Colorimetric Films Research Articles

Rapid and Facile Synthesis of Homoporous Colorimetric Films Using Leaf Vein-Mediated Emulsion Evaporation Method for Visual Monitoring of Food Freshness.

A new method for rapid and facile fabrication of homoporous films with high volatile amine sensitivity was developed. First, red cabbage anthocyanin was encapsulated in ethyl cellulose to form water-in-organic (W/O) emulsion. Afterward, the W/O emulsion was rapidly dried using the supporting matrix Magnolia Grandiflora Linn leaf vein at 60% relative humidity and 50 °C to form a colorimetric film with regular hexagonal pores with an average side length of about 23 μm. The films exhibited good sensitivity to ammonia (NH3), dimethylamine, and trimethylamine, with limit of detection of 0.26, 0.24, and 0.38 μM, respectively, and high stability when stored in high humid environments. An obvious color change of the films from pink to green was clearly observed during the freshness monitoring of pork, chicken, salmon, and shrimp. Thus, this work offered a novel and reliable method for the development of porous films for food freshness monitoring.

Design, synthesis, solvatochromism, and colorimetric detection of amines based on isolated perylene bisimide anionic radical π-dimers

Some π-molecular radicals typically exist in solution as π-dimers with metastable characteristics. Therefore, attempting to improve the stability of radical π-dimers is a fascinating endeavor. Herein, a series of hydroxyl-functionalised isolated perylene bisimide anionic radical π-dimers were obtained by using intramolecular hydrogen bond assistance in a one-step process for the first time. It is also found that these radical π-dimers exhibit solvatochromism and acid-base discoloration, when the intermolecular hydrogen bonds are disrupted. Perylene bisimide anionic radical π-dimers exhibit unique properties such as solvatochromism and acid-base discoloration. These characteristics make them suitable for ultra-sensitive colorimetric and fluorescent dual-signal detection of amines. Among them the π-dimer 3 achievable the lowest detection limits of 0.13 ppb, 0.02 ppb and 0.049 ppb for primary, secondary and tertiary amines, respectively. Additionally, colorimetric films prepared using these radical π-dimers demonstrate high sensitivity, enabling detection of amines at ppb levels. We believe that this class of radical π-dimers could be develop into a new class of environmental stimuli-responsive materials.

The Use of Novel Colorimetric Films to Monitor the Freshness of Pork, Utilizing Konjac Glucomannan With Curcumin/Alizarin

In this study, different proportions of curcumin (CUR) and alizarin (ALI) were added to konjac glucomannan (KG)/ polyvinyl alcohol (PVA) to prepare an active intelligent packaging film and evaluate its potential to indicate pork freshness. The mixed indicator had a richer color hierarchy in the buffer solution with pH = 2–12. The surface of the KG-2C2A and KG-1C3A films is smoother and has fewer cross-section faults. With the increase of CUR content in the film, the crystal structure becomes more prominent, leading to poor compatibility with KG. The WAC of KG-3C1A and KG-1C3A films was significantly higher than that of the other groups, and they had better hydrophobicity. With the increase of CUR content in the films, the thermal stability of the films was enhanced, and the KG-C films showed the highest thermal stability. Among them, the KG-2A2C and KG-1C3A films showed the most significant color change during pork spoiling and could be used to monitor the freshness of pork. As a pH colorimetric indicator, CUR and ALI-coated KG films might be of great potential in fresh meat monitoring.

A new design of colorimetric films using bacterial cellulose nanocrystals derived from nata de coco for sensing volatile organic compounds

In this work, bacterial cellulose (BC) derived from Nata de Coco is a polysaccharide material, and it is further processed into bacterial cellulose nanocrystal (BCNC) via acid hydrolysis. Then BCNC is doped with transition metals to enhance its amine/hydrogen sulfide response. Therefore, the aim of this study is to investigate the use of transition metals as indicators to detect amine and hydrogen sulfide gas for efficiently monitoring food spoilage. BCNCs were treated with various concentrations of silver nitrate (AgNO3) and copper sulfate pentahydrate (CuSO4·5H2O). Then the dropwise addition of ascorbic acid was applied to reduce Ag+ and Cu2+ to Ag0 (silver nanoparticle) and Cu0 (copper nanoparticle), which refer to red brown and red wine colors, respectively. The results indicated that BCNC/Ag nanoparticles were spherical, while BCNC/Cu nanoparticles exhibited a rod-like structure. XRD results also presented the incorporation of Ag and Cu nanoparticles, as confirmed by both crystallography structures. Furthermore, UV–Vis spectra showed the adsorption bands at 422–430 nm and 626–629 nm, belonging to Ag and Cu nanoparticles. After H2S and ammonia gas exposure, BH/Ag and BH/Cu films turned black from brown and red. In conclusion, transition metal-doped BCNCs exhibit potential for innovative food spoilage gas sensors.

Biofilms from poly-vinyl alcohol/palmyra root sprout with Boswellia serrata, carbon dots and anthocyanin for sensing the freshness of sardine fish

One of the main issues that customers worldwide have is food adulteration. In commercial packages, freshness cannot always be determined visually. Here, we propose sensitive films for use in food packaging that could alter colour to indicate a change in freshness. Hybrid, multifunctional, and eco-friendly films were prepared from polyvinyl alcohol/palmyra root sprout (PVA/PRS), fused with soy protein isolate carbon dot (CD), Boswellia serrata (BS), and Clitoriaternatea anthocyanin (CTE). The films showed pH sensitivity, antioxidant, and UV barrier properties. By creating hydrogen bonds between PRS and the other fillers, adding these substances makes PVA less crystallized. These interactions were verified by infrared Fourier-transform analysis. When compared to PVA, PRS films had significantly lower moisture content and swelling ratios. The UV-blocking capabilities of the films were greatly improved by the addition of CD, BS, and CTE without compromising their mechanical, thermal, or water vapor barrier properties. The composite film PVA/PRS/CD/BS/CTE exhibited a maximum tensile strength value of 69.47 ± 1.49 MPa. The CT extract provides the film with superior antioxidant properties. The colorimetric films PVA/PRS/CTE and PVA/PRS/CD/BS/CTE showed distinct pH-responsive colour-change properties as well as good colour stability. The colorimetric films were used to test the freshness of sardine fish, and they revealed unique colour changes that indicated whether the fish sample was spoiled or not.

Intelligent System/Equipment for Quality Deterioration Detection of Fresh Food: Recent Advances and Application.

The quality of fresh foods tends to deteriorate rapidly during harvesting, storage, and transportation. Intelligent detection equipment is designed to monitor and ensure product quality in the supply chain, measure appropriate food quality parameters in real time, and thus minimize quality degradation and potential financial losses. Through various available tracking devices, consumers can obtain actionable information about fresh food products. This paper reviews the recent progress in intelligent detection equipment for sensing the quality deterioration of fresh foods, including computer vision equipment, electronic nose, smart colorimetric films, hyperspectral imaging (HSI), near-infrared spectroscopy (NIR), nuclear magnetic resonance (NMR), ultrasonic non-destructive testing, and intelligent tracing equipment. These devices offer the advantages of high speed, non-destructive operation, precision, and high sensitivity.

Characterization of a Food‐Safe Colorimetric Indicator Based on Black Rice Anthocyanin/PET Films for Visual Analysis of Fish Spoilage

ABSTRACTThe safety of food products is of prime importance for consumers and manufacturers. Many means can be used to validate a food product's safety before it is consumed. This study is about the preparation, characterization and evaluation of a generally recognized as safe (GRAS) sensitive colorimetric sensor that detects volatile gases (TVB‐N) resulting from fish spoilage, thus indicating the pH variation of packaged fish products. This is performed by coating a thin layer of ink sensors on the surface of the supporting matrix (corona‐treated PET). Various visual pH indicators were prepared based on black rice anthocyanin as an FDA‐approved dye. Black rice, which contains more than 80% cyanidin‐3‐glucoside, is the most prevalent anthocyanin component. Because of its low toxicity and high concentration, it can be utilized as a natural food colourant. pH indicators based on black rice can show distinct colours in various pH: from red (low pH) to violet (4–6) and deep purple/blue (6–7), blue (7–9) to yellowish/light brown (9–13) throughout the acid–base reaction by the analyte. The ink formulation was prepared by incorporating a binder system (PVOH‐PEG) for higher surface wettability, a crosslinking agent (citric acid) for higher adhesion, an antifoaming agent (natural vanillin) and acetic acid as a pH fixing agent. Corona treatments affected substrate surface chemistry in this study. The samples with thermal treatment passed the ASTM D3330 tape test, the 8000 passages for dry sponge and the 25 passages for wet sponge through the abrasion method. Anthocyanin concentration in formulated ink based on calculation by UV–vis spectra is 0.240 mg/100 g. Sensitivity tests towards TVB‐N gases were carried out at a temperature of 4°C to evaluate the performance of colorimetric films with formulated ink along with thermal treatment (temperature: 165°C, time: 5 min) using the volatile gases emitted by the fish sample inside the package.

Colorimetric Films Based on Polyvinyl Alcohol and Anthocyanins Extracted from Purple Tomato to Monitor the Freshness of Shrimp.

Anthocyanin extracts from purple tomato (PTA) were incorporated with polyvinyl alcohol (PVA), resulting in a series of colorimetric PVA/PTA films with PTA concentrations of 0%, 1%, 3%, and 5% (based on PVA). The role of anthocyanin on color response, Fourier-transform infrared (FTIR), thickness, water content, mechanical properties, antioxidant activity, and water vapor permeability (WVP) through the films was examined. In addition, its application in smart packaging to assess the freshness of shrimp was studied. It was found that the tensile strength, contact angle and WVP of PVA/PTA films increases with the addition of more PTA, while the elongation at break and water content decreased. FTIR analysis showed that there are interactions between PTA and the PVA matrix. The addition of anthocyanins caused significant improvement in the antioxidant properties of PVA films. Furthermore, the total volatile alkaline nitrogen (TVB-N), total plate count (TPC), and pH value of shrimp were monitored after 4 days of refrigeration, and the color change of the indexes was recorded. The PVA/PTA films changed color from purple to yellow-green during the storage time of 0-4 days for shrimp. This suggests that the film could be used in smart packaging as a real-time freshness indicator for shrimp.

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

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. 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). 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.

Preparation and evaluation of smart food packaging films with anthocyanin Sardasht black grape based on Astragalus gummifer and chitosan nanoparticles

A new and green development in the field of food packaging is the use of colorimetric films containing anthocyanins, which not only can respond to food spoilage but also have no environmental risk and help the environment full of unacceptable and polluted substances created by humans. In this research, a completely natural film (GCNG) was made using natural materials including tragacanth gummifer (G), chitosan nanoparticles (C), and an extract containing anthocyanins of a type of wild grape called Sardasht black (G) with Alumina nanoparticles (N) for use in food packaging. This biodegradable film (GCNG) presented relatively wide color differences from red to blue in different buffer solutions (pH 2–12), which was clearly observed by the naked eye. Sardasht black grape extract contains large amounts of anthocyanins and antioxidants that can be extracted and used in the preparation of packaging films. The properties of prepared films, including mechanical properties, permeability to water vapor, solubility, swelling, as well as antimicrobial properties were checked by measuring the diameter of the diffusion area by agar disk test. GCNG films showed strong antioxidant activity and good antibacterial activity against E. coli and S. aureus. The results suggested this film has promising potential as an active and smart packaging material for applications in the food industry.

Application of biodegradable colorimetric films based on purple tomatoes anthocyanins loaded chitosan and polyvinyl alcohol in pork meat.

A series of biodegradable colorimetric films were prepared by using chitosan and polyvinyl alcohol as matrix, in which, the weight ratio of chitosan: Polyvinyl alcohol was 100: 0, 80: 20, 50: 50, 20: 80, or 0: 100, with addition of 10% (w/w, relative to chitosan) anthocyanins extracted from purple tomatoes (purple tomatoes anthocyanin) as pigment. The aim of this study was to observe the effect of weight ratio (chitosan: Polyvinyl alcohol) on the mechanical properties, contact angle, swelling rate, pH sensitivity, antioxidant properties of chitosan-polyvinyl alcohol/purple tomatoes anthocyanins films, and the antibacterial activity of films produced for pork packaging. In addition, the films as a smart colorimetric indicator for monitoring the freshness of pork was investigated. The results showed that as the ratio of chitosan to polyvinyl alcohol decreases, the elongation at break, hydrophilicity, and swelling rate of the films increased especially from 16.5% to 174.2% for elongation at break and 93.0° to 53.8° for water contact angle, however, the tensile strength decreased from 67.3 to 24.7 MPa. With decreasing of chitosan: Polyvinyl alcohol, the antibacterial activity on pork was decreased, and the antioxidant properties of films increased first then decreased. Fourier transform infrared spectroscopy indicated there were interactions among chitosan, polyvinyl alcohol, and purple tomatoes anthocyanins. The color response of films was depended on pH, as well as the immersion time. The longer immersion resulted in a more pronounced color change. The color changed from purplish red (pH 2-4) to green (pH 5-10) to yellow (pH 10-12). In monitoring the freshness of pork, the film showed a nice visual color change, indicating a potential application in smart packaging. These bio-based materials may be useful alternatives to synthetic plastics for food applications such as active and smart packaging, thereby improving the environmental friendliness and sustainability of the food supply.

FoodSmarTag: An innovative dynamic labeling system based on pyranoflavylium-based colorimetric films for real-time monitoring of food freshness

A colorimetric pyranoflavylium-based pH-indicator with an improved formulation was obtained and studied as an intelligent label for food freshness monitoring. Pyranoflavylium pigment at 0.2% (w/w) and glycerol at 30% (w/w) were immobilized in a cellulose acetate matrix, and a thin film was obtained by the solvent casting method. The pH-responsive properties of the film were evaluated in solutions at different pH values (pH 4 to 8) and compared with a previous formulation. Film photostability and pigment migration over time were assessed. The label's performance was evaluated using real samples (fish and meat) at controlled conditions (3 °C and modified atmosphere packaging). The results showed that increased pigment concentration visually favored its colorimetric efficacy. Regarding pigment migration and photostability, the label showed to be suitable for application in fresh meat and fish packaging. The best performance was observed for the freshness monitoring of fish samples. The indicator demonstrated high efficacy in detecting spoilage of Atlantic horse mackerel (Trachurus trachurus). After 5 days of storage, freshness parameters exceeded the limit defined by EU regulations, indicating that the fish was unfit for consumption. Simultaneously, the yellow label started to turn purple, effectively indicating the beginning of the spoilage process.

Sugarcane-derived Bio‐Amine‐Responsive Colorimetric Films for real-time visual monitoring of the seafood freshness

A new type of bio-amine-response colorimetric film with excellent flexibility and biodegradability was fabricated by the main components of sugarcane, including sugarcane skin anthocyanin (SSA), bagasse cellulose fibers (CF), and cellulose nanofibers (CNF). Benefiting from the rich hydroxyl groups and large specific surface area of CNF, the sample of adding 10 wt% CNF in CF (CF/CNF10/SSA) presented good mechanical properties (33 Mpa), reusability (10 cycles), excellent color change (ΔE＞5), and excellent antioxidant properties (the free radical scavenging rate of ABTS: 86%). Furthermore, the film had good water resistance (water contact angle only decreases about 20° after 60 s), color stability up to 28 days, and rapid response to ammonia (1–2 s). Thus, CF/CNF10/SSA was successfully used as a low-cost, inoxidizable, and pH/NH3 responsive smart tag to monitor the freshness of seafood in real-time, achieving the high-value utilization of sugarcane waste components.

Chitosan‐based film incorporated with anthocyanins of red poppy (Papaver rhoeas L.) as a colorimetric sensor for the detection of shrimp freshness

SummaryThis study introduces a novel intelligent film based on chitosan (Ch) incorporated with a new natural dye of red poppy as a colorimetric sensor for the real‐time detection of shrimp freshness. The colour changeability of red poppy anthocyanins (RPAs) in a pH range of 2–12 was confirmed by the UV–vis spectra. The indicator film can respond to the ammonia vapour, with the colour changing of RPAs (brown/light yellow to dark brown) over time. The colorimetric films' light screening, tensile strength and antioxidant properties after the addition of RPAs show an increase. The anthocyanin‐loaded films produce a substantial colour change from brown to light yellow consistent with the shrimp spoilage at the pH threshold, which can inform the quality deterioration of the shrimp. Due to these benefits, the Ch‐RPAs indicator film can be used to visually and real‐timely monitor shrimp freshness in package.

Films Sensor Containing Extracted Natural Dyes for Monitoring Freeze-Thawing of Frozen Chicken

Films sensors include natural sensitive dyes and enzymes were used to create freezing-thawing sensitive films. Gliadin/glycerol, as well as anthocyanin, chlorophyll, and beta-carotene, were used to make the films. This type of biosensor is an efficient way to deal with the problem of freeze-thawing meat and provides a low-cost, colorimetric indicator for raising consumer awareness about freeze-thawed chicken. As a result of response enzymes, Glucose oxidase, and alpha-amylase have an impact on intensifying pigments films and reacting to freezing-thawing meat, the naked eye is capable of distinguishing between the colors of films, which changed from red, yellow, and green to faint colors. Sensing films’ color stability was tested, and the results demonstrated that the films were extremely stable and could be kept for longer than three weeks. Finally, real samples could be used to monitor misuse of utilizing storage temperature for chicken meat by using freeze-thawing sensitive colorimetric films. The best concentrations of GOX enzyme are 0.9%(activity270U/0.09g), 0.9%(117U/0.09g) of α-Amylase, and 5% of natural extracted pigments for preparing freezing-thawing sensitive films were of enzymes and, while the best concentration1:0.1 of Gliadin/glycerol composition films. The results of the colorimetric enzymatic system produced with different concentrations of enzymes and exposed to 8 and 35°C revealed that the same concentration of enzymes results in varying stability times when exposed to different temperature conditions, pH levels, and moisture.

Deciphering the correlation between color response, temperature, and relative humidity in a photo-patternable polymeric nanofilm for tunable multimodal display

Relative humidity (RH) and temperature responsive nanofilms have been developed as colorimetric sensors based on light interference, with the sensors providing rapid and easy detection, high accuracy, good mobility, wearability, and power-free sensing ability. However, current studies on RH and temperature-sensitive colorimetric films focus only on the effect of either temperature or RH on the sensing ability. With an inherent relationship between temperature and RH, this constraint leads to significant limitations for the use of thin film sensors in practical applications. In this work, we address these limitations by examining the correlation between structural color (thickness), temperature, and RH using nanolayered polyelectrolyte films made from chitosan (CHI) and carboxymethyl cellulose (CMC). We propose a novel 3-dimensional (3D) non-linear regression model to describe the correlation between the normalized thickness, temperature, and RH; with the thickness prediction showing high agreement with experimental results. Furthermore, photoreactive carboxymethyl cellulose-azido derivative (CMC-N3) was used to build CHI/CMC-N3 films that can be covalently crosslinked upon UV irradiation. By taking advantage of different swelling behaviors of CHI/CMC-N3 films before and after UV treatment, a variety of colors and crosslinked patterns are hidden/displayed at selected RHs and temperatures. This enables a tunable multimodal display of the pattern-encoded information. Remarkably, in temperature ranges from 2 °C to 55 °C, uniform colors covering the entire visible spectra were observed, while in the low temperature (2–10 °C) and high RH (∼80%) regimes, the film demonstrated vivid color changes with 1 °C resolution. We expect the film to provide a versatile platform for potential applications in environmental sensing, anticounterfeiting, food storage, and quality control in drug transport.

Highly biologically active and pH-sensitive collagen hydrolysate-chitosan film loaded with red cabbage extracts realizing dynamic visualization and preservation of shrimp freshness

Accurate and efficient detection of food freshness is of great significance to guarantee food safety. Herein, pH sensitive colorimetric films with considerable biological activities have been prepared by combining red cabbage anthocyanin extracts (RCE) with collagen hydrolysate-chitosan (CH-CS) matrix film. The formation mechanism of CH-CS-RCE films was discussed by SEM, FT-IR and XRD, which showed that RCE was successfully fixed in CH-CS film through hydrogen bonding and electrostatic interaction. The CH-CS-RCE films exhibited good mechanical properties, high barrier ability, excellent thermal stability, significant antioxidant and antimicrobial activity, and especially sensitive response to pH and ammonia. Fickian diffusion was the main mechanism for the release of RCE from CH-CS-RCE films and such release mechanism facilitated the maintenance of functional features of films. During the storage of shrimps at 4 °C, CH-CS-RCE2% showed a remarkable preservation effect on shrimps, and their shelf life was prolonged from 2 d to 5 d. Furthermore, CH-CS-RCE2% provided a dynamic visual color switching to detect the freshness of shrimp, realizing real-time monitoring of freshness. Color information (RGB) extracted via smartphone APP was used to enhance the accuracy and universality of freshness indication. Thus, this multifunctional film has great potential in food preservation and freshness monitoring.

Cellulosic material-based colorimetric films and hydrogels as food freshness indicators

Cellulosic material-based colorimetric films and hydrogels as food freshness indicators

Dual Responsive Dependent Background Color Based on Thermochromic 1D Photonic Crystal Multilayer Films.

In this paper, we present dual responsive one-dimensional (1D) photonic crystal (PC) multilayer films that utilize a high-humidity environment and temperature. Dual responsive 1D PC multilayer films are fabricated on precoated thermochromic film by sequential alternate layer deposition of photo-crosslinkable poly(2-vinylnaphthalene-co-benzophenone acrylate) (P(2VN-co-BPA)) as a high refractive index polymer, and poly(4-vinylpyrollidone-co-benzophenone acrylate) P(4VP-co-BPA) as a low refractive index polymer. The thermochromic film shows a vivid color transition from black to white at 28 °C. Three different colors of thermochromic 1D PC multilayer films are prepared by thickness modulation of P(4VP-co-BPA) layers, and the films on a black background exhibit visible spectrum color only in a high-humidity environment (over 90% relative humidity (RH)). For the three films placed on a hands display, three different composite colors are synthesized by the reflection of light, including yellow, magenta, and cyan, due to the changing of backgrounds from black to white with temperature. Additionally, the films show remarkable color transitions with reliable reversibility. The films can be applied as anti-counterfeiting labels and can be used for smart decoration films. To the best of our knowledge, this is the first report of dual response colorimetric films that change color in various ways depending on temperature and humidity changes, and we believe that it can be applied to various applications.

Intelligent colorimetric soy protein isolate-based films incorporated with curcumin through an organic solvent-free pH-driven method: Properties, molecular interactions, and application

The preparation of intelligent colorimetric films based on soy protein isolate and curcumin at different final pHs was investigated by using blending and pH-driven methods with curcumin-free films as blank controls. It was found that the films loaded with curcumin using the pH-driven method exhibited enhanced ductility and water resistance with an elongation at break of 122 ± 6% and water vapor permeability of 1.70 ± 0.01 × 10 −10 g·m/m 2 ·Pa·s. The Fourier transform infrared (FTIR) spectroscopy results showed that curcumin was loaded in the film network mainly through hydrogen bonds and hydrophobic interactions. The curcumin encapsulated using the pH-driven method was present in an amorphous form, which effectively suppressed the adverse effect of curcumin blending on film opacity and increased the UV blocking ability of the films. The high encapsulation efficiency and reduced thermal degradation of curcumin resulted in enhanced antioxidant activity of the films with high 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities of 102.91 ± 0.83 Trolox equivalent (TE)/g and 211.47 ± 5.20 μg TE/g, respectively. Furthermore, films showed better color responsiveness to volatile amines than curcumin-blended films. In particular, the films generated with a film-forming solution at pH 8 had the strongest color sensitivity in the presence of low concentrations of volatile amines. In shrimp storage experiments, only the films prepared using the pH-driven method identified the freshness of the shrimp based on visual observation. Hence, the pH-driven method might represent a promising organic solvent-free method for the preparation of intelligent packaging films. • An organic solvent-free strategy was proposed to prepare curcumin-loaded films. • Amorphous curcumin was loaded by hydrogen bonds and hydrophobic interactions. • The films had good antioxidant activity and color response to volatile amines. • The films were suitable for real-time freshness monitoring of shrimp.