Development and preparation of active starch films carrying tea polyphenol

The synergistic effect of polyphenols and polypeptides for plant-based bioplastic film - Enhanced UV resistance, antioxidant and antibacterial performance

The exceptional biodegradability and active biological functions of bio-based packaging materials have attracted increasing interest. In this study, a bioplastic film was developed by introducing simultaneously polyphenols (tea polyphenols, TPs) and peptides (nisin) into a soy protein isolate/sodium alginate (SPI/SA) based film-forming matrix. The research results revealed that the dynamic coordinated interaction between TPs and nisin enhanced mechanical properties, UV-resistance, and thermal stability of bioplastic films. Furthermore, the bioplastic film exhibited antibacterial activity and antioxidant properties. Significantly, biofilm growth of Staphylococcus aureus treated with TPs-5/Nisin-5 bioplastic film was inhibited by 91.12% compared to the blank group. The shelf life of beef with TPs-5/Nisin-5 bioplastic film was prolonged by 2 days because of the synergistic effect of TPs and nisin. Additionally, the bioplastic film biodegraded in the natural environment about 21 days. This environmentally friendly regeneration strategy and the integration of advantageous functions provided ideas for the development of active food packaging.

Effects of starch filling on physicochemical properties, functional activities, and release characteristics of PBAT-based biodegradable active films loaded with tea polyphenols

In this work, the modification of poly(butylene adipate-co-terephthalate) (PBAT) was combined with the development of active packaging films. PBAT, starch, plasticizer, and tea polyphenols (TP) were compounded and extrusion-blown into thermoplastic starch (TPS)/PBAT-TP active films. Effects of TPS contents on physicochemical properties, functional activities, biodegradability, and release kinetics of PBAT-based active films were explored. Starch interacted strongly with TP through hydrogen bonding and induced the formation of heterogeneous structures in the films. With the increase in TPS contents, surface hydrophilicity and water vapor permeability of the films increased, while mechanical properties decreased. Blending starch with PBAT greatly accelerated degradation behavior of the films, and the T30P70-TP film achieved complete degradation after 180 days. As TPS contents increased, swelling degree of the films increased and TP release were improved accordingly, resulting in significantly enhanced antioxidant and antimicrobial activities. This work demonstrated that filling starch into PBAT-based active films could achieve different antioxidant and antimicrobial activities of the films by regulating film swelling and release behavior.

Slow-release antimicrobial preservation composite coating based on bamboo-derived xylan-A new way to preserve blueberry freshness

In recent years, the biocompatibility and environmental friendliness of xylan-based materials have demonstrated great potential in the field of food packaging and coatings. In this study, the cationized xylan based composite coating (CXC) was developed using a hybrid system of cationic-modified bamboo xylan (CMX) and sodium alginate (SA) combined with thyme oil microcapsules (TM). The optimized CXC-B was composed of 1.27 % TM, 2.42 % CMX (CMX: SA = 3:2), and 96.31 % distilled water. When applied to the surface of a blueberry, the CXC-B treatment extended the ambient storage time of the fruit to 10 days while substantially reducing its morbidity (P < 0.05) and protecting its texture, flavor, and nutritional integrity. The resulting composite coating provides a promising solution to the problem of blueberry perishability during ambient storage.

Effects of Microwave Treatment on Physicochemical Attributes, Structural Analysis, and Digestive Characteristics of Pea Starch-Tea Polyphenol Complexes

Addressing the challenge of blood glucose fluctuations triggered by the ingestion of pea starch, we have adopted an eco-friendly strategy utilizing microwave irradiation to synthesize the novel pea starch-tea polyphenol complexes. These complexes exhibit high swelling capacity and low solubility, and their thermal profile with low gelatinization temperature and enthalpy indicates adaptability to various processing conditions. In vitro digestion studies showed that these complexes have a small amount of rapidly digestible starch and a large amount of resistant starch, leading to a slower digestion rate. These features are particularly advantageous for diabetics, mitigating glycemic excursions. Structurally, the pea starch-tea polyphenol complexes exhibited a B + V-shaped dense network with low crystallinity, high orderliness, and a prominent double helix content, enhancing its stability and functionality in food applications. In summary, these innovative complexes served as a robust platform for developing low glycemic index foods, catering to the nutritional needs of diabetics. It offers an environmentally sustainable approach to food processing, fostering human well-being and propelling innovation in the food industry.

Effects of biodegradation of starch-nanocellulose films incorporated with black tea extract on soil quality

This study aimed to investigate the biodegradation behaviour of starch/nanocellulose/black tea extract (SNBTE) films in a 30-day soil burial test. The SNBTE films were prepared by mixing commercial starch, nanocellulose (2, 4, and 6%), and an aqueous solution of black tea extract by a simple mixing and casting process. The chemical and morphological properties of the SNBTE films before and after biodegradation were characterized using the following analytical techniques such as field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and fourier transform infrared (FTIR). The changes in soil composition, namely pH, electrical conductivity (EC), moisture content, water holding capacity (WHC), soil respiration, total nitrogen, weight mean diameter (MDW), and geometric mean diameter (GMD), as a result of the biodegradation process, were also estimated. The results showed that the films exhibited considerable biodegradability (35-67%) within 30 days while increasing soil nutrients. The addition of black tea extract reduced the biodegradation rate due to its polyphenol content, which likely resulted in a reduction in microbial activity. The addition of nanocellulose (2-6% weight of starch) increased the tensile strength, but decreased the elongation at break of the films. These results suggest that starch nanocellulose and SNBTE films are not only biodegradable under soil conditions but also positively contribute to soil health, highlighting their potential as an environmentally friendly alternative to traditional plastic films in the packaging industry.

Immobilization of biosynthesized gallium nanoparticles in Polyvinylpyrrolidone/Sodium alginate films: Potent bactericidal protection against food spoilage bacteria

The increasing threat of spoilage bacterial infections, driven by the resistance of bacteria to many antimicrobial treatments, is a significant worldwide public health problem, especially concerning food preservation. To tackle these difficulties, this research investigates the possibility of using packaging sheets that include antimicrobial agents and increasing the prolonged storage time by preventing the bioburden of foodborne pathogens. This approach uses metal nanoparticles' ability to prevent harmful bacteria that cause food spoiling. Gallium nanoparticles (GaNPs) were created using a water-based extract from Andrographis paniculata leaves as a bioreducing agent. The GaNPs were added to a film made of sodium alginate (SA) and polyvinylpyrrolidone (PVP). The study showed that incorporating GaNPs into polymer films resulted in films with a desirable contact angle and decreased water vapor permeability. Significantly, the developed films demonstrated increased efficiency against E.coli O157 compared to other species. Also, it exhibited increased vulnerability to bacterial strains at the biofilm stage, surpassing PVP-SA/GaNPs-0. Remarkably, the toxicity tests showed that the films exhibited no cytotoxicity. Overall, the films indicated their potential for avoiding bacterial bioburden, prolonging the shelf life of perishable products, and contributing to diverse antimicrobial applications in the food industry.

Development of novel carboxymethyl cellulose/gelatin-based edible films with pomegranate peel extract as antibacterial/antioxidant agents for beef preservation

Novel antioxidant and antibacterial composite films were fabricated by incorporating pomegranate peel extract (PPE) into gelatin and carboxymethyl cellulose matrices. Increasing PPE concentration significantly (p < 0.05) altered physical properties and improved UV (decrease in light transmission 87.30 % to 9.89 % at 400 nm) and water resistance, while FTIR and molecular docking results revealed hydrogen bonding between PPE and film matrix. PPE incorporation enhanced antioxidant activity up to 84.15 ± 0.12 % and also restricted gram-positive and gram-negative bacterial growth by 72.4 % and 65.9 % respectively after 24 h, measured by antimicrobial absorption assays. For beef packaging applications at refrigeration temperatures, PPE films were most effective at extending shelf-life up to 3 days, as evidenced by reduced total viable counts, total volatile basic nitrogen, weight loss, and pH changes compared to control films. Therefore, these antioxidant and antibacterial films have potential applications in food packaging to protect against mechanical stress, light exposure, microbial spoilage, and oxidative free radicals.

Enhanced antioxidant and antibacterial activities of chitosan/zein nanoparticle Pickering emulsion-incorporated chitosan coatings in the presence of cinnamaldehyde and tea polyphenol

Pickering emulsions were prepared by using zein/chitosan nanoparticles as stabilizer and then incorporated into chitosan coatings. To improve the stability and performances, tea polyphenol and cinnamaldehyde (CA) were used to modulate the formation and functionalities of Pickering emulsions. The oil phase in Pickering emulsions were set at 5 % and 20 % to alter the hydrophobicity of chitosan coatings. Physical, structural, antioxidant and antibacterial activities of chitosan coatings with Pickering emulsions were characterized. Tea polyphenol significantly enhanced antioxidant capacity of chitosan coatings from 2.09 % to 57.61 % of DPPH value and from 2.63 % to 38.85 % of ABTS value. CA effectively increased the antibacterial activity of chitosan coatings against S. aureus and E. coli. Under 20 % oil content, the inhibition zones on S. aureus and E. coli increased from 3.03 ± 0.23 mm to 18.39 ± 1.22 mm and 7.66 ± 1.61 mm to 15.70 ± 1.75 mm, respectively. The preservative effect of chitosan coatings on fresh pork was further confirmed that the shelf-life of fresh pork could be extended by >4 days. These results suggested a great potential application of Pickering emulsion-incorporated chitosan coatings in the preservation of fresh pork.

Active Films of Cassava Starch Incorporated with Carvacrol Nanocapsules

The synthesis of active films with natural antimicrobials from renewable sources offers an alternative to conventional non-biodegradable packaging and synthetic additives. This study aimed to develop cassava starch films with antimicrobial activity by incorporating either free carvacrol or chia mucilage nanocapsules loaded with carvacrol (CMNC) and assess their impact on the physical, mechanical, and barrier properties of the films, as well as their efficacy against foodborne pathogens. The addition of free carvacrol led to a reduction in mechanical properties due to its hydrophobic nature and limited interaction with the polymeric matrix. Conversely, CMNC enhanced elongation at break and reduced light transmission, with a more uniform distribution in the polymeric matrix. Films containing 8% carvacrol exhibited inhibitory effects against Salmonella and Listeria monocytogenes, further potentiated when encapsulated in chia mucilage nanocapsules. These findings suggest that such films hold promise as active packaging materials to inhibit bacterial growth, ensuring food safety and extending shelf life.

Eco-Friendly, Biodegradable Starch-Based Packaging Materials with Antioxidant Features

Due to the extensive application of petroleum-based plastics as packaging materials and problems related to their degradation/recycling, developing new solutions in the field of novel biopolymer-based materials has become imperative. Natural substitutes for synthetic polymers (starch, cellulose, chitosan) require modifications that enable their processing and provide them with additional properties (i.e., mechanical strength, controlled biodeterioration, antimicrobial and antioxidative activity). The antioxidant activity of natural packaging materials still requires further investigation. In this research paper, novel materials used for packaging perishable food susceptible to oxidizing agents were designed from potato starch (NS) reinforced with antioxidants such as dialdehyde starch (DS) and caffeic acid (CA)/quinic acid (QA). The use of spectroscopic techniques (ATR-FTIR, Raman) and X-ray diffraction allowed the examination of the chemical structure and arrangement of the blend and confirmed the component interactions. The film surface was examined by AFM. DS, functioning as a cross-linker, enhanced the film barrier as well as the mechanical and thermal properties, and it promoted starch amorphization when blended with other antioxidants. The antioxidant activity of caffeic acid was greater than that of quinic acid. Dialdehyde starch improves elasticity, whereas acids (particularly caffeic acid) influence film stiffness. A high susceptibility to biodegradation is valuable for potential eco-friendly packaging applications.

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.

Nanocomplexes film composed of gallic acid loaded ovalbumin/chitosan nanoparticles and pectin with excellent antibacterial activity: Preparation, characterization and application in coating preservation of salmon fillets

Active packaging has been recognized as an effective approach to extend the shelf life of food, but the rapid release of active substances limits the preservation effect. In this study, gallic acid (GA)-loaded ovalbumin (OVA)/chitosan (CS) nanoparticles with slow-release properties were prepared and embedded into the pectin matrix to refine the rapid release of GA in the pectin and elongate the shelf life of salmon fillets. Our results showed that GA could be released continuously from the OVA/CS nanoparticles. The pectin film incorporated with GA-loaded OVA/CS nanoparticles exhibited good light barrier and mechanical properties. The opacity value of the film reached 1.65 ± 0.06 UA/mm, and the tensile strength and elongation at break were 15.97 ± 1.55 MPa and 7.29 ± 0.42 %, respectively. In addition, the pectin film combined with GA-loaded OVA/CS nanoparticles showed improved antibacterial activity against two common biogenic amine-producing bacteria (Morganella morganii and Escherichia coli). Moreover, the nanocomposite film delayed salmon fillets' biogenic amine generation, and the shelf life was extended by 3 days compared with the control group. These promising properties supported using the GA-loaded OVA/CS nanoparticle-pectin films as preservation materials for fish.

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.

Effects of benzalkonium chloride as a cationic surfactant on the physicochemical properties of adlay millet starch films

The effects of benzalkonium chloride (BC) as a cationic surfactant on the mechanical, water barrier, microstructural, and thermal properties of adlay millet starch (AS) films were investigated in this study. With increasing BC concentration, tensile strength (from 5.93 to 6.15 MPa) and elongation at break (from 41.39 to 45.48%) of AS-BC films significantly increased, whereas their moisture content, water solubility, and water vapor permeability were reduced, indicating water resistance improvement. Fourier transform infrared spectroscopy and scanning electron microscopy analysis showed that BC at concentrations below 1% did not cause noticeable changes in the microstructure of AS-BC films. In addition, the thermal stability of AS-BC films was not affected by BC, indicating good miscibility between AS and BC. Therefore, BC could improve the physicochemical properties of starch films, and AS-BC films developed in this study can be applied as novel biodegradable packaging materials in the food packaging industry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01383-1.

Polyphenol-fortified extruded sweet potato starch vermicelli: Slow-releasing polyphenols is the main factor that reduces the starch digestibility

To investigate the digestive behavior of extruded starch-polyphenols system, extruded sweet potato starch vermicelli (ESPSV) was used as a model. The multi-scale structure, starch digestibility, polyphenol release, digestive enzyme activity during digestion and their correlation of ESPSV supplemented with matcha (MT), green tea extract (GTE), tea polyphenols (TP) and epigallocatechin gallate (EGCG) (at 1% polyphenol level) were discussed. Results showed that tea products in whatever form could retard starch digestion, with EGCG working best. The predicted glycemic index (pGI) of ESPSV was decreased from 82.50 to 65.46 after adding EGCG. Starch formed larger molecular aggregates with tea products under extrusion, showing a "B + V" type pattern. The order of V-type crystals content was EGCG + ESPSV (1.41) > TP + ESPSV (1.50) > GTE + ESPSV (1.88) > MT + ESPSV (2.62) > ESPSV (3.20). Under external pressure, EGCG, as tea monomer, was more likely to enter the spiral cavity of amylose and form V-type inclusion complex. Notably, polyphenols released during digestion could still reduce digestive enzyme activity, with a 15.53% decrease in EGCG + ESPSV compared to ESPSV. This was verified by correlation analysis, where RDS content (0.961, p < 0.01) and pGI (0.966, p < 0.01) were highly significantly correlated with the enzyme activity. Furthermore, tea products did not break or even enhance the quality of ESPSV as the final product.

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

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

Recent advances in edible coatings and their application in food packaging

The food packaging industries are facing the challenge of food waste generation. This can be addressed through the use of edible coating materials. These coatings aid in extending the shelf life of food products, reducing waste. The key components of these coatings include food-grade binding agents, solvents, and fillers. The integration of polysaccharide, protein, lipids, bioactive and composite-based materials with edible coating matrix aids to combat substantial post-harvest loss of highly perishable commodities and elevates the quality of minimally processed food. The aim of this review is to introduce the concept of edible coatings and discuss the different coating materials used in the food industry, along with their properties. Additionally, this review aims to classify the coating types based on characteristic features and explore their application in various food processing industries. This review provides a comprehensive overview of edible coatings, including the integration of polysaccharides, proteins, lipids, bioactive, and composite-based materials into the coating matrix. This review also addresses the significant post-harvest loss of highly perishable commodities and emphasizes the enhancement of quality in minimally processed food. Furthermore, the antimicrobial, anti-corrosive, and edible characteristics are highlighted, showcasing their potential applications in different food packaging industries. Moreover, it also discusses the challenges, safety and regulatory aspects, current trends, and future perspectives, aiming to shed light on the commercialization and future investigation of edible coatings.

Antioxidant Edible Films Based on Pear Juice and Pregelatinized Cassava Starch: Effect of the Carbohydrate Profile at Different Degrees of Pear Ripeness

Edible films based on fruit and vegetable purees combined with different food-grade biopolymeric binding agents (e.g., pectin, gelatin, starch, sodium alginate) are recognized as interesting packaging materials that benefit from the physical, mechanical, and barrier properties of biopolymers as well as the sensory and nutritional properties of purees. In the current contribution, edible antioxidant films based on pear juice and pregelatinized cassava starch were developed. In particular, the suitability of using pregelatinized cassava starch for the non-thermal production of these novel edible films was evaluated. In addition, the effects on the films' properties derived from the use of pear juice instead of the complete puree, from the content of juice used, and from the carbohydrate composition associated with the ripening of pears were all studied. The produced films were characterized in terms of their total polyphenol content, water sensitivity, and water barrier, optical, mechanical and antioxidant properties. Results showed that the use of pear juice leads to films with enhanced transparency compared with puree-based films, and that juice concentration and carbohydrate composition associated with the degree of fruit ripeness strongly govern the films' properties. Furthermore, the addition of pregelatinized cassava starch at room temperature discloses a significant and favorable impact on the cohesiveness, lightness, water resistance, and adhesiveness of the pear-juice-based films, which is mainly attributed to the effective interactions established between the starch macromolecules and the juice components.

Starch-based films doped with porphyrinoid photosensitizers for active skin wound healing

Starch is a biodegradable and biocompatible carbohydrate that, when combined with bioactive molecules, can be processed as biomimetic platforms with enhanced performance, allowing its use as active wound dressing materials. Porphyrinoid photosensitizers can tune the physicochemical/functional profile of biomacromolecules, allowing their use in anti-infective strategies. In this work, the feasibility of using the cationic 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin tetraiodide (TMPyP) to enhance the physicochemical, mechanical, antimicrobial performance, and wound healing ability of casted starch-based films was studied. TMPyP conferred a reddish coloration to the films, maintaining their pristine transparency. It increased by 87 % the films hydrophobicity and, depending on the TMPyP used, conferred mobility to the starch polymeric chains. Starch/TMPyP-based films effectively photoinactivated Escherichia coli (>99.99 %) and favored the wound healing process, even in the absence of light. Therefore, the incorporation of TMPyP into starch-based formulations revealed to be a promising strategy to tune the films compaction degree while giving rise to water tolerant and photosensitive biomaterials that can act as multitarget antimicrobial medical dressings and glycocarriers of active compounds relevant for effective skin wound healing.

Effects of Chitosan and Cellulose Derivatives on Sodium Carboxymethyl Cellulose-Based Films: A Study of Rheological Properties of Film-Forming Solutions

Bio-based packaging materials and efficient drug delivery systems have garnered attention in recent years. Among the soluble cellulose derivatives, carboxymethyl cellulose (CMC) stands out as a promising candidate due to its biocompatibility, biodegradability, and wide resources. However, CMC-based films have limited mechanical properties, which hinders their widespread application. This paper aims to address this issue by exploring the molecular interactions between CMC and various additives with different molecular structures, using the rheological method. The additives include O-carboxymethylated chitosan (O-CMCh), N-2-hydroxypropyl-3-trimethylammonium-O-carboxymethyl chitosan (HTCMCh), hydroxypropyltrimethyl ammonium chloride chitosan (HACC), cellulose nanocrystals (CNC), and cellulose nanofibers (CNF). By investigating the rheological properties of film-forming solutions, we aimed to elucidate the influencing mechanisms of the additives on CMC-based films at the molecular level. Various factors affecting rheological properties, such as molecular structure, additive concentration, and temperature, were examined. The results revealed that the interactions between CMC and the additives were dependent on the charge of the additives. Electrostatic interactions were observed for HACC and HTCMCh, while O-CMCh, CNC, and CNF primarily interacted through hydrogen bonds. Based on these rheological properties, several systems were selected to prepare the films, which exhibited excellent transparency, wettability, mechanical properties, biodegradability, and absence of cytotoxicity. The desirable characteristics of these selected films demonstrated the strong biocompatibility between CMC and chitosan and cellulose derivatives. This study offers insights into the preparation of CMC-based food packaging materials with specific properties.

Composite films of sodium alginate and konjac glucomannan incorporated with tea polyphenols for food preservation

At present, food waste has become a serious issue and the use of petroleum-based food packaging films has resulted in a series of potential hazards. Therefore, more attention has been focused on the development of new food packaging materials. The polysaccharide-based composite film loaded with active substances considered to be an excellent preservative material. A novel packaging film based on sodium alginate and konjac glucomannan (SA-KGM) blended with tea polyphenols (TP) was prepared in the present study. The excellent microstructure of films was shown by atomic force microscopy (AFM). It was indicated by FTIR spectra that the components could interact with each other through hydrogen bonds, which was also confirmed by molecular docking simulation. Meanwhile, the mechanical properties, barrier property, oxidation property, antibacterial activity, and stability of the structure of the TP-SA-KGM film were significantly improved. The AFM images and results of molecular docking simulation indicated that TP could affect the cell wall of bacteria by acting with peptidoglycan. Finally, the film showed excellent preservation effects in both beef and apples, which suggested that TP-SA-KGM film could be a novel bioactive packaging material with wide application potential in food preservation.

Extraction, identification, and starch-digestion inhibition of phenolics from Euryale ferox seed coat

BACKGROUND

Euryale ferox is an important cash crop and valuable tonic in traditional medicine. The seeds of E. ferox are rich in starch, which is hard to digest, and the digestion speed is significantly slower than that of rice starch. The goal of this study was to evaluate the effects of E. ferox seed-coat phenolics (EFCPs) on the digestion of E. ferox seed starch.

RESULTS

EFCPs were extracted and identified by ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. We optimized the extraction parameters, and the final extraction yield was about 1.49%. We identified seven phenolics from the E. ferox seed-coat extracts: gallic acid, digalloylhexoside, catechin, procyanidin B2, epicatechin, ellagic acid, and epicatechin gallate. Quantitative analysis results showed that the E. ferox seed phenolics mainly distributed in the seed coat and the gallic acid, digalloylhexoside, and epicatechin gallate were three main phenolic compounds. The phenolics displayed strong inhibitory activities on α-glucosidase and α-amylase with an IC₅₀ of 3.25 μg mL^-1 and 1.36 mg mL^-1 respectively. Furthermore, these phenolics could interact with starch by hydrogen bonds, which might make its starch more difficult to digest.

CONCLUSION

Our investigation suggests that the EFCPs can strongly inhibit the digestion of E. ferox seed starch by inhibiting the α-amylase and α-glucosidase activities and interacting with starch by hydrogen bonds; therefore, E. ferox seeds have a promising application prospect in foods for hypoglycemia. © 2023 Society of Chemical Industry.

Simultaneous improvement of the physical and biological properties of starch films by incorporating steviol glycoside-based solid dispersion

Bioactive compounds are frequently incorporated into polysaccharides (e.g., starch) to form active biodegradable films for food packaging, but some of them are water insoluble (e.g., curcumin, CUR) that will make the films have undesirable performance. Herein, CUR was successfully solubilized into the aqueous starch film solution by steviol glycoside (STE, a natural sweetener)-based solid dispersion. The mechanisms of solubilization and film formation were explored through molecular dynamic simulation and various characterization methods. The results showed that the amorphous state of CUR combined with micellar encapsulation of STE achieved the solubilization of CUR. STE and starch chains cooperated to form the film via hydrogen bonding, while CUR was uniformly and densely distributed within the film in the form of needle-like microcrystals. The as-prepared film exhibited high flexibility, great moisture barrier, and excellent UV barrier (UV transmittance: ∼0 %). Compared with the film containing CUR alone, the as-prepared film possessed higher release efficiency, antibacterial activity, and pH response sensitivity due to the assistance of STE. Hence, the introduction of STE-based solid dispersion can simultaneously improve the biological and physical properties of starch films, which provides a green, nontoxic, and facile strategy for the perfect integration of hydrophobic bioactive compounds and polysaccharide-based films.

Bioaccessibility and Bioavailability of Diet Polyphenols and Their Modulation of Gut Microbiota

It is generally accepted that diet-derived polyphenols are bioactive compounds with several potentially beneficial effects on human health. In general, polyphenols have several chemical structures, and the most representative are flavonoids, phenolic acids, and stilbenes. It should be noted that the beneficial effects of polyphenols are closely related to their bioavailability and bioaccessibility, as many of them are rapidly metabolized after administration. Polyphenols-with a protective effect on the gastrointestinal tract-promote the maintenance of the eubiosis of the intestinal microbiota with protective effects against gastric and colon cancers. Thus, the benefits obtained from dietary supplementation of polyphenols would seem to be mediated by the gut microbiota. Taken at certain concentrations, polyphenols have been shown to positively modulate the bacterial component, increasing Lactiplantibacillus spp. and Bifidobacterium spp. involved in the protection of the intestinal barrier and decreasing Clostridium and Fusobacterium, which are negatively associated with human well-being. Based on the diet-microbiota-health axis, this review aims to describe the latest knowledge on the action of dietary polyphenols on human health through the activity of the gut microbiota and discusses micro-encapsulation of polyphenols as a strategy to improve the microbiota.

Extrusion-blown starch/PBAT biodegradable active films incorporated with high retentions of tea polyphenols and the release kinetics into food simulants

To reduce thermal degradation of tea polyphenols (TP) in final active packaging materials, poly(butylene adipate-co-terephthalate) (PBAT), starch, plasticizer, and TP were directly synthesized into masterbatches by one-pot method in this study without pre-dispersion, and then blown into active films. TP interacted with starch through hydrogen bonds, with little interaction with PBAT. Barrier properties were improved by incorporating TP into the films, whereas mechanical properties slightly decreased. Blending starch into PBAT greatly accelerated the degradation of the film. And the incorporation of TP slowed down the short-term degradation of the starch/PBAT film, but accelerated the long-term degradation. The initial total polyphenol content in the active film was positively related to the TP loading, whereas the initial retention rate remained above 95 % regardless of TP loadings. The retention rate of TP in active films decreased with storage time, but it was still above 80 % after 12 months, with a favorable stability. TP-loaded films displayed efficient antioxidant and antimicrobial activities with strong dose dependence. The release of TP into food simulants was mainly induced by random diffusion, with little effect from polymer swelling. The short-term release kinetics was well described by Fick's second law. This work has demonstrated the feasibility of TP being incorporated into the active films with high retention through high-throughput fabrication, which provides formula and technical options for the industrial development of active packaging materials.

Potato Starch-Based Film Incorporated with Tea Polyphenols and Its Application in Fruit Packaging

Effects of tea polyphenols (TP) on the physical properties, barrier properties and functionality of potato starch-based film were determined, while the interaction mechanism between TP and starch in film and the application of this film in fruit packaging were further evaluated. TP exhibited different effects on the physical properties of potato starch-based film, including thickness (0.083 to 0.087 mm), moisture content (9.27% to 9.68%), color (ΔE value: 5.41 to 10.55), light transmittance (51% to 62%), tensile properties and thermal properties, and improved its barrier properties, including water vapor permeability (9.68 to 11.84 × 10-11 g m-1 s-1 Pa-1),oxygen permeability (1.25 to 2.78 × 10-16 g m-1 s-1 Pa-1) and antioxidant activity. According to the determination of wide-angle X-ray diffraction, Fourier transform infrared and scanning electron microscope, TP could interact with starch chains via hydrogen bonds to form non-crystal complexes, thus affecting the cross-linking among starch chains and further changing the microstructure of film. Furthermore, film incorporated with TP could improve the storage quality (including weight and texture) of blueberries, and inhibit the enzymatic browning of fresh-cut bananas during storage. All present results suggested that tea polyphenols had potential to enhance the properties and function of potato starch-based film, and the film exhibited the application prospect in fruit packaging and preservation.

Efficient and recyclable degradation of organic dye pollutants by CeO2@ZIF-8 nanozyme-based non-photocatalytic system

Advanced oxidation processes-based catalysis system as the most typical pollutant degradation technology always suffer from poor durability and photo-dependent. Inspired by the fact that some nanomaterials exhibit catalytic properties closer to natural enzymes, a high peroxidase-like activity and stability CeO₂@ZIF-8 nanozyme was synthesized in this study for non-photodegradation of dyes pollution. Multiple characterization techniques were applied to prove the successful synthesis of the nanozyme. The influence of different parameters on the catalytic degradation of organic dye by nanozyme was investigated. This nanozyme achieved a maximum degradation efficiency of 99.81% for methyl orange and maintained its catalytic performance in repeated experiments. Possible degradation intermediates and pathways for methyl orange were then proposed. In addition, the CeO₂@ZIF-8 loaded starch/agarose films were prepared for the portable and recyclable remediation of real dye wastewater, which maintained more than 80% degradation efficiency after 5 successive cycles. These results suggested that nanozyme based non-photocatalytic system is a potential catalyst for dye degradation and it opens a new avenue to develop high-performance and recyclable catalysts for pollutant remediation.

A smart film incorporating anthocyanins and tea polyphenols into sodium carboxymethyl cellulose/polyvinyl alcohol for application in mirror carp

Multifunctional food packaging films were developed based on polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), tea polyphenol (TP) and black carrot anthocyanin (CA). Results of Zeta potential, scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction showed that CA enhanced the stability of the particle dispersion system through hydrogen bonding and electrostatic interactions, promoted the compatibility between TP and PVA-CMC (PC) substrates, and enhanced the binding between the components of the films. Because of the interaction of TP and CA, PC-TP-CA films had better water resistance and water vapor barrier properties, thermal stability, antioxidant and antimicrobial properties. PC-CA and PC-TP-CA films exhibited excellent UV-blocking properties. They also showed distinct color responsiveness in the pH range of 2-13, significant sensitivity to ammonia vapor in a short period of time and excellent color stability over 20 days of storage under different conditions. When the film was applied to fish, it was found that PC-TP-CA film could extend the shelf life of fish by 1-2 days and successfully monitor the freshness of the fish in real-time. Considering all the physical and functional properties, the non-toxic and biodegradable PC-TP-CA film has excellent potential as a new multifunctional food packaging material in the future.

An Overview on Wood Waste Valorization as Biopolymers and Biocomposites: Definition, Classification, Production, Properties and Applications

Bio-based polymers, obtained from natural biomass, are nowadays considered good candidates for the replacement of traditional fossil-derived plastics. The need for substituting traditional synthetic plastics is mainly driven by many concerns about their detrimental effects on the environment and human health. The most innovative way to produce bioplastics involves the use of raw materials derived from wastes. Raw materials are of vital importance for human and animal health and due to their economic and environmental benefits. Among these, wood waste is gaining popularity as an innovative raw material for biopolymer manufacturing. On the other hand, the use of wastes as a source to produce biopolymers and biocomposites is still under development and the processing methods are currently being studied in order to reach a high reproducibility and thus increase the yield of production. This study therefore aimed to cover the current developments in the classification, manufacturing, performances and fields of application of bio-based polymers, especially focusing on wood waste sources. The work was carried out using both a descriptive and an analytical methodology: first, a description of the state of art as it exists at present was reported, then the available information was analyzed to make a critical evaluation of the results. A second way to employ wood scraps involves their use as bio-reinforcements for composites; therefore, the increase in the mechanical response obtained by the addition of wood waste in different bio-based matrices was explored in this work. Results showed an increase in Young's modulus up to 9 GPa for wood-reinforced PLA and up to 6 GPa for wood-reinforced PHA.

Bioactive Edible Sodium Alginate Films Incorporated with Tannic Acid as Antimicrobial and Antioxidative Food Packaging

Currently, biodegradable and functional food packaging materials have attracted more and more attention due to their potential advantages. Biopolymers are one of the promising materials used to produce biodegradable food packaging films, and sodium alginate (SA) is one of the most used polysaccharides. In this work, we explored a novel edible sodium alginate (SA)/tannic acid (TA) film as biodegradable active food packaging material. The impact of TA concentration on the UV light blocking ability, transparency, water vapor barrier ability, mechanical strength, antioxidant, and antimicrobial activity of the SA-TA films was comprehensively investigated. Fourier transform infrared spectroscopy results revealed that strong hydrogen bonding was the main intermolecular interaction between SA and TA. As TA concentration in the films increased, the water vapor permeability (WVP) decreased from 1.24 × 10^-6 to 0.54 × 10^-6 g/m/h/Pa, the DPPH radical scavenging activity increased from 0.008% to 89.02%. Moreover, the incorporation of TA effectively blocked UV light and elevated antimicrobial activity against Escherichia coli. Overall, the SA films with TA exhibited better water vapor barrier ability, remarkable UV-light barrier ability and antioxidant activity while showing a slight decrease in light transmittance. These results indicated the potential application of TA as a functional additive agent for developing multifunctional food packaging materials.

Potato starch films by incorporating tea polyphenol and MgO nanoparticles with enhanced physical, functional and preserved properties

Due to the massive environmental pollution caused by synthetic plastic packaging accumulation and contemporary necessities of food packaging materials, the biodegradable and multifunctional bionanocomposite films based on potato starch (PS) incorporating tea polyphenol (TP) and MgO nanoparticles (MgO-NPs) were successfully fabricated by the solution casting method, and their physical and functional properties and application in fruits preservation were systematically investigated. Incorporation of TP and MgO-NPs improved the films' tensile strength, UV light-blocking, hydrophobicity and thermal stability, and decreased their moisture content (from 14.02 % to 11.21 %), water solubility (from 19.57 % to 16.56 %), and water vapor permeability (from 17.32 to 9.07 × 10^-11 g∙m^-1∙s^-1∙Pa^-1). Moreover, the PS/TP/MgO-NPs films exhibited strong antioxidant activity, and remarkable antibacterial activity against Escherichia coli and Staphylococcus aureus with the diameter of inhibition zone of 25.60 mm and 27.50 mm, respectively. SEM, ATR-FTIR and XRD analyses indicated the TP and MgO-NPs were dispersed homogeneously in the PS matrix, and identified the molecular interactions of hydrogen bond, hydrophobic interaction and electrostatic attraction. Biodegradability assessment showed that all the films were rapidly decomposed within ~20 days under simulated environmental conditions. Compared to control, the PS/TP/MgO-NPs film-forming solution coatings were capable of maintaining fruit quality by reducing the change in weight loss, firmness and total soluble solids. Overall, these results suggested that the multifunctional bionanocomposite films could be a potential approach for developing sustainable active food packaging.

Preparation and characterization of chitosan films incorporating epigallocatechin gallate: Microstructure, physicochemical, and bioactive properties

Novel chitosan films incorporating epigallocatechin gallate (EGCG) were prepared and demonstrated the ideal physical and mechanical properties required of candidate food packaging materials alongside desirable antioxidant and antibacterial activity. Compared with traditional chitosan films, chitosan films incorporated with EGCG were thicker, had higher tensile strength and water solubility, and had lower elongation at break, moisture content, degree of swelling, and water contact angles. Although EGCG-containing films were slightly darker in color than pure chitosan films, they exhibited a greater inhibitory effect on light-induced oxidation with obviously improved UV-vis barrier capability and opacity. Scanning electron microscopy results suggested that EGCG-incorporated samples had a rougher surface structure. This was further confirmed by atomic force microscopy and indicated that the addition of EGCG facilitated the formation of protective barriers through the interaction between the film and food surface. FTIR spectroscopy confirmed that EGCG interacted with chitosan by intermolecular hydrogen bonding and effectively improved the thermal stability of chitosan films. Notably, the incorporation of EGCG significantly enhanced the antioxidant and antibacterial activity of chitosan films. Hence, chitosan films incorporating EGCG have potential applications in the food industry as a novel active packaging material, especially in preventing food oxidation and spoilage in perishable foods.

Development of xanthan gum/hydroxypropyl methyl cellulose composite films incorporating tea polyphenol and its application on fresh-cut green bell peppers preservation

The aim of this work was to develop an edible packaging material with good performance that can be used for fresh-cut vegetables preservation. The xanthan (XG)-hydroxypropyl methylcellulose (HPMC)-tea polyphenols (TP) composite film (XHT) was prepared by adding TP to the composite film-forming solution of XG and HPMC. At optimum TP dosage of 6% (XHT6), the tensile strength and elongation at break were at the maximum. The antioxidant activity and antibacterial properties were also enhanced, demonstrated good inhibitory ability to Staphylococcus aureus. After 8 days, the amount of Vitamin C that was retained by XHT6 was 127.81% and 7.83% higher than unpackaged and XHT0, respectively. Additionally, the MDA content in green peppers were 39.16% and 78.87% higher than that of unpackaged and XHT0, respectively. Practical applications of XHT films in preserving fresh-cut bell peppers had also shown positive results, making it possible as potential food packaging.

Protein-based natural antibacterial materials and their applications in food preservation

Plastics materials used for food packaging are recalcitrant, leading to a growing global environmental problem, which arouses the attention of environmental protection departments in many countries. Therefore, to meet the increasing demand for sustainable and environment-friendly consumer products, it is necessary for the food industry to develop natural antibacterial materials for food preservation. This review summarizes the common biodegradable natural antimicrobial agents and their applications in food preservation; as well as an overview of five commonly used biodegradable protein-based polymers, such as zein, soy protein isolate, gelatin and whey protein, with special emphasis on the advantages of protein-based biopolymers and their applications in food packaging industry.

Characterization of a novel starch-based foam with a tunable release of oxygen

Here, we used techniques of extrusion and coating to produce starch-based foams with a combined function of buffering and controlled release of oxygen. The foams presented open-cell structures and showed a compression recovery ratio of 94%. After coating with poly(vinyl alcohol) solution, in which calcium peroxides were loaded, the developed functional foams showed a behavior of controllable oxygen release under a wet condition, as well as a high compression strength (≥2.2 MPa). Also, these foams showed an improved moisture resistance with a reduction in maximum moisture absorption from 25 to 14%. Under a vibrated storage condition to simulate food transportation, guavas packaged with functional foams showed a reduced physical damage, and browning index from 5.00 to 2.97, owing to the foams' superior buffering ability and self-regulation of storage atmosphere. The functional packaging system of the starch-based foams developed in our work is promising for fruit and vegetable preservations.