Intelligent colorimetric film incorporated with anthocyanins-loaded ovalbumin-propylene glycol alginate nanocomplexes as a stable pH indicator of monitoring pork freshness

Fast and sustainable production of smart nanofiber mats by solution blow spinning for food quality monitoring: Potential of polycaprolactone and agri-food residue-derived anthocyanins

The shelf life of perishable foods is estimated through expensive and imprecise analyses that do not account for improper storage. Smart packaging, obtained by agile manufacturing of nanofibers functionalized with natural pigments from agri-food residues, presents promising potential for real-time food quality monitoring. This study employed the solution blow spinning (SBS) technique for the rapid production of smart nanofiber mats based on polycaprolactone (PCL), incorporating extracts of agricultural residues rich in anthocyanins from eggplant (EE) or purple cabbage (CE) for monitoring food quality. The addition of EE or CE to the PCL matrix increased the viscosity of the solution and the diameter of the nanofibers from 156 nm to 261-370 nm. The addition of extracts also improved the mechanical and water-related properties of the nanofibers, although it reduced the thermal stability. Attenuated total reflectance Fourier-transform infrared spectroscopy confirmed the incorporation of anthocyanins into PCL nanofibers. Nanofiber mats incorporated with EE or CE exhibited visible color changes (ΔE ≥ 3) in response to buffer solutions (pH between 3 and 10), and ammonia vapor. Smart nanofibers have demonstrated the ability to monitor fish fillet spoilage through visible color changes (ΔE ≥ 3) during storage. Consequently, smart nanofibers produced by the SBS technique, using PCL and anthocyanins from agro-industrial waste, reveal potential as smart packaging materials for food.

Intelligent Food Packaging: Quaternary Ammonium Chitosan/Gelatin Blended Films Enriched with Blueberry Anthocyanin-Derived Cyanidin for Shrimp and Milk Freshness Monitoring

Blueberry anthocyanin-derived cyanidin (BAC) was used to prepare a series of responsive food freshness packaging films by compounding it with quaternary chitosan (QC) and gelatin (G). The fundamental properties, pH sensitivity, and functional attributes of the films were examined. The BAC solutions exhibited notable variations in color (from red to pink to violet) under different pH conditions. The incorporation of BAC resulted in improved UV-vis shielding capabilities but compromised the mechanical strength of the films (with tensile strength values from 85.02 to 44.89 MPa, elongation at break from 13.08% to 3.6%, and water vapor transmission rates from 5.24 × 10-9 to 7.80 × 10-9 g m-1 s-1 Pa-1). The QC-G-BAC films, containing 5-15 wt% BAC, exhibited noticeable color changes in acidic/ammonia environments within a short timeframe, easily discernible to the naked eye. Furthermore, the inclusion of BAC significantly enhanced the antioxidant and antimicrobial properties of the films. The addition of 5-15 wt% BAC to QC-G-BAC films could be employed for assessing the freshness of fresh shrimp (from red to dark red) and pasteurized milk (from red to dark earthy yellow). Among them, the total color difference (ΔE) of QC-G-BAC5 film was significantly correlated with the pH, acidity, and total colony count of pasteurized milk (R = 0.846, -0.930, -0.908, respectively). This new concept in smart packaging offers a straightforward and user-friendly freshness indicator.

Hybrid chiral nanocellulose-cyanidin composite with pH and humidity response for visual inspection and real-time tracking of shrimp quality and freshness

Biobased multi-stimulation materials have received considerable attention for intelligent packaging and anti-counterfeiting applications. Cellulose nanocrystals (CNCs) and cyanidins are good material candidates for monitoring food freshness as they are eco-friendly natural substances. This work incorporated cyanidin with a CNC-hosting substrate to develop a simple, environment-friendly colorimetric device to visualize food freshness. Across the pH range of 2-13, the indicator exhibited noticeable color changes ranging from red to gray and eventually to orange. The CNC-cyanidin (CC) film exhibited a dramatic color change from blue to dark red and high sensitivity at a relative humidity of 30 %-100 %. In corresponding to the total volatile elemental nitrogen (TVB-N) level of shrimp, the indicator showed distinguishable colors at different stages of shrimp. The findings imply that the samples have substantial potential for use as an intelligent indicator for tracking shrimp freshness.

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.

A review on improving the sensitivity and color stability of naturally sourced pH-sensitive indicator films

Naturally sourced pH-sensitive indicator films are of interest for real-time monitoring of food freshness through color changes because of their safety. Therefore, natural pigments for indicator films are required. However, pigment stability is affected by environmental factors, which can in turn affect the sensitivity and color stability of the pH-sensitive indicator film. First, natural pigments (anthocyanin, betalain, curcumin, alizarin, and shikonin) commonly used in pH-sensitive indicator films are presented. Subsequently, the mechanisms behind the change in pigment color under different pH environments and their applications in monitoring food freshness are also described. Third, influence factors, such as the sources, types, and pH sensitivity of pigments, as well as environmental parameters (light, temperature, humidity, and oxygen) of sensitivity and color stability, are analyzed. Finally, methods for improving the pH-sensitive indicator film are explored, encapsulation of natural pigments, incorporation of a hydrophobic film-forming matrix or function material, and protective layer have been shown to enhance the color stability of indicator films, the addition of copigments or mental ions, blending of different natural pigments, and the utilization of electrospinning have been proved to increase the color sensitivity of indicator films. This review could provide theoretical support for the development of naturally sourced pH-sensitive indicator films with high stability and sensitivity and facilitate the development in the field of monitoring food freshness.

Recent advances in protein-polysaccharide based biocomposites and their potential applications in food packaging: A review

This review addresses the current trend of replacing petroleum-based polymers in food packaging with bio-based alternatives, specifically focusing on proteins and polysaccharides. While these biopolymers exhibit excellent film-forming properties and are abundant in nature, their individual use in packaging lacks ideal plastic-like characteristics, especially in terms of mechanical and barrier properties. A recent solution involves the formulation of biocomposites through the reinforcement of one biopolymer with another (e.g., protein with a polysaccharide), significantly enhancing the physical, mechanical, and barrier properties of packaging materials. The review concentrates on the integration of proteins and polysaccharides in biocomposite materials, emphasizing their potential applications in active and intelligent food packaging systems. It covers sources, manufacturing methods, interaction mechanisms, recent developments, perspectives, and opportunities. The exploration extends to practical implementations of these biocomposites in enhancing food quality, safety, and shelf life-a green technological approach contributing to the reduction of food waste and loss.

Preparation and properties of polyvinyl alcohol/chitosan-based hydrogel with dual pH/NH3 sensor for naked-eye monitoring of seafood freshness

To address the issue of food spoilage causing health and economic loss, we developed a pH/NH3 dual sensitive hydrogel based on polyvinyl alcohol/chitosan (PVA/CS) containing chitosan-phenol red (CP). The CP was synthesized via Mannich reaction and immobilized it in PVA/CS hydrogel through freezing/thawing method to prepare the final PVA/CS/CP hydrogel. The synthesis of CP was confirmed by 1H NMR, FT-IR, XRD, UV-vis, and XPS. The characteristics of hydrogel were evaluated by FT-IR, XRD, SEM, mechanical properties, thermal stability, leaching, and color stability tests. The PVA/CS/CP hydrogel showed distinctly different color at various pH and NH3 vapor levels (yellow to purple). The hydrogel exhibited obvious color changes (ΔE = 46.95) in response to shrimp spoilage, stored at 4 °C. It showed positive and strong correlation between the ΔE values of the indicator hydrogel and total volatile basic nitrogen (TVB-N) as (R2 = 0.9573) and with pH as (R2 = 0.8686), respectively. These results clearly show that the PVA/CS/CP hydrogel could be applied for naked-eye real-time monitoring of seafood freshness in intelligent packaging.

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.

Formation of pH-responsive hydrogel beads and their gel properties: Soybean protein nanofibers and sodium alginate

Hydrogel beads prepared from protein nanofibers are popular because of their safety, sleek appearance, and protection of biologically active substances. However, extreme external environmental variations, such as pH and temperature, can limit their practical application. To meet the application requirements of hydrogel beads in different environments, non-covalent mixtures of CaCl2 cross-linked soybean protein nanofibers (SNF) and sodium alginate (SA) were used to prepare hydrogel beads. In the present study, the hardness (782.48 g) and elasticity of hydrogel beads formed at SNF/SA = 7:3 and CaCl2 concentration of 0.1 mol/L were the maximum. Furthermore, the water content and pH swelling also reached a peak (98.68 %, 43.85 g/g) due to the best morphology and regular internal network structure. Meanwhile, the pH-responsive hydrogel beads with added anthocyanins were able to respond to the ambient pH under different temperatures and pH conditions and maintained color stability during 96 h of storage (ΔE < 5). In this experiment, a pH-responsive hydrogel bead based on soybean protein nanofiber (SNF) and sodium alginate (SA) was prepared by simple ionic crosslinking. It provides a theoretical and experimental basis for the future application of plant protein nanofibers as pH-responsive hydrogel materials.

Development of smart packaging film incorporated with sodium alginate-chitosan quaternary ammonium salt nanocomplexes encapsulating anthocyanins for monitoring milk freshness

This study focused on the preparation, functionality, and application of smart food packaging films based on polyvinyl alcohol (PVA) and anthocyanins (ACNs) -loaded sodium alginate-chitosan quaternary ammonium salt (HACC-SA) nanocomplexes. The average encapsulation rate of anthocyanins-loaded nanocomplexes reached 62.51 %, which improved the hydrophobicity and water vapor barrier of the PVA film. FTIR confirmed that the nanocomplexes were immobilized in the PVA film matrix by hydrogen bonding, which improved the mechanical properties of the film. The SEM and XRD results demonstrated that the HACC-SA-ACNs nanocomplexes were uniformly distributed in the film matrix and the crystallinity of PVA was decreased. The P/HACC-SA-ACNs film showed a significant response to buffers of pH 2-13 and high color stability after 21 days of storage compared to the P/ACNs film. Furthermore, the color of the composite film changed from purple to red as the milk freshness decreased during 72 h of milk freshness monitoring, indicating that the P/HACC-SA-ACNs films were suitable and promising for application as smart packaging materials.

A Colorimetric Nanofiber Film Based on Ethyl Cellulose/Gelatin/Purple Sweet Potato Anthocyanins for Monitoring Pork Freshness

In this study, colorimetric indicator nanofiber films based on ethyl cellulose (EC)/gelatin (G) incorporating purple sweet potato anthocyanins (PSPAs) were designed via electrospinning technology for monitoring and maintaining the freshness of pork. The film presented good structural integrity and stability in a humid environment with water vapor permeability (WVP) of 6.07 ± 0.14 × 10-11 g·m-1s-1Pa-1 and water contact angle (WCA) of 81.62 ± 1.43°. When PSPAs were added into the nanofiber films, the antioxidant capacity was significantly improved (p < 0.05) with a DPPH radical scavenging rate of 68.61 ± 1.80%. The nanofiber films showed distinguishable color changes as pH changes and was highly sensitive to volatile ammonia than that of casting films. In the application test, the film color changed from light pink (fresh stage) to light brown (secondary freshness stage) and then to brownish green (spoilage stage), indicating that the nanofiber films can be used to detect the real-time freshness of pork during storage. Meanwhile, it could prolong the shelf life of pork by inhibiting the oxidation degree. Hence, these results suggested that the EC/G/PSPA film has promising future for monitoring freshness and extending shelf life of pork.

3D Printing of smart labels with curcumin-loaded soy protein isolate

A two-step method for preparing smart labels that can monitor food freshness through color change is presented. The conventional casting method for such labels is not cost-effective, as it uses organic solvents and requires additional cutting processes. Our method is more eco-friendly and customizable, as it uses water as the sole solvent and 3D printing as the fabrication technique. First, curcumin was encapsulated with soy protein isolate (SPI) by a pH-driven method involving hydrogen bonding and hydrophobic interactions. Subsequently, the SPI-curcumin complex was blended with gelatin to create a printable ink. The ink has suitable rheological properties for extrusion, with a yield stress of 400-600 Pa and a viscosity of 122.93-142.82 Pa·s at the optimal printing temperature. The complex modulus of the ink increases to above 2 × 103 Pa when cooled to 25 °C, indicating rapid gel formation. The application of these smart labels to minced meat demonstrated their ability to reflect its freshness by transitioning from yellow to red. Furthermore, the printability and mechanical properties of the labels can be adjusted by changing the glycerol/water ratio. This innovative approach is a promising solution for producing environmentally friendly and customizable smart labels for food freshness monitoring.

Mechanically Robust Poly(vinyl alcohol)-Egg White Composite Hydrogel with Enhancing Biocompatibility by Unidirectional Nanopore Dehydration

A simple and green method, unidirectional nanopore dehydration (UND), directly processes 10% poly(vinyl alcohol) (PVA) aqueous solution containing 20% egg white (EW) into a composite hydrogel membrane (PVA-EW). The tensile strength and elongation of the UND-based PVA-EW at 25 °C were 0.91 MPa and 534.17%, respectively, while the two values at 70 °C were increased by 700 and 38%, respectively. The PVA-EW (70 °C) was still dominated by random coils and α-helical structures. The hydroxyl groups of intramolecules and intermolecules of both PVA and EW could be able to combine and form either more hydrogen bonds or stronger hydrogen bonds. PVA-EW is soft and translucent, has good mechanical properties, and has a porous networked structure with pores that have a diameter of 1-10 μm. L-929 mouse fibroblasts were found to be able to adhere, grow, and proliferate well on the hydrogel composite membrane. This novel PVA-EW biomaterial has potential applications in biomaterials especially medical tissue engineering.

Recent advances on natural colorants-based intelligent colorimetric food freshness indicators: fabrication, multifunctional applications and optimization strategies

With the increasing concerns of food safety and public health, tremendous efforts have been concentrated on the development of effective, reliable, nondestructive methods to evaluate the freshness level of different kinds of food. Natural colorants-based intelligent colorimetric indicators which are typically constructed with natural colorants and polymer matrices has been regarded as an innovative approach to notify the customers and retailers of the food quality during the storage and transportation procedure in real-time. This review briefly elucidates the mechanism of natural colorants used for intelligent colorimetric indicators and fabrication methodologies of natural colorants-based food freshness indicators. Subsequently, their multifunctional applications in intelligent food packaging systems like antioxidant packaging, antimicrobial packaging, biodegradable packaging, UV-blocking packaging and inkless packaging are well introduced. This paper also summarizes several optimizing strategies for the practical application of this advanced technology from different perspectives. Strategies like adopting a hydrophobic matrix, constructing double-layer film and encapsulation have been developed to improve the stability of the indicators. Co-pigmentation, metal ion complexation, pigment-mixing and using substrates with high surface area are proved to be effective to enhance the sensitivity of the indicators. Approaches include multi-index evaluation, machine learning and smartphone-assisted evaluation have been proven to improve the accuracy of the intelligent food freshness indicators. Finally, future research opportunities and challenges are proposed. Based on the fundamental understanding of natural colorants-based intelligent colorimetric food freshness indicators, and the latest research and findings from literature, this review article will help to develop better, lower cost and more reliable food freshness evaluation technique for modern food industry.

Fabricating a visibly colorimetric film via self-releasing of anthocyanins from distributed mulberry pomace particles in hydrophilic sodium carboxymethyl starch-based matrix to monitor meat freshness

A highly distinguishable indicator film was developed based on sodium carboxymethyl starch, κ-carrageenan, carboxylated cellulose nanocrystals and mulberry pomace particles (MPPs). As the content of MPPs increased from 0 % to 6 %, the tensile strength decreased from 11.71 MPa to 5.20 MPa, the elongation at break increased from 26.84 % to 43.76 %, respectively, and the haze increased from 34.12 % to 52.10 %. The films accurately exhibit a color change from purple to blue-green under alkaline conditions. The enhanced haze improved the visible resolution of the films during the color-changing process. The films with the size of 7.50 mm × 7.50 mm and 10.0 mm × 10.0 mm exhibited obvious color changes when the total volatile basic nitrogen reached 14.60 mg/100 g and 19.04 mg/100 g, respectively, which accurately indicated the quality of pork and fish. This study will offer a simplified path to improve both accurate sensitivity and distinguishability for smart films.

A critical review on protein-based smart packaging systems: Understanding the development, characteristics, innovations, and potential applications

The use of packaging in the food industry is essential to protect food and improve its shelf life. However, traditional packaging, based on petroleum derivatives, presents some problems because it is non-biodegradable and is obtained from nonrenewable sources. In contrast, protein-based smart packaging is presented as an environmentally friendly strategy that also permits obtaining packaging with excellent characteristics for the formation of smart films and coatings. This review aims to summarize recent developments in smart packaging, focusing on edible films/coatings materials, originating from animal and plant protein sources. Various characteristics like mechanical, barrier, functional, sensory, and sustainability of packaging systems are discussed, and the processes used for their development are also described. Moreover, relevant examples of the application of these smart packaging technologies in muscle foods and some innovations in this area are presented. Protein-based films and coatings from plant and animal origins have great potential to enhance food safety and quality, and reduce environmental issues (e.g., plastic pollution and food waste). Some characteristics of the packages can be improved by incorporating polysaccharides, lipids, and other components as antioxidants, antimicrobials, and nanoparticles in protein-based composites. Promising results have been shown in many muscle foods, such as meat, fish, and other seafood. These innovative smart packaging systems are characterized by their renewable and biodegradable nature, and sustainability, among other features that go beyond typical protection barriers (namely, active, functional, and intelligent features). Nonetheless, the utilization of protein-based responsive films and coatings at industrial level still need optimization to be technologically and economically valid and viable.

Allergenicity, assembly and applications of ovalbumin in egg white: a review

Ovalbumin (OVA), the most abundant protein in egg whites, has been widely used in various industries. Currently, the structure of OVA has been clearly established, and the extraction of high-purified OVA has become feasible. However, the allergenicity of OVA is still a serious problem because it can cause severe allergic reactions and may even be life-threatening. The structure and allergenicity of the OVA can be altered by many processing methods. In this article, a detailed description on the structure and a comprehensive overview on the extraction protocols and the allergenicity of OVA was documented. Additionally, the information on assembly and potential applications of OVA was summarized and discussed in detail. Physical treatment, chemical modification, and microbial processing can be applied to alter the IgE-binding capacity of OVA by changing its structure and linear/sequential epitopes. Furthermore, research indicated that OVA could assemble with itself or other biomolecules into various forms (particles, fibers, gels, and nanosheets), which expanded its application in the food field. OVA also shows excellent application prospects, including food preservation, functional food ingredients and nutrient delivery. Therefore, OVA demonstrates significant investigation value as a food grade ingredient.

Recent advancements in natural colorants and their application as coloring in food and in intelligent food packaging

Colorants are widely employed in the food industry as an essential ingredient in many products since color is one of the most valued attributes by consumers. Furthermore, the utilization of colorants is currently being extended to the food packaging technologies. The objective of this review was to compile recent information about the main families of natural coloring compounds, and to describe their real implications in food coloring. In addition, their technological use in different food systems (namely, bakery products, beverages, meat and meat products, and dairy products) and their utilization in intelligent packaging to monitor the freshness of foodstuffs with the aim of extending food shelf life and improving food properties was discussed. The potential of using natural colorant in different food to improve their color has been demonstrated, although color stability is still a challenging task. More interestingly, the application of intelligent colorimetric indicators to exhibit color changes with variations in pH can enable real-time monitoring of food quality.

The properties of pH-responsive gelatin-based intelligent film as affected by ultrasound power and purple cabbage anthocyanin dose

A pH-sensitive intelligent film was prepared using gelatin as base substrate and purple cabbage anthocyanins (PCA) as indicator with the aid of ultrasound. Fourier transforms infrared and X-ray diffraction analysis showed that 600 W ultrasound brought changes to characteristic bands of gelatin and PCA, and flattened diffraction peak around 2θ = 20°. Film prepared with 600 W ultrasound exhibited high tensile strength and elongation at break and showed high transition temperature and surface hydrophobicity by differential scanning calorimetry and contact angle analysis. The incorporation of <0.35 % PCA had no effect on mechanical properties of films, but it improved the antioxidative activity. Films with 0.14 %, 0.21 % and 0.28 % PCA suggested pronounced color difference at pH 5-8, in accordance with the sharp ΔE difference. Films with 0.28 % PCA was applied for monitoring chilled-stored fish quality. It showed visible color change from pink to atrovirens during storage. The difference of ΔE at various days was ≥5 and ΔE highly correlated with total volatile basic nitrogen. Therefore, gelatin along with PCA under appropriate ultrasound treatment could prepare intelligent film to preserve and monitor the quality of chilled-stored fish.

Preparation of an indicator film based on pectin, sodium alginate, and xanthan gum containing blueberry anthocyanin extract and its application in blueberry freshness monitoring

An active pH-sensitive film based on pectin-sodium alginate-xanthan gum composite film (PAX) was prepared, containing blueberry anthocyanin extract (BAEs), to monitor the freshness of blueberries. The effects of different contents of BAEs on the microstructure and physical properties of intelligent polysaccharide films were comprehensively evaluated. It was found that 75-BAEs-PAX film had a solid response to pH value and showed different and easily distinguishable colors at different pH values. In addition, when the freshness of blueberries stored at different temperatures (-1 °C, 4 °C, 10 °C, 15 °C, 25 °C) was monitored, the color of 75-BAEs-PAX film changed from purple to light pink from neutral to acidic environment, which was consistent with the change of pH value of blueberries from fresh to spoilage. The Arrhenius equation verified that the difference between the activation energy of the indicator film and the blueberry quality was less than 25 kJ/mol. Therefore, the 75-BAEs-PAX film can be used as an indicator film for blueberries freshness monitoring. In this study, the freshness of blueberries was monitored by BAEs, and the purpose of using ontology to monitor ontology was achieved. The freshness of blueberries was visualized during storage and transportation, which could effectively reduce the waste of blueberries. In the future, the method of ontology monitoring ontology could be extended to other foods.

Research advance of non-thermal processing technologies on ovalbumin properties: The gelation, foaming, emulsification, allergenicity, immunoregulation and its delivery system application

Ovalbumin (OVA) is the most abundant protein in egg white, with excellent functional properties (e.g., gelling, foaming, emulsifying properties). Nevertheless, OVA has strong allergenicity, which is usually mediated by specific IgE thus results in gut microbiota dysbiosis and causes atopic dermatitis, asthma, and other inflammation actions. Processing technologies and the interactions with other active ingredients can influence the functional properties and allergic epitopes of OVA. This review focuses on the non-thermal processing technologies effects on the functional properties and allergenicity of OVA. Moreover, the research advance about immunomodulatory mechanisms of OVA-mediated food allergy and the role of gut microbiota in OVA allergy was summarized. Finally, the interactions between OVA and active ingredients (such as polyphenols and polysaccharides) and OVA-based delivery systems construction are summarized. Compared with traditional thermal processing technologies, novel non-thermal processing techniques have less damage to OVA nutritional value, which also improve OVA properties. OVA can interact with various active ingredients by covalent and non-covalent interactions during processing, which can alter the structure or allergic epitopes to affect OVA/active components properties. The interactions can promote OVA-based delivery systems construction, such as emulsions, hydrogels, microencapsulation, nanoparticles to encapsulate bioactive components and monitor freshness for improving foods quality and safety.

Encapsulation of Grape (Vitis vinifera L.) Pomace Polyphenols in Soybean Extract-Based Hydrogel Beads as Carriers of Polyphenols and pH-Monitoring Devices

In this work, novel bio-based hydrogel beads were fabricated by using soybean extract as raw waste material loaded with Lambrusco extract, an Italian grape cultivar. The phenolic profile and the total amount of anthocyanins from the Lambrusco extract were evaluated before encapsulating it in soybean extract-based hydrogels produced through an ionotropic gelation technique. The physical properties of the produced hydrogel beads were then studied in terms of their morphological and spectroscopic properties. Swelling degree was evaluated in media with different pH levels. The release kinetics of Lambrusco extract were then studied over time as a function of pH of the release medium, corroborating that the acidity/basicity could affect the release rate of encapsulated molecules, as well as their counter-diffusion. The pH-sensitive properties of wine extract were studied through UV-Vis spectroscopy while the colorimetric responses of loaded hydrogel beads were investigated in acidic and basic solutions. Finally, in the framework of circular economy and sustainability, the obtained data open routes to the design and fabrication of active materials as pH-indicator devices from food industry by-products.

Preparation, characterization and food packaging application of nano ZnO@Xylan/quaternized xylan/polyvinyl alcohol composite films

Xylan could be considered as a good potential candidate for food packaging film because of the vast source and biodegradability, however, its application was restricted by the drawbacks of poor film-forming property, humidity sensitivity, weak mechanical strength and poor antibacterial property. In this paper, xylan was firstly modified by quaternization to improve the film-forming property, then ZnO nanoparticles encapsulated by xylan (nano ZnO@Xylan) was prepared by nanoprecipitation method, finally a series of biodegradable composite films were prepared using quaternized xylan and polyvinyl alcohol with incorporation of nano ZnO@Xylan. The surface morphology, molecular structure and crystallography structure of the films were characterized. The addition of nano ZnO@Xylan decreased water vapor permeability and solubility, meanwhile obviously increased the ultraviolet shielding performance as well as the antibacterial properties of the films. The bacteriostasis rate of the films against E. coli and S. aureus reached up to 99 %. Furthermore, the preservation time of cherry tomatoes covered with ZnO@Xylan/QX/PVA films was extended to at least 21 days. In conclusion, all the results ensure that the fabricated composite films have considerable promising application in the food packaging industry.

Fabrication and characterization of a smart film based on cassava starch and pomegranate peel powder for monitoring lamb meat freshness

Nowadays, the development of pH‐sensitive smart edible films using biopolymers and natural plant extracts (especially those rich in anthocyanins) has attracted much attention. Therefore, in this study, the intelligent edible film was produced and characterized using cassava starch and pomegranate peel powder (PPP) and the possibility of using production films to monitor the freshness of lamb meat. The smart films were prepared using different concentrations of PPP (2, 4, 6, and 8% w/w) and the solvent casting method. The results showed that the incorporation of PPP had a significant effect on the mechanical parameters of the starch films. With increasing the levels of PPP, the color of the films became darker and redder. Increasing the PPP levels also led to an increase in total phenol content (TPC) (from 0 to 13 mg GAE (gallic acid equivalent)/g) and antioxidant activity (from 0% to 70% DPPH (1,1‐diphenyl‐2‐picryl hydrazyl) radical scavenging) of the produced films (p < .05). The intelligent film was used in the lamb meat packaging, and the color of the film changed from red to green during the storage period at 25°C. The amount of total volatile basic nitrogen (TVB‐N) in the meat could be detected by color changes of the intelligent films. Finally, this study demonstrated that the film based on cassava starch and PPP could be used as an intelligent and pH‐sensitive film to monitor the freshness of meat and meat products.

Myofibrillar Protein Interacting with Trehalose Elevated the Quality of Frozen Meat

This work studied the interactions between trehalose/chitooligosaccharide (COS) and myofibrillar protein (MP), and the effect of such interactions on the quality of meat after freezing was also evaluated. Fourier transform infrared spectroscopy showed that both trehalose and COS could enhance the content of hydrogen bonds of MP. Zeta potential measurement displayed trehalose/COS reduced the absolute value of the surface potential of MP. The results of Raman spectroscopy suggested that the hydrophobic residues of MP were more exposed after treatment with trehalose/COS. Thus, trehalose and COS could both interact with MP through non-covalent bonds. Subsequently, the evaluation of the effect of trehalose and COS on the physicochemical properties of frozen meat was conducted. Results showed that both trehalose and COS significantly reduced thawing loss of frozen meat, and sensory evaluation showed that trehalose had a better performance from the perspective of smell, texture, and overall consumer acceptance. In conclusion, trehalose/COS interacting with MP can reduce meat thawing loss, which might provide technical guidance in the quality control of frozen meat.

Formation of Natural Egg Yolk Granule Stabilized Pickering High Internal Phase Emulsions by Means of NaCl Ionic Strength and pH Change

Pickering high internal phase emulsions (HIPEs) are gel-like concentrated emulsions that have the potential to be an alternative to partially hydrogenated oil (PHO). In this study, egg yolk granules (EYGs), natural complexes of protein and lipid isolated from egg yolk, were used as an emulsifier to prepare Pickering HIPEs. Gel-like HIPEs with an oil phase volume fraction of 85% and with an emulsifier concentration of only 0.5% could be prepared by using EYGs as an emulsifier. The EYGs were able to form stable HIPEs at NaCl ionic strengths over 0.2 M and at pH over 5.0 with NaCl ionic strength of 0.3 M. The EYGs, which could stabilize HIPEs, were easily to adsorb and cover the oil-water interface to form emulsion droplets with small particle size. In addition, interacting EYGs in the aqueous phase formed a continuous network structure, and the oil droplets packed closely, exhibiting high elasticity and shear thinning behavior. Furthermore, the formed HIPEs had suitable storage stability with no significant changes in appearance and microstructure after storage for 60 days. This work can transform traditional oils from liquid-like to solid-like by using EYGs to enrich food processing diversity and improve the storage stability of oils while reducing the intake of PHO and providing a healthier diet for consumers.