Development of active and intelligent films based on cassava starch and Chinese bayberry (Myrica rubra Sieb. et Zucc.) anthocyanins

Corncob-derived biodegradable packaging films: A sustainable solution for raspberry post-harvest preservation

Plastic food packaging, with its harmful migration of microplastics and nanoplastics into food, presents significant ecological imbalance and human health risks. In this regard, using food and agricultural byproducts as packaging materials reduces environmental and economic concerns and supports their sustainable management. Herein, cellulosic residue from corncob was employed as a renewable source for developing biodegradable packaging films. It was solubilized in ZnCl2 solution, crosslinked with Ca2+ ions, and plasticized with sorbitol to form films and used to improve the shelf-life of raspberries. The optimized film possesses water vapor permeability, tensile strength, and elongation at break of 1.8(4) x10-10 g-1 s-1 Pa-1, 4.7(1) MPa, and 15.4(7)%, respectively. It displays UV-blocking and antioxidant properties and biodegrades within 29 days at 24% soil moisture. It preserves raspberries for 7 and 5 more days at room temperature and refrigeration conditions, respectively, compared to polystyrene film. Overall, more value addition could be envisioned from agricultural residues to minimize post-harvest losses and food waste through biodegradable packaging, which also aids in mitigating plastic perils.

Transparent, flexible, and eco-friendly starch-based films for reversible optoelectronic noses for food spoilage monitoring in smart packaging

A reversible optoelectronic nose is presented consisting of ten acid-base indicators incorporated into a starch-based film, covering a wide pH range. The starch substrate is odorless, biocompatible, flexible, and exhibits high tensile resistance. This optical artificial olfaction system was used to detect the early stages of food decomposition by exposing it to the volatile compounds produced during the spoialge process of three food products (beef, chicken, and pork). A smartphone was used to capture the color changes caused by intermolecular interactions between each dye and the emitted volatiles over time. Digital images were processed to generate a differential color map, which uses the observed color shifts to create a unique signature for each food product. To effectively discriminate among different samples and exposure times, we employed chemometric tools, including hierarchical cluster analysis (HCA) and principal component analysis (PCA). This approach detects food deterioration in a practical, cost-effective, and user-friendly manner, making it suitable for smart packaging. Additionally, the use of starch-based films in the food industry is preferable due to their biocompatibility and biodegradability characteristics.

Natural colorant incorporated biopolymers-based pH-sensing films for indicating the food product quality and safety

The current synthetic plastic-based packaging creates environmental hazards that impact climate change. Hence, the topic of the current research in food packaging is biodegradable packaging and its development. In addition, new smart packaging solutions are being developed to monitor the quality of packaged foods, with dual functions as food preservation and quality indicators. In the creation of intelligent and active food packaging, many natural colorants have been employed effectively as pH indicators and active substances, respectively. This review provides an overview of biodegradable polymers and natural colorants that are being extensively studied for pH-indicating packaging. A comprehensive discussion has been provided on the current status of the development of intelligent packaging systems for food, different incorporation techniques, and technical challenges in the development of such green packaging. Finally, the food industry and environmental protection might be revolutionized by pH-sensing biodegradable packaging enabling real-time detection of food product quality and safety.

Gelatin/agar pH-indicator film based on cranberry extract loaded with linalool nanoparticle: Survey on physical, antimicrobial, and antioxidant properties

In this study, linalool-nanoparticles (L-NPs) were prepared (encapsulation efficiency was 68.54 %) and introduced pH-indicator film based on cranberry-extract (CEF) to develop multifunctional smart films. XRD analysis and FTIR spectroscopy indicated that cranberry-extract (CE) and L-NPs were uniformly distributed in the gelatin/agar matrix and could change the intermolecular structure of the film. Color change of smart films showed that CE endowed the film with pH-sensitive property. As CE and L-NPs were added to the film, the water contact angle (WCA) was increased from 57.03° to 117.73°, the elongation at break (EAB) was increased from 12.30 % to 34.60 %. Additionally, the introduction of L-NPs enhanced the antioxidant activity (DPPH free radical scavenging rate increased from 26.80 % to 36.35 %) and antibacterial activity (against S. aureus and E. coli) of the smart film, which were verified by its retarding effect on pork spoilage.

Green Synthesis of Ceria Nanoparticles from Cassava Tubers for Electrochemical Aptasensor Detection of SARS-CoV-2 on a Screen-Printed Carbon Electrode

Green synthesis approaches for making nanosized ceria using starch from cassava as template molecules to control the particle size are reported. The results of the green synthesis of ceria with an optimum calcination temperature of 800 °C shows a size distribution of each particle of less than 30 nm with an average size of 9.68 nm, while the ratio of Ce3+ to Ce4+ was 25.6%. The green-synthesized nanoceria are applied to increase the sensitivity and attach biomolecules to the electrode surface of the electrochemical aptasensor system for coronavirus disease (COVID-19). The response of the aptasensor to the receptor binding domain of the virus was determined with the potassium ferricyanide redox system. The screen-printed carbon electrode that has been modified with green-synthesized nanoceria shows 1.43 times higher conductivity than the bare electrode, while those modified with commercial ceria increase only 1.18 times. Using an optimized parameter for preparing the aptasensors, the detection and quantification limits were 1.94 and 5.87 ng·mL-1, and the accuracy and precision values were 98.5 and 89.1%. These results show that green-synthesized ceria could be a promising approach for fabricating an electrochemical aptasensor.

Fabrication of multifunctional ethyl cellulose/gelatin-based composite nanofilm for the pork preservation and freshness monitoring

In this study, an active and intelligent nanofilm for monitoring and maintaining the freshness of pork was developed using ethyl cellulose/gelatin matrix through electrospinning, with the addition of natural purple sweet potato anthocyanin. The nanofilm exhibited discernible color variations in response to pH changes, and it demonstrated a higher sensitivity towards volatile ammonia compared with casting film. Notably, the experimental findings regarding the wettability and pH response performance indicated that the water contact angle between 70° and 85° was more favorable for the smart response of pH sensitivity. Furthermore, the film exhibited desirable antioxidant activities, water vapor barrier properties and also good antimicrobial activities with the incorporation of ε-polylysine, suggesting the potential as a food packaging film. Furthermore, the application preservation outcomes revealed that the pork packed with the nanofilm can prolong shelf life to 6 days, more importantly, a distinct color change aligned closely with the points indicating the deterioration of the pork was observed, changing from light pink (indicating freshness) to light brown (indicating secondary freshness) and then to brownish green (indicating spoilage). Hence, the application of this multifunctional film in intelligent packaging holds great potential for both real-time indication and efficient preservation of the freshness of animal-derived food items.

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.

Enhanced antibacterial properties of polyvinyl alcohol/starch/chitosan films with NiO-CuO nanoparticles for food packaging

Packaging is very important to maintain the quality of food and prevent the growth of microbes. Therefore, the use of food packaging with antimicrobial properties protects the food from the growth of microorganisms. In this study, antibacterial nanocomposite films of polyvinyl alcohol/starch/chitosan (PVA/ST/CS) together with nickel oxide-copper oxide nanoparticles (NiO-CuONPs) are prepared for food packaging. NiO-CuONPs were synthesized by the co-precipitation method, and structural characterization of nanoparticles (NPs) was carried out by XRD, FTIR, and SEM techniques. Composites of PVA/ST/CS, containing different percentages of NPs, were prepared by casting and characterized by FTIR and FESEM. The mechanical properties, diffusion barrier, and thermal stability were determined. The nanoparticles have a round structure with an average size of 6.7 ± 1.2 nm. The cross-section of PVA/ST/CS film is dense, uniform, and without cracks. In the mechanical tests, the addition of NPs up to 1% improved the mechanical properties (TS = 31.94 MPa), while 2% of NPs lowered TS to 14.76 MPa. The fibroblast cells toxicity and the films antibacterial activity were also examined. The films displayed stronger antibacterial effects against Gram-positive bacteria (Staphylococcus aureus) compared to Gram-negative bacteria (Escherichia coli). Furthermore, these films have no toxicity to fibroblast cells and the survival rate of these cells in contact with the films is more than 84%. Therefore, this film is recommended for food packaging due to its excellent mechanical and barrier properties, good antibacterial activity, and non-toxicity.

Multifunctional Sensors Made with Conductive Microframework and Biomass Hydrogel for Detecting Packaging Pressure and Food Freshness

Food packaging detection devices have attracted attention to optimize storage situations and reduce food spoilage. However, low-cost and highly sensitive multifunctional sensors for detecting both food freshness and packaging pressure are still lacking. In this study, a multifunctional sensor was developed consisting of a MXene coated alcohol-soluble polyurethane fiber network (MXene/APU) and composite biohydrogel films made of konjac glucomannan, chitosan, and blueberry anthocyanin (KCB). Based on the pressure sensitivity of MXene/APU and the color changes of KCB in response to pH values, the sensor can detect internal package bulging, external squeezing, and food deterioration. The pressure sensor shows a sensitivity of 1.16 kPa-1, a response time of 200 ms, a wide strain range of 1092%, and stability over multiple loops. The pressure sensor could detect human motion and identify surface morphologies. The excellent sensor performance was attributed to the porous structure and large specific surface area of microfiber networks, conductivity of MXene nanosheets, and protective effect of KCB films coated on the conductive membrane. Besides, the microfluidic blow-spinning method used to prepare microfiber networks showed the advantages of low energy consumption and high production efficiency. Based on the color changes of blueberry anthocyanin loaded in KCB films in response to pH, the sensor realized sensitive spoilage detection of food containing protein. This study provides a new multifunctional food packaging sensing device and a greater understanding of the optimization and application of related devices.

Halochromic smart packaging film based on montmorillonite/polyvinyl alcohol-high amylose starch nanocomposite for monitoring chicken meat freshness

Polyvinyl alcohol (PVA) was blended with high amylose starch (HAS) at a ratio of 3:1, and reinforced with montmorillonite (MMT K10) at different concentrations (1, 2, 5, and 7 % w/w of polymers) and anthocyanins (ANT) to develop an active and smart packaging film. MMT addition enhanced the film's mechanical, barrier, thermal, and water resistance properties. Incorporating ANT extracted from roselle calyx into the optimal nanocomposite film (MMT/PVA-HAS II) increased the films' antioxidant, pH-response, and antibacterial properties. FTIR, XRD, and SEM confirmed the intermolecular interactions and even distribution of ANT and MMT in the film matrix. Release rate of ANT was dependent on type of simulant, with higher rate in aqueous solutions compared to alcoholic/fatty food simulants, and cytotoxicity evaluation proved safety of films for food packaging applications. Storage experiments confirmed the potential applicability of the novel halochromic smart film as a promising candidate for monitoring chicken spoilage under abusive storage conditions.

Development of cassava starch-based films incorporated with phenolic compounds produced by an Amazonian fungus

Drug-release systems have attracted attention over the last few years since they can be used as a substitute for traditional methods of drug delivery. These have the advantage of being directly administered at the treatment site and can maintain the drug at adequate levels for a longer period, thus increasing their efficacy. Starch-based films are interesting candidates for use as matrices for drug release, especially due to starch's non-toxic properties and its biocompatibility. Endophytic fungi are an important source of bioactive molecules, including secondary metabolites such as phenolic compounds with antioxidant activity. In the present study, cassava starch-based films were developed to act as release systems of phenolic compounds with antioxidant activity. The Amazonian endophytic fungus Aspergillus niger MgF2 was cultivated in liquid media, and the fungal extract was obtained by liquid-liquid partition with ethyl acetate. The starch-based films incorporated with the fungal extract were characterized in regards to their physicochemical properties. The release kinetics of the extract from the film and its antioxidant and cytotoxic properties were also evaluated. The films incorporated with the extract presented maximum release after 25 min at 37 °C and pH 6.8. In addition, it was observed that the antioxidant compounds of the fungal extract maintain their activity after being released from the film, and were non-toxic. Therefore, considering the promising physicochemical properties of the extract-incorporated films, and their considerable antioxidant capacity, the films demonstrate great biotechnological potential with diverse applications in the pharmacological and cosmetic industries.

Influence of Epilobium parviflorum Herbal Extract on Physicochemical Properties of Thermoplastic Starch Films

In this study, for the first time, Epilobium parviflorum Schreb. (E, hoary willowherb) aqueous extract was introduced into edible biopolymer films and its influence on physicochemical properties of the final products were investigated. Potato starch was gelatinized in the herbal tea to obtain thermoplastic starch (TPS) films via the casting method. The characterization of the films included mechanical, antioxidative, water (WVTR, contact angle, swelling degree) and UV radiation barrier properties as well as microstructure analysis (SEM). Obtained results indicated that the presence of the extract (rich in phenolic compounds) in the films acted as a co-plasticizer for starch and led to a higher elongation at break, up to 70%, with a parallel increase in tensile strength up to ca. 9 MPa. Moreover, TPS films with E exhibited lower WVTR values and absorption of UV light in comparison with the control TPS film. DPPH scavenging activity of TPS E films immersed in methanol was ca. 92%, and it was related to the release of the extract into liquid media. Novel TPS E films are characterized by multifunctional properties that can be used, e.g., in the active packaging sector.

Preparation and characterization of corn starch-based antimicrobial indicator films containing purple corncob anthocyanin and tangerine peel essential oil for monitoring pork freshness

A novel antibacterial indicator film was prepared by mixing corn starch with tangerine peel essential oil (TEO) Pickering emulsion emulsified by ultrasonic and esterified modified starch (UDSt), and then incorporated with purple corncob anthocyanin (PCA), which was used to monitor the freshness of pork. The results showed that the UDSt can effectively stabilize the TEO emulsion. PCA showed obvious color changes at different pH. With the increase of pH, the color of film changed from red to yellow, and its response to volatile ammonia changed from pink to cyan, showing better response ability. The loading of TEO conferred the film excellent bacteriostatic ability against E. coli and S. aureus. The film also had good ability of light blocking and free radical scavenging. In the process of pork deterioration, the antibacterial indicator film changed from pink to yellow, which was closely related to pork quality and had a good linear indicator correlation. The addition of TEO reduced the release of PCA in the antibacterial indicator film and helped to maintain the functional properties of the film. This type of antibacterial indicator film had considerable application potential in indicating food freshness.

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

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

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

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

Optical Anisotropy and Dimple Formation on Films Formed after Drying of Gelatinized Starch Solution Droplets

We study the microstructures in the drying droplets of gelatinized starch solutions on a flat substrate. Cryogenic scanning electron microscopy studies on the vertical cross-section of these drying droplets for the first time reveal a relatively thinner solid elastic crust of uniform thickness at the free surface, an intermediate mesh region below the crust, and an inner core of a cellular network structure made of starch nanoparticles. We find that the deposited circular films formed after drying are birefringent and azimuthally symmetric with a dimple at their center. We propose that the dimple formation in our sample occurs due to the evaporation-induced stress on the gel network structure in the drying droplet. The polarizing optical microscopic studies show that these films are optically uniaxial at their center and increasingly biaxial away from the center.

Development of intelligent and active potato starch films based on purple corn cob extract and molle essential oil

The present study aims to develop of an active and "intelligent" film that uses potato starch as a polymeric matrix, anthocyanins from purple corn cob as a natural dye, and molle essential oil as an antibacterial compound. The color of anthocyanin solutions is pH-dependent, and the developed films shows a visual color change from red to brown after immersion in solutions with pH values ranging from 2 to 12. SEM and FTIR analyses suggested that anthocyanins have favorable dispersibility and good compatibility with the starch-glycerol matrix. The study found that both anthocyanins and molle essential oil significantly enhanced the ultraviolet-visible light barrier performance; moreover, tensile strength, elongation at break, and elastic modulus reached values of 3.21 MPa, 62.16 %, and 12.87 MPa, respectively. The biodegradation rate in vegetal compost also accelerated during the three-week period, achieving a weight loss of 95 %. Moreover, the film presented an inhibition halo for Escherichia coli, indicating its antibacterial activity. The results suggest that the developed film has the potential to be used as food-packaging material.

A mechanically robust biodegradable bioplastic of citric acid modified plasticized yam starch with anthocyanin as a fish spoilage auto-detecting smart film

The current scenario of environmental pollution caused by non-biodegradable plastic and depleting non-renewable resources has called upon the need for biodegradable bioplastic production from renewable resources. Starch bioplastics production from underutilized sources is a viable option for packaging materials that are non-toxic, environmentally benign, and easily biodegradable under disposed conditions. Pristine bioplastic production results in some undesirable qualities and hence requires further modification in order to elevate its potential applicability in real-world scenarios. In this work, yam starch was extracted from a local variety of yams through an eco-friendly and energy-efficient process which was further utilized for bioplastic production. The produced virgin bioplastic was subjected to physical modification through the introduction of plasticizers such as glycerol, while citric acid (CA) was employed as modifier in order to produce the desired starch bioplastic film. The different compositions of starch bioplastics were analyzed for their mechanical properties and maximum tensile strength of 24.60 MPa was observed as the best possible experimental result. The biodegradability feature was further highlighted through soil burial test. Apart from their general function of preservation and protection, the produced bioplastic can be employed for pH-sensitive food spoilage detection through the minute introduction of plant-derived anthocyanin extract into it. The produced pH-sensitive bioplastic film showed distinct changes in color upon an extreme change in the pH value and hence has potential to be used as a smart food packaging material.

Purple red rice bran anthocyanins reduce the digestibility of rice starch by forming V-type inclusion complexes

Purple red rice bran, a by-product of the rice polishing process, contained abundant anthocyanins. However, most of them were discarded resulting in a waste of resources. This study investigated the effects of purple red rice bran anthocyanin extracts (PRRBAE) on the physicochemical properties and digestive properties of rice starch and its mechanism of action. Infrared spectroscopy and X-ray diffraction indicated that PRRBAE could interact with rice starch through non-covalent bonds to form intrahelical V-type complexes. The DPPH and ABTS⁺ assays showed that PRRBAE could confer better antioxidant activity on rice starch. In addition, the PRRBAE could increase the resistant starch content and decrease the enzyme activities by changing the tertiary and secondary structure of starch-digesting enzymes. Further, molecular docking suggested that aromatic amino acids play a key role in the interaction of starch-digesting enzymes with PRRBAE. These findings will contribute to a better understanding of the mechanism of PRRBAE reducing starch digestibility, and to the development of high value-added products and low glycemic index (GI) foods.

Cassava starch films for food packaging: Trends over the last decade and future research

Cassava starch is one of the most available and cost-effective biopolymers. This work aimed to apply a bibliometric methodology to identify the most impactful scientific data on cassava starch and its residues for food packaging in the last ten years. As a result, an increasing interest in this subject has been observed, mainly in the past five years. Among the 85 selected scientific publications, Brazil and China have been leading the research on starch-based films, accounting for 39 % of the total. The International Journal of Biological Macromolecules was the main scientific source of information. Besides cassava starch, 41.18 % of these studies added other biopolymers, 5.88 % added synthetic polymers, and 4.71 % added a combination of both. Studies analyzed suggested that different modifications in starch can improve films' mechanical and barrier properties. In addition, 52.94 % of articles evaluated the film's bioactivity. Still, only 37.65 % assessed the performance of those films as food packaging, suggesting that more studies should be conducted on assessing the potential of these alternative packages. Future research should consider scale-up methods for film production, including cost analysis, assessment life cycle, and the impact on the safety and quality of a broader range of foods.

Antimicrobial Activity of Chitosan/Gelatin/Poly(vinyl alcohol) Ternary Blend Film Incorporated with Duchesnea indica Extract in Strawberry Applications

Chitosan (CTS)/gelatin (GEL)/poly(vinyl alcohol) (PVA)-based composite films with different concentrations of Duchesnea indica extract (DIE) (6.25 and 25 mg/mL), an antimicrobial agent, were manufactured using a casting technique. Results indicated that elongation at break decreased as DIE was added at higher concentrations. Composite films showed no significant differences in thickness, tensile strength, and water vapor permeability. Scanning electron microscopy images revealed that DIE was successfully incorporated into film matrices to interact with polymers. The addition of DIE to the film inhibited the growth of S. aureus by up to 4.9 log CFU/mL. The inhibitory effect on S. aureus using DIE-incorporated coating applied to strawberries was greatest at room temperature storage for 24 h only when it was coated twice or more. The maximum inhibition in strawberries was 2.5 log CFU/g when they were coated twice and 3.2 log CFU/g when they were coated three times. The results of this study suggest that DIE could be used as a natural antimicrobial agent, and DIE-integrated CTS/GEL/PVA films or coatings have potential as a food packaging alternative for preventing foodborne pathogen contamination.

Fabrication and Characterization of Intelligent Multi-Layered Biopolymer Film Incorporated with pH-Sensitive Red Cabbage Extract to Indicate Fish Freshness

This study aimed to fabricate an intelligent monolayer and multi-layered biodegradable films incorporated with red cabbage extract (RCE) to act as a safe and reliable freshness indicator. A film-forming solution (FFS) of gelatin, carboxymethyl cellulose (CMC) and chitosan was prepared and fortified with 0.5% (w/v) of RCE for developing intelligent monolayer films. The intelligent multi-layer film was prepared via layer by layer casting of gelatin, chitosan (added with 0.5% of RCE) and CMC biopolymers. The thickness of the multi-layered film was the highest (0.123 ± 0.001 mm) compared to gelatin-, CMC- and chitosan-based monolayer films (p < 0.05). Chitosan film has the highest tensile strength (p < 0.05), followed by multi-layer, CMC and gelatin films. Elongation at break was slightly higher in CMC (35.67 ± 7.62%) compared to the multi-layer film (33.12 ± 9.88%) and gelatin film (p > 0.05). Water vapor permeability was higher in the multi-layer film (1.244 ± 0.05 × 10−5 g mm h−1cm−2 P−1) than the other monolayer films. Moisture content was highest in chitosan film followed by the multi-layered film (p < 0.05) and then the CMC and gelatin films. CMC film showed the highest solubility compared to multi-layered and chitosan film (p < 0.05). Additionally, transmittance and transparency values in the multi-layered film were the lowest compared to the chitosan-, CMC- and gelatin-based films. L* and a* values were the lowest, while b* values increased in the multi-layered film compared to the other film samples (p < 0.05). pH sensitivity and ammonia gas tests revealed similar color changes in chitosan and multi-layer films. However, FTIR spectra confirmed that dye leaching was not detected for the multi-layered film soaked in ethanol. The biodegradability test showed rapid degradation of multi-layered and chitosan films within 1 month. Based on the optimum results of the multi-layered film, it was applied to monitor the fresh quality of tilapia fish fillets at 4 °C for 10 days. The results of freshness acceptability were noted on day 6 due to the change in color of the multi-layer film with an estimated total volatile basic nitrogen content of 21.23 mg/100 g. Thus, the multi-layered film can be used as an indicator to monitor the quality of the fish freshness without leaching dye onto the food surface.

Development of Shrimp Freshness Indicating Films by Embedding Anthocyanins-Rich Rhododendron simsii Flower Extract in Locust Bean Gum/Polyvinyl Alcohol Matrix

Freshness indicating films containing anthocyanins are one type of smart packaging technology. Anthocyanins in the films can show visual color changes when food spoilage occurs, thereby indicating the freshness degree of food in real-time. Rhododendron simsii is a landscape plant with attractive flowers that are abundant in anthocyanins. In this study, smart packaging films were prepared by embedding 2% and 4% R. simsii flower anthocyanins (RA) in locust bean gum- (LBG) and polyvinyl alcohol- (PVA) based matrices. The micro-structure, barrier, mechanical, thermal, antioxidant, and color-changeable properties of the films were determined. The potential application of the films in indicating the freshness of shrimp at 4 °C was also investigated. Results showed that the RA interacted with the LBG/PVA matrices through hydrogen bonds, which significantly improved the barrier, mechanical, thermal, antioxidant, pH-sensitive, and ammonia-sensitive properties of the films. Meanwhile, the performance of the films was remarkably influenced by the content of the RA. The film containing 4% RA had the highest light blocking ability, tensile strength (38.32 MPa), elongation at break (58.18%), and antioxidant activity, and also showed the lowest water vapor permeability (22.10 × 10^-11 g m^-1 s^-1 Pa^-1) and oxygen permeability (0.36 cm³ mm m^-2 day^-1 atm^-1). The films containing 2% and 4% RA could effectively change their colors when the level of total volatile basic nitrogen in the shrimp exceeded the safe value, which demonstrated the suitability of the films for indicating the freshness degree of shrimp.

Shikonin Functionalized Packaging Film for Monitoring the Freshness of Shrimp

A shikonin embedded smart and active food packaging film was produced using a binary mixture of gelatin and cellulose nanofiber (CNF). Shikonin is an alcohol-soluble natural pigment extracted from Lithospermum erythrorhizon root. The fabricated film showed good pH-responsive color changes and volatile gas sensing properties. Moreover, the film exhibited excellent antioxidant and antibacterial activity against foodborne pathogens. The shikonin incorporated gelatin/CNF-based film showed excellent UV-light barrier properties (>95%) and high tensile strength (>80 MPa), which is useful for food packaging. The hydrodynamic properties of the film were also slightly changed in the presence of shikonin, but the thermal stability and water vapor permeability remained unaffected. Thus, the inclusion of shikonin in the gelatin/CNF-based film improves not only the physical properties but also the functional properties. The film’s color indicator properties also clearly show shrimp’s freshness and spoilage during storage for 48 h. The shikonin-based functional film is expected to be a promising tool for multi-purpose smart and active food packaging applications.

Preparation and characterization of an intelligent film based on fish gelatin and Coleus scutellarioides anthocyanin to monitor the freshness of rainbow trout fish fillet

In this study, a pH-sensitive indicator based on fish gelatin and Coleus scutellarioides anthocyanin extract (CSAE) was prepared and characterized. Films were prepared using the solvent casting method and different levels of CSAE, including 10 ml (CSG1), 20 ml (CSG2), and 30 ml (CSG3), and 0 ml (CSG0) as a control sample. The mechanical, optical, and pH sensing of active films and the release of anthocyanins from the films were investigated. The relationship between the total volatile basic nitrogen (TVB-N) of fish fillets and a* color index of films was studied. By incorporation of CSAE, the flexibility of films increased, while the tensile strength and UV-Vis light transmittance through the films decreased (p < .05). The films containing the CSAE had a darker, yellowish, and reddish color than the control film. There was a significant relationship between the pH variation and the film color. The films had a purple color at acidic pH, and their color changed to green at an alkaline pH, indicating the sensitivity of the produced films to pH changes. There was a significant relationship between the TVB-N value of fish fillets and the a* index of the film during the 16 h storage time. The results showed that by increasing TVB-N values of the fillets, the a* color index decreased, and the films' color changed from purple to colorless. In summary, the active films prepared with fish gelatin and CSAE could be used as pH-sensitive intelligent packaging to display the freshness of fishery products.

Characterisation and Colour Response of Smart Sago Starch-Based Packaging Films Incorporated with Brassica oleracea Anthocyanin

To meet the need for food products to be safe and fresh, smart food packaging that can monitor and give information about the quality of packaged food has been developed. In this study, pH-sensitive films with sago starch and various anthocyanin concentrations of Brassica oleracea also known as red cabbage anthocyanin (RCA) at 8, 10, 12, and 14% (w/v) were manufactured using the solvent casting process. Investigation of the physicochemical, mechanical, thermal, and morphological characteristics of the films was performed and analysed. The response of these materials against pH changes was evaluated with buffers of different pH. When the films were exposed to a series of pH buffers (pH 3, 5, 9, 11, and 13), the RCA-associated films displayed a spectacular colour response. In addition, the ability of the starch matrix to overcome the leaching and release of anthocyanins was investigated. Higher concentrations of RCA can maintain the colour difference of films after being immersed in a series of buffer solutions ranging from acidic to basic conditions. Other than that, incorporating RCA extracts into the starch formulation increased the thickness whereas the water content, swelling degree, tensile strength, and elongation at break decreased as compared to films without RCA. The immobilisation of anthocyanin into the film was confirmed by the FTIR measurements. The surface patterns of films were heterogeneous and irregular due to the presence of RCA extract aggregates, which increased as the extract concentration enhanced. However, this would not affect the properties of films. An increase in thermal stability was noted for the anthocyanin-containing films at the final stage of degradation in TGA analysis. It is concluded that RCA and sago starch formulation has great potential to be explored for food packaging purposes.

Characterization of electrospun nanofibers and solvent-casted films based on Centaurea arvensis anthocyanin-loaded PVA/κ-carrageenan and comparing their performance as colorimetric pH indicator

In this research, PVA/Ҡ-carrageenan-based colorimetric indicators incorporated with Centaurea arvensis anthocyanin (CAE) were fabricated by two electrospinning and solvent casting methods and their performance as pH indicators were assessed. Chemical immobilization of CAE on PVA and PVA/Ҡ-carrageenan matrixes was approved by FT-IR analysis. According to SEM images, Ҡ-carrageenanaddition improved the homogeneity of films and decreased the diameter of nanofibers. The crystalline structure and thermal properties of polymeric matrixes were affected by anthocyanin incorporation. CAE had an adverse effect on mechanical properties of films and nanofibers. The preparation method and type of solid matrix affected the responsiveness and the tonality of responded color. Electrospun nanofibers showed high responsiveness (10 s) than colorimetric films (15-40 min) to pH changes. The indicators displayed color variations from heather violet to green over the 2-12 pH range. The designed indicators have potential to be applied as visual pH label in food intelligent packaging.

Valorization of Berries' Agro-Industrial Waste in the Development of Biodegradable Pectin-Based Films for Fresh Salmon (Salmo salar) Shelf-Life Monitoring

The healthy properties of berries are known; however, red fruits are very perishable, generating large losses in production and marketing. Nonetheless, these wastes can be revalued and used. The main objective of this study was the development of biodegradable pectin films with berry agro-industrial waste extracts to monitor salmon shelf-life. The obtained extracts from blueberries, blackberries, and raspberries wastes were evaluated in terms of flavonols, phenols and anthocyanins contents, and antioxidant capacity. Then, pectin films with the extracts of different berries were developed and characterized. The results showed that the blueberry extract film was thicker (0.248 mm), darker (L* = 61.42), and opaquer (17.71%), while the highest density (1.477 g/cm3) was shown by the raspberry films. The results also showed that blueberries were the best for further application due to their composition in bioactive compounds, antioxidant capacity, and color change at different pHs. The salmon samples wrapped in blueberry films showed lower values of pH and deterioration of fish during storage compared to the control and pectin samples. This study contributes to the valorization of berries agro-industrial waste by the development of eco-friendly films that can be used in the future as intelligent food packaging materials contributing to the extension of food shelf-life as a sustainable packaging alternative.

Fabrication of intelligent/active films based on chitosan/polyvinyl alcohol matrices containing Jacaranda cuspidifolia anthocyanin for real-time monitoring of fish freshness

The present work describes the natural anthocyanin from Jacaranda cuspidifolia (JC) flower immobilized within a biopolymer matrix composed of chitosan (CS) and polyvinyl alcohol (PVA) gave novel intelligent/active packaging films (CPC). We introduced microwave irradiation to prepare polymeric composite films noticed faster mixing of the polymers and extract take place than the conventional method. The prepared composite films are characterized by various analytical and spectroscopic techniques. The smooth SEM images demonstrated CS/PVA matrix miscibility and compatibility with anthocyanin for the film formation. The addition of anthocyanin to the CS/PVA films significantly reduced UV-Vis light transmission, while causing a slight decrease in the films transparency. An increased anthocyanin concentration on polymer films showed improved oxygen permeability (77.09 %), moisture retention capacity (11.64 %), and water vapor transmission rate (43.10 %) substantially. Additionally, the prepared CPC smart films exhibited strong antioxidant (97.92 %) as well as antibacterial activities against common foodborne pathogens such as S. aureus, and E. coli. Furthermore, the prepared smart films demonstrated pink color in acidic, while grey to yellowish in basic solvent. Further, the color response of the freshness label was consistent with the spoilage Total Volatile Basic-Nitrogen (TVB-N) content determined in the fish samples with varied time period. The CPC smart films also showed promising application in terms of monitoring freshness of the fish fillets at room temperature. The obtained results suggested that, the prepared CPC smart films have potential to be used as quality indicator in the marine food packaging system.

Valorization of Starch to Biobased Materials: A Review

Many concerns are being expressed about the biodegradability, biocompatibility, and long-term viability of polymer-based substances. This prompted the quest for an alternative source of material that could be utilized for various purposes. Starch is widely used as a thickener, emulsifier, and binder in many food and non-food sectors, but research focuses on increasing its application beyond these areas. Due to its biodegradability, low cost, renewability, and abundance, starch is considered a "green path" raw material for generating porous substances such as aerogels, biofoams, and bioplastics, which have sparked an academic interest. Existing research has focused on strategies for developing biomaterials from organic polymers (e.g., cellulose), but there has been little research on its polysaccharide counterpart (starch). This review paper highlighted the structure of starch, the context of amylose and amylopectin, and the extraction and modification of starch with their processes and limitations. Moreover, this paper describes nanofillers, intelligent pH-sensitive films, biofoams, aerogels of various types, bioplastics, and their precursors, including drying and manufacturing. The perspectives reveal the great potential of starch-based biomaterials in food, pharmaceuticals, biomedicine, and non-food applications.

Characterization of Natural Anthocyanin Indicator Based on Cellulose Bio-Composite Film for Monitoring the Freshness of Chicken Tenderloin

Intelligent packaging with indicators that provide information about the quality of food products can inform the consumer regarding food safety and reduce food waste. A solid material for a pH-responsive indicator was developed from hydroxypropyl methylcellulose (HPMC) composited with microcrystalline cellulose (MCC). MCC at 5%, 10%, 20%, and 30% w/w was introduced into the HPMC matrix and the physical, barrier, thermal, and optical properties of the HPMC/MCC bio-composite (HMB) films were analyzed. At 5, 10, and 20% MCC, improved mechanical, transparency, and barrier properties were observed, where HMB with 20% of MCC (H20MB) showed the best performance. Therefore, H20MB was selected as the biodegradable solid material for fabricating Roselle anthocyanins (RA) pH sensing indicators. The performance of the RA-H20MB indicator was evaluated by monitoring its response to ammonia vapor and tracking freshness status of chicken tenderloin. The RA-H20MB showed a clear color change with respect to ammonia exposure and quality change of chicken tenderloin; the color changed from red to magenta, purple and green, respectively. These results indicated that RA-H20MB can be used as a biodegradable pH sensing indicator to determine food quality and freshness.

pH indicator films fabricated from soy protein isolate modified with chitin nanowhisker and Clitoria ternatea flower extract

Sensor films are finding wide range of applications. Different type of sensing films is fabricated for the identification of chemicals, ions, heavy metals, changes in the pH, etc. The present report is on the fabrication of pH sensitive films from completely natural sources-soy protein isolate, chitin nano whiskers and flower extract. The highly crystalline chitin nano whiskers (CNW) were extracted from prawn shell under neutral condition via steam explosion technique. Multifunctional Soy protein isolate (SPI) films were prepared by adding chitin nanowhisker and Clitoria ternatea flower extract and its effect on thermal, mechanical and moisture properties of SPI film was investigated. The isolated CNW presented a needle like morphology with a diameter of 10–50 nm and a crystallinity index of 99.67%. The extracted chitin nanowhisker was used to prepare biodegradable films with soy protein isolate immobilized with anthocyanin from Clitoria ternatea flower extract. The prepared Soy protein -chitin nanowhisker films was found to have a tensile strength of about 15.45 ± 0.97 MPa with 8% chitin nanowhisker addition. The addition of CTE was found to decrease the tensile strength of SPI-CNW film but was found to make the film pH sensitive. The developed indicator film showed visible color changes in acidic and basic medium and hence can be used to monitor the freshness of food materials.

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Thin films were fabricated from soy protein isolate, chitin and anthocyanin.

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Packaging films from fully greener and bio origin.

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pH sensing smart films.

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Easy to fabricate and handle.

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Superior mechanical properties and stability.

Intelligent pH-sensing film based on jaboticaba peels extract incorporated on a biopolymeric matrix

Food spoilage is associated with pH change. Thus, the aim of this study was to develop a pH-sensing film based on the addition of anthocyanin extracted from jaboticaba peel to a biopolymeric matrix. UV-Vis spectroscopy analysis of the anthocyanin extract was performed to detect the color change in a broad pH range (1-11). Also, the thermal properties, morphology, moisture content (MC), water solubility (WS), water vapor permeability (WVP) and release test results were examined. The applicability of the pH-sensing film as intelligent packaging was tested by monitoring milk spoilage. Results showed that the film developed has satisfactory thermal stability up to 200 °C. Also, the MC and WVP properties of the film were reduced when the anthocyanin extract was present, 11.5% and 6.5 × 10^-10 g H₂O Pa^- 1 s^-1 m^-1, respectively, while the WS showed an increase (54.33%). Release tests showed remarkable performance in simulated alcoholic and fatty aqueous foods. The food application test demonstrated the potential use of the anthocyanin-based film as a food quality indicator due to film visual color change ( Δ E >10, after 8 days of milk spoilage monitoring).

Smart packaging films based on locust bean gum, polyvinyl alcohol, the crude extract of Loropetalum chinense var. rubrum petals and its purified fractions

Loropetalum chinense var. rubrum is an ornamental shrub rich in polyphenolic compounds. In this study, polyphenolic compounds were extracted from L. chinense var. rubrum petals (LCP) and further purified on macroporous resin column to afford two fractions. The crude extract of LCP (LCP-CE) and its two purified fractions (LCP-25PF and LCP-50PF) were individually incorporated into locust bean gum/polyvinyl alcohol matrix to develop smart packaging films. The structures, physical and functional properties of the films were compared. Results showed LCP-25PF was mainly composed of anthocyanins, while LCP-50PF was mainly composed of chlorogenic acid and vanillin. LCP-CE, LCP-25PF and LCP-50PF interacted with locust bean gum/polyvinyl alcohol matrix through hydrogen bonds, thereby improving the light and oxygen barrier ability, tensile strength, thermal stability, antioxidant activity and antimicrobial activity of the film. The film containing LCP-25PF showed the lowest water vapor permeability (10.36 × 10^-11 g m^-1 s^-1 Pa^-1) and oxygen permeability (0.42 cm³ mm m^-2 day^-1 atm^-1) but the highest tensile strength (29.76 MPa), antioxidant activity and antimicrobial activity. In addition, the films containing LCP-CE and LCP-25PF had pH-/ammonia-sensitivity and effectively indicated shrimp freshness at 4 °C. Results suggested the film containing LCP-25PF could be used as smart packaging film.