Preparation and characterization of active and intelligent packaging films based on cassava starch and anthocyanins from Lycium ruthenicum Murr

Preparation of aldehyde-recognition nanofiber label for monitoring oxidative deterioration in processed meat products

In this study, an oxidation label for the quantitative identification of aldehydes was developed using polyvinyl alcohol (PVA) as the carrier polymer, blueberry anthocyanin (BA) as the chromogenic agent, and hydroxylamine sulfate (HAS) as the coupling agent. Electrospinning technology was employed in this process. Based on aldehyde-specific recognition, the PVA-BA-HAS oxidation label displayed noticeable changes from white to rose pink corresponding to varying degrees of oxidation in processed meat products, with a detection time of less than 1 min. The label showed exceptional morphology and performance, including hydrophobicity, thermal stability, and biocompatibility, etc. Moreover, the assessment of oxidation levels obtained from the PVA-BA-HAS labels were in good agreement with the data measured through POV analysis, confirming practicability of the oxidation label. These results indicated that the prepared oxidation label could be utilized for real-time monitoring of oxidation levels with high accuracy and efficiency, expanding new possibilities for meat quality grading.

Active films incorporated with pequi (Caryocar brasiliense Camb.) or buriti (Mauritia flexuosa L.) oil as strategy to protection of lipid oxidation and carotenoids photodegradation

Pequi (Caryocar brasiliense Camb.) and buriti (Mauritia flexuosa L.) are fruits with potential for extraction of edible vegetable oil with high carotenoid content. The aim of this study was incorporated these oils (5 % or 10 %) into cassava starch-based films and verify their photoprotective effect on pigments and maintenance of lipid oxidative stability. Vegetable oils showed a similar profile for carotenoids, with β-carotene being the major pigment (74-77 %). The hydrophobic character and presence of carotenoids in the oils, led to reduced hydrophilicity of the films, better barrier to UV-visible light transmission and to the plasticizing effect. The active films showed rapid biodegradability in soil (60-70 % after 15 days), in addition to a protective effect against photodegradation of the β-carotene solution by increasing the half-life (t1/2). When applied as packaging for storing corn oil under accelerated oxidation conditions, there was less formation of degradation compounds, which demonstrates potential application as food packaging.

Crosslinked starch/konjac glucomannan active films containing encapsulated thymol for cherry tomatoes preservation

Active films attracted growing interest due to environmental protection and safety of food packaging materials. In this study, we developed cross-linking corn starch/konjac glucomannan active films by incorporating thymol microcapsules (TMs). FTIR, XRD and SEM results indicated the formation of molecular interactions and good compatibility between cross-linking matrixes and TMs. The cross-linking effect with citric acid (CA) significantly reduced the water vapor permeability and swelling rate of the films. Addition of TMs in the composite films improved mechanical property, moisture content, light barrier property and antibacterial activities against E. coli and S. aureus. Additionally, the MCSK4 films effectively reduced weight loss, maintained firmness, and enhanced total phenolic content and total flavonoid content of cherry tomatoes. The synergistic effects of CA and TMs improved the structural and functional properties of composite films, providing a potential application for fruit and vegetable preservation.

A novel bio-based time-temperature dependent colorimetric indicator film incorporated with Amaranthus leaf extract for beef freshness tracking

Leveraging amaranthus leaf extract (ALE) as an indicator, polyvinyl alcohol (P), and citric acid (C) as film fabricating materials, an innovative time-temperature indicator (TTI) for beef freshness tracking film, known as PC-ALE was successfully created. The films were characterized in terms of their kinetic modeling, molecular properties, morphological characterization, and physiochemical properties. Arrhenius model was made by utilizing the colorimetric values of TTI films collected from -10 to 35 °C. The correlation coefficient and activation energy of the fitting model were 0.9467, 0.9399, 0.6886, and 123, 57, 95 kJ.mol-1 for ALE containing films with 0.250, 0.375, and 0.500 g, respectively. However, Fourier transform-infrared spectroscopy spectra showed interactions between the molecules. Mechanical properties of the TTI films showed that the addition of ALE enhanced its tensile strength (99.58 to 139.23 MPa) and elongation at break (151.25 to 216.35 %). Due to its optimal colorimetric response, best-fitting reaction kinetic model (R2 = 0.9399), significant time-temperature sensitivity, and balanced mechanical properties, PC-ALE-0.375 films are the most suitable for monitoring beef freshness.

Multifunctional chitosan-based indicator films containing composite pigments stabilized by extracellular and cell wall polysaccharides from Auricularia cornea var. Li. waste for visualization of salmon freshness

Smart packaging can indicate the meat freshness through color variations of natural pigments within the films, whose instability have hindered their industrial application. This study developed multifunctional indicator films (CS-ACPS-CB) that possessed ultraviolet resistance, antioxidant properties, and pH sensitivity by incorporating extracellular and cell wall polysaccharides from Auricularia cornea var. Li waste (ACPS) into chitosan (CS) matrix with curcumin/betalain as indicators. Results revealed the extracellular component was acidic heteropolysaccharides, while the cell wall comprised glucose, mannose, xylose, rhamnose and galactaric acid. The electrostatic interactions and hydrogen bonding between cell wall polysaccharides and CS strongly stabilized composite pigments, allowing for controlled release at pH above 8.0. Additionally, CS-ACPS-CB demonstrated color changes corresponding to increases in total volatile basic nitrogen values, effectively signaling the progressive spoilage of salmon. These findings offer an environmentally friendly solution for utilizing Auricularia cornea var. Li waste and a sustainable application for ACPS in smart packaging materials.

Antioxidant pH-sensitive films incorporating CMC/SA/starch, anthocyanins, and tea polyphenols for monitoring freshness of pork

It is important to find an intelligent packaging which can monitor pork freshness immediately and extend its shelf life in food science. The aim of this study was developing a novel pH sensitive film with high antioxidant activity based on sodium carboxymethylcellulose (CMC), sodium alginate (SA), and cassava starch (CS) incorporating Lycium ruthenicum anthocyanins (LRA), and tea polyphenols (TP). The pH response, physical properties, color stability, antioxidant activity, and the ability to monitor the freshness of pork of the films were analyzed. The results indicated that LRA was sensitive in the solution of pH 1-14. After the addition of LRA and TP, the thickness of the films was increased, the mechanical properties were affected, and the water content, and WVP were decreased. LRA and TP significantly improved the light-resistance performance. Fourier transform infrared spectroscopy revealed that CMC, SA, and CS had good compatibility, and LRA and TP were successfully incorporated into the film. TP significantly increased the antioxidant activities of the film as determined by DPPH, and FRAP methods. In addition, the film showed remarkable color change in response to the increase of volatile basic nitrogen content in pork during spoilage. The films containing 0.2 % TP obviously inhibited lipid oxidation, and extended the shelf life of pork. Our findings suggested that CSC/LRA/TP films could be applied as antioxidant materials with freshness monitor effect for pork packaging. This research provides an alternative for the visual intelligent packaging of pork.

Synergistically engineered starch-based composite films: Multifunctional platforms integrating quaternary ammonium chitosan and anthocyanins for intelligent food monitoring and sustainable packaging

This study introduces a starch-based composite film integrated with quaternary ammonium chitosan (QCS) and Lycium ruthenicum anthocyanins (LRA) via a facile casting method, designed for intelligent food packaging. The influences of varying concentrations of QCS and/or LRA on water sensitivity, mechanical attributes, UV transmittance, antioxidant capacity, antibacterial performance, and pH-responsive characteristics were meticulously examined. The optimized film demonstrated a tensile strength of ∼0.68 MPa, a contact angle of ∼123.69°, and ABTS radical scavenging efficiency exceeding 80 %. The film exhibited pH-responsive color changes from pink to green across a pH range of 2-12, alongside excellent UV-blocking and antibacterial properties. Shrimp preservation experiments revealed a 16-h shelf-life extension, coupled with real-time freshness monitoring. These findings put forward an exceedingly promising approach to the promotion of starch-based films boasting diverse functionalities in the realm of intelligent food packaging, signifying a stride in this domain.

Development of pH-sensitive colorimetric bioindicator antimicrobial films from oak tree acorn starch, red onion peel extract and methyl cellulose for freshness monitoring of chicken meat

The research on finding alternative natural and inexpensive materials for the development of biodegradable intelligent food packaging materials is increasing day by day to reduce plastic waste in the environment. In this study, new oak tree acorn starch-based films (S) with pH-sensitive and antimicrobial property were developed using oak tree acorns, quercetin (QUE) extract obtained from red onion peel and ZnO nanoparticles and their physicochemical, mechanical, thermal and barrier properties were compared with those of methyl cellulose-based films. S-QUE film having colorimetric pH-indicator property showed an obvious color variation from pink to green/yellow at different pH values (pH 1-12). Compared to S film, the maximum tensile stress and maximum tensile strain values of the S-QUE film increased by 93.34 % and 296.56 %, respectively. The presence of QUE extract in the film matrix increased the thermal stability of films and ZnO nanoparticles decreased it. The use of QUE extract and ZnO nanoparticles in film formulation led to an improvement in the water vapor barrier properties of films. The effectiveness of S-QUE and S-QUE-ZnO films in monitoring the spoilage of chicken meat was tested. These films showed visible color responses as the chicken meat spoiled.

Green synthesis of silver nanoparticles using persimmon polysaccharides for enhanced polysaccharide-based film performance

Herein, the polysaccharide-based film was prepared by using persimmon polysaccharides extraction (PPE) and sodium alginate (SA) with the synthesized silver nanoparticles (AgNPs). Firstly, PPE was used as reducing and stabilizing agents for the green synthesis of PPE-AgNPs for the first time. The synthesized AgNPs had face-centered-cubic crystal structure with an average particle size of 55.88 nm. Also, the synthesized AgNPs solution exhibited superior dispersion with yellow-brown, and showed excellent antimicrobial activity (p < 0.05). Then, with incorporating AgNPs, the SA-PPE-AgNPs film showed excellent performance, the tensile strength (TS) and elongation at break (EAB) reached 18.24 MPa and 21.94 %, the water vapor permeability (WVP) decreased to 4.91 × 10-11 g·m-1·s-1 Pa-1, and significantly improved UV-vis barrier property. Moreover, the SA-PPE-AgNPs film showed excellent antibacterial activities (p < 0.05) against Escherichia coli, Staphylococcus aureus, Saccharomyces cerevisiae and Aspergillus niger, with the highest antibacterial activity against Escherichia coli (inhibition zone diameter for 16.92 ± 0.14 mm). Preservation tests on sugar oranges showed that the SA-PPE-AgNPs coating treatment maintained the good appearance and color, slowed down the loss of weight (8.34 %), firmness (8.58 N), titratable acid (decreased by 30.23 %) and total soluble solids content (decreased by 10.46 %), and kept the stability of pH (4.26) and Vitamin C (Vc) (decreased by 17.51 %) during the storage period. In summary, SA-PPE-AgNPs film was an effective method for maintaining fruit freshness instead of the traditional films.

Smart bacteria cellulose facial mask for sensing and recovering skin pH

The utilization of skin care products and cleansers is a prevalent method for maintaining facial skin health. However, excessive use of these products is an unnoticed factor that can result in serious skin problems. Currently, there are no products on the market to provide users with skin acclimatization and restoration services. Herein, we introduce a facial mask with a smart pH sensor to monitor and repair facial skin. Specifically, bacterial cellulose fragments were mechanically dispersed, co-mingled with carboxymethyl cellulose and hydroxypropyltrimethylammonium chloride chitosan, with anthocyanin added as a pH-indicating reagent. The composite mask was then prepared by hot air drying. This mask exhibited notable anti-hornification effect, robust water absorption, water retention, wet strength, and antibacterial and antioxidant properties, making it suitable for a high-end facial mass base material with an excellent pH sensitivity within the range of 2.0-12.0, which could be observed directly through colorimetry with the naked eye.

Rhododendron arboreum Sm. anthocyanin-infused starch, chitosan, and polyvinyl alcohol based composite films: Comparative analysis of physical, UV barrier, antioxidant and intelligent behavior

Rhododendron arboreum Sm. is found abundantly in the Himalayan region of Nepal and other Asian countries, and anthocyanins extracted from its flower were utilized to develop intelligent food packaging films. The films were synthesized by blending chitosan (CS) with starch (ST), CS with polyvinyl alcohol (PVA), and ST with PVA, incorporating anthocyanin from R. arboreum. A comparative analysis was conducted to evaluate their potential applications in food packaging. Analytical techniques like FESEM, IR spectroscopy, XRD, and TGA confirmed strong interactions between the polymer matrix and anthocyanins through hydrogen bonding and electrostatic attraction. All samples containing anthocyanins exhibited effective UV light barrier properties, with the PVA/ST/ACNs films showing UV blocking up to 450 nm and exhibiting superior antioxidant properties. The pH sensing ability, antioxidant properties, and ammonia sensitivity depend both on anthocyanin and the composition of the polymer matrix. Ammonia sensitivity was highest for PVA/ST/ACNs (70.1 %), followed by PVA/CS/ACNs (47.8 %) and CS/ST/ACNs (5.6 %). Chicken meat packaged with PVA/ST/ACNs films for 48 h showed TVB-N at 46.39 mg/100 g, pH 8.6, and film color changed from reddish pink to greenish-yellow, signifying spoilage. These findings suggest potential for the film as intelligent packaging to monitor meat freshness, correlating TVB-N, pH, and film color.

Preparation and characterization of chitosan / corn starch based films loaded with Vaccinium vitis-idaea anthocyanin nanocomplexes and the application in shrimp preservation

In this experiment, the nanocomposite film prepared by adding of nanocomplexes (ACNs-CHC/CMC-WPI) of Vaccinium vitis-idaea anthocyanins encapsulated with carboxymethyl chitosan (CMC), chitosan hydrochloride (CHC), and whey protein isolate (WPI) to chitosan/corn starch (CTS/Corn) blend matrix for food packaging. The functionality and stability of anthocyanin-loaded nanocomplexes and anthocyanin-containing films were determined and compared. Good encapsulation was observed by transmission electron microscopy. The freshness preservation effect of the prepared films on shrimp was investigated. Scanning electron microscopy results showed that ACNs-CHC/CMC-WPI was uniformly dispersed in chitosan-corn starch matrix, indicating the formation of a stable CTS/Corn-anthocyanin nanocomplex film (CTS/Corn-AN film). Although CTS/Corn-free anthocyanin (CTS/Corn-FA film) had better antioxidant activity in the short term, the CTS/Corn-AN film could better maintain the antioxidant activity and original color after 28 days of light exposure. In summary, the CTS/Corn-AN film possessed better mechanical property with elongation at break at 88.67 %, oxidation resistance with DPPH scavenging of 28.71 % at 28th, and other physicochemical properties than those of the CTS/Corn-FA film. Finally, the CTS/Corn-AN film showed effective freshness preservation of shrimp at 4 °C for 10 days compared to the control group due to durable antibacterial and antioxidant properties. Therefore, CTS/Corn-AN film was promising active packaging material in shrimp preservation.

Yam starch-based sustainable edible films loaded with bioactive components from aroeira leaf extract: Mechanical, physical, and antioxidant properties

This study aimed to investigate the impact of adding aroeira leaf extract (Schinus terebinthifolius Raddi) to a yam starch film matrix, focusing on the development of potentially active films and the evaluation of their physicochemical, mechanical, optical, and antioxidant properties. Films were produced using the casting method with varying extract concentrations (0, 3, 6, 12, and 15 %), yam starch (2 %), and glycerol (1 %). The antioxidant properties were analyzed by determining the total phenolic content, 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) radical scavenging, ferric reducing power, and 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical elimination, which revealed a significant increase in antioxidant properties as the extract concentration increased. The incorporation of the extract resulted in increased film thickness and decreased solubility, water activity, and moisture, as well as changes in brightness (L*), tensile strength, and elongation. X-ray diffraction (XRD) showed an increase in the crystallinity of the films, whereas Fourier-transform infrared (FTIR) analysis revealed similar spectra among the films. The thermal stability did not exhibit significant variations with the addition of the extract, indicating high heat resistance. Films with 15 % extract showed changes in the surface microstructure, indicating greater roughness than the control film. Thus, formulations with 3 %, 6 %, and 9 % aroeira extract emerged as the most promising, suggesting their potential for application in active packaging and as a sustainable alternative for food preservation.

Açaí powder-enriched biodegradable starch films: Characterization, release in food simulants and protective effect in photodegradation system

Açaí is an important source of natural pigments with antioxidant capacity, such as anthocyanins. Among the various possibilities for its application is its incorporation into biodegradable films, which can act as carriers of these bioactive compounds. The objective of this study was to develop biodegradable films based on starch with different açaí powder concentrations (5 % and 15 %). The films were developed using the casting technique and evaluated in relation to barrier properties, physicochemical, biodegradability, release to food simulants, and protective effect against photodegradation of β-carotene. The addition of the natural antioxidant led to the development of films with greater color intensity and improved light barrier and mechanical properties (tensile strength and elongation). The retention of açaí powder in the polymer matrix was identified in the FTIR analysis through the intensification of some regions in relation to the control film. The cohesion and interaction between film:active compound showed an improvement in water-related properties, such as reduced permeability and water absorption. Furthermore, the active films showed sustained release of anthocyanins into the food simulant (maximum of 3.04 mg cyanidin 3-glycoside/100 g and 8.06 mg cyanidin 3-glycoside/100 g for films AP5% and AP15%, respectively) and better protection against photodegradation of the β-carotene solution (35-50 % retention when exposed to high light intensity). The rapid biodegradability, thermal stability, and stability at different pH may indicate potential application as packaging for foods susceptible to photodegradation.

Development of Plasma-Treated Corn-Starch-Based Film Incorporated with Acerola and Grape Pomace Extract Possessing pH-Sensing Capability

This study explores the development of biodegradable starch-based films treated with dielectric barrier discharge (DBD) plasma and incorporated with acerola residue and grape pomace extracts. The primary aim was to enhance the films' physicochemical properties and introduce pH-sensing capabilities. Plasma treatment at 200 Hz for 20 min modified the films' amylose content (by 13.2%), solubility (by 13.3%), contact angle (by 12.7%), moisture content (by 14.2%), and surface morphology. The addition of the extracts changed the short-range ordered structure parameters of the films (by 111.4%), solubility (by 11.1%), moisture content (by 18.4%), and water vapor permeability (by 6.1%). The films with acerola residue and grape pomace extracts exhibited good colorimetric responses for pH indication. The films with acerola residue extract tended to intensify the yellowish color, while those with grape pomace extract showed more significant color changes varying from purple to green. Integrating natural pigments like anthocyanins from grape pomace and carotenoids from acerola improved the films' functional properties and provided a visual indication of food freshness through pH changes.

Preparation and Characterization of Antioxidative and pH-Sensitive Films Based on κ-Carrageenan/Carboxymethyl Cellulose Blended with Purple Cabbage Anthocyanin for Monitoring Hairtail Freshness

Developing pH-sensitive materials for real-time freshness monitoring is critical for ensuring seafood safety. In this study, pH-responsive indicator films were prepared by incorporating purple cabbage anthocyanin (PCA) into a κ-carrageenan/carboxymethyl cellulose (CA/CMC) matrix via solution casting, with PCA concentrations of 2.5%, 5.0%, 7.5%, and 10% (w/w). The films exhibited remarkable pH sensitivity, with distinct color changes across pH 2.0-11.0. Incorporating PCA enhanced film crystallinity, antioxidant properties, and opacity while reducing water vapor transmission (WVP). High PCA content resulted in rougher morphology, lowering tensile strength (TS) but improving elongation at break (EB). The indicator film had good environmental stability, and the color difference was not visible after 10 days in the dark and 4 °C conditions. The CA/CMC/PCA-10% film showed the most pronounced pH-responsive color changes, transitioning from purple to green as hairtail freshness deteriorated. This innovative approach highlights the potential of CA/CMC/PCA films as reliable, eco-friendly indicators for real-time seafood freshness monitoring, offering significant advancements in smart packaging technology.

Development and characterization of a double-layer smart packaging system consisting of polyvinyl alcohol electrospun nanofibers and gelatin film for fish fillet

This study aimed to develop a double-layer film composed of an intelligent, gelatin-based film integrated with active polyvinyl alcohol electrospun nanofibers (PVANFs). Eggplant skin extract (ESE), a colorimetric indicator, was incorporated into the gelatin-based film at varying concentrations ranging from 0 % to 8 % w/w. The gelatin film containing 8 % ESE was identified as the optimal formulation based on its superior color indication, water barrier, and mechanical properties. Savory essential oil (SEO)-loaded PVANFs were electrospun onto the optimized gelatin film to fabricate the double-layer film. Analysis of the chemical and crystalline structures and the double-layer film's thermal properties confirmed the gelatin film's physical integration with PVANFs. Morphological examination revealed a smooth surface on the film and a uniform fibrillar structure within the PVANFs. Furthermore, the developed double-layer film effectively detected spoilage in trout fish while controlling pH, oxidation, and microbial changes during storage.

Variation of nanoparticles in pickering emulsion optimize the physical, control-release and sustained antioxidant properties of hydroxypropyl methylcellulose based microporous film

The proper encapsulation of liposoluble tea polyphenols (LTP) is expected to better protect oil system. Chitosan hydrochloride-carboxymethyl starch (CHC-CMS) nanoparticles-based Pickering emulsions and hydroxypropyl methylcellulose/sodium citrate (HPMC/SC) microporous film were combined to embed and control-release LTP. With the CHC:CMS ratio varied from 1:0.5 to 1:2, the average size of LTP droplets of Pickering emulsion increased from 6.0 μm to 8.5 μm, the average area of cross-sectional pores of functional films increased from 1.78 μm2 to 3.22 μm2, the water vapor permeability of functional films increased from 2.02 × 10-10 to 2.44 × 10-10 g·mm-1·s-1·Pa-1, the light transmittance and the quantity of cross-sectional pores decreased. The release ratio first increased (<24 days) and then remained stable (≥24 days), the stable release ratio was positively correlated with the size of the emulsion droplets in the emulsion and the size of cross-sectional pores in the film. Functional films had better protection effect on oil than free LTP during later storage period (≥32 days), among which, functional film containing CHC-CMS 1:2 showed optimal sustained antioxidant effect on Perilla seed oil, which corresponded well to its highest stable release ratio.

A novel carboxymethyl cellulose/gum xanthan and citric acid-based film that enhances the precision of blackcurrant anthocyanin-induced color detection for beef spoilage tracking

Leveraging blackcurrant anthocyanin (BC) as an indicator and carboxymethyl cellulose (CMC), gum xanthan (GX), and citric acid (CA) as film fabricating materials, an innovative amine-responsive beef freshness intelligent film, known as CGC-BC, was successfully created. It was found that the physical characteristics, sensitivity to the biogenic amine reaction, and original color of the film were all highly influenced by the pH of the film-forming solutions. The film's freshness monitoring ability was assessed at 4, 25, and 35 °C, and various color changes were employed to monitor beef deterioration. ΔE values and the visual color difference of the low-concentration (SCG-BC-0.08 and SCG-BC-0.16) ammonia-sensitive indicator films demonstrated significant color changes than the high-concentration (SCG-BC-0.24 and SCG-BC-0.32) films. The films biodegradation (37.16 to 51.49%) ability was enhanced with increase in the proportions of BC. As the TVB-N and pH values of beef increased with the different temperatures and time and different color changes were observed from red to pink, black to brown, and yellow.

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.

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.

Polysaccharide-Based Composite Films: Promising Biodegradable Food Packaging Materials

With growing concerns about environmental protection and sustainable development, the development of new biodegradable food packaging materials has become a significant focus for the future of food packaging. Polysaccharides, such as cellulose, chitosan, and starch, are considered ideal biodegradable packaging materials due to their wide availability, good biocompatibility, and biodegradability. These materials have garnered extensive attention from researchers in food packaging, leading to considerable advancements in the application of polysaccharide-based food packaging films, coatings, aerogels, and other forms. Therefore, this review focuses on the application of polysaccharide-based packaging films in food storage and preservation and discusses their preparation methods, application progress, challenges, and future development directions. Through an in-depth analysis of the existing literature, this review aims to provide sustainable and environmentally friendly solutions for the food packaging industry.

A review of Lycium ruthenicum Murray: Geographic distribution tracing, bioactive components, and functional properties

Lycium ruthenicum (LRM), endemic to Northwest China, is known as hei goji or black goji and is renowned for its rich bioactive compounds. This review analyzes LRM's geographic distribution and traceability and highlights challenges and future developments in geographical traceability. The work also focuses on LRM's bioactive constituents, especially on anthocyanins and polysaccharides, demonstrating a clear clue for understanding their updated extraction methods, identification, and diverse bioactive activities, including antioxidation, anti-inflammation, and immunomodulation, which is beneficial to developing novel functional foods and new medical materials. Moreover, the paper elucidates advances in the potential application of LRM in food preservation, packaging, and other domains. Notably, we figure out gaps in LRM research, such as traceability technology and the proven efficacy of biological activities. This study provides a foundation for future perspectives on developing nutraceuticals and functional foods, disease treatment supplements, and green food packaging materials by bridging these gaps.

Improved barrier, mechanical and antioxidant properties of pH-responsive film by incorporating dialdehyde starch and anthocyanins into rice protein/sodium alginate

This study aimed to develop rice protein/sodium alginate (RP/SA) pH-responsive films with enhanced properties by incorporating dialdehyde starch (DAS) and Lycium ruthenicum anthocyanins (LRA) and the film was applied to monitor the fruit freshness. The effect of the DAS and LRA content on the morphology, mechanical, water barrier, oxygen barrier, ultraviolet-blocking and thermal stability properties of RP/SA-based films was investigated. The best water vapor permeability of the film was 3.33 g·mm/(m2·d·kPa) with 10 % DAS. With increasing the DAS content from 0 % to 20 %, the tensile strength of the film was increased by 66.3 % compared with that of the film without DAS, while the thermal stability, oxygen barrier and ultraviolet light barrier properties were significantly enhanced. These results may be due to the formation of a compact structure observed by scanning electron microscopy, and stronger hydrogen bonding interactions and lower binding energy in the RP/SA/DAS/LRA system obtained by Fourier transform infrared spectroscopy, X-ray diffraction and molecular dynamics simulation. The RP/SA/DAS10/LRA5 film had 51.6 times higher antioxidant property than the film without LRA and exhibited significant color variations with changes in fresh-cut cantaloupe quality. The developed RP/SA-based films with improved properties are potential intelligent food packaging materials.

A Highly CO2-Sensitive Wood-Based Smart Tag for Strawberry Freshness Monitoring

Smart tags are used for monitoring the freshness of foods. However, they often lack significant color changes, and their accuracy needs to be improved. In this study, a poplar veneer with a natural pore structure was selected as a matrix to prepare a smart tag with high pH sensitivity for tracking the freshness of strawberries. The delignified veneer was modified using 2,3-epoxypropyltrimethylammonium chloride (EPTAC) to be given positive charges to adsorb bromothymol blue (BTB) through electrostatic interactions. The adsorption capacity of the veneer reached 7.0 mg/g at 50 °C for 4 h, and the veneer showed an obvious blue color. The smart tags exhibited distinct color changes at different pHs and showed quick color changes in response to acetic acid. As the freshness of strawberries decreased, the color of the smart tags changed from blue to yellow-green, which indicated that the accuracy was high. In this study, an effective method was fabricated to prepare a highly sensitive tag, promoting popular application to ensure food quality.

Sodium alginate-based indicator film with enhanced physicochemical properties induced by cellulose nanocrystals and monitor the freshness of chilled meat

Intelligent indicator films with colorimetric pH indicator properties were developed, incorporating black soybean seed coat anthocyanin (BA), cellulose nanocrystals (CNC), and sodium alginate (SA) to monitor meat freshness. The effect of different CNC additions on the microstructure, water barrier properties of the films, and BA release kinetics were comprehensively investigated. The results showed that with the increasement of CNC addition, the mechanical properties of SA/BA/CNC films were improved, the water contact angle significantly increased from 51.6° to 69°. Moreover, water solubility, vapor adsorption, and permeability significantly decreased, indicating enhanced water barrier properties. The release kinetic results showed that BA was released rapidly within 72 h and slowly thereafter, and its release process was described by Fick's model. Films with 7 % and 10 % CNC had lower BA diffusion coefficients. Their diffusions were formulated as linear regression equations (y = nx + a), where R2 was >0.80 and n was <0.50. Structural characterization showed that CNC immobilized BA mainly through hydrogen bonding, forming compact network microstructures with SA and BA. Meat freshness monitoring results showed that the film containing 7 % CNC showed visible color changes with increasing total volatile basic nitrogen and pH, along with low BA release, high water barrier and mechanical properties. Therefore, CNC has great potential for improving the physicochemical properties of indicator films, and the intelligent colorimetric indicator film could be applied to various food product.

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

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

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

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

A starch/gelatin-based Halochromic film with black currant anthocyanin and Nanocellulose-stabilized cinnamon essential oil Pickering emulsion: Towards real-time Salmon freshness assessment

Neoterically, food packaging systems designed solely for prolonging shelf life or monitoring freshness could not fulfil the dynamic demands of consumers. In this current investigation, using the solvent casting method, a versatile halochromic indicator was created by integrating black currant anthocyanin and cinnamon essential oil-loaded Pickering emulsion into a starch/gelatin matrix. The resulting indicator film underwent scrutiny for its structural, pH-sensitive, antioxidant, and antimicrobial attributes. Unexpectedly, the amalgamation of anthocyanin and essential oil led to decreased antioxidant activity, dropping from 73.23 ± 2.17 to 28.87 ± 2.50 mg Trolox equivalent/g sample. Additionally, no discernible antimicrobial properties were detected in the composite film sample against both Staphylococcus aureus and Escherichia coli. Fourier transform infrared analyses unveiled robust intermolecular interactions among the film-forming components, providing insights into the observed antagonistic effect. The indicator film displayed distinctive colour changes corresponding to the fresh (greyish-brown), onset of decomposition (khaki), and spoiled (dark green) stages of the stored fish sample. This highlights its promising potential for providing real-time indications of food spoilage. These findings are important for the efficient design of composite films incorporating anthocyanins and essential oils. They serve as a guide towards their potential use as multifunctional packaging materials in the food industry.

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 double-layer film based on gellan gum/modified anthocyanin/curcumin/sodium alginate/zinc oxide for monitoring shrimp freshness

In this study, intelligent double-layer films were prepared using modified black rice anthocyanin (MBRA)-curcumin (CUR)-gellan gum (GG) as the inner indicator layer and sodium alginate (ALG)‑zinc oxide (ZnO) as the outer antimicrobial layer. The bilayer films were successfully prepared, as revealed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction measurements. The mechanical characteristics, moisture content, and water vapor resistance of GG-MBRA/CUR1@ALG-ZnO, GG-MBRA/CUR2@ALG-ZnO, and GG-MBRA/CUR3@ALG-ZnO films showed significant enhancement compared to GG-MBRA/CUR3 and ALG-ZnO films. The bilayer films exhibited excellent pH responsiveness and reacted effectively to ammonia. The outer layer significantly improved the antioxidant and antibacterial properties of the inner layer. When the films were applied to shrimp, it was found that the double-layer films not only monitored the freshness of the shrimp in real-time but also were influential in extending the shelf life of the shrimp by about 1 d. Therefore, the double-layer film demonstrated potential as a smart packaging material for real-time monitoring of meat product freshness.

Development of pH-responsive intelligent films based on κ-carrageenan/straw lignin and anthocyanin from Padus virginiana peel for real-time monitoring of chicken

A series of intelligent films with pH-responsive properties were prepared using Padus virginiana peel extract (PVE) as a smart response factor, κ-carrageenan (κC) as a matrix, and complexed with rice straw lignin (SL). Following the addition of 5 mL PVE at a concentration of 430.99 mg/L, tensile strength and elongation at break of the films increased to a maximum value of 21.25 ± 0.75 MPa and 24.04 ± 0.69 %, respectively. The water vapour permeability of the films decreased with increasing PVE addition, and the minimum value was 5.85 ± 0.09 × 10-11 g m-1 s-1 Pa-1. All the films had favourable thermal stability, transparency, haze and antioxidant properties. PVE-containing films all exhibited excellent pH and ammonia response properties. The higher the humidity of the environment, the faster the ammonia response, and the films were capable of rapid discoloration at 75 % relative humidity. κC/SL-PVE5 can be used to monitor the freshness of chicken breast meat. When the total volatile basic nitrogen of chicken breast meat was increased to 14.27 mg/100 g, κC/SL-PVE5 changed from pink to greyish-yellow. In conclusion, κC/SL-PVE intelligent films hold great promise for real-time monitoring of meat freshness.

Biopolymer-based intelligent packaging integrated with natural colourimetric sensors for food safety and sustainability

Increasing concerns about global food safety and security demands innovative solutions, particularly in food packaging technologies. This review paper investigates the advanced integration of natural colourimetric sensors with biopolymer-based packaging materials, with a focus on developments over the past 5 years. These sensors change colour in response to environmental stimuli such as oxygen, temperature, pH and relative humidity, intuitively indicating food freshness and safety. The paper emphasizes the recent advancements in using natural colourants, such as alizarin, anthocyanins, betacyanins, chlorophyll, curcumin and shikonin. When combined with either natural or synthetic biopolymers, these colourants contribute to a sustainable and eco-friendly approach to food packaging. Such technological advances could notably decrease the incidence of foodborne illnesses by signaling potential spoilage or contamination, while also addressing food wastage by providing clear indications of edibility. Although challenges remain in sensor longevity and widespread adoption, the prospects for biopolymer-based food packaging with embedded natural colourimetric sensors are promising.

Enhancement of Colorimetric pH-Sensitive Film Incorporating Amomum tsao-ko Essential Oil as Antibacterial for Mantis Shrimp Spoilage Tracking and Fresh-Keeping

Anthocyanin-based smart packaging has been widely used for food freshness monitoring, but it cannot meet the requirements of smart films with antibacterial properties. This study aimed to enhance the antibacterial properties of intelligent films by incorporating Amomum tsao-ko essential oil (AEO) for mantis shrimp spoilage tracking and keeping the product fresh. A smart film was designed by introducing AEO and purple potato anthocyanin (PPA) to a polyvinyl alcohol/cellulose nanocrystal (PVA/CNC) polymer matrix. Our findings revealed that APP and AEO imparted the smart film with a favorable oxygen barrier, UV protection, mechanical properties, and antioxidant and pH/NH3-sensitive functions. Interestingly, the PVA/CNC-AEO-PPA film achieved 45.41% and 48.25% bactericidal efficacy against S. putrefaciens and V. parahaemolyticus, respectively. Furthermore, a visual observation confirmed that the target film (PVA/CNC-AEO-PPA) changed color significantly during mantis shrimp spoilage: rose red-light red-pink-light gray-dark gray. Meanwhile, the PVA/CNC-AEO-PPA film retarded the quality deterioration of the mantis shrimp effectively. The PVA/CNC-AEO-PPA film shows great application potential in mantis shrimp preservation and freshness monitoring; it is expected to become a rapid sensor for detecting seafood quality non-destructively and a multifunctional film for better preservation of product quality.

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.

Edible film preparation by anthocyanin extract addition into acetylated cassava starch/sodium carboxymethyl cellulose matrix for oxidation inhibition of pumpkin seeds

In this study, an edible film was fabricated by incorporating anthocyanin extract from black rice (AEBR) into acetylated cassava starch (ACS)/carboxymethyl-cellulose (CMC) to enhance the shelf life of pumpkin seeds. The effects of AEBR on the rheological properties of film-forming solutions, as well as the structural characterization and physicochemical properties of the film, were evaluated. Rheological properties of solutions revealed that AEBR was evenly dispersed into polymer matrix and bound by hydrogen bonds, as confirmed by Fourier transform infrared spectroscopy analysis. The appropriate AEBR addition could be compatible with polymer matrix and formed a compact film structure, improving the mechanical properties, barrier properties, and opacity. However, with further addition of AEBR, the tensile strength and water vapor permeability decreased and the tight structure was destroyed. After being stored separately under thermal and UV light accelerated conditions for 20 days, the peroxide value and acid value of roasted pumpkin seeds coated with the AEBR film showed a significant reduction. Moreover, the storage stability of AEBR was improved through the embedding of ACS/CMC biopolymers. These results indicated that AEBR film could effectively delay pumpkin seeds oxidation and prolong their shelf life as an antioxidant material.

An Anthocyanin-Based Eco-Friendly Triboelectric Nanogenerator for pH Monitoring and Energy Harvesting

In recent years, renewable and sustainable triboelectric nanogenerators have attracted attention due to their high energy conversion rate, and enhancing their functionality further contributes to their applicability across various fields. A pH-sensitive triboelectric nanogenerator (pH-TENG) has been prepared by electrostatic spinning technology, with anthocyanin as the pH indicator and environmentally friendly polyvinyl alcohol (PVA) as the substrate. Among many friction-negative materials, the pH-TENG exhibits the best combination with fluorinated ethylene propylene (FEP) and yields an open-circuit voltage of 62 V, a short-circuit current of 370 nA, and a transferred charge of 21.8 nC. At a frequency of 3 Hz, it can charge a 4.7 μF capacitor to 2 V within 45 s, effectively powering a thermometer. Furthermore, the presence of anthocyanin does not affect the pH-TENG's power generation performance and enables the monitoring of a wide range of environmental pH changes, with an ΔE change of 28.8 ± 7.6. Therefore, pH-TENG prepared with environmentally friendly materials can bring new available materials to the biological and medical fields.

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.

Smart labels based on polyvinyl alcohol incorporated with chitosan nanoparticles loaded with grape extract: Functionality, stability and food application

Anthocyanins (ACNs) are natural compounds with potential applications due to their colorimetric response to pH. Due to their sensitivity to various environmental factors, nanoencapsulation with biopolymers is a successful strategy for stabilizing ACNs. In this work ACNs were extracted from grape skins and encapsulated into chitosan (CS) nanoparticles by ionic gelation using sodium tripolyphosphate (TPP) as a cross-linking agent. CS nanoparticles loaded with ACNs had particle sizes between 291 and 324 nm and polydispersity index around 0.3. The encapsulation efficiency of ACNs was approximately 60 %; and encapsulated anthocyanins (ACN-NPs) exhibited color change properties under different pH conditions. pH-sensitive labels based on polyvinyl alcohol (PVA) were prepared by the casting method. The effect of incorporating ACN-NPs on the physical, structural, and pH-sensitive properties of PVA labels was evaluated, and its application as shrimp freshness indicator was studied. The nanoencapsulation protected ACNs against heat and light treatments, preserving the original purple color. When applying the label, visible changes from red to blue until reaching yellow were observed with the change in the quality of the shrimp at the refrigeration temperature. The results suggest that PVA labels containing ACNs encapsulated in C-NPs can be used as smart packaging labels in the food industry.

Effect of using biodegradable film constituting red grape anthocyanins as a novel packaging on the qualitative attributes of emergency food bars during storage

This study presents a novel packaging film based on whey protein isolate/κ-carrageenan (WC) with red grape pomace anthocyanins (RGA) to investigate its impact on some qualitative attributes of emergency food bars (EFBs) for 6 months at 38°C. Increasing the RGA dose in WC films from 5% (WCA5) to 10% (WCA10) reduced hydrogen bonding between polymers and polymer homogeneity in the matrix according to FTIR and SEM. Tensile strength slightly declined in WCA5 from 7.47 ± 0.26 to 6.97 ± 0.12, while elongation increased from 27.74 ± 1.36 to 32.36 ± 1.25% compared to WC film. The maximum weight loss temperature (TM) increased by incorporating 5 wt% RGA from 182.95°C to 244.36°C, whereas TM declined to 187.19°C in WCA10 film. WVP and OTR slightly changed in WCA5 (from 7.83 ± 0.07 and 2.57 ± 0.18 to 8.41 ± 0.03 g H2O.m/m2.Pa.s × 10-9 and 1.79 ± 0.32 cm3 O2/m2.d.bar, respectively), but significantly impaired in WCA10 compared to WC film. WCA5 and WCA10 films had high AA%, 68.77%, and 79.21%, respectively. WCA10 film presented great antimetrical properties against Staphylococcus aureus with an inhibition zone of 6.00 mm. The light transmission of RGA-contained films in the UV spectrum was below 10%. The WCA5 film effectively restrained moisture loss and hardness increment until the end of the storage period, which were 14.33% and 28.76%, respectively, compared to day 0. Antioxidant films provided acceptable resistance against oxidation to EBF treatment. Sensory panels scored WCA5 and WCA10 higher in overall acceptance with 5.64 and 5.40 values, respectively, while complaining about the hardness of OPP treatment. The results of this investigation demonstrated that incorporating RGA, preferably 5 wt%, into WC-based film effectively improved the qualitative properties of EFB during the 6-month shelf life. This film might be a promising alternative for packaging light and oxygen-sensitive food products.

Development of Intelligent Indicators Based on Cellulose and Prunus domestica Extracted Anthocyanins for Monitoring the Freshness of Packaged Chicken

Meat is a widely consumed food globally; however, variations in storage conditions along its supply chain can pose a potential food safety risk for consumers. Addressing this concern, we have developed freshness indicators designed to monitor the condition of packaged chicken. In this study, anthocyanins were infused with cellulose paper measuring 2 × 2 cm, and subsequent analysis focused on examining color changes concerning deteriorating chicken stored at 30°C for 48 h, with varying sample sizes being considered. The rise in total volatile nitrogen (TVB-N) compounds from an initial value of 3.64 ± 0.39 mg/100 g to 28.17 ± 1.46 mg/100 g acted as the stimulus for the color change in the indicator, simultaneously influencing the pH from the initial 7.03 ± 0.16 to 8.12 ± 0.39. The microbial load (aerobic plate count) of the chicken samples was also significantly increased. This collective shift in various parameters strongly suggests the occurrence of spoilage in chicken meat. The pH indicators exhibited a dark pink to red color for fresh chicken. As the chicken meat turned towards spoilage, the indicators changed to a dark blue and then a pale green color. FTIR spectroscopy results confirmed the presence of cellulose and anthocyanins. The FTIR analysis also validated the immobilization of plum anthocyanins within the cellulose paper and assessed their stability after 8 months of storage. Notably, the indicators demonstrated rapid sensitivity, showing a 20.5% response within one minute of ammonia exposure, which further increased to 29.5% after 3 min of exposure. The total color difference (ΔE) steadily rose in all the examined samples and also under various storage conditions. Overall, the indicators developed in this study exhibited a highly pronounced color transition, capable of distinguishing between fresh and spoiled chicken samples depending on the extent of spoilage and the specific day of observation.

Development and evaluation of Bauhinia Kockiana extract-incorporated sago starch intelligent film strips for real-time freshness monitoring of coconut milk

The aim of this work was to fabricate an intelligent film using sago starch incorporated with the natural source of anthocyanins from the Bauhinia Kockiana flower and use it to monitor the freshness of coconut milk. The films were developed using the casting method that included the addition of the different concentrations (0, 5, 10, 15 mg) of Bauhinia Kockiana extract (BKE) obtained using a solvent. The anthocyanin content of Bauhinia Kockiana was 262.17 ± 9.28 mg/100 g of fresh flowers. The spectral characteristics of BKE solutions, cross-section morphology, physiochemical, barrier, and mechanical properties, and the colour variations of films in different pH buffers were investigated. Films having the highest BKE concentration demonstrated the roughest structure and highest thickness (0.16 mm), moisture content (9.72 %), swelling index (435.83 %), water solubility (31.20 %), and elongation at break (262.32 %) compared to the other films. While monitoring the freshness of coconut milk for 16 h, BKE15 showed remarkable visible colour changes (from beige to dark brown), and the pH of coconut milk dropped from 6.21 to 4.56. Therefore, sago starch film incorporated with BKE has excellent potential to act as an intelligent pH film in monitoring the freshness of coconut milk.

Preparation of hydroxypropyl methylcellulose/pueraria-based modified atmosphere film and its influence on delaying the senescent process of postharvest Agaricus bisporus

Based on the key factor of spontaneous modified atmosphere packaging (MAP)-gas permeability, a spontaneous MAP film was created for the preservation of Agaricus bisporus by delaying the senescence of white mushrooms. Compared with other mixed films, hydroxypropyl methylcellulose (HPMC)/pueraria (P)-2 showed better mechanical properties, barrier properties and thermal stability energy. Applying the HPMC/P-2 film for preserving white mushrooms can spontaneously adjust the internal gas environment. Moreover, the O2 concentration in the package remained stable at 1-2 %, and the CO2 concentration was between 8 % and 14 %. The film can effectively reduce the respiration rate of white mushrooms, inhibit enzymatic browning, maintain their good color and texture, and delay their aging. In conclusion, the HPMC/P-2 film can be used not only for fruit and vegetables preservation but also provide theoretical basis for sustainable food packaging.

Functional pH-Sensitive Film Containing Purple Sweet Potato Anthocyanins for Pork Freshness Monitoring and Cherry Preservation

An antioxidative and pH-sensitive multifunctional film, incorporating anthocyanin-rich purple sweet potato extract (PPE) was fabricated from polyvinyl alcohol (PVA) and sodium alginate (SA)/sodium carboxymethyl cellulose (CMC-Na). The film was composed of 6:4 PVA:SA/CMC-Na (mass ratio, SA:CMC-Na at 1:1) with added PPE, and changed color with changes in pH, and also had useful UV-blocking, antioxidant, mechanical, and water vapor barrier properties, which enable its use as a food coating film. In addition, the incorporation of 300 mg PPE increased the biodegradability of the film in soil from 52.47 ± 1.12% to 64.29 ± 1.75% at 17 days. The pH sensitivity of the film enabled its successful use for the evaluation of pork freshness. Cherries coated with the film had an extended shelf life from 3-4 to 7-9 days, during storage at 25 °C. Consequently, the multifunctional film can be applied to packaging for real-time pH/freshness monitoring and for effectively preserving the freshness of meat and fruit.

Effect of apple polyphenols on physicochemical properties of pea starch/pulp cellulose nanofiber composite biodegradable films

A pea starch (PS) and pulp cellulose nanofibers (CNF-P) hybrid matrix biodegradable film was prepared using apple polyphenol (AP) as the active substance. SEM and thermogravimetric analyses showed that apple polyphenols could be uniformly distributed and form hydrogen bonds with the matrix, and the increase in crystallinity improved the thermal stability of the films (the final residue of the films increased from 22.66 % to 31.82 %). The TS and EAB of the films reached their maximum values of 11.14 ± 1.73 MPa and 71.55 ± 8.8 %, respectively, at an AP content of 1.5 %. It should be noted that the antioxidant properties of the films were significantly positively correlated with the AP content, and the DPPH radical scavenging rate of the films reached 73.77 % at an AP content of 4.5 %, which was about 49 times higher than that of the control film. The same trend was observed in the UV-vis spectra. In addition, the total color difference and water solubility of the membranes increased from 4.29 ± 0.29 to 31.86 ± 1.90 and from 20.01 ± 0.97 % to 21.70 ± 1.99 %, respectively, and the biodegradability also showed an upward trend. These findings provide a theoretical basis and data support for the development of multifunctional biodegradable food packaging materials.

pH-responsive color-indicating film of pea protein isolate cross-linked with dialdehyde carboxylated cellulose nanofibers for pork freshness monitoring

The limited mechanical performance and responsiveness of protein-based smart packaging materials have hindered their development. To address these issues, this study prepared a pH-responsive smart film by introducing dialdehyde carboxylated cellulose nanofibers (DCCNFs) as the cross-linking agent capable of covalently reacting with proteins, and bilberry extract (BE) as a pH-responsive indicator into pea protein isolate (PPI) matrix. The results demonstrated that adding DCCNF and BE enhanced the PPI film's thermal stability, density, and UV barrier properties. Tensile tests revealed significant improvements in both tensile strength and elongation at the break for the resulting film. Furthermore, films containing DCCNF and BE exhibited lower moisture content, swelling ratio, water vapor permeability, and relative oxygen transmission compared to PPI films. Notably, the anthocyanins in BE endowed the film with visual color changes corresponding to different pH values. This feature enabled the film to monitor pork freshness; a transition from acidic to alkaline in pork samples was accompanied by a color change from brown to brownish green in the film as storage time increased. Overall, these findings highlight that this developed film possesses excellent physicochemical properties and sensitive pH response capabilities, making it a promising candidate for future smart packaging applications.

Characterization of starch film incorporating Hom Nil rice extract for food packaging purposes

Poor water resistance, mechanical properties and stability limit the food packaging applications of starch films. Since the properties of starch films are improved by incorporating phenolic compounds and anthocyanins from natural plant extracts, Hom Nil rice (HN) extract was incorporated into cassava starch solution to produce a starch-based packaging film. We evaluated the extraction condition to optimize the total phenolic and anthocyanin contents of the HN extract. The optimal ratio of ethanol solution:Hom Nil rice powder was 5:1 v/w% and the optimal extraction time was 60 min. The influence of HN extract on the viscosity of the film solution and the properties of the obtained films were investigated. The results showed that the HN extract increased the viscosity of the starch solution. A film containing 8 wt% of HN extract produced the highest water contact angle and tensile strength, and hindered the retrogradation process. Therefore, cassava starch film modified with the proposed HN extract has the potential to be used as a food packaging material.

Starch films loaded with tannin: the study of rheological and physical properties

Recently, the research on innovative food packaging has been oriented toward biodegradable materials to lower the environmental impact generated by conventional plastics. The films often carry functional additives interacting with the matrix and modifying its physical properties. In this work tannin, a scarcely exploited active additive, was used to obtain potato starch-based films, and its content was optimized on the basis of mechanical and microscopic tests. Rheological measurements were adopted to evaluate the tannin-starch interaction and the microstructure of the film forming solutions (FFSs). Their thickness, color, thermal conductivity, elastic modulus (Eel), elongation at break (EAB), surface wettability and water solubility were evaluated. Furthermore, microstructure was investigated through Fourier-transform infrared spectroscopy (FTIR), polarized light (POM) and scanning electron microscopy (SEM). It was observed that all FFSs behave as weak gels and tannin addition weakens the gel structure and decreases the gelatinization temperature from about 60 °C to 57 °C. Plastic and deformable films (Eel = 1.96 MPa and EAB = 189 %) were obtained at low tannin fractions, whereas, at a higher concentration, stiffer films (Eel = 12 MPa and EAB = 10 %), with hydrophobic behavior were produced. Among the tested tannin fractions, an intermediate value of 1.7 % (w/w) was found to be promising for industrial purposes.

Effect of kaolin impregnated with calico plant extract on properties of starch films

Starch film has poor tensile properties and poor water resistance. We aimed to improve these properties by adding kaolin impregnated with calico plant extract (CP-Kaolin). UV-Vis spectrophotometry showed that the calico plant extract (CPE) contained 4867.52 mg/L of total phenolic compounds and betacyanins were the predominant constituents. CP-Kaolin was characterized by Fourier transform infrared spectroscopy (FTIR), zeta potential, scanning electron microscopy (SEM) and x-ray diffraction (XRD) analysis. FTIR analysis showed that betacyanins were adsorbed on kaolin via hydrogen bonding. Zeta potential analysis confirmed the adsorption of betacyanins on kaolin. The intercalation of betacyanins between kaolin platelets was observed by XRD. SEM revealed that CP-Kaolin was well dispersed and embedded within the starch matrix. It was found that the addition of 10 wt% of CP-Kaolin increased the water resistance, tensile strength and thermal stability of starch film. Moreover, starch film containing 10 wt% of CP-Kaolin was sensitive to the change in pH of the fish during storage. Therefore, the addition of CP-Kaolin improved the properties of starch film and starch film composite with CP-Kaolin could be applied as a smart packaging in the food industry.