Characterization and application of novel composite films based on soy protein isolate and sunflower oil produced using freeze drying method

Characteristics of whey protein concentrate/egg white protein composite film modified by transglutaminase and its application on cherry tomatoes

In order to obtain food packaging film with better performance, whey protein concentrate (WPC) and egg white protein (EWP) were used as film-forming substrates, and its film properties were modified by transglutaminase (TG). Then the effect of TG on the mechanical, physical, barrier, and microstructural properties of the WPC/EWP composite biodegradable film was investigated, and its preliminary application potential was explored. Compared to WPC and EWP films, WPC/EWP composite film had higher transmittance, tensile strength (TS), and thermal stability. Fluorescence results showed that the film experienced fluorescence quenching after TG treatment. Fourier transform infrared and x-ray diffraction results showed that WPC and EWP had good compatibility in the biodegradable film, the hydrogen bond interaction of film was increased due to TG, resulting in an increase in TS. Meanwhile, the water vapor permeability and contact angle of WPC/EWP film treated with TG at 5 U/g protein increased by 28% and 76.1%, respectively. Besides, the WPC/EWP biodegradable film modified by TG (TG-W/E) was applied as a coating film on cherry tomatoes, effectively reducing the weight loss rate during storage from 14.2% to 10.8%. Furthermore, indexes, such as solid content, spoilage rate, hardness, pH, and lycopene, showed that the film had a good preservation effect on cherry tomatoes. To conclude, the appropriate addition of TG has a positive effect on the film properties of the WPC/EWP biodegradable film, which is beneficial to the development and utilization of protein-based film. WPC/EWP biodegradable film modified by TG has a great application prospect in extending the shelf life of fruit and vegetable.

Development of κ-carrageenan-based transparent and absorbent biodegradable films for wound dressing applications

Wound healing remains a critical challenge in healthcare, requiring advanced wound dressings with superior properties like transparency, absorbency, and biocompatibility. However, gaps exist in the use of marine-derived biopolymers for sustainable dressings. This study addresses this gap by combining κ-carrageenan (KC) with polyvinyl pyrrolidone (PVP) to develop transparent and absorbent biodegradable films through solvent casting and lyophilization techniques. Lyophilized films exhibited superior absorbency (9.17 g/cm2) and moisture management, with a water vapour transmission rate of 3990.67 g/m2/24 h, while solvent-cast films showed 78 % transmittance, enabling wound visualization. Mechanical testing revealed high tensile strength (31.5 MPa) and folding endurance (410 folds), ensuring durability. In vitro bactericidal assays confirmed efficacy against MRSA and E. coli, and in vivo tests on Wistar rats showed complete wound healing within 16 days with 91.1 % closure, outperforming untreated controls (76.7 %). This is the first study to explore lyophilized KC-PVP films for wound dressing applications, demonstrating potential for drug release, absorbency, and biodegradability. The innovative combination of biopolymers and fabrication techniques offers a sustainable, high-performance solution for wound care.

Sacrificial hydrogen bonds enhance the performance of covalently crosslinked composite films derived from soy protein isolate and dialdehyde starch

Soy protein films have the advantage of being eco-friendly and renewable, but their practical applications are hindered by the mechanical properties. The exceptional tensile strength and fracture toughness of natural silk stem from sacrificial hydrogen bonds it contains that effectively dissipates energy. In this study, we draw inspiration from silk's structural principles to create biodegradable films based on soy protein isolate (SPI). Notably, composite films containing sodium lignosulfonate (LS) demonstrate exceptional strain at break (up to 153%) due to the augmentation of reversible hydrogen bonding, contrasted to films with the addition of solely dialdehyde starch (DAS). The enhancement of tensile strength is realized through a combination of Schiff base cross-linking and sacrificial hydrogen bonding. Furthermore, the incorporation of LS markedly improves the films' ultraviolet (UV) blocking capabilities and hydrophobicity. This innovative design strategy holds great promise for advancing the production of eco-friendly SPI-based films that combine strength and toughness.

Ozone treatment increase the whiteness of soy protein isolate through the degradation of isoflavone

The color of soy protein isolate (SPI) influences the appearance of products such as tofu and soymilk, consequently impacting consumer preferences. Typically, whiter-colored SPIs were more favorite. However, products currently manufactured in the industry predominantly exhibit a yellowish hue. In our study, the incorporation of gaseous ozone into the production process of SPI notably improved its appearance on color. Simultaneously, a reduction in the isoflavone content enriched in SPI due to ozone treatment was observed, suggesting a potential mechanism for improving the whiteness of SPI. In addition, we discovered that the introduction of ozone for different times oxidized ozone-sensitive sulfhydryl groups, tryptophan, and tyrosine in proteins, thereby affecting the protein structure. This finding was determined through the analysis of free sulfhydryl groups, disulfide bonds, SDS-PAGE electrophoresis, FTIR, and endogenous fluorescence spectroscopy of SPIs. Meanwhile, the ozone treatment did not induce protein aggregation or alter its functional properties.

Development and characterization of gelatin-based biodegradable films incorporated with pistachio shell hemicellulose

This study aimed to incorporate pistachio shell hemicellulose into a film of gelatin and glycerol for the production of biodegradable films. The gelatin and glycerol are chosen because of their functional properties, which make it extensively used in food industry. The film composition was defined after a statistical optimization by central composite face-centered design and response surface methodology. The hemicellulose/gelatin ratio of 35.93% and the glycerol ratio of 18.02% were the optimum conditions to obtain lower film water solubility, higher tensile strength, and elongation at break values. The physical, structural, mechanical, and barrier properties of the developed hemicellulose-gelatin film were analyzed and compared with those of the gelatin film. Tensile strength and film water solubility values were reduced significantly with hemicellulose incorporation from 20.41 to 16.64 MPa and 49.57 to 39.21%, respectively, while EB was enhanced by 4.34 times. In addition, hemicellulose incorporation enhanced the water vapor permeability and the film degradation in the soil. The films were also examined by Fourier transform infrared spectroscopy and differential scanning calorimetry. The novelty of this study is to use pistcahio shell hemicellulose in the production of an edible film for the first time.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-05968-4.

A Review of Recent Developments in Edible Films and Coatings-Focus on Whey-Based Materials

Packaging for food products is particularly important to preserve product quality and shelf life. The most used materials for food packaging are plastic, glass, metal, and paper. Plastic films produced based on petroleum are widely used for packaging because they have good mechanical properties and help preserve the characteristics of food. However, environmental concerns are leading the trend towards biopolymers. Films and coatings based on biopolymers have been extensively studied in recent years, as they cause less impact on the environment, can be obtained from renewable sources or by-products, are relatively abundant, have a good coating and film-forming capacity, are biodegradable and have nutritional properties that can be beneficial to human health. Whey protein-based films have demonstrated good mechanical resistance and a good barrier to gases when at low relative humidity levels, in addition to demonstrating an excellent barrier to aromatic compounds and especially oils. The use of whey proteins for films or coatings has been extensively studied, as these proteins are edible, have high nutritional value, and are biodegradable. Thus, the main objective of this document was to review new methodologies to improve the physicochemical properties of whey protein films and coatings. Importance will also be given to the combinations of whey proteins with other polymers and the development of new techniques that allow the manipulation of structures at a molecular level. The controlled release and mass transfer of new biomaterials and the improvement of the design of films and packaging materials with the desired functional properties can increase the quality of the films and, consequently, broaden their applications.

Research Advances in Plant Protein-Based Products: Protein Sources, Processing Technology, and Food Applications

Plant proteins are high-quality dietary components of food products. With the growing interest in sustainable and healthy food alternatives, plant proteins have gained significant attention as viable substitutes for animal-based proteins. Understanding the diversity of protein sources derived from plants, novel processing technology, and multiple applications is crucial for developing nutritious and sustainable plant protein-based products. This Review summarizes the natural sources of traditional and emerging plant proteins. The classifications, processing technologies, and applications of plant protein-based products in the food industry are explicitly elucidated. Moreover, the advantages and disadvantages of plant protein-based food products are revealed. Strategies such as protein fortification and complementation to overcome these shortcomings are critically discussed. We also demonstrate several issues that need to be addressed in future development.

Soy protein isolate/kappa-carrageenan/cellulose nanofibrils composite film incorporated with zenian essential oil-loaded MOFs for food packaging

Edible films applied in food packaging must possess excellent inhibitory and mechanical properties. Protein-based films exhibit a high capacity for film formation and offer good gas barrier properties. However, they have weak mechanical and water barrier characteristics. The objective of this research was to develop active composite films based on reinforced soy protein isolate (SPI)/Kappa-carrageenan (K) with varying concentrations of bacterial cellulose nanofibrils (BCN). Increasing the BCN concentration improved the morphological, structural, mechanical, water vapor barrier, and moisture content properties. In comparison to the pure SPI film (S), the film with a high BCN concentration demonstrated a significant decrease in WS (22.98 ± 0.78 %), MC (21.72 ± 0.68 %), WVP (1.22 ± 0.14 g mm-1 S-1 Pa-1 10-10), and EAB (57.77 ± 5.25 %) properties. It should be emphasized that there was no significant alteration in the physicomechanical properties of the optimal film (SKB0.75) containing Zenian-loaded metal-organic frameworks (ZM). However, it substantially enhanced the thermal stability of this film, which can be attributed to the strong interfacial interactions between polymer chains and ZM. Furthermore, the ZM films inhibited the growth of pathogenic bacteria and increased the DPPH antioxidant activity. Thus, SKB0.75-ZM2 films can be utilized as practical components in food packaging.

Preparation and Application of pH-Sensitive Film Containing Anthocyanins Extracted from Lycium ruthenicum Murr

A new pH-sensitive film was developed using Artemisia sphaerocephala Krasch. gum (ASKG), soybean protein isolate (SPI), and natural anthocyanin extracted from Lycium ruthenicum Murr. The film was prepared by adsorbing anthocyanins dissolved in an acidified alcohol solution on a solid matrix. ASKG and SPI were used as the solid matrix for the immobilization of the Lycium ruthenicum Murr. anthocyanin extract, which was absorbed into the film as a natural dye using the facile-dip method. Regarding the mechanical properties of the pH-sensitive film, the tensile strength (TS) values increased approximately 2-5-fold, but the elongation at break (EB) values decreased significantly by about 60% to 95%. With the increase in anthocyanin concentration, the oxygen permeability (OP) values first decreased by about 85%, and then increased by about 364%. The water vapor permeability (WVP) values increased by about 63%, and then decreased by about 20%. Colorimetric analysis of the films revealed variations in color at different pH values (pH 2.0-10.0). Fourier-transform infrared (FT-IR) spectra and XRD patterns indicated compatibility among ASKG, SPI, and anthocyanin extracts. In addition, an application test was conducted to establish a correlation between film color change and carp meat spoilage. At storage temperatures of 25 °C and 4 °C, when the meat was totally spoiled, the TVB-N values reached 99.80 ± 2.53 mg/100 g and 58.75 ± 1.49 mg/100 g, and the film's color changed from red to light brown and from red to yellowish green, respectively. Therefore, this pH-sensitive film could be used as an indicator to monitor the freshness of meat during storage.

Investigating functional properties of halloysite nanotubes and propolis used in reinforced composite film based on soy protein/basil seed gum for food packaging application

This study aimed to investigate the effect of halloysite nanotubes (HNTs) on the physicochemical characteristics of the soy protein isolated/basil seed gum (SPI/BSG) film activated with propolis (PP). The obtained results of scanning electron microscope (SEM), thermal gravimetric analysis (TGA), and tensile investigations illustrated that the addition of HNTs as nanofiller led to positive changes in the morphology, thermal stability, and mechanical characteristics of SPI/BSG films. The barrier properties of films considerably decreased with incorporation of HNTs. Furthermore, the encapsulation of PP as bioactive agent into the produced films significantly increased (P < 0.05) the antioxidant potential of the samples in DPPH radical-scavenging activity assays. The antibacterial effects of film also significantly increased (P < 0.05) after the encapsulation of PP. In conclusion, the produced films illustrated acceptable efficiency for usage in food packaging system.

Development of edible films by incorporating nanocrystalline cellulose and anthocyanins into modified myofibrillar proteins

In this study, a myofibrillar protein (MP) system was used to investigate the film properties changes by adjusting the intensity of the interaction of proteins with other food components. The structure and rheological properties of several film-forming solutions were then determined. Furthermore, the structure of these composite films was examined using Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The smooth and uniform surface acquired by scanning electron microscopy (SEM) substantiated the increased compatibility and continuity observed for films with greater food component interaction. In addition, the MP-based edible films with stronger food component interactions (the MP-Myr/ANT/NCC group) displayed superior mechanical (tensile strength: 6.68 MPa, elongation at break: 94.43%), water vapor barrier (10.01 × 10^-9 g m^-1 s^-1 Pa^-1), and ammonia sensitivity (total color difference: 17.00) capabilities compared to those of the other groups (the MP/ANT/NCC, MP-Lut/ANT/NCC, and MP-Que/ANT/NCC groups).

Effects of pre-emulsion prepared using sucrose esters with different hydrophile-lipophile balances on characteristics of soy protein isolate emulsion films

The preparation of emulsion films using pre-emulsification has received extensive attention due to the enhancement of oil binding capacity. However, the different effects of water in oil (W/O) and oil in water (O/W) pre-emulsions on the physicochemical properties of films are still unclear. Therefore, the soy protein isolate (SPI) based emulsion films were prepared by W/O or O/W pre-emulsion using sucrose esters with different hydrophile-lipophile balances to investigate the properties of SPI emulsion (SPIE) films. The viscosity, storage moduli, and loss moduli of film-forming solutions (FFSs) with O/W pre-emulsion were higher than those of FFSs with W/O pre-emulsion. The oil droplets of FFSs with W/O pre-emulsion were large and uneven, and the oil droplet size increased after drying. Phase separation and macroporous network appeared in cross-sectional of SPIE films with W/O pre-emulsion according to scanning electron microscope images. Meanwhile, the SPIE films with W/O pre-emulsion demonstrated higher oil concentration and hydrophobicity on the upper surface compared with the SPIE films with O/W pre-emulsion. Low tensile strength, glass transition temperature, and high elongation at break and transparency value of SPIE films with O/W pre-emulsions were founded. The water vapor permeability of SPIE films with W/O pre-emulsion increased with the addition of oil, whereas the opposite trend appeared in that with O/W pre-emulsion. In conclusion, the structure and porosity of emulsion films could be affected by the pre-emulsion types, which can determine the application ranges.

Control of Beany Flavor from Soybean Protein Raw Material in Plant-Based Meat Analog Processing

The development of plant-based meat analogs is currently hindered by the beany flavor generated by raw soybean protein and extrusion processing. Wide concern has led to extensive research on the generation and control of this unwanted flavor, as an understanding of its formation in raw protein and extrusion processing and methods through which to control its retention and release are of great significance for obtaining ideal flavor and maximizing food quality. This study examines the formation of beany flavor during extrusion processing as well as the influence of interaction between soybean protein and beany flavor compounds on the retention and release of the undesirable flavor. This paper discusses ways to maximize control over the formation of beany flavor during the drying and storage of raw materials and methods to reduce beany flavor in products by adjusting extrusion parameters. The degree of interaction between soybean protein and beany compounds was found to be dependent on conditions such as heat treatment and ultrasonic treatment. Finally, future research directions are proposed and prospected. This paper thus provides a reference for the control of beany flavor during the processing, storage, and extrusion of soybean raw materials used in the fast-growing plant-based meat analog industry.

Physicochemical properties of soybean β-conglycinin-based films affected by linoleic acid

To explore the interaction between lipids and proteins during emulsion film formation, the linoleic acid concentration effects on the physicochemical properties of soybean β-conglycinin (7S) films were studied. The viscosity and size of oil droplets in the film-forming solution gradually increased with the increasing linoleic acid concentration. As the linoleic acid concentration increased, the number of oil droplets on the film surfaces and elongation at break of films gradually increased, whereas the tensile strength decreased. The films containing 20% linoleic acid had the highest water vapor permeability value, which was decreased by increasing or decreasing the linoleic acid concentration. According to the molecular dynamics simulation and chemical interactions, 7S could be adsorbed at the linoleic acid interface and bind stably, resulting in the decreased ionic and hydrogen bonds but the increased hydrophobic interactions and covalent bonds among proteins in the films.