Effect of the unsaturation degree and concentration of fatty acids on the properties of WPI-based edible films

Structural and Physicochemical Properties of Glycerol-Plasticized Edible Films Made from Pea Protein-Based Emulsions Containing Increasing Concentrations of Candelilla Wax or Oleic Acid

Hydrophobization could improve the moisture resistance of biopolymer-based materials, depending on the methods and materials used, providing benefits for packaging applications. The aim of this study was to compare the effect of increasing concentrations (0-2.0%) of candelilla wax (CW) and oleic acid (OA) on the structural and physicochemical properties, including water affinity, of glycerol-plasticized pea protein isolate (PPI) films. OA acidified the film-forming solution and increased its viscosity more effectively than CW. At the highest concentration, OA prevented cohesive film formation, indicating a weakening of protein self-interaction. OA caused less yellowing, matting, and a smaller reduction in UV/VIS light transmittance compared to CW. Both lipids caused a slight reduction in the films' water content. Phase separation (creaming) of CW enhanced surface hydrophobicity, resulting in a greater reduction in water vapor permeability than OA (~37-63% vs. 2-18%). The addition of lipids did not reduce film solubility or water absorption, and OA even increased these parameters. Increasing lipid content decreased the mechanical strength and stretchability of the films by 28-37% and 18-43%, respectively. The control film exhibited low heat-sealing strength (0.069 N/mm), which improved by 42% and 52% with the addition of CW and OA at optimal levels.

Physicochemical and thermal characterization of the edible shellac films incorporated with oleic acid to enhance flexibility, water barrier and retard aging

In this work, shellac plasticized with oleic acid was solvent cast to prepare the flexible and water-resistant film for packaging applications. The films were prepared with varying amounts of oleic acid and studied in detail for appearance, surface morphology, thermal, chemical, barrier, mechanical, and robustness. The surface morphology confirmed the smooth surface of films up to SH-OA20 (100:20 w/w; shellac: oleic acid). Fourier-transform infrared spectroscopy confirmed that oleic acid reduced the hydrogen bonding of the shellac matrix to provide a plasticization effect. Also, the thermal analysis showed a reduction in the melting enthalpy. Moreover, the plasticized films had a better barrier to water vapor due to increased smoothness and reduction in brittleness. Adding oleic acid also increased the elongation at break up to 40 % without any changes in tensile strength. The flexibility of the films increased with the oleic acid content, making them resistant to burst, crumbling, bending, rolling, and stretching. Oleic acid also showed the retardation of aging and thermal aging of shellac. In the future, the long-term stability and migration of the films can be investigated.

The Role of Virgin Coconut Oil in Corn Starch/NCC-Based Nanocomposite Film Matrix: Physical, Mechanical, and Water Vapor Transmission Characteristics

Corn starch-based nanocomposite films usually have low moisture barrier properties. Adding virgin coconut oil (VCO) as a hydrophobic component can improve the nanocomposite film's characteristics, especially the film's permeability and elongation properties. This study aimed to determine the role of VCO with various concentrations (0, 3, 5 wt%) on the physical, mechanical, and water vapor transmission characteristics of corn starch/NCC-based nanocomposite films. Adding 3% VCO to the film showed the lowest WVTR value by 4.721 g/m2.h. At the same time, the value of tensile strength was 4.243 MPa, elongation 69.28%, modulus of elasticity 0.062 MPa, thickness 0.219 mm, lightness 98.77, and water solubility 40.51%. However, adding 5 wt% VCO to the film increased the film's elongation properties by 83.87%. The SEM test showed that adding VCO formed a finer structure with pores in several areas. The FTIR films showed that adding VCO caused a slightly higher absorption peak shift at the O-H groups and new absorption peaks at wave numbers 1741 cm-1 and 1742 cm-1. The results of this study may provide opportunities for the development of nanocomposite films as biodegradable packaging in the future.

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.

Fabrication of active whey Protein isolate/oleic acid emulsion based film as a promising bio-material for cheese packaging

Emulsion is a colloidal dispersion for delivering natural antimicrobial, antioxidant, and bioactive compounds to improve the product's quality. The present study aimed to develop the active emulsion film based on whey protein isolate (WPI) by adding oleic acid (OA) (0, 10, and 20% w/w) and green tea extract (GTE) (0 and 0.5% w/v) for cheese packaging. Results showed that the opacity, flexibility, and water barrier properties of WPI hydrogel-based film were significantly increased by adding 10% OA. Active release from emulsion-based films was governed by pH and the nature of food model systems. The minimum release occurred in the acidic food model system. After 5 h exposure in the acid food model system, the obtained release from the active film containing OA 0, 10, and 20% was 52.39, 48.97, and 57.24% of incorporated GTE, respectively. The log reduction value (LRV) of active emulsion film against bacteria was significantly affected by the food model system. Moreover, packed lactic coagulated cheese delivered more phenolic compound of GTE than processed spread cheese. Korsmeyer-Peppas model and Weibull with lag were suggested as appropriate models to forecast the release kinetic of GTE.

Cocoa Nanoparticles to Improve the Physicochemical and Functional Properties of Whey Protein-Based Films to Extend the Shelf Life of Muffins

A novel nanocomposite whey protein-based film with nanoemulsified cocoa liquor (CL) was prepared using one-stage microfluidization to evaluate the emulsion properties and the effect of CL on the film properties by response surface methodology (RSM). The results indicated that the number of cycles by microfluidization had a significant effect (p < 0.05) on the particle size and polydispersity of the nanoemulsion, with a polyphenol retention of approximately 83%. CL decreased the solubility (<21.87%) and water vapor permeability (WVP) (<1.57 g mm h^-1 m^-2 kPa^-1) of the film. FTIR analysis indicated that CL modified the secondary protein structure of the whey protein and decreased the mechanical properties of the film. These results demonstrate that applying the film as a coating is feasible and effective to improve the shelf life of bakery products with a high moisture content. This nanocomposite film is easy to produce and has potential applications in the food industry.

Disposable Food Packaging and Serving Materials-Trends and Biodegradability

Food is an integral part of everyone’s life. Disposable food serving utensils and tableware are a very convenient solution, especially when the possibility of the use of traditional dishes and cutlery is limited (e.g., takeaway meals). As a result, a whole range of products is available on the market: plates, trays, spoons, forks, knives, cups, straws, and more. Both the form of the product (adapted to the distribution and sales system) as well as its ecological aspect (biodegradability and life cycle) should be of interest to producers and consumers, especially considering the clearly growing trend of “eco-awareness”. This is particularly important in the case of single-use products. The aim of the study was to present the current trends regarding disposable utensils intended for contact with food in the context of their biodegradability. This paper has summarized not only conventional polymers but also their modern alternatives gaining the attention of manufacturers and consumers of single-use products (SUPs).

Excellent coating of collagen fiber/chitosan-based materials that is water- and oil-resistant and fluorine-free

Collagen fiber has attracted much attention due to its good biocompatibility and biodegradability. In the present research, we prepared a type of non-fluorine hydrophobic and oil-resistant material using collagen fiber, chitosan, and polydimethylsiloxane (PDMS) as raw materials. To improve oil/grease resistance, the first layer filled the porous matrix and was made from the cross-linking product of collagen fiber/chitosan and glutaraldehyde. This was followed by a simple coating of PDMS, to increase hydrophobicity and water resistance. Notably, 10 g/m² of cross-linking product and 6 g/m² of PDMS had a low pore size as well as a smooth and uniform surface, which made the composites exhibit excellent hydrophobic and oil-resistant properties (water contact angles of 141°), water and oil resistance (kit rating value of 12/12) and mechanical properties. Fluorine-free environment-friendly materials with high water and oil resistance play an important role in promoting the development of high-performance materials for food packaging.

Edible films based on aqueous emulsions of low-methoxyl pectin with recovered and purified sunflower waxes

BACKGROUND

Edible films were obtained from aqueous emulsions prepared with low-methoxyl pectin at different concentrations (10, 20 and 30 g kg^-1 ) and two sunflower wax samples recovered from two waste samples of filter cakes produced in the winterization process of sunflower oil. The two sunflower waxes samples recovered (from the normal hybrid, NSFW, and from the high-oleic hybrid, HOSFW) were added in three proportions (0.1, 0.2 and 0.3 g g^-1 of pectin). Films were evaluated according to their structure, water resistance, water vapor permeability, mechanical properties and thermal behavior.

RESULTS

In general, good dispersion of the lipid material was observed in the cross-sections of the film. Increase in the water resistance (lower swelling index and water adsorption) was associated with a greater pectin content crosslinked with Ca²⁺ and the hydrophobic nature of waxes. The reduction in water vapor transfer rates was influenced by the effect of the wax addition, their fatty acid composition and their good distribution on the film. More resistant, rigid and less flexible films were obtained with lower pectin content, finding an inverse relationship between tensile strength and elongation percentage values.

CONCLUSION

These results evidence a promising alternative in the development of innovative strategies to valorize sunflower waxes derived from waste material. © 2020 Society of Chemical Industry.

Application of Protein-Based Films and Coatings for Food Packaging: A Review

As the IV generation of packaging, biopolymers, with the advantages of biodegradability, process ability, combination possibilities and no pollution to food, have become the leading food packaging materials. Biopolymers can be directly extracted from biomass, synthesized from bioderived monomers and produced directly by microorganisms which are all abundant and renewable. The raw materials used to produce biopolymers are low-cost, some even coming from agrion dustrial waste. This review summarized the advances in protein-based films and coatings for food packaging. The materials studied to develop protein-based packaging films and coatings can be divided into two classes: plant proteins and animal proteins. Parts of proteins are referred in this review, including plant proteins i.e., gluten, soy proteins and zein, and animal proteins i.e., casein, whey and gelatin. Films and coatings based on these proteins have excellent gas barrier properties and satisfactory mechanical properties. However, the hydrophilicity of proteins makes the protein-based films present poor water barrier characteristics. The application of plasticizers and the corresponding post-treatments can make the properties of the protein-based films and coatings improved. The addition of active compounds into protein-based films can effectively inhibit or delay the growth of microorganisms and the oxidation of lipids. The review also summarized the research about the storage requirements of various foods that can provide corresponding guidance for the preparation of food packaging materials. Numerous application examples of protein-based films and coatings in food packaging also confirm their important role in food packaging materials.

Development and characterization of bilayer films based on pea starch/polylactic acid and use in the cherry tomatoes packaging

Renewable and biodegradable packaging materials are desired for numerous applications. Pea starch (PS) and polylactic acid (PLA) are promising alternatives to petrochemical-based polymers except that their phase separation causes poor mechanical properties. To surmount this problem, PS/PLA films with a double-layer structure were designed. The bilayer films displayed better toughness, thermal stability and barrier capacity over those of PLA films. The incorporation of PLA on a PS layer increased water resistance and tensile strength over those of a monolayer PS film. Weak interfacial adhesion between the PS and PLA layers was revealed by Fourier transform infrared spectroscopy and scanning electron microscopy. The bilayer films reduced weight loss ratio of cherry tomatoes and extended the retention of organic acids and vitamin C. A bilayer architecture represents a promising route to develop packaging materials that display the advantageous properties of each material layer.

Antimicrobial activity and hydrophobicity of edible whey protein isolate films formulated with nisin and/or glucose oxidase

The use of edible antimicrobial films has been reported as a means to improve food shelf life through gradual releasing of antimicrobial compounds on the food surface. This work reports the study on the incorporation of 2 antimicrobial agents, nisin (N), and/or glucose oxidase (GO), into the matrix of Whey protein isolate (WPI) films at pH 5.5 and 8.5. The antimicrobial activity of the edible films was evaluated against Listeria innocua (ATCC 33090), Brochothrix thermosphacta (NCIB10018), Escherichia coli (JMP101), and Enterococcus faecalis (MXVK22). In addition, the antimicrobial activity was related to the hydrophobicity and water solubility of the WPI films. The greatest antibacterial activity was observed in WPI films containing only GO. The combined addition of N and GO resulted in films with lower antimicrobial activity than films with N or GO alone. In most cases, a pH effect was observed as greater antimicrobial response at pH 5.5 as well as higher film matrix hydrophobicity. WPI films supplemented with GO can be used in coating systems suitable for food preservation.

Propriedades mecânicas e molhabilidade de filmes de zeínas extraídas de glúten de milho

Zeínas são proteínas de reserva do milho (prolaminas), que podem ser extraídas através de solubilização em meio alcoólico. Essas proteínas são altamente hidrofóbicas, com elevado grau de polimerização. Neste estudo, zeínas do tipo a (massa molecular entre 10 e 22 kDa) foram extraídas do glúten do milho e caracterizadas com respeito às suas principais bandas de absorção espectroscópica na região do infravermelho. Blendas de zeínas com ácido oléico (AO) como plastificante foram avaliadas em diversas proporções e filmes processados por casting sobre superfície apolar. Filmes de zeínas sem plastificante mostraram-se inviáveis para manipulação e medidas, mas a adição de 1 e 2% em massa de AO proporcionou um significativo aumento do módulo de elasticidade, segundo análise realizada por DMA. A presença de plastificante introduz também irregularidades superficiais e leva a uma perda das características hidrofóbicas dessas proteínas.

Wheat Gluten-Laminated Paperboard with Improved Moisture Barrier Properties: A New Concept Using a Plasticizer (Glycerol) Containing a Hydrophobic Component (Oleic Acid)

This paper presents a novel approach to reduce the water vapor transmission rate (WVTR) and water absorbance of wheat gluten/paperboard laminates by introducing a hydrophobic component (oleic acid (OA)) into the hydrophilic plasticizer (glycerol). Whereas the paperboard showed immeasurably high WVTR, the laminate with gluten/glycerol yielded finite values. More importantly, by incorporating 75 wt.% OA into the plasticizer, the WVTR and water absorbance were reduced by, respectively, a factor of three and 1.5–2. Of particular interest was that the mechanical properties were not changing dramatically between 0 and 50 wt.% OA. The results showed clear benefits of combining a gluten film with paperboard. Whereas the paperboard provided toughness, the WG layer contributed with improved moisture barrier properties. In addition, WVTR indicated that the paperboard reduced the swelling of the outer gluten/glycerol layer in moist conditions; a free standing gluten/glycerol film would yield infinite, rather than finite, WVTR values.