A novel pH-sensing indicator based on bacterial cellulose nanofibers and black carrot anthocyanins for monitoring fish freshness

A simple optical pH sensor based on pectin and Ruellia tuberosa L-derived anthocyanin for fish freshness monitoring

A simple optical pH sensor using the active compound anthocyanin (ACN), derived Ruellia tuberosa L. flower immobilized in a pectin membrane matrix, was been fabricated and employed to monitor the freshness of tilapia fish at room temperature and 4 oC storage. The optimum pectin weight and ACN concentrations were 0.1% and 0.025 mg/L. The sensor showed good sensitivity at 0.03 M phosphate buffer solution. The sensor's reproducibility was evaluated using 10 replicate sensors where a standard deviation of 0.045 or relative standard deviation of 9.15 was achieved. The sensor displayed an excellent response after 10 minutes of exposure, possessing a response stability for 10 consecutive days. The decrease in pH value of the Tilapia fish from 7.3 to 5 was observed in a 48 hour test, which can be used as the parameter when monitoring fish freshness.

A simple optical pH sensor based on pectin and Ruellia tuberosa L-derived anthocyanin for fish freshness monitoring

A simple optical pH sensor using the active compound anthocyanin (ACN), derived Ruellia tuberosa L. flower immobilized in a pectin membrane matrix, was been fabricated and employed to monitor the freshness of tilapia fish at room temperature and 4 oC storage. The quantitative pH values were measured based on the UV-Vis spectroscopy absorbance. The optimum pectin weight and ACN concentrations were 0.1% and 0.025 mg/L. The sensor showed good sensitivity at 0.03 M phosphate buffer solution. The sensor's reproducibility was evaluated using 10 replicate sensors where a standard deviation of 0.045 or relative standard deviation of 9.15 was achieved. The sensor displayed an excellent response after 10 minutes of exposure, possessing a response stability for 10 consecutive days. The decrease in pH value of the Tilapia fish from 7.3 to 5 was observed in a 48 hour test, which can be used as the parameter when monitoring fish freshness. Overall, this reported optical pH sensor has a novelty as it could be used to monitor the rigor mortis phase of fish meat, which is useful in food industry.

Glycerol-Based Dendrimer Nanocomposite Film as a Tunable pH-Sensor for Food Packaging

Large amounts of food are wasted during the food supply chain. This loss is in part due to consumer confusion over dates on food packages that can indicate a variety of quality indicators in the product (e.g., expiration date, "best by" date, "sell by" dates, etc.). To reduce this food loss, much research has been focused on the films that offer simple and easily manipulated indication systems to detect food spoilage. However, these materials are usually hydrophilic biopolymers that can detect the food spoilage in a wide pH range but do not provide highly sensitive real-time measurements. In this work, a glycerol-based nanocomposite core-shell latex film was synthesized to create a responsive packaging material that can provide real-time pH detection of food with high sensitivity. First, the pH-responsive dendrimer comonomer was synthesized from glycerol and diamine. Then, the nanoencapsulation polymerization process via miniemulsion was conducted to form a core-shell structure with tunable nanoshell thickness for a sensible pH-responsive release (<0.5 pH change). Next, the flexible film encapsulated a color-indicative dye that provided highly sensitive and visible color changes as both the pH dropped and the time elapsed in the food. This film also provided a barrier to water and heat and resisted deformation. Ultimately, this nanocomposite flexible film pending a pH sensor has the potential as an intelligent food packaging material for a universal, accurate, easy-to-use, and real-time food spoilage monitoring system to reduce food waste.

Recent Advances in the Development of Smart and Active Biodegradable Packaging Materials

Interest in the development of smart and active biodegradable packaging materials is increasing as food manufacturers try to improve the sustainability and environmental impact of their products, while still maintaining their quality and safety. Active packaging materials contain components that enhance their functionality, such as antimicrobials, antioxidants, light blockers, or oxygen barriers. Smart packaging materials contain sensing components that provide an indication of changes in food attributes, such as alterations in their quality, maturity, or safety. For instance, a smart sensor may give a measurable color change in response to a deterioration in food quality. This article reviews recent advances in the development of active and smart biodegradable packaging materials in the food industry. Moreover, studies on the application of these packaging materials to monitor the freshness and safety of food products are reviewed, including dairy, meat, fish, fruit and vegetable products. Finally, the potential challenges associated with the application of these eco-friendly packaging materials in the food industry are discussed, as well as potential future directions.

Fabrication of halochromic smart films by immobilizing red cabbage anthocyanins into chitosan/oxidized-chitin nanocrystals composites for real-time hairtail and shrimp freshness monitoring

In this study, halochromic smart films were produced, characterized, and applied to monitor the freshness of hairtail and shrimp in real-time. Red cabbage anthocyanins (RCAs) solution illustrated significant color variations (red-pink-blue-green) in different pH environments. RCAs were successfully immobilized into chitosan (CS)/oxidized-chitin nanocrystals (OCN) composites through hydrogen bonding, and cohesive film structures were formed. When the proper concentration of RCAs was incorporated into the composites, improved water vapor permeability (WVP), oxygen permeability (OP), mechanical, UV-blocking, and antioxidant properties were observed. Moreover, the smart films exhibited distinguishable changes of color to ammonia vapor and acidic/alkaline environment within short time intervals, which were easy to discern by naked eyes. Finally, the smart films were applied to monitor the freshness of hairtail (Trichiurus lepturus) and shrimp (Penaeus vannamei). The film color changed significantly during storage time, and three stages of product freshness (fresh, medium fresh, and spoiled) were successfully differentiated. Strong correlations among three freshness indicators and two colorimetric parameters were also identified and analyzed. Overall, the smart system assembled from non-toxic and biodegradable components could contribute to monitoring the freshness of seafood, like hairtail and shrimp, in real-time.

Development and properties of bacterial cellulose, curcumin, and chitosan composite biodegradable films for active packaging materials

To deal with serious environmental damage resulting from plastic packaging materials, biodegradable films using natural products have gained considerable attention. Here, we provide a simple, fast, and environmentally-friendly route to construct a biodegradable film using chitosan (CS), bacterial cellulose (BC), and curcumin (Cur). Composite films (CSn-BC-Cur) using CS with different molecular weights were investigated, and their water moisture content (MC), water solubility (WS), contact angle (CA), mechanical properties, barrier properties, and antioxidant properties were compared. The obtained films were characterized by SEM, XRD, and TGA. The results showed that chitosan with a higher molecular weight presented higher contact angles and mechanical properties, along with a lower moisture content, water vapor transmission rate, and oxygen transmission rate. Furthermore, when the composite film was placed in 95 % ethanol, it released active substances. The results suggest that these composite films can be used as promising materials for food packaging.

The potential of anthocyanins in smart, active, and bioactive eco-friendly polymer-based films: A review

Among the bioactive compounds that are considered important for the food industry, anthocyanins, which are flavonoid compounds presenting antioxidant activity and are responsible for beneficial health effects, have received researchers' attention in the last decades. In addition, anthocyanins are highly reactive and can be used as indicators of foodstuff quality conditions, particularly as a packaging ingredient. Considering this line of work, the eco-friendly film is a novel packaging technology that arose from the concern to reduce non-renewable resources and their impact on the environment. These films can be vehicles for loading bioactive compounds such as anthocyanins. Among the contribution of films in the food industry, we can highlight several potential applications: i) smart film: assess food quality and safety, transmitting food information to consumers and increasing the reliability of their consumption without breaking the packaging; ii) active film: use to preserve food quality through the release of active agents; and iii) bioactive film: carry substances in desired concentrations until their controlled or rapid diffusion within the gastrointestinal tract so that they can promote its benefit to human health. Thus, this review presents anthocyanin extract's potential as a powerful tool to improve the development of eco-friendly films, directing its purpose to the application as smart, active, and bioactive films.

Colorimetric indicator based on purple tomato anthocyanins and chitosan for application in intelligent packaging

Intelligent colorimetric indicator films were prepared to monitor freshness/spoilage of milk and fish by incorporating purple tomato anthocyanin (PTA) into chitosan (CS) matrix via solution casting method with PTA concentration (w/w, based on CS) of 10%, 30%, and 50%, respectively. The pH-response, UV absorption, Swelling Index, and the mechanical properties of CS/PTA films were determined. It was found that the color of the original CS/PTA films became darker with an improvement of PTA content and expressed well pH-sensitivity. With increasing of pH, the color of the CS/PTA films exposed to pH = 3-11 solutions became darker and the change in color of the CS/10% PTA film was the most discernable. The tensile strength and Young's modulus of the CS/PTA film was much lower than that of CS film, however, the elongation at breaking and Swelling Index were both improved by adding PTA. The intelligent films with 10% PTA changed their color during progressive spoilage of milk or fish, revealing their potential application for monitoring food freshness/spoilage.

Preparation of pH-sensitive food packaging film based on konjac glucomannan and hydroxypropyl methyl cellulose incorporated with mulberry extract

A pH-sensitive food packaging film was prepared based on konjac glucomannan (KGM) and hydroxypropyl methyl cellulose (HPMC) incorporated with mulberry extracts² (MBE). FT-IR and XRD analysis revealed that there are good molecular interactions among the three components. The incorporation of MBE into KGM and HPMC (KH) films can significantly improve the mechanical properties and UV resistance. Notably, the KH-MBE-20% film almost completely blocked UV light in the range of 200-600 nm. The best antioxidant and antibacterial properties were obtained when the addition of MBE in the composite film was 20%. In addition, KH-MBE film has good responsiveness to buffers with pH range from 2 to 12. In visual monitoring experiments using the film on fresh fish, the color of the KH-MBE film changed from purple to gray to yellow as the freshness of the fish decreased, and the KH-MBE-20% film had the best color stability. Therefore, intelligent packaging of KH-MBE film has potential applications in real-time monitoring of fish freshness.

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and pKa values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.

Application of Nanotechnology in Wood-Based Products Industry: A Review

Wood-based industry is one of the main drivers of economic growth in Malaysia. Forest being the source of various lignocellulosic materials has many untapped potentials that could be exploited to produce sustainable and biodegradable nanosized material that possesses very interesting features for use in wood-based industry itself or across many different application fields. Wood-based products sector could also utilise various readily available nanomaterials to enhance the performance of existing products or to create new value added products from the forest. This review highlights recent developments in nanotechnology application in the wood-based products industry.

Biotech nanocellulose: A review on progress in product design and today's state of technical and medical applications

Biotech nanocellulose (bacterial nanocellulose, BNC) is a high potential natural polymer. Moreover, it is the only cellulose type that can be produced biotechnologically using microorganisms resulting in hydrogels with high purity, high mechanical strength and an interconnecting micropore system. Recently, the subject of intensive research is to influence this biosynthesis to create function-determining properties. This review reports on the progress in product design and today's state of technical and medical applications. A novel, dynamic, template-based technology, called Mobile Matrix Reservoir Technology (MMR Tech), is highlighted. Thereby, shape, dimensions, surface properties, and nanonetwork structures can be designed in a process-controlled manner. The formed multilayer materials open up new applications in medicine and technology. Especially medical materials for cardiovascular and visceral surgery, and drug delivery systems are developed. The effective production of layer-structured composites and coatings are important for potential applications in the electronics, paper, food and packaging technologies.

Bacterial Nanocellulose-A Biobased Polymer for Active and Intelligent Food Packaging Applications: Recent Advances and Developments

The aim of this review is to provide an overview of recent findings related to bacterial cellulose application in bio-packaging industry. This constantly growing sector fulfils a major role by the maintenance of product safety and quality, protection against environmental impacts that affect the shelf life. Conventional petroleum-based plastic packaging are still rarely recyclable and have a number of harmful environmental effects. Herein, we discuss the most recent studies on potential good alternative to plastic packaging-bacterial nanocellulose (BNC), known as an ecological, safe, biodegradable, and chemically pure biopolymer. The limitations of this bio-based packaging material, including relatively poor mechanical properties or lack of antimicrobial and antioxidant activity, can be successfully overcome by its modification with a wide variety of bioactive and reinforcing compounds. BNC active and intelligent food packaging offer a new and innovative approach to extend the shelf life and maintain, improve, or monitor product quality and safety. Incorporation of different agents BNC matrices allows to obtain e.g., antioxidant-releasing films, moisture absorbers, antimicrobial membranes or pH, freshness and damage indicators, humidity, and other biosensors. However, further development and implementation of this kind of bio-packaging will highly depend on the final performance and cost-effectiveness for the industry and consumers.

Preparation of a shikonin-based pH-sensitive color indicator for monitoring the freshness of fish and pork

A novel intelligent pH-responsive color indicator was prepared by adsorbing a natural naphthoquinone pigment, shikonin, onto cellulose paper. FTIR results indicated that shikonin was crosslinked with the cellulose of the indicator paper. The addition of shikonin increased antioxidant activity, thermal stability, and water resistance properties of the paper. The indicator changed the color from red to dark blue, depending on the pH of buffer solutions. Also, the indicator showed high stability after 4 months of storage and maintained high sensitivity to pH changes. This indicator was used to monitor fish and pork freshness during storage at room temperature, and the results showed a high correlation between the color change of the indicator and the pH change of the sample. The shikonin-adsorbed indicator with stable and sensitive color change depending on pH can be used in the intelligent food packaging applications to monitor the quality of packaged food in real-time.

Application of electrospinning technique in development of intelligent food packaging: A short review of recent trends

Intelligent food packaging refers to packages with the ability to sense foodstuff changes and to inform customers of the packaging content variations. They are often accompanied by smart detecting devices. Providing a suitable platform to include these devices into packaging polymers has always been discussing. Electrospun nanofibers produced through the electrospinning have been recently utilized as an outstanding and novel platforms for this purpose. Thus, the main aim of this study is to investigate recent trends in producing intelligent food packaging using electrospinning technique. In this regard, this paper was categorized into two chief sections, including (a) the principal of electrospinning technique to fabricate fine nanofibers and the parameters affecting the quality of electrospun fibers, and (b) the role of nanofibers as a platform to cover pH indicators in intelligent food packaging.

Anthocyanins from Ocimum sanctum L., a promising biomolecule for development of cost-effective and widely applicable pH indicator

A novel cost-effective and widely applicable pH indicator was developed using anthocyanins extracted from the purple subtype of Ocimum sanctum L. and common lab filter paper. This pH indicator was successfully tested to monitor the pH of a wide range of buffers, solutions, irrigation water, and soil solution. Upon testing, the indicator displayed specific colors at corresponding pH ranges. Sucrose showed a stabilizing effect for the color of the extracted anthocyanins. Further, molecular analysis indicated that the leaves from the purple subtypes showed higher transcripts abundance for chalcone synthase, chalcone isomerase, anthocyanidin synthase, and dihydroflavonol 4-reductase than that of the green subtype. Similarly, transcription factors HY5 and a bHLH putatively involved in the biosynthesis of anthocyanins showed up-regulation in the purple subtype of O. sanctum.

Functional Polymers and Polymer-Dye Composites for Food Sensing

The sensitive, safe, and portable detection of food spoilage is becoming unprecedentedly important because it is closely related to the public health and economic development, particularly given the globalization of food supply chain. However, the existing approaches for food monitoring are still limited to meet these requirements. To address this challenge, much research has been done to develop an ideal food sensor that can indicate food quality in real-time in a sensitive and reliable way. So far, many sensors such as time-temperature indicators, smart trademarks, colorimetric tags, electronic noses, and electronic tongues, have been developed and even commercialized. In this feature article, the recent progress of food sensors based on functional polymers, including the molecular design of polymer structures, sensing mechanisms, and relevant processing techniques to fabricate a variety of food sensor devices is reviewed.

Preparation of on-package halochromic freshness/spoilage nanocellulose label for the visual shelf life estimation of meat

In this work, grape anthocyanins (GA) were embedded in bacterial nanocellulose (BNC) by ex-situ method to fabricate an easy-to-use colorimetric label. The label revealed visible color responses to the pH buffers (2-11). According to the color parameter results [L*, a*, b*, and total color difference (TCD)], the label also presented appropriate color stability during the 60-day storage. During the application in minced beef, the label was bright red on the 1st day of storage at 4 °C. In accordance with the meat quality parameters [TVB-N, total mesophilic count, and sensory attributes], the label turned into purplish-red color on the 3rd and 5th days of storage (medium freshness meat) and turned into blue on the 7th day, representing the spoilage state. All the mentioned color changes could be distinguished by naked eyes. A strong Pearson's correlation coefficient was obtained between the TCD values and meat quality parameters, confirming the capability of the pH-sensing label to correctly distinguish the fresh meat from the spoiled meat.

A smart and active film with tunable drug release and color change abilities for detection and inhibition of bacterial growth

Antimicrobial resistance has become a global issue and thus the development of natural products/biomedical materials composites with antibacterial activities is urgently needed. When acute wounds develop into chronic wounds, the wound environments become alkaline. As long as infections occur, the wound pH further increases, making the wounds difficult to heal. Besides, bacterial growth in poultry, meat, fish and seafood products is usually reflected in a marked increase of pH values. Herein, smart, stimuli responsive self-assembled multilayer and complex film were constructed through the formation of hydrogen bonds and hydrophobic interactions between hydroxypropyl methylcellulose (HPMC) and epigallocatechin-3-gallate (EGCG), thereby greatly reducing the hydrophilicity of HPMC and offering enhanced mechanical strength, superior free radical scavenging capability, and improved water vapor and light barrier properties. The EGCG/HPMC complex film was able to control EGCG release by tuning pH or temperature of the release medium. Furthermore, incorporation of CuS nanoparticles into the film allowed it to triggers EGCG release in an on-demand fashion under near-infrared (NIR) exposure. Bacterial growth in glucose-free nutrient broth medium caused pH to rise (near pH 8.0), leading to transformation of EGCG from phenol type to phenolate ion and then quinone, allowing for spontaneous generation of H₂O₂ to kill bacteria. The complex films changed their color in response to bacterial growth because EGCG transformed from phenol type to quinone type under alkaline condition. The green synthesized EGCG/HPMC complex films can be used as a colorimetric pH indicator and an antibacterial material for wound dressing and food packaging applications.

Anthocyanin food colorant and its application in pH-responsive color change indicator films

Recently, interest in smart packaging, which can show the color change of the packaging film according to the state of the food and evaluate the quality or freshness of the packaged food in real-time, is increasing. As a color indicator, a natural colorant, anthocyanin, drew a lot of attention due to their various colors as well as useful functions properties such as antioxidant activity and anti-carcinogenic and anti-inflammatory effects, prevention of cardiovascular disease, obesity, and diabetes. In particular, the pH-responsive color-changing function of anthocyanins is useful for making color indicator smart packaging films. This review addressed the latest information on the use of natural pigment anthocyanins for intelligent and active food packaging applications. Recent studies on eco-friendly biodegradable polymer-based color indicator films incorporated with anthocyanins have been addressed. Also, studies on the use of smart packaging films to monitor the freshness of foods such as milk, meat, and fish were reviewed. This review highlights the potential and challenges for the use of anthocyanins as pH-responsive color-changing films for intelligent food packaging applications, which may be beneficial for further development of smart color indicator films for practical use.

CMC and CNF-based alizarin incorporated reversible pH-responsive color indicator films

Smart color-changing indicator films were prepared using two different types of cellulose (CMC and CNF) and pH-sensitive dye, alizarin. pH-responsive color indicator films were produced by ionization and deprotonation of hydroxyl groups of alizarin phenolic compounds. The X-ray diffraction pattern of the color indicator film showed a new weak diffraction peak at 2θ = 13°, indicating the semi-crystalline character of alizarin. The indicator film showed UV-vis light screening properties and radical scavenging activity with enhanced thermal stability. The indicator film showed a distinct color change of alizarin from yellow to purple in the pH range of 2-12. In addition, the color indicator film showed stable and reversible color changes even after repeated changes in environmental pH. The pH-responsive color indicator films are likely to be used as an acid or base gas sensor due to the rapid response and reversible color change to the pH change in the packaging environment.

A colorimetric sensor array based on natural pigments for the discrimination of saccharides

A colorimetric sensor array based on natural pigments was developed to discriminate between various saccharides. Anthocyanins, pH-sensitive natural pigments, were extracted from fruits and flowers and used as components of the sensor array. Variation in pH, due to the reaction between saccharides and boronic acids, caused obvious colour changes in the natural pigments. Only by observing the difference map with the naked eye could 11 common saccharides be divided into independent individuals. In conjunction with pattern recognition, the sensor array clearly differentiated between sugar and sugar alcohol with highly accuracy and allowed rapid quantification of different concentrations of maltitol and fructose. This sensor array for saccharides is expected to become a promising alternative tool for food monitoring. The link between anthocyanin and saccharide detection opened a new guiding direction for the application of anthocyanins in foods.

Development of an easy-to-use colorimetric pH label with starch and carrot anthocyanins for milk shelf life assessment

An intelligent freshness indicator was developed by immobilizing anthocyanins of black carrot (ABC) within the starch matrix (total anthocyanins content of 10 mg/100 mL) to monitor freshness/spoilage of milk. The microstructural, spectral, swelling and solubility properties as well as color stability (as a function of time, temperature and light) of the indicator at different pHs were characterized. The incorporation of ABC did not change the swelling index and water solubility. The prepared label showed visible color changes as a function of pH and excellent color stability after one month storage at different conditions. The total color difference (TCD) value of the indicator corresponded to the pH, acidity, and microbial growth of the pasteurized milk. The Pearson correlation coefficient showed a high correlation between TCD and pH (R = -0.979), while a high and positive correlation between TCD and acidity as well as TMC (R = 0.983 and 0.968, respectively) was observed. The developed label can discriminate fresh milk form the milk entered into the initial (TCD: 7.8 after 24 h) and final (TCD: 34.8 after 48 h) steps of spoilage. The fabricated label opens a new perspective to use anthocyanins-incorporated biopolymers in the milk intelligent packaging as a simple and easy-to-use freshness indicator.

A fluorescent biosensor based on catalytic activity of platinum nanoparticles for freshness evaluation of aquatic products

In this study, a fluorescence biosensor based on the peroxidase mimicking activity of platinum nanoparticles (Pt NPs) was fabricated for rapid detection of hypoxanthine (Hx), which is a sensitive indicator of the freshness of aquatic products. The fluorescence intensity of the sensing system had a linear relationship with the concentration of Hx in the range of 8-2500 μM, and the limit of detection was as low as 2.88 μM (S/N = 3). Moreover, benefiting from the excellent selectivity of the biosensor, Hx content in fish, shrimp and squid samples could be quickly detected with good recovery rates (103.94-109.00%). And the Pt NPs used in the biosensor was reusable, which was proved by the recovery rate was only slightly decreased to 91% after three cycles. In addition to the advantages of facile preparation and low cost, the proposed biosensor will be a promising candidate for rapid and convenient freshness evaluation of aquatic products.

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

pH-responsive pectin-based functional films have been prepared by incorporating curcumin and sulfur nanoparticles (SNP). FTIR and SEM results indicated that curcumin and SNP were uniformly dispersed in the pectin to form a well-developed composite film. Addition of curcumin and SNP significantly influenced the surface color and UV-blocking properties of the composite films. The composite films showed a higher water contact angle and thermal stability compared with the neat pectin film, however, the mechanical and water vapor barrier properties did not change significantly. The composite film exhibited antibacterial activity against E. coli and L. monocytogenes, and strong antioxidant activity. When applied to shrimp packaging, the film showed a pH-responsive highly distinctive color change from yellow to orange as the quality of the shrimp changed.

Development of bacterial cellulose/chitin multi-nanofibers based smart films containing natural active microspheres and nanoparticles formed in situ

Nanofiber-based materials have recently gained increasing attention in food packaging, drug delivery, and biomedical applications. In this study, a multi-nanofibers composite film was developed based on bacterial cellulose nanofiber (BCNF)/chitin nanofiber (CNF) hybridization. The nanofibers were responsible for the formation of well-dispersed curcumin (Cur) micro/nanoparticles in the nanocomposite films. The release of Cur from the films were affected by CNF and the sizes of Cur particles formed in situ. The Cur particles reduced tensile strength and increased water vapor permeability of BCNF film. However, CNF improved the mechanical strength and barrier property of the Cur/BCNF/CNF composite film. Moreover, the multi-nanofibers composite film showed excellent dynamic antioxidant capacity and antibacterial activity, as well as was capable to monitor pH change and trace amount of boric acid. Results of this study suggested that the Cur/BCNF/CNF composite film can be used as a smart and active food packaging material.