis C.H. Wright, a novel and underutilized industrial crop resource. In this study, an intelligent packaging film able to indicate food freshness was developed and characterized. D. zingiberensis starch (DZS) was bleached first, and its particle size, total starch content, amylose content, and gelatinization temperature were then measured. Butterfly pea (Clitoria ternatea Linn.) flowers were selected as the source of polyphenols, which rendered the prepared film intelligent and progressively blue-violet. SEM and FT-IR analyses showed the homogeneous dispersion of butterfly pea flower extract (BPE) in the film. The BPE-loaded film showed improved flexibility and resistance to UV and oxidation while maintaining sufficient mechanical strength and physical properties. Moreover, the film underwent a distinguishable color change from red to blue-violet and finally to green-yellow with increasing pH from 2 to 13. Similar color alteration also occurred when the film was exposed to ammonia. When the film was used to monitor the freshness of chicken stored at room temperature, it exhibited an obvious color change, implying its deterioration. Therefore, the newly developed BPE-DZS film, which was produced from readily accessible natural substances, can serve as an intelligent packaging material, indicating food freshness and prolonging shelf life.

Multi-functional konjac glucomannan/chitosan bilayer films reinforced with oregano essential oil loaded β-cyclodextrin and anthocyanins for cheese preservation

In this work, a multifunctional bilayer film was prepared by solvent casting method. Elderberry anthocyanins (EA) were incorporated into konjac glucomannan (KGM) film as the inner indicator layer (KEA). β-cyclodextrin (β-CD) loaded with oregano essential oil (OEO) inclusion complexes (β-CD@OEO) was prepared and incorporated into chitosan (CS) film as the outer hydrophobic and antibacterial layer (CS-β-CD@OEO). The impacts of β-CD@OEO on the morphological, mechanical, thermal, water vapor permeability and water resistance properties, pH sensitivity, antioxidant, and antibacterial activities of bilayer films were thoroughly evaluated. The incorporation of β-CD@OEO into bilayer films can significantly improve the mechanical properties (tensile strength (TS): 65.71 MPa and elongation at break (EB): 16.81 %), thermal stability, and water resistance (Water contact angle (WCA): 88.15°, water vapor permeability (WVP): 3.53 g mm/m² day kPa). In addition, the KEA/CS-β-CD@OEO bilayer films showed color variations in acid-base environments, which could be used as pH-responsive indicators. The KEA/CS-β-CD@OEO bilayer films also presented controlled release of OEO, good antioxidant, and antimicrobial activity, which exhibited good potential for the preservation of cheese. To sum up, KEA/CS-β-CD@OEO bilayer films have potential applications in the field of food packaging industry.

The degradation of single-use plastics and commercially viable bioplastics in the environment: A review

Plastics have become an integral part of human life. Single-use plastics (SUPs) are disposable plastics designed to be used once then promptly discarded or recycled. This SUPs range from packaging and takeaway containers to disposable razors and hotel toiletries. Synthetic plastics, which are made of non-renewable petroleum and natural gas resources, require decades to perpetually disintegrate in nature thus contribute to plastic pollution worldwide, especially in marine environments. In response to these problems, bioplastics or bio-based and biodegradable polymers from renewable sources has been considered as an alternative. Understanding the mechanisms behind the degradation of conventional SUPs and biodegradability of their greener counterpart, bioplastics, is crucial for appropriate material selection in the future. This review aims to provide insights into the degradation or disintegration of conventional single-use plastics and the biodegradability of the different types of greener-counterparts, bioplastics, their mechanisms, and conditions. This review highlights on the biodegradation in the environments including composting systems. Here, the various types of alternative biodegradable polymers, such as bacterially biosynthesised bioplastics, natural fibre-reinforced plastics, starch-, cellulose-, lignin-, and soy-based polymers were explored. Review of past literature revealed that although bioplastics are relatively eco-friendly, their natural compositions and properties are inconsistent. Furthermore, the global plastic market for biodegradable plastics remains relatively small and require further research and commercialization efforts, especially considering the urgency of plastic and microplastic pollution as currently critical global issue. Biodegradable plastics have potential to replace conventional plastics as they show biodegradation ability under real environments, and thus intensive research on the various biodegradable plastics is needed to inform stakeholders and policy makers on the appropriate response to the gradually emerging biodegradable plastics.

Designing Antioxidant and Antimicrobial Polyethylene Films with Bioactive Compounds/Clay Nanohybrids for Potential Packaging Applications

In the present work, direct incorporation of bioactive compounds onto the surface and interlayer of nanoclays before their incorporation into the final polymeric film was conducted, based on a green methodology developed by our group that is compatible with food packaging. This will lead to the higher thermal stability and the significant reduction of the loss of activity of the active ingredients during packaging configuration. On this basis, the essential oil (EO) components carvacrol (C), thymol (T) as well as olive leaf extract (OLE), which is used for the first time, were incorporated onto organo-modified montmorillonite (O) or inorganic bentonite (B) through the evaporation/adsorption method. The prepared bioactive nanocarriers were further mixed with low-density polyethylene (LDPE), via melt compounding, in order to prepare films for potential use as fresh fruit and vegetable packaging material. Characterization of the bioactive nanocarriers and films were performed through XRD, TGA, tensile, antimicrobial and antioxidant tests. Films with organically modified montmorillonite loaded with carvacrol (OC), thymol (OT) and olive leaf extract (OOLE) at 5% wt. showed better results in terms of mechanical properties. The films with polyethylene and organically modified montmorillonite loaded with carvacrol or thymol at 20% wt. (PE_OC20 and PE_OT20), as well as with olive leaf extract at 5 or 10 %wt., clay:bioactive substance ratio 1:0.5 and 10% compatibilizer (PE_OOLE5_MA10 and PE_OOLE10_MA10) exhibited the highest antioxidant activity. The resulting films displayed outstanding antimicrobial properties against Gram-negative Escherichia coli (E. coli) with the best results appearing in the films with 10% OC and OT.