pH-responsive pectin-based multifunctional films incorporated with curcumin and sulfur nanoparticles

Development of temperature-regulating CR/PVA bionanocomposite films with phase change materials and antibacterial properties for ice cream packaging

This study focuses on the development of active packaging for anti-heating food packaging using film materials based on Carrageenan (CR) and polyvinyl alcohol (PVA). The aim is to effectively manage the temperature of food products during storage and transportation to preserve their quality and freshness. Temperature-controlled bionanocomposite films were synthesized by incorporating phase change materials (PCMs) into the CR/PVA blend matrix. Specifically, polyethylene glycol (PEG) was grafted onto cellulose nanocrystals supported by copper nanoparticles to create a solid-solid PCM-Cu with exceptional thermal storage efficiency. The resulting nanocomposite films exhibited buffering properties at cold chain temperatures compared to pure CR/PVA films. The presence of copper nanoparticles also contributed antibacterial activity, further ensuring food safety. These nanocomposite films demonstrate significant potential for application in food packaging, as they effectively address temperature-related challenges within the food industry. The findings highlight the effectiveness of these innovative films in preserving the freshness of ice cream even when exposed to periods outside the freezer.

Improving the hydrophobic nature of biopolymer based edible packaging film: A review

Biopolymer-based polymer compounds mainly protein and polysaccharide are commonly used in biodegradable packaging. Gelatin, cellulose, starch, chitosan, pectin, and alginate are widely used for producing biodegradable packaging films because of their nontoxicity and safety. However, some drawbacks need to be solved before employing them in food packaging, such as inappropriate wettability, low barrier properties, low mechanical properties and high moisture sensitivity. To overcome the hurdle, film-surface modifications with hydrophobic agents improve oxygen and carbon dioxide permeation while reducing moisture permeability. Some of the method used in tuning hydrophobicity is plasma treatment and coating, high pressure processing, electrospinning, etc. Additionally, hydrophobic coatings are applied on the inner surfaces of packaging films to minimize water losses, prevent leakages, and reduce spoilage and contamination of food. This article discusses the various methodologies in improving hydrophobicity for biodegradable packaging films by introducing hydrophobic agents and other active constituents to increase their functioning and intelligence.

Preparation of edible films from pectin/carboxymethyl chitosan incorporating polyphenol-rich roselle leaf extracts for food packaging applications

This study aimed to design an innovative antioxidant and antibacterial film for functional and health-promoting food packaging materials using food-grade polysaccharides incorporated with polyphenol-rich roselle leaf extracts (RLE). The films were fabricated using the casting method of pectin (P), carboxymethyl chitosan (CMC), and RLE. Six sets of films; 3 control films such as pectin (P-0), carboxymethyl chitosan (CMC-0), pectin plus carboxymethyl chitosan (PCMC-0), and 3 treated films such as pectin (PR-3), carboxymethyl chitosan (CMCR-3), (PCMCR-3) with 3 % RLE were prepared respectively to study the effects of RLE on the properties and function of prepared films. The water vapor permeability of the films ranged from 4.16 ± 0.04 g mm/h·m2·kPa to 6.93 ± 0.07 g mm/h·m2·kPa, with RLE-incorporated samples exhibiting lower permeability than the control sample. The maximum tensile strength (53.00 ± 1.07 MPa) and elongation of break (85.83 ± 2.81 %) were observed at PCMCR-3 containing 3 % RLE. The highest water contact angle (109.4 ± 0.16) was also noted in the PCMCR-3 film. The incorporation of RLE decreased the roughness of the film microstructure. The addition of RLE film CMC-R and PCMCR-3 notably enhanced the antibacterial and antioxidant properties of the edible film. Overall, the PCMCR-3 films extended the shelf life of fresh fish preserved at 4 ± 1 °C, offering promising innovative food preservation packaging materials for preserving perishable food products.

Effects of different saccharides glycosylation modified soy protein isolate on its structure and film-forming characteristics

With the serious impact of traditional plastic packaging on the environment, the development of safe, environmentally friendly and degradable packaging materials has become a research hotspot. Glycosylation reaction has been explored by researchers because of its green, efficient and simple. In this study, the film-forming properties of soy protein isolate (SPI) were improved by glycosylation modification. Different types of saccharides (monosaccharides: glucose, fructose, xylose; oligosaccharides: maltose, fructooligosaccharide, xylooligosaccharide; polysaccharide: gum arabic) were introduced into the SPI by moist heat method. The results show that the xylose-modified SPI film has the best performance in mechanical properties and thermal stability, and its tensile strength is increased to 5.1 MPa, and its elongation reached 117.8 %. Structural analysis revealed that glycosylation resulted in a decrease in α-helix content of SPI, while β-sheets and random coils increased, forming a tighter cross-linked network, improving film density and stability. Furthermore, xylose modification significantly reduced the water vapor transmission rate to only 12.64 g/m2·24 h. These modifications significantly enhance the comprehensive properties of SPI films, especially in terms of thermal stability and moisture barrier properties. The correlation analysis between SPI film properties and internal structure shows that glycosylation can change the internal structure of protein and further affect the film properties. The research in this paper provides a theoretical basis for the glycosylation modification of SPI, and provides a new idea for the sustainable development of food packaging materials.

Antimicrobial, antioxidative, and UV-blocking pectin/gelatin food packaging films incorporated with tannic acid and silver nanoparticles for strawberry preservation

In the face of the increasingly serious food pollution and safety problems, the development of an antimicrobial and antioxidant food packaging material is imminent. In this study, tannic acid (TA) was used as a reducing agent to reduce silver ions into silver nanoparticles (AgNPs), which were then added into pectin/gelatin matrix to prepare antimicrobial, antioxidative, and UV-blocking nanocomposite food packaging films. The transmittance of the nanocomposite film was only 0.28 % in the 200-280 nm range, demonstrating that the nanocomposite film could block almost all UV rays. In addition, TA and AgNPs significantly increased the water vapor barrier and antioxidant activity of the nanocomposite film. The water vapor permeability of the nanocomposite film was 1.62 ± 0.09 × 10-10 g·m-1·s-1·Pa-1, and its free radical scavenging activities against DPPH and ABTS were 71.33 ± 0.06 % and 96.23 ± 0.15 %, respectively. At the same time, the nanocomposite film exhibited strong antibacterial activity against S. aureus and E. coli. In strawberry preservation experiments, it was found that the composite film extended the shelf life of the strawberry, which demonstrates its potential application in efficiently safeguarding perishable fruits.

Development of pH-responsive active intelligent chitosan film incorporated with pomegranate cellulose nanocrystals and curcumin nanoparticles

Casein Sodium coated curcumin nanocapsules (Cas@Cur) were fabricated by a pH shift method, which improved the water solubility of curcumin (Cur). Hydrogen bonds and hydrophobic interactions were the main forces for the formation of Cas@Cur. Chitosan films (CS) reinforced with pomegranate cellulose nanocrystals (PCNCs), Cas@Cur, PCNC/Cas@Cur, and PCNC/Cur were developed and named CP, CS-Cas@Cur, CP-Cas@Cur and CP-Cur, respectively. The addition of Cas@Cur decreased the moisture content, crystallinity and water contact angle of chitosan film, and increased its water solubility and light barrier property. The CP-Cur film presented the roughest cross-sectional SEM image owing to the hydrophobicity of Cur. CP-Cas@Cur film exhibited the excellent cumulative release of Cur, and was 1.60 and 3.70 times of that of CP-Cur in the semi-fatty and fatty food simulation systems at 2 h, respectively, owing to the controlled-release function of PCNCs and great water solubility of Cas@Cur. Furthermore, the CP-Cas@Cur film displayed excellent antioxidant property, antibacterial activity and sensitive color responsiveness to pH and NH3. Interestingly, the CP-Cas@Cur films exhibited a visible color change at pH 3-7. The application of CP-Cas@Cur film in the preservation of milk and shrimp indicated its potential for the visual monitoring of food freshness.

Pectin-Based Active and Smart Film Packaging: A Comprehensive Review of Recent Advancements in Antimicrobial, Antioxidant, and Smart Colorimetric Systems for Enhanced Food Preservation

This review provides a comprehensive overview of recent advancements in biodegradable active and smart packaging utilizing pectin from various origins for food applications. It critically examines the challenges and limitations associated with these developments, initially focusing on the structural influences of pectin on the properties of packaging films. Methods such as spray drying, casting, and extrusion are detailed for manufacturing pectin films, highlighting their impact on film characteristics. In discussing active pectin films, the review emphasizes the effectiveness of incorporating essential oils, plant extracts, and nanoparticles to enhance mechanical strength, moisture barrier properties, and resistance to oxidation and microbial growth. Smart biodegradable packaging is a significant research area, particularly in monitoring food freshness. The integration of natural colorants such as anthocyanins, betacyanins, and curcumin into these systems is discussed for their ability to detect spoilage in meat and seafood products. The review details the specific mechanisms through which these colorants interact with food components and environmental factors to provide visible freshness indicators for consumers. It underscores the potential of these technologies to fulfill sustainability goals by providing eco-friendly substitutes for traditional plastic packaging.

A novel emulsifier for Pickering emulsion composed of whey protein and OSA-pectin loaded with Monascus pigments

Protein-polysaccharide complex carrier can solve the problem of insufficient stability of Monascus pigments (MPs), a kind of natural pigments, against heat and light. It also has the function to stabilize Pickering emulsion (PE) that can be used as fat replacer in meat products. In this study, heat denatured whey protein (HWP) and pectin modified by octenyl succinic anhydride (OSA-pectin) were prepared into complex by adding Ca2+ loaded with MPs. The complex carrier significantly enhanced the light and heat stabilities of MPs and exhibited excellent wettability. It was then used to prepare PE (HOCM-PE) as a fat replacer to improve the color performance of meat patties. The microstructure and rheological properties of HOCM-PE clarified that the main stable mechanism was to form network structure wrapped around oil droplets in the continuous phase. This structure conferred excellent viscoelasticity and stability to the emulsion. The key quality parameters of meat patties showed that HOCM-PE as a fat substitute was able to maintain the textural properties of the meat patties while providing bright red color. The research provided an ideal dual-functional emulsion for the development of low-fat and low-nitrite meat products.

Resveratrol nanoparticles coated by metal-polyphenols supramolecular enhance antioxidant activity and long-term stability of dietary gel

Resveratrol (RES) is an important functional substance with multiple active properties. However, RES is susceptible to natural environmental conditions that reduce its bioactivity. To improve the bioavailability of RES, in this study, Catechin and Fe3+/Ca2+ were selected to form supramolecules, which were then coated on the surface of hydrophobic RES nanoparticles (RES NPs) to create composite RES NPs. The obtained composite RES NPs demonstrated higher antioxidant capacity and better photo-thermal stability than RES NPs. Additionally, a pectin (PE) dietary gel was designed as a delivery carrier for RES. The results showed that the incorporation of composite RES NPs not only endowed the gels with significant dietary activity but also enhanced the texture, water retention capacity and hydrophobicity. After 28 days of storage, the retention rate of RES could be maintained above 90 % in the dietary gels. Meanwhile, the controlled release of RES was achieved in in vitro simulated digestion.

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.

Next-generation methods for precise pH detection in ocular chemical burns: a review of recent analytical advancements

Ocular burns due to accidental chemical spillage pose an immediate threat, representing over 20% of emergency ocular traumas. Early detection of the ocular pH is imperative in managing ocular chemical burns. Alkaline chemical burns are more detrimental than acidic chemical burns. Current practices utilize litmus, nitrazine strips, bromothymol blue, fluorescent dyes, and micro-combination glass probes to detect ocular pH. However, these methods have inherent drawbacks, leading to inaccurate pH measurements, less sensitivity, photodegradation, limited pH range, and longer response time. Hence, there is a tremendous necessity for developing relatively simple, accurate, precise ocular pH detection methods. The current review aims to provide comprehensive coverage of the conventional practices of ocular pH measurement during accidental chemical burns, highlighting their strengths and weaknesses. Besides, it delves into cutting-edge technologies, including pH-sensing contact lenses, microfluidic contact lenses, fluorescent scleral contact lenses, fiber optic pH technology, and pH-sensitive thin films. The study meticulously examines the reported work since 2000. The collected data have also helped propose future directions, and the research gap needs to be filled to provide a more rapid, sensitive, and accurate measurement of ocular pH in eye clinics. For the first time, this review consolidates current techniques and recent advancements in ocular pH detection, offering a strategic overview to propel ophthalmic-related research forward and enhance ocular burn management during a chemical spillage.

Antimicrobial nanoparticle-containing food packaging films for controlling Listeria spp.: An overview

Bacteria of the genus Listeria are ubiquitous in nature and are found in various food products and food processing facilities. The species Listeria monocytogenes is a food-borne pathogen that causes listeriosis with a high fatality rate. For the prevention and control of listeriosis, the identification of effective antilisterial compounds is desirable. The number of investigations on nanoparticles (NPs) with antimicrobial activity has increased in recent years. In this context, green nanotechnology is a field of science that focuses on the synthesis of NPs through biological pathways using a wide range of microorganisms and plant extracts, which has led to the biofabrication of novel antimicrobial agents that have demonstrated remarkable potential against pathogenic bacteria. In this review, in vitro studies of the inhibitory action of antimicrobial NPs obtained by green biosynthesis, including silver, gold, zinc, zinc oxide, copper, palladium, and selenium NPs, on the growth of Listeria spp. were comprehensively summarized. This review mainly highlights antimicrobial NPs in biopolymer films against L. monocytogenes. Furthermore, studies on NPs in biopolymer-based functional food packaging films against L. monocytogenes are listed. Finally, safety considerations are indicated. This review provides an overview of the antilisterial activity of bio-based antimicrobial NPs and the potential of nanotechnology as an innovative technology for the development of food packaging films containing antimicrobial NPs to control Listeria spp.

A comprehensive review on the functionality and biological relevance of pectin and the use in the food industry

Pectin is a natural biopolymer, which can be extracted from food by-products, adding value to raw material, with a structure more complex than that of other polysaccharides. The gelling properties of these molecules, together with the bioactivity that these can exert, make them suitable to be used as ingredients and bioactive agents. In this review, the characterization of pectin (structure, sources, techno-functional, and biological properties), the extraction methods, and their use in the food industry (food packaging, as carriers, and as ingredients) are described. Different by-products can be used as substrates to extract pectin, enhancing a sustainable food system as described by the circular economy principles. Pectin is characterized for their techno-functional and biological properties, such as gelling and thickening properties or modulation of microbiota both in animals and humans. Such properties make these molecules suitable for a wide range of applications within the food chain, serving as packaging or carriers in foodstuff, or for direct use as functional ingredients as fiber. Overall, pectin has been shown to exert as promising components to be introduced in the food system, although further research on scaling-up the production process and feasibility has to be done.

Multifunctional composite film of curcumin Pickering emulsion stabilized by lignocellulose nanofibrils isolated from bamboo shoot shells for monitoring shrimp freshness

Concerns about food safety and environmental impact from chemical surfactants have prompted interest in natural lignocellulosic materials as alternatives. In this study, we combined hydrated deep eutectic solvent (DES) pretreatment with ultrasound treatment to prepare lignocellulosic nanofibrils (LCNF) from bamboo shoot shells with appropriate surface properties for stabilizing Pickering emulsions. The pretreatment intensity effectively modulated the surface characteristics of LCNF, achieving desirable wettability through lignin retention and in-situ esterification. The resulting LCNF/curcumin Pickering emulsion (CPE) demonstrated curcumin protection and pH-responsive color changes, while the ensuing CPE/PVA composite film exhibited ultraviolet shielding, mechanical strength, oxygen barrier, and antioxidant properties. Furthermore, the CPE/PVA film showed promise as a real-time indicator for monitoring shrimp freshness, maintaining sensitivity to spoilage even after six months of storage. These findings advance the advancement of green LCNF technologies, providing eco-friendly solutions for valorizing bamboo shoot shells and enhancing the application of LCNF in Pickering emulsions.

Pectin/zinc alginate films containing anthocyanins from dragon fruit peel as intelligent pH indicators for shrimp freshness monitor

The novel incorporation of dragon fruit peel extract (DE), rich in anthocyanins, Zn2+ (from Zinc Alginate) and pectin was applied to create active and intelligent food packaging composite films. These films were characterized for their microstructure and properties. Various levels of anthocyanin extracts (1 %, 3 %, and 5 %) were evaluated for their impact on the films' physical and functional properties, incorporating microstructure, mechanical strength, barrier properties, pH sensitivity, and bacteriostatic effectiveness. The films exhibited a significant antibacterial rate of up to 99.99 % against common foodborne pathogens, enhanced flame retardancy with an enhancement of 32.7 %, and a broad pH sensitivity range, indicating their adaptability to various conditions. The results demonstrated that the prepared indicator film achieved a 50 % reduction in water vapor permeability. Additionally, the mechanical properties were enhanced, with only a slight decrease of 12.2 % in tensile strength and 14.0 % in elongation at break. In tests monitoring shrimp freshness, pectin/ZA/DE films showed notable color changes correlating with shrimp quality. These specific values highlight the pectin/ZA/DE films' potential for real-world applications, suggesting that they have potential applications as smart packaging materials in the food industry.

Incorporating functional colorants in whey protein isolate-cellulose nanocrystal-blended edible films for pork freshness prediction

In this study, intelligent pH- and ammonia-sensing edible films are designed based on whey protein isolate (WPI)-cellulose nanocrystal-based biopolymers by incorporating different functional colorants (curcumin, phycocyanin, and modified lycopene), alone and paired, to promote food freshness and monitoring efforts. Incorporating the colorants endowed the films were endowed with pH- and ammonia-responsiveness and enhanced UV-blocking, antioxidant, and antibacterial capabilities. Phycocyanin induces WPI unfolding, increasing the accessibility of curcumin; hence, combining curcumin with phycocyanin promotes the sensitivity of films to pH and NH3 compared with those containing a single colorant. In the pork freshness monitoring analysis, the combined-colorants film underwent a noticeable color change as the meat spoiled. Moreover, the meat packaged with the combined film exhibited lower levels of lipid oxidation than those packaged in single-colorant films. These results suggest that curcumin-phycocyanin-containing films have multifunctional potential in intelligent food packaging.

Poly(vinyl alcohol)/tannic acid nanofibrous membrane containing curcumin as an intelligent indicator of food spoilage

In recent years, active packaging technology for extending food shelf life and intelligent packaging technology for monitoring food freshness have become essential for ensuring food safety. Among sensing technologies, pH-sensitive sensors have notable advantages, including simplicity, compactness, and affordability, making them ideal for monitoring food freshness. This study proposes an intelligent food indicator based on a composite nanofiber membrane fabricated by electrospinning. The membrane, composed of poly(vinyl alcohol) (PVA), tannic acid (TA), and the natural pH-sensitive dye curcumin (CUR), was heat-treated to enhance its moisture stability for food packaging. Furthermore, the incorporation of TA and CUR into PVA provides additional benefits such as UV-blocking, antioxidant, and antimicrobial properties, effectively delaying food spoilage. The CUR-incorporated nanofibrous membrane exhibited faster detection of shrimp spoilage via colorimetric changes under increasingly alkaline conditions than film samples. Moreover, compared to film-based samples, the composite nanofiber membrane exhibited faster color change responsiveness owing to its porous and high surface area structure, thus serving as an efficient and intelligent indicator.

Preparation of soybean isolate protein/xanthan gum/agar-Lycium ruthenicum anthocyanins intelligent indicator films and its application in mutton preservation

The preparation of intelligent indicator films containing anthocyanins and their utilization for real-time monitoring of meat freshness represents a prominent research topic of food packaging. In this study, anthocyanins (ALR) were extracted from Lycium ruthenicum (LR) using solvent extraction. Subsequently, these anthocyanins were incorporated into films composed of soybean isolate protein (SPI), xanthan gum (XG) and agar, resulting in SPI/XG/Agar-ALR pH-responsive intelligent indicator films. The physical properties, structural characterization and application in mutton preservation were evaluated to identify the intelligent indicator films with the optimal addition ratio of ALR. The results indicated that the SPI/XG/Agar-5 % films exhibited exceptional performance in terms of thickness, mechanical properties, water vapor transmission rate, oxygen transmission rate and light transmission rate. Scanning electron microscope observations revealed that the SPI/XG/Agar-5 % films possessed a smooth and flat surface, while fourier transform infrared spectroscopy analysis confirmed their excellent compatibility. The DPPH radical scavenging rate of the SPI/XG/Agar-5 % film reached 80.75 ± 0.63 %. When applied to the preservation of mutton, the SPI/XG/Agar-5 % film significantly extended the shelf life and effectively monitored the freshness of the meat. This study not only broadens the application scope of Lycium ruthenicum anthocyanins but also provides a foundation for the development of smart packaging materials.

Physical and thermal improvement of bioplastics based on potato starch/agar composite functionalized with biogenic ZnO nanoparticles

This study investigated potato starch/agar-based bioplastics' structure, properties, and biodegradability by adding ZnO nanoparticles (NPs) biogenically synthesized using Coriandrum sativum extract. ZnO NPs presented crystalline structure, good optical properties, and a size of 6.75 ± 1.4 nm, which were added at various concentrations (419.66-104.23 ppm) in bioplastics and their presence was confirmed via EDS elemental analysis and X-ray fluorescence. The highest NPs concentration contributed to a smoother surface, while FTIR and Raman analyses suggested interactions between the NPs and functional groups of the biopolymeric matrix. ZnO NPs addition slightly reduced bioplastic transparency but significantly improved UV-A and UV-B blocking capacities. It also increased hydrophobicity, evidenced by a 22 % reduction in water absorption and a 55 % increase in contact angle. Thermogravimetric analysis (TGA) indicated that NPs raised the bioplastic's thermal stability. Mechanical property tests showed that ZnO NPs concentrations had negligible or negative effects probably due to the heterogeneous distribution of NPs, or the non-isotropic characteristic of the bioplastic. Finally, biodegradability assays in seawater and soil revealed over 43.5 % and 66 % degradation after 15 and 28 days, respectively. Therefore, biosynthesized ZnO NPs mainly enhanced the bioplastic's UV-blocking capacity, hydrophobicity, and thermal properties, offering an eco-friendly option for future studies/applications.

Development and investigation of a polysaccharide ternary nanocomposite based on basil seed gum/graphene oxide/anthocyanin for intelligent food packaging

A new pH-sensitive intelligent packaging system was developed composed of extracted and purified basil seed gum (BG) containing aqueous malva sylvestris extract (MS) and varying amounts of synthesized graphene oxide (GO). In the following, the characteristics of prepared films including spectroscopic, physio-mechanical, thermogravimetry, fracture-surface morphology, anthocyanin release, and pH and TVB-N sensitivity, were investigated. Our results revealed that the addition of 0.5 wt % MS into the BG matrix induced pH sensitivity to the film and resulted in a visible color change from pH 2.0 to 14.0; however, it reduced the thermal and physio-mechanical properties. In this regard, the effective presence of the optimum concentration of GO (0.25 wt%) in enhancing the mechanical and thermal properties of the BG-MS films was shown. Moreover, inspecting the release kinetics demonstrated a controllable release for BG-MS-GO film compared to the BG-MS film in 48 h. Furthermore, the total volatile basic nitrogen (TVB-N) content and pH value were shown to be highly correlated with the color changes of the freshness indicator film during the storage of salmon fillets at 25 °C for 36 h. Therefore, it was shown that BG-MS-GO film can be used as a highly effective freshness/spoilage indicator of proteinic products.

Seeking materials from nature for interrupting eye damage: Ultraviolet to blue light blocking clear cellulose films enabled by curcumin

The harms caused by ultraviolet (UV) and blue light to eyes are attracting momentous concern due to growing exposure to artificial illumination and modern IT devices. Herein, a simple and eco-friendly adsorption approach was employed to integrate curcumin, a natural bioactive compound, into the cellulose substrate for the development of flexible and biodegradable filters capable of blocking harmful light. The curcumin/cellulose films demonstrate excellent UV-screening competence and photostability, with UV-A and UV-B screening ratios ranging from 92.8 % to 100 % and 89.2 % to 100 %, respectively. The films could block >96 % of blue light in the wavelength range of 400-500 nm. Meanwhile, the films maintain high transmittance (85.2-89.4 %) and low haze (2.0-2.7 %). The films can efficiently block blue light emanated from sunlight, light-emitting diodes, lighting systems, computer and mobile phone screens. Encouragingly, the incorporation of curcumin led to a substantial increase in the water contact angle, elevating it from 41.6 to 81.3°. Furthermore, the films exhibit excellent antimicrobial properties, biodegradability, and tensile strength in excess of 72 MPa. Therefore, these films fabricated entirely from natural resources have the potential to achieve practical applications such as food packaging and spectacle lens, especially suitable for electronic screen protectors.

Citrus oil gland and cuticular wax inspired multifunctional gelatin film of OSA-starch nanoparticles-based nanoemulsions for preserving perishable fruit

Inspired by the citrus oil gland and cuticular wax, a multifunctional material that stably and continuously released the carvacrol and provided physical defenses was developed to address issues of fresh-cut fruits to microbial infestation and moisture loss. The results confirmed that low molecular weight and loose structure of starch nanoparticles prepared by the ultrasound-assisted Fenton system were preferable for octenyl succinic anhydride modification compared to native starch, achieving a higher degree of substitution (increased by 18.59 %), utilizing in preparing nanoemulsions (NEs) for encapsulating carvacrol (at 5 % level: 81.58 %). Furthermore, the NEs-based gelatin (G) film improved with surface hydrophobic modification by myristic acid (MA) successfully replicated the citrus oil gland and cuticular wax, providing superior antioxidant (enhanced by 3-4 times) and antimicrobial properties (95.99 % and 84.97 % against Staphylococcus aureus and Escherichia coli respectively), as well as the exceptional UV shielding (nearly 0 transmittance in the UV region), mechanical (72 % increase in tensile strength), and hydrophobic (WCA 133.63°). Moreover, the 5%NE-G@MA film inhibited foodborne microbial growth (reduced by 50 %) and water loss (controlled below 15 %), extending the shelf life of fresh-cut navel orange and kiwi. Thus, the multifunctional film was a potential shield for preserving perishable fresh-cut products.

Enhancing biodegradable smart food packaging: Fungal-synthesized nanoparticles for stabilizing biopolymers

The increasing global concern over environmental plastic waste has propelled the progress of biodegradable supplies for food packaging. Biopolymer-based packaging is undergoing modifications to enhance its mechanical properties, aligning with the requirements of smart food packaging. Polymer nanocomposites, incorporating reinforcements such as fibers, platelets, and nanoparticles, demonstrate significantly improved mechanical, thermal, optical, and physicochemical characteristics. Fungi, in particular, have garnered significant interest for producing metallic nanoparticles, offering advantages such as easy scaling up, streamlined downstream handling, economic feasibility, and a large surface area. This review provides an overview of nano-additives utilized in biopackaging, followed by an exploration of the recent advancements in using microbial-resistant metal nanoparticles for food packaging. The mycofabrication process, involving fungi in the extracellular or intracellular synthesis of metal nanoparticles, is introduced. Fungal functionalized nanostructures represent a promising avenue for application across various stages of food processing, packaging, and safety. The integration of fungal-derived nanostructures into food packaging materials presents a sustainable and effective approach to combatting microbial contamination." By harnessing fungal biomass, this research contributes to the development of economical and environmentally friendly methods for enhancing food packaging functionality. The findings underscore the promising role of fungal-based nanotechnologies in advancing the field of active food packaging, addressing both safety and sustainability concerns. The study concludes with an investigation into potential fungal isolates for nanoparticle biosynthesis, highlighting their relevance and potential in advancing sustainable and efficient packaging solutions.

A versatile bilayer smart packaging based on konjac glucomannan/alginate for maintaining and monitoring seafood freshness

This study introduces a novel multi-functional double-layer intelligent packaging. It focuses on developing a dual-function system capable of real-time monitoring and freshness preservation. Specifically, cellulose nanocrystalline (CNC) was obtained through acid hydrolysis, and then CNC/soybean protein isolate (CNC/SPI) complex colloid particles were prepared via antisolvent method. These particles served as stabilizers to prepare oil-in-water (O/W) cinnamon essential oil Pickering emulsion (CSCEO). The CSCEO was then integrated into the emulsified hydrophobic layer of a konjac glucomannan (Kgm) matrix through intermolecular hydrogen bonding. Finally, alginate (Alg) matrix containing alizarin (Al) as an indicator was added to construct the bilayer structure using a layer-by-layer casting strategy. The inner layer Alg/Al was the pH/NH3-responsive indicator layer, while the outer layer Kgm/CSCEO acted as the high-barrier bacteriostatic layer. The obtained dual-function, double-layer film (Alg/Al-Kgm/CSCEO), which possesses a sensitive, reversible and rapid response towards pH/NH3, shows exceptional antibacterial and antioxidant properties, as well as excellent mechanical property, light-blocking capability and hydrophobicity. For monitoring and maintaining the actual freshness of shrimp, such a bilayer packaging displays smallest change of ∆E and TVB-N (18.65 mg/100 g) even after 72 h, which further highlighting its potential in enhancing food safety and extending shelf life.

A review on the role of pH-sensitive natural pigments in biopolymers based intelligent food packaging films

As food packaging evolves, consumer interests are shifting from traditional to intelligent food packaging systems. Intelligent packaging includes active components that display changes in a visual or interactive form perceivable by consumers. This offers real-time monitoring of the quality and shelf life of the packaged food and enhances transparency. For example, pH-sensitive natural pigment-based films change color in response to variations in pH levels, enabling the film/labels to reflect alterations in the acidity or basicity of the food inside the package. Natural pigments like anthocyanins, curcumin, betalains, chlorophyll, and carotenoids have been comprehensively reported for developing biodegradable pH-sensitive films of starch, protein, chitosan, and cellulose. Natural pigments offer great compatibility with these biopolymers and improve the other performance parameters of the films. However, these films still lack the strength and versatility of petroleum-based synthetic plastic films. But these films can be used as an indicator and combined with primary packaging to monitor freshness, time-temperature, and leak for muscle foods, dairy products, fruits and vegetables, and bakery products. Therefore, this review provides a detailed overview of pH-sensitive pigments, their compatibility with natural polymers, their role in film performance in monitoring, and their food packaging applications.

Active and smart biomass film with curcumin Pickering emulsion stabilized by chitosan-adsorbed laurate esterified starch for meat freshness monitoring

The multifunctional active smart biomass film was prepared by incorporating chitosan-adsorbed laurate esterified starch curcumin Pickering emulsion into the starch film matrix, with nano-cellulose serving as reinforcing agents. The mechanical and functional properties of the film were studied, and the film was used to monitor the freshness of pork. The results demonstrated a relatively uniform distribution of curcumin and Pickering emulsion droplets within the film matrix. Furthermore, the thermal stability was minimally impacted by the introduction of curcumin Pickering emulsion, while the tensile strength and tensile strain of the film were increased, and both its hydrophobicity and antioxidant properties were improved. The free radical scavenging rate reached 56.01 %, with sustained high antioxidant capacity even after 8 days. Additionally, the presence of curcumin provided the film with pH indicating ability and delayed pork spoilage. Therefore, this work provides an attractive strategy for constructing green, active, and smart biomass packaging films for meat packaging applications.

Recent advancements in chitosan-based intelligent food freshness indicators: Categorization, advantages, and applications

With an increasing emphasis on food safety and public health, there is an ongoing effort to develop reliable, non-invasive methods to assess the freshness of diverse food products. Chitosan-based food freshness indicators, leveraging properties such as biocompatibility, biodegradability, non-toxicity, and high stability, offer an innovative approach for real-time monitoring of food quality during storage and transportation. This review introduces intelligent food freshness indicators, specifically those utilizing pH-sensitive dyes like anthocyanins, curcumin, alizarin, shikonin, and betacyanin. It highlights the benefits of chitosan-based intelligent food freshness indicators, emphasizing improvements in barrier and mechanical properties, antibacterial activity, and composite film solubility. The application of these indicators in the food industry is then explored, alongside a concise overview of chitosan's limitations. The paper concludes by discussing the challenges and potential areas for future research in the development of intelligent food freshness indicators using chitosan. Thus, chitosan-based smart food preservation indicators represent an innovative approach to providing real-time data for monitoring food quality, offering valuable insights to both customers and retailers, and playing a pivotal role in advancing the food industry.

Intelligent food packaging for smart sensing of food safety

In this contemporary era, with over 8 billion people worldwide, ensuring food safety has become more critical than ever. To address this concern, the introduction of intelligent packaging marks a significant breakthrough. Essentially, this innovation tackles the challenge of rapid deterioration in perishable foods, which is vital to the well-being of communities and food safety. Unlike traditional methods that primarily emphasize shelf-life extension, intelligent packaging goes further by incorporating advanced sensing technologies to detect signs of spoilage and contamination in real-time, such as changes in temperature, oxygen levels, carbon dioxide levels, humidity, and the presence of harmful microorganisms. The innovation can rely on various packaging materials like plastics, metals, papers, or biodegradable polymers, combined with sophisticated sensing techniques such as colorimetric sensors, time-temperature indicators, radio-frequency identification tags, electronic noses, or biosensors. Together, these elements form a dynamic and tailored packaging system. This system not only protects food from spoilage but also offers stakeholders immediate and adequate information about food quality. Moreover, the real-world application on seafood, meat, dairy, fruits, and vegetables demonstrates the feasibility of using intelligent packaging to significantly enhance the safety and shelf life of a wide variety of perishable goods. By adopting intelligent packaging for smart sensing solutions, both the food industry and consumers can significantly reduce health risks linked with contamination and reduce unnecessary food waste. This underscores the crucial role of intelligent packaging in modern food safety and distribution systems, showcasing an effective fusion of technology, safety, and sustainability efforts aimed at nourishing a rapidly growing global population.

Novel films of pectin extracted from ambarella fruit peel and jackfruit seed slimy sheath: Effect of ionic crosslinking on the properties of pectin film

Here, we prepared ionically crosslinked films using pectin extracted from agro-wastes, specifically ambarella peels (AFP) and jackfruit seed slimy sheath (JFS). Physiochemical properties of pectins, including moisture content, molecular weight (Mw), degree of esterification (DE), and galacturonic acid (GA), were analyzed. Optimal extraction was determined, i.e., citric acid concentration 0.3 M, time 60 min, solid/liquid ratio 1:25, and temperature 90 °C for AFP or 85 °C for JFS. Pectin yields under these conditions were 29.67 % ± 0.35 % and 29.93 ± 0.49 %, respectively. AFP pectin revealed Mw, DE, and GA values of 533.20 kDa, 67.08 % ± 0.68 %, and 75.39 ± 0.82 %, while JFS pectin exhibited values of 859.94 kDa, 63.04 % ± 0.47 %, and 78.63 % ± 0.71 %, respectively. The pectin films crosslinked with Ca2+, Cu2+, Fe3+, or Zn2+ exhibited enhanced tensile strength and Young's modulus, along with reduced elongation at break, moisture content, water solubility, water vapor permeability, and oxygen permeability. Structural analyses indicated metal ions were effectively crosslinked with carboxyl groups of pectin. Notably, the Cu2+-crosslinked film demonstrated superior water resistance, mechanical properties, and exhibited the highest antioxidant and antibacterial activities among all tested films. Therefore, the pectin films represent a promising avenue to produce eco-friendly food packaging materials with excellent properties.

Trends in polysaccharide-based hydrogels and their role in enhancing the bioavailability and bioactivity of phytocompounds

Over the years, polysaccharides such as chitosan, alginate, hyaluronic acid, k-carrageenan, xanthan gum, carboxymethyl cellulose, pectin, and starch, alone or in combination with proteins and/or synthetic polymers, have been used to engineer an extensive portfolio of hydrogels with remarkable features. The application of polysaccharide-based hydrogels has the potential to alleviate challenges related to bioavailability, solubility, stability, and targeted delivery of phytocompounds, contributing to the development of innovative and efficient drug delivery systems and functional food formulations. This review highlights the current knowledge acquired on the preparation, features and applications of polysaccharide/phytocompounds hydrogel-based hybrid systems in wound management, drug delivery, functional foods, and food industry. The structural, functional, and biological requirements of polysaccharides and phytocompounds on the overall performance of such hybrid systems, and their impact on the application domains are also discussed.

Development of amine-sensitive intelligent film with MIL-100(Fe) as function filler based on anthocyanins/pectin for monitoring chilled meat freshness

To enhance the amine-sensitivity of intelligent films for accurate monitoring of chilled meat freshness, different additions (0, 1, 2, 3 wt%) of MIL-100(Fe) were incorporated into the matrix composed of anthocyanins (ANs) and pectin (P). Results indicated that the tensile strength, thermal stability, barrier performance and absorption capacity of the films with MIL-100(Fe) were improved significantly (p < 0.05). Especially, the film with 2 % MIL-100(Fe) exhibited the best performance due to its compact structure and the highest crystallinity. Additionally, adsorption isotherms of the films with MIL-100(Fe) were fitted on the Langmuir and the Freundlich isotherm, and adsorption kinetics were fitted on the pseudo-second-order model and Elovich model, respectively (R2 > 0.96), suggesting a combined mechanism of chemisorption and intraparticle diffusion. Besides, when the films were exposed in ammonia environment, they changed color from purple to blue-violet, finally to green. Ultimately, film with 2 % MIL-100(Fe) was used to monitor the chilled meat freshness, as expected, similar color variation was observed at three stages of meat freshness (fresh, sub-fresh, and spoiled), which enabled the accurate differentiation of meat freshness. Thus, films with MIL-100(Fe) demonstrated the potential to be amine-sensitive intelligent packaging for monitoring chilled meat freshness in real time.

Fabrication and Characterization of Pectin Films Containing Solid Lipid Nanoparticles for Buccal Delivery of Fluconazole

Fluconazole (FZ) is a potential antifungal compound for treating superficial and systemic candidiasis. However, the use of conventional oral drug products has some limitations. The development of buccal film may be a potential alternative to oral formulations for FZ delivery. The present study involved the development of novel FZ-loaded solid lipid nanoparticles (FZ-SLNs) in pectin solutions and the investigation of their particle characteristics. The particle sizes of the obtained FZ-SLNs were in the nanoscale range. To produce pectin films with FZ-SLNs, four formulations were selected based on the small particle size of FZ-SLNs and their suitable polydispersity index. The mean particle sizes of all chosen FZ-SLNs formulations did not exceed 131.7 nm, and the mean polydispersity index of each formulation was less than 0.5. The properties of films containing FZ-SLNs were then assessed. The preparation of all FZ-SLN-loaded pectin films provided the mucoadhesive matrices. The evaluation of mechanical properties unveiled the influence of particle size variation in FZ-SLNs on the integrity of the film. The Fourier-transform infrared spectra indicated that hydrogen bonds could potentially form between the pectin-based matrix and the constituents of FZ-SLNs. The differential scanning calorimetry thermogram of each pectin film with FZ-SLNs revealed that the formulation was thermally stable and behaved in a solid state at 37 °C. According to a drug release study, a sustained drug release pattern with a burst in the initial stage for all films may be advantageous for reducing the lag period of drug release. All prepared films with FZ-SLNs provided a sustained release of FZ over 6 h. The films containing FZ-SLNs with a small particle size provided good permeability across the porcine mucosa. All film samples demonstrated antifungal properties. These results suggest the potential utility of pectin films incorporating FZ-SLNs for buccal administration.

Apple pectin-based active films to preserve oil: Effects of naturally branched phytoglycogen-curcumin host

Pectin has excellent film-forming properties, but its functional properties need to be enhanced. Therefore, we constructed naturally branched phytoglycogen (PG) nanoparticles to solubilize curcumin (CCM) and further enhance the properties of apple pectin-based active films. The size of the PG spherical particles ranged from 30 to 100 nm with some aggregates. The branch density of the PG was 6.02 %. These PG nanoparticles increased the solubility of CCM nearly 1742-fold and a nanosized phytoglycogen-curcumin (PG-CCM) host was formed via hydrogen bonding and hydrophobic interaction. This host promoted the formation of pectin-based films with a dense structure and increased their tensile strength to 23.51 MPa. The coefficient to water vapor permeability, oxygen permeability and carbon dioxide permeability were all decreased indicating their barrier performance were improved. Among them, the oxygen permeability coefficient decreased most, from 1.14 × 10-7 g·m-1·s-1 to 0.8 × 10-7 g·m-1·s-1. Also, the transmittance of the active film at 280 nm and 660 nm decreased to 0.65 % and 72.10 %. Antioxidant and antibacterial properties were significantly enhanced (P < 0.05). And the results showed this film was an excellent oil packaging material. The active film incorporating PG-CCM host can replace heat-sealed plastic bags/pouch made from polyethylene and polypropylene synthetic plastics, and solve the problem that plastic packaging is difficult to degrade and cannot be squeezed clean. This provides a new conceptual framework for developing pectin-based active films by incorporating of PG and CCM.

Curcumin and silver nanoparticles loaded antibacterial multifunctional pectin/gelatin films for food packaging applications

Renewable biomass-based materials have a huge potential to replace petroleum-based products in food packaging. Herein, pectin/gelatin films loaded with curcumin and silver nanoparticles (AgNPs) are prepared by solution-pouring technology to serve as antimicrobial multifunctional food packaging films. AgNPs and curcumin are found to equally distribute in the films. Fourier transform infrared spectroscopy (FT-IR) reveal the hydrogen bonding and electrostatic interaction among curcumin, AgNPs, pectin and gelatin. The composite films show good antioxidant activity, mechanical performance, hydrophobicity and antibacterial ability. The films of P-GCA 0.5 showed 99.57 ± 0.16 % and 100 % inhibition against E. coli and S. aureus, respectively. The films also demonstrate excellent water vapor barrier qualities. In addition, the composite films possess pH-responsive color change behaviors from yellow (pH 3-8) to light red (pH 8-9) to dark red (pH 11-12), which is suitable for monitoring the freshness of shrimp packaging based on pH changes during deterioration process. As sustainable biomass-based materials, the multifunctional composite films are promising in intelligent food packaging applications.

Electrospun fiber mats based on chitosan-carrageenan containing Malva sylvestris anthocyanins: Physic-mechanical, thermal, and barrier properties along with application as intelligent food packaging materials

This study aimed to encapsulate Malva sylvestris extract (MSE) into chitosan-carrageenan (CH-KC) fibers using the electrospinning technique and monitor the freshness of silver carp fillets during the refrigerated storage conditions for 8 days. The CH-KC + MSE 4 % fiber mats were red at pH values lower than 3, purple at pH 4-6, dark blue at pH 7, green at pH 8-10, and brown at pH 11-12. The tensile strength, elongation at break, water vapor permeability, oxygen transmission rate, moisture content, and water solubility of fabricated fiber mats were 7.71-11.02 MPa, 13.12 %-30.00 %, 7.35-20.01 × 10-4 g mm/m2 h Pa, 3.81-8.23 cm3/m2 h, 15.74 %-27.34 %, and 3.90 %-7.56 %, respectively. Regarding the potential application of a fabricated indicator for freshness monitoring of silver carp fillets, total viable count, psychrotrophic bacterial count, pH, and total volatile basic nitrogen reached 8.91 log CFU/g, 8.03 log CFU/g, 8.10, and 40.18 mg N/100 g at the end of the study, respectively. Meanwhile, the CH-KC + MSE 4 % fiber mat color changed from white to green. These findings suggest that CH-KC + MSE 4 % fiber mats can be further utilized in the food industry to control the freshness of refrigerated silver carp fillets.

Eggshell membrane as a novel and green platform for the preparation of highly efficient and reversible curcumin-based colorimetric sensor for the monitoring of chicken freshness

Herein, for the very first time, we report a paper-like biomass, eggshell membrane (ESM), as a suitable platform for the fabrication of a colorimetric sensor (E-Cot). Green ethanolic extract, curcumin (CUR), was used as a sensing material to coat with the ESM. The present E-Cot effectively changed its color (yellow to red) in the real-time monitoring for chicken spoilage. The E-Cot exhibits barrier properties due to its inherent semi-permeability characteristics. Interestingly, the E-Cot showed a significant change in total color difference value (ΔE, 0 days - 0.0-39.6, after 1 day - 39.6-42.1, after 2 days - 42.1-53.6, after 3 days- 53.6-60.1, and after 4 days - 60.1-66.3, detectable by the naked eye) in the real-time monitoring for chicken freshness. In addition, the present E-Cot smart colorimetric sensor is reversible with a change in pH, and the sensor can be reused. Further, the hydrophobic nature of the E-Cot was confirmed by water contact angle analysis (WCA, contact angle of 101.21 ± 8.39). Good antibacterial, barrier, and optical properties of the present E-Cot were also found. Owing to the advantages such as green, efficient, cost-effective, biodegradable, reusable, sustainable, and simple preparation, we believe that the present E-Cot would be a more attractive candidate.

Development of pH-freshness smart label based on gellan gum film incorporated with red cabbage anthocyanins extract and its application in postharvest mushroom

Novel colorimetric films based on gellan gum (GG) containing red cabbage anthocyanins extract (RCAE) were prepared as pH-freshness smart labels for real-time visual detection of mushroom freshness. The GG/RCAE films had excellent pH and ammonia sensitivity. The GG/RCAE-0.2-0.3 films had the highest sensitivity to acetic acid. The SEM micrographs, AFM images, FT-IR and XRD spectra demonstrated that RCAE were successfully combined into the film-forming substrate. The incorporation of RCAE resulted in the increase of thermal stability, opacity and surface hydrophobicity of films. Meanwhile, the GG/RCAE-0.2 film exhibited stronger tensile strength and excellent color stability at 4℃. The color changes of GG/RCAE-0.2 film were visually easier to distinguish during the storage of mushroom. The results showed the GG/RCAE films could be used as pH-freshness smart labels to detect the freshness of fruits and vegetables.

A novel anthocyanin indicator film with rosmarinic acid copigmentation having enhanced stability and pH indicator ability for monitoring pork freshness

BACKGROUND

Anthocyanin-based pH-sensing films have been widely fabricated for potential application in monitoring food freshness. However, the color fading of anthocyanins limits their application for the food industry due to their low stability. In addition, the color sensitivity and pH indicator ability of anthocyanin-based films currently available are not satisfied and need to be improved.

RESULTS

Chitosan/xanthan gum (CX)-based colorimetric films with addition of purple cabbage anthocyanin (PAN) and different amounts of rosmarinic acid (RA) were fabricated. RA copigmentation in chitosan/xanthan gum-purple cabbage anthocyanin-rosmarinic acid (CX-P-RA) films significantly improved the stability and pH response sensitivity of PAN, and the combined copigmentation of RA and xanthan gum exhibited an additive effect. The addition of RA significantly improved the tensile strength and elongation at break, thermal stability, antioxidant and antibacterial activities of CX-P-RA films. Moreover, addition of RA enhanced the pH sensitivity and colorimetry of CX-P-RA films, which exhibited a good response to different pH values. CX-P-RA2 film was tested to monitor the freshness of pork. It showed visible color changes during the storage of pork. In addition, the ∆E of CX-P-RA2 film was highly correlated with changes in total volatile basic nitrogen in pork (R2  = 0.951).

CONCLUSION

These results indicated that CX-P-RA2 film can be used as a pH-sensing indicator with good stability and high sensitivity for real-time monitoring of pork freshness. © 2023 Society of Chemical Industry.

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.

Smart and UV-Resistant Edible Coating and Films Based on Alginate, Whey Protein, and Curcumin

In this work, smart edible coating and films with excellent UV barrier properties were prepared from alginate, whey protein isolate, and curcumin. The primary focus of this investigation centered on assessing the impact of whey protein and curcumin on the physical and functional properties of the alginate films. Whey protein reduced the film transparency while simultaneously enhancing the hydrophobicity and antioxidant properties of the alginate film. Curcumin imparted a yellow hue to the film, consequently decreasing the transparency of the film. It also substantially improved hydrophobicity, antioxidant activity, and UV-blocking efficiency within the films. Remarkably, curcumin demonstrated a significant reduction in the water vapor transmission rate of the film. For the preservation of apples, a higher concentration of curcumin was required, which effectively suppressed the respiration rate and moisture loss post-harvest, resulting in an extended shelf-life for the apples. As a result, the coated apples exhibited significantly reduced enzymatic browning and weight loss in comparison to their uncoated counterparts. Furthermore, these curcumin-containing films underwent a reversible color change from orange to red when exposed to ammonia vapor. This attribute highlights the potential of the developed coating and film as a smart, active food packaging solution, particularly for light-sensitive food products.

Exploring novel organocatalytic-acetylated pea starch blends in the development of hot-pressed bioplastics

Acetylated starch shows enhanced thermal stability and moisture resistance, but its compatibilization with other more hydrophilic polysaccharides remains poor or unknown. In this study, the feasibility of thermomechanically compounding organocatalytically acetylated pea starch (APS), produced at two different degrees of substitution with alkanoyl groups (DSacyl, 0.39 and 1.00), with native pea starch (NPS), high (HMP) and low methoxyl (LMP) citrus pectin, and sugar beet pectin (SBP, a naturally acetylated pectin) for developing hot-pressed bioplastics was studied. Generally, APS decreased hydrogen bonding (ATR-FTIR) and crystallinity (XRD) of NPS films at different levels, depending on its DSacyl. The poor compatibility between APS and NPS or HMP was confirmed by ATR-FTIR imaging. Contrariwise, APS with DSacyl 1 was effectively thermomechanically mixed with the acetylated SBP matrix, maintaining homogeneous distribution within it (ATR-FTIR imaging). APS (any DSacyl) significantly increased the visible/UV light opacity of NPS-based films and decreased their water vapor transmission rate (WVTR, by ca. 11 %) and surface water wettability (by ca. 3 times). In comparison to NPS-APS films, pectin-APS showed higher visible/UV light absorption, tensile strength (ca.2.9-4.4 vs ca.2.4 MPa), and Young's modulus (ca.96-116 vs ca.60-70 MPa), with SBP-APS presenting significantly lower water wettability than the rest of the films.

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.

Impact of soybean protein isolate concentration on chitosan-cellulose nanofiber edible films: Focus on structure and properties

Chitosan and cellulose nanofiber films are frequently employed as biodegradable materials for food packaging. However, many exhibit suboptimal hydrophobicity and antioxidant properties. To address these shortcomings, we enhanced the performance by adding different concentrations of soybean protein isolate (SPI) to chitosan-cellulose nanofiber (CS-CNF) films. As SPI concentration varied, the turbidity, particle size, and ζ-potential of the film-forming solutions initially decreased and subsequently increased. This suggests that 1 % SPI augments the electrostatic attraction and compatibility. Rheological analysis confirmed a pronounced apparent viscosity at this concentration. Analyses using Fourier transform infrared spectra, Raman spectra, X-ray diffraction, and Scanning electron microscope revealed the presence of hydrogen bonds and electrostatic interactions between SPI and CS-CNF, indicative of superior compatibility. When SPI concentration was set at 1 %, notable enhancements in film attributes were observed: improvements in tensile strength and elongation at break, a reduction in water vapor permeability by 8.23 %, and an elevation in the contact angle by 18.85 %. Furthermore, at this concentration, the ABTS+ and DPPH scavenging capacities of the film surged by 61.53 % and 46.18 %, respectively. Meanwhile, the films we prepare are not toxic. This research offers valuable insights for the advancement and application of protein-polysaccharide-based films.

On-site colorimetric food spoilage monitoring with smartphone embedded machine learning

Real-time and on-site food spoilage monitoring is still a challenging issue to prevent food poisoning. At the onset of food spoilage, microbial and enzymatic activities lead to the formation of volatile amines. Monitoring of these amines with conventional methods requires sophisticated, costly, labor-intensive, and time consuming analysis. Here, anthocyanins rich red cabbage extract (ARCE) based colorimetric sensing system was developed with the incorporation of embedded machine learning in a smartphone application for real-time food spoilage monitoring. FG-UV-CD100 films were first fabricated by crosslinking ARCE-doped fish gelatin (FG) with carbon dots (CDs) under UV light. The color change of FG-UV-CD100 films with varying ammonia vapor concentrations was captured in different light sources with smartphones of various brands, and a comprehensive dataset was created to train machine learning (ML) classifiers to be robust and adaptable to ambient conditions, resulting in 98.8% classification accuracy. Meanwhile, the ML classifier was embedded into our Android application, SmartFood++, enabling analysis in about 0.1 s without internet access, unlike its counterpart using cloud operation via internet. The proposed system was also tested on a real fish sample with 99.6% accuracy, demonstrating that it has a great advantage as a potent tool for on-site real-time monitoring of food spoilage by non-specialized personnel.

Development of seaweed-derived polysaccharide/cellulose nanocrystal-based antifogging labels loaded with alizarin for monitoring aquatic products' freshness

Intelligent freshness indicator labels have attracted great interest for their massive potential in monitoring the freshness of aquatic products over the years. However, there is still a challenge where fogging on the labels during dramatic temperature changes affects the reading of freshness. At the same time, the freshness indicator labels need high mechanical strength to resist collision damage during transportation and storage. Herein, an antifogging freshness indicator label was developed based on seaweed extracts and alizarin. Firstly, soluble polysaccharides and insoluble components were extracted from Gelidium amansii, and cellulose nanocrystal (CNC) was further prepared from the insoluble components by sulfuric acid hydrolysis. Subsequently, a polysaccharide-based film was fabricated using soluble polysaccharides as the matrix materials and CNC as the reinforcement agent. Antifogging experiments showed that the hydrophilic composite films presented good antifogging performance. After loading with alizarin, the composite indicator label exhibited both antifogging and freshness-indicating properties for the salmon sample. The work provided a new idea for developing freshness indicator labels suitable for low-temperature transportation and storage.

Preparation and characterization of smart indicator films based on gellan gum/modified black rice anthocyanin/curcumin for improving the stability of natural anthocyanins

In order to improve the stability of natural anthocyanins in intelligent packaging materials, this work first modified black rice anthocyanins (BRA) by acylation with acetic acid, then modified the acylated BRA by co-coloring with different ratios of curcumin (CUR), and finally added the mixed indicator to gellan gum (GG) to develop intelligent packaging films with good stability. The UV spectroscopy results showed that acetic acid had successfully modified the BRA, while the thermal, photostability and pH stability of the modified black rice anthocyanin (MBRA) were significantly enhanced. The indicators of BRA, MBRA and MBRA mixed with CUR showed excellent pH sensitivity in different buffer solutions. The SEM, FT-IR and XRD results indicated apparent crystalline aggregates on the surface of the films added with a high concentration of CUR. Compared with GG-BRA film, GG-MBRA film improved all properties except for antioxidant performance. Notably, the GG-MBRA/CUR series composite films exhibited significant improvements over the GG-BRA and GG-MBRA films in terms of optical characteristics, mechanical properties, water vapor barrier, oxidation resistance, and color stability; meanwhile, all films exhibited excellent pH sensitivity. Considering all the properties of the films, GG-MBRA/CUR3 film has tremendous potential as a smart indicator film for improving freshness accuracy.

Modification methods, biological activities and applications of pectin: A review

Pectin is a complex and functionally rich natural plant polysaccharide that is widely used in food, medical, and cosmetic industries. It can be modified to improve its properties and expand its applications. Modification methods for natural pectin can be divided into physical, chemical, enzymatic, and compound methods. Different modification methods can result in modified pectins (MPs) exhibiting different physicochemical properties and biological activities. The objectives of this paper were to review the various pectin modification methods explored over the last decade, compare their differences, summarize the impact of different modification methods on the biological activity and physicochemical properties of pectin, and describe the applications of MPs in food and pharmaceutical fields. Finally, suggestions and perspectives for the development of MPs are discussed. This review offers a theoretical reference for the rational and efficient processing of pectin and the expansion of its applications.

Intelligent double-layer polymers based on carboxymethyl cellulose-cellulose nanocrystals film and poly(lactic acid)-Viola odorata petal anthocyanins nanofibers to monitor food freshness

The present study was conducted with the aim of fabricating smart bilayer polymers based on carboxymethyl cellulose-cellulose nanocrystals film and poly(lactic acid)-Viola odorata extract nanofibers (CMC-CNC and PLA-VOE) for freshness monitoring of Pacific white shrimps, minced lamb meat, chicken fillets, and rainbow trout fillets, during refrigerated storage conditions. The fabricated indicators based on CMC-PLA-VOE 5%, CMC-CNC 1%-PLA-VOE 5%, and CMC-CNC 3%-PLA-VOE 5% presented remarkable color changes in pH 1-12 buffer solutions, including red at pH 1-6, violet at pH 7-8, green at pH 9-10, and brown at pH 11-12. Significantly lower water vapor permeability and oxygen transmission rate of prepared polymers were found in comparison with the control groups (P < 0.05). Regarding the monitoring of food samples in real-time, the samples spoiled after 3 days, evidenced by total viable count, psychrotrophic bacterial count, total volatile basic nitrogen, and pH values of 7.17-7.54 log CFU/g, 5.68-6.23 log CFU/g, 25.14-28.12 mg N/100 g, and 7.10-7.66, respectively. Meanwhile, the noticeable color change of prepared indicators from white to violet (day 3) and finally dark violet (day 7) was observed, indicating a potential application in intelligent packaging for real-time control of the freshness of perishable food samples.

Colorimetric pH indicators based on well-defined amylose and amylopectin matrices enriched with anthocyanins from red cabbage

This study aimed to prepare a novel colorimetric indicator film from virtually pure (99 %) amylose (AM) and anthocyanins extracted from red cabbage (RCA). The AM used was a unique engineered bulk material extracted from transgenic barley grains. Films produced by solution casting were compared to normal barely starch (NB) and pure barley amylopectin (AP), with amylose contents of 30 % and 0 %, respectively. The pH-indicator films were produced by incorporation of RCA into the different starch support matrices with different amylose contents. Barrier, thermal, and mechanical properties, photo degradation stability, and release behavior data revealed that RCA interact differently through the glucan matrices. Microstructural observations showed that RCA were evenly dispersed in the glucan matrix, and AM+RCA indicator films showed high UV-barrier and mechanical performance over normal starch. FTIR revealed that RCA was properly affected by the AM matrix. Moreover, the AM+RCA films showed sensitive color changes in the pH range (2-11) and a predominant Fickian diffusion release mechanism for RCA. This study provides for the first time data regarding AM films with RCA and their promising potential for application as support matrices in responsive food and other industrial biodegradable packaging materials.

Role of biotechnology in the advancement of biodegradable polymers and functionalized additives for food packaging systems

Biodegradable polymers have shown enormous potential for application in food packaging systems and offer solutions to mitigate the challenges of single-use plastics. Over the past decade, advances in fermentation technology, metabolic engineering of microorganisms, and synthetic biology have enabled the optimization and functionalization of biodegradable polymers for food packaging application. This article provides an overview of the biotechnological approaches/methods used in advancing the production of biopolymers and summarizes the recent developments in the application of functionalized biopolymers for decision-making and quality control. It discusses the current applications and future perspectives of extracellular biopolymers in food systems. Finally, this review highlights the complexities of public acceptance, safety, and government regulations and legislations.