Characterization of whey protein-based films incorporated with natamycin and nanoemulsion of α-tocopherol

Macro and nano level intervention of reinforcing agents for production of novel edible whey composite films and their applications in food systems: A review

Whey protein-based biocomposite films (WBF) are gaining significant importance as edible packaging materials due to their eco-friendly, biodegradable and barrier properties. The review aims to explore the impact of different reinforcing agents on the techno-functional properties of WBF. The incorporation of reinforcing agents, such as polysaccharides, lipids, starch, chitosan, cellulose, essential oils, and hydrocolloid gums, plays a crucial role in shaping the techno-functional properties of WBF. The review article suggests that whey biocomposite films, when strengthened with various additives, have the potential to be used as edible food packaging materials with desirable attributes. However, despite extensive studies, the utilization of WBF in model food systems remains limited, highlighting a significant gap for further exploration. Further research in this domain could potentially unlock new opportunities for utilizing WBF in various model food systems.

Films Based on Biopolymers Incorporated with Active Compounds Encapsulated in Emulsions: Properties and Potential Applications-A Review

The rising consumer demand for safer, healthier, and fresher-like food has led to the emergence of new concepts in food packaging. In addition, the growing concern about environmental issues has increased the search for materials derived from non-petroleum sources and biodegradable options. Thus, active films based on biopolymers loaded with natural active compounds have great potential to be used as food packaging. However, several lipophilic active compounds are difficult to incorporate into aqueous film-forming solutions based on polysaccharides or proteins, and the hydrophilic active compounds require protection against oxidation. One way to incorporate these active compounds into film matrices is to encapsulate them in emulsions, such as microemulsions, nanoemulsions, Pickering emulsions, or double emulsions. However, emulsion characteristics can influence the properties of active films, such as mechanical, barrier, and optical properties. This review addresses the advantages of using emulsions to encapsulate active compounds before their incorporation into biopolymeric matrices, the main characteristics of these emulsions (emulsion type, droplet size, and emulsifier nature), and their influence on active film properties. Furthermore, we review the recent applications of the emulsion-charged active films in food systems.

Incorporating oregano (Origanum vulgare L.) Essential oil onto whey protein concentrate based edible film towards sustainable active packaging

The study's objectives were to develop a packaging film incorporating oregano essential oil, and evaluate the antioxidant, antibacterial, mechanical, and physicochemical activities of the film toward grapes packaging. The films were developed by casting method, after adding nano-emulsion of essential oil into WPC-glycerol film forming solution. The effects of the Oregano Essential Oil (OEO) at different concentrations of 1, 2, 3, and 4% (w/w) in the WPC edible films were studied. The light transmittance, colour aspects, water aspects, mechanical, antioxidant, antimicrobial activities, FTIR, SEM microstructure, and biodegradability of the film were studied. Acidity, weight, TSS, pH and 9-point hedonic sensory analysis of grapes packed in WPC-OEO film were evaluated. Results showed that 3% OEO incorporated WPC film displayed positive inhibition towards pathogenic bacteria; Staphylococcus aureus and Escherichia coli (25.36 ± 0.52-28.0 ± 0.5 mm), the antioxidant activity of 86.89 ± 0.087% and 51.24 ± 0.031% for DPPH, FRAP respectively and degradation after 10 days. The film displayed reduced light transmittance, lower water solubility (44.04 ± 2.361%) and prominent surface characteristics in SEM microstructure and FTIR spectra. The grapes packed in WPC-3% OEO film were firmer, had less surface colour change and showed negligible change in weight, pH, acidity, and Brix value throughout the storage period. Thus, the developed film displayed excellent antibacterial and antioxidant properties that potentially extended the quality of fresh grapes during refrigerated storage.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05763-7.

Incorporation of α-Tocopherol into Pea Protein Edible Film Using pH-Shifting and Nanoemulsion Treatments: Enhancing Its Antioxidant Activity without Negative Impacts on Mechanical Properties

The aim of this study is to develop an antioxidant film based on pea protein isolate (PPI) without sacrificing the packaging properties. To achieve this, α-tocopherol was incorporated to impart antioxidant activity to the film. We investigated the effects on film properties resulting from the addition of α-tocopherol in a nanoemulsion form and pH-shifting treatment of PPI. The results revealed that direct addition of α-tocopherol into un-treated PPI film disrupted film structure and formed a discontinuous film with rough surface, and thereby significantly decreasing the tensile strength and elongation at break. However, pH-shifting treatment in combination with the α-tocopherol nanoemulsion, formed a smooth and compact film, which greatly improved the mechanical properties. It also significantly changed the color and opacity of PPI film, but had little effects on film solubility, moisture content, and water vapor permeability. After the addition of α-tocopherol, the DPPH scavenging ability of PPI film was greatly improved and the release of α-tocopherol was mainly within the first 6 h. Additionally, pH-shifting and nanoemulsion did not affect the film's antioxidant activity nor the release rate. In conclusion, pH-shifting combined with nanoemulsion is an effective method to incorporate hydrophobic compounds such as α-tocopherol into protein-based edible films without negative impacts on film mechanical properties.

Strategies for Exploiting Milk Protein Properties in Making Films and Coatings for Food Packaging: A Review

Biopolymers of different natures (carbohydrates, proteins, etc.) recovered from by-products of industrial processes are increasingly being studied to obtain biomaterials as alternatives to conventional plastics, thus contributing to the implementation of a circular economy. The food industry generates huge amounts of by-products and waste, including unsold food products that reach the end of their shelf life and are no longer usable in the food chain. Milk proteins can be easily separated from dairy waste and adapted into effective bio-based polymeric materials. Firstly, this review describes the relevant properties of milk proteins and the approaches to modifying them for subsequent use. Then, we provide an overview of recent studies on the development of films and coatings based on milk proteins and, where available, their applications in food packaging. Comparisons among published studies were made based on the formulation as well as production conditions and technologies. The role of different additives and modifiers tested for the performances of films and coatings, such as water vapor permeability, tensile strength, and elongation at break, were reviewed. This review also outlines the limitations of milk-protein-based materials, such as moisture sensitivity and brittleness. Overall, milk proteins hold great potential as a sustainable alternative to petroleum-based polymers. However, their use in food packaging materials at an industrial level remains problematic.

Effects of grape seed oil nanoemulsion on physicochemical and antibacterial properties of gelatin‑sodium alginate film blends

The present study aimed to evaluate the impact of incorporating grape seed oil (GSO) nanoemulsion (NE) at varying concentrations into the film matrix on the physicochemical and antimicrobial properties of the resulting films. In this study, ultrasonic treatment was used to prepare GSO-NE, and different levels (2, 4, and 6 %) of nanoemulsioned GSO were incorporated into gelatin (Ge)/sodium alginate (SA)-based films to produce films with improved physical and antibacterial properties. The results revealed that incorporation of GSO-NE at 6 % concentration decreased the tensile strength (TS) and puncture force (PF) significantly (p < 0.05). The whiteness index (WI) of the films decreased from 63.4 to 47.79, while the total color change (ΔE) increased significantly (p < 0.05) with the increase in GSO-NE concentration. Thermogravimetric analysis (TGA) results showed that GSO-NE at different concentrations had improved the thermal stability of Ge/SA-based films. The incorporation of GSO-NE into the films led to the formation of a slightly porous structure. The incorporation of GSO-NE at 4 and 6 % concentrations decreased the water vapor permeability (WVP), moisture content (MC) %, and water solubility (WS) % significantly (p < 0.05). All composite films exhibited hydrophobic surfaces with contact angles θ > 90°. Ge/SA/GSO-NE films were found to be effective against both Gram-positive and Gram-negative bacteria. The prepared active films containing GSO-NE had a high potential for preventing food spoilage in food packaging.

Whey Protein Films for Sustainable Food Packaging: Effect of Incorporated Ascorbic Acid and Environmental Assessment

The management of food waste and by-products has become a challenge for the agri-food sector and an example are whey by-products produced in dairy industries. Seeking other whey valorisation alternatives and applications, whey protein films for food packaging applications were developed in this study. Films containing different amounts (0, 5, 10, and 15 wt%) of ascorbic acid were manufactured via compression-moulding and their physicochemical, thermal, barrier, optical, and mechanical properties were analysed and related to the film structure. Additionally, the environmental assessment of the films was carried out to analyse the impact of film manufacture. Regarding physicochemical properties, both FTIR and water uptake analyses showed the presence of non-covalent interactions, such as hydrogen bonding, between whey protein and ascorbic acid as band shifts at the 1500-1700 cm^-1 region as well as a water absorption decrease from 380% down to 240% were observed. The addition of ascorbic acid notably improved the UV-Vis light absorbance capacity of whey protein films up to 500 nm, a relevant enhancement for protecting foods susceptible to UV-Vis light-induced lipid oxidation. In relation to the environmental assessment, it was concluded that scaling up film manufacture could lead to a reduction in the environmental impacts, mainly electricity consumption.

Designing Deferoxamine-Loaded Flaxseed Gum and Carrageenan-Based Controlled Release Biocomposite Hydrogel Films for Wound Healing

In this study, biocomposite hydrogel films made from flaxseed gum (FSG)/kappa carrageenan (CGN) were fabricated, using potassium chloride as a crosslinker and glycerol as a plasticizer. The composite films were loaded with deferoxamine (DFX), an iron chelator that promotes neovascularization and angiogenesis for the healing of wounds. The properties of the biocomposite hydrogel films, including swelling, solubility, water vapor transmission rate, tensile strength, elongation at break, and Young’s modulus studies, were tested. The films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). In addition, drug release studies in PBS at pH 7.2 were investigated. In vivo analysis was performed by assessing the wound contraction in a full-thickness excisional wound rat model. Hematoxylin & eosin (H & E) and Masson’s trichome staining were performed to evaluate the effect of the films on wound healing progress. The visual and micro-morphological analysis revealed the homogenous structure of the films; however, the elongation at break property decreased within the crosslinked film but increased for the drug-loaded film. The FTIR analysis confirmed the crosslinking due to potassium chloride. A superior resistance towards thermal degradation was confirmed by TGA for the crosslinked and drug-loaded films. Drug release from the optimum film was sustained for up to 24 h. In vivo testing demonstrated 100% wound contraction for the drug-loaded film group compared to 72% for the pure drug solution group. In light of the obtained results, the higher potential of the optimized biocomposite hydrogel film for wound healing applications was corroborated.

Milk protein-based active edible packaging for food applications: An eco-friendly approach

Whey and casein proteins, in particular, have shown considerable promise in replacing fossil-based plastics in a variety of food applications, such as for O₂ susceptible foods, thereby, rendering milk proteins certainly one of the most quality-assured biopolymers in the packaging discipline. Properties like excellent gas barrier properties, proficiency to develop self-supporting films, adequate availability, and superb biodegradability have aroused great attention toward whey and other milk proteins in recent years. High thermal stability, non-toxicity, the ability to form strong inter cross-links, and micelle formation, all these attributes make it a suitable material for outstanding biodegradability. The unique structural and functional properties of milk proteins make them a suitable candidate for tailoring novel active package techniques for satisfying the needs of the food and nutraceutical industries. Milk proteins, especially whey proteins, serve as excellent carriers of various ingredients which are incorporated in films/coatings to strengthen barrier properties and enhance functional properties viz. antioxidant and antimicrobial. In this review, the latest techniques pertaining to the conceptualization of active package models/ systems using milk proteins have been discussed. Physical and other functional properties of milk protein-based active packaging systems are also reviewed. This review provides an overview of recent applications of milk protein-sourced active edible packages in the food packaging business.

Application of innovative packaging technologies to manage fungi and mycotoxin contamination in agricultural products: Current status, challenges, and perspectives

The consumer demand for safe, "healthy," and premium foods, preferably with an extended shelf-life; demand for easy packaging; and choice for more sustainable food packaging have contributed to the development of novel packaging technologies. The application of adequate packaging materials has recently become a major post-harvest challenge concerning the control of fungi and mycotoxin. This review will describe the current antifungal packaging technology involved to prevent the contamination of fungi and mycotoxin, along with the characteristics and mechanism of action in food products. Antifungal packaging has incredible potential in the food packaging sector. The most suitable approach for the safe storage of agricultural produce for farmers is the hermetic packaging technology, which maintains quality while providing a good barrier against fungi and mycotoxin. Furthermore, active antifungal packaging is a viable method for incorporating antifungal agents against pathogenic fungi. Essential oils and organic acid have received more scientific attention due to their increased efficacy against mold growth. Polypeptides, chitosan, and natamycin incorporated in active packaging significantly reduced fungi. Even though nanotechnological advancements in antifungal packaging are promising, safety and regulation issues remain significant concerns.

Ultrasound-assisted synthesis of nanoemulsion/protein blend for packaging application

In the present work, we studied the formation of sunflower oil nanoemulsion using ultrasound techniques. Later, we investigated the development of active films based on a mixture of whey protein containing sunflower oil base nanoemulsion with different concentrations (10, 25, and 50% of total whey protein). The prepared film was by analyzing using the Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and field‐emission scanning electron microscope (FE‐SEM). The film shows no changes in its integrity and crystallinity compared to the virgin film. The presence of nanoemulsion improves the mechanical properties from 2.75 MPa to 3.52 MPa while it decreases the water vapor permeability from 3.4 × 10^–10 to 1.3 × 10⁻¹⁰g/m.s.Pa for concentrations NE (50% of Whey protein). The antioxidant activity for Tween 20 nanoemulsion is 38.7% compared to 36.1% for Tween 80 nanoemulsion. The antimicrobial activity of the film contains sunflower nanoemulsion higher than virgin films. The results showed the potential of blend film of whey protein with nanoemulsion for active films for novel food protection.

Efficacy of Two Stabilizers in Nanoemulsions with Whey Proteins and Thyme Essential Oil as Edible Coatings for Zucchini

Edible coatings are important for horticulture crops preservation and reducing food waste. Application of edible coatings followed by low-temperature storage prolongs the storability, preserves quality, and decreases the overall postharvest losses. This study evaluated the efficacy of two nanoemulsions formulae containing thyme essential oil and whey proteins as coatings for zucchini, with the purpose of extending their shelf-life. The nanoemulsions were rheologically evaluated and the formula with guar and arabic gum mix stabilizer (S) showed a better capacity to restructure after strain compared to the formulae with Tween 20 (T). The S coating material had a better capacity to integrate nanoparticles compared to T. However, when applied on zucchini, T coating was more effective in reducing weight loss showing 16% weight loss compared to 21% in S, after 42 days. At the end of storage at 10 °C, the T-coated zucchini had better firmness (p < 0.05) compared with S and both coatings were superior to control (p < 0.05). POD (peroxidase) activity was high in peel at the end of storage when also CAT (catalase) showed a sudden increase. On the 42nd day of storage, the highest enzymes activity (CAT, POD, and APX (ascorbate peroxidase)) was present in the S-coated zucchini peel. The most abundant volatile in T coating was α-pinene and 4-carene in S. Sensory analysis showed that T coating delayed the appearance of senescence while S exhibited surface cracks.

Application of Nanotechnology to Improve the Performance of Biodegradable Biopolymer-Based Packaging Materials

There is great interest in developing biodegradable biopolymer-based packaging materials whose functional performance is enhanced by incorporating active compounds into them, such as light blockers, plasticizers, crosslinkers, diffusion blockers, antimicrobials, antioxidants, and sensors. However, many of these compounds are volatile, chemically unstable, water-insoluble, matrix incompatible, or have adverse effects on film properties, which makes them difficult to directly incorporate into the packaging materials. These challenges can often be overcome by encapsulating the active compounds within food-grade nanoparticles, which are then introduced into the packaging materials. The presence of these nanoencapsulated active compounds in biopolymer-based coatings or films can greatly improve their functional performance. For example, anthocyanins can be used as light-blockers to retard oxidation reactions, or they can be used as pH/gas/temperature sensors to produce smart indicators to monitor the freshness of packaged foods. Encapsulated botanical extracts (like essential oils) can be used to increase the shelf life of foods due to their antimicrobial and antioxidant activities. The resistance of packaging materials to external factors can be improved by incorporating plasticizers (glycerol, sorbitol), crosslinkers (glutaraldehyde, tannic acid), and fillers (nanoparticles or nanofibers). Nanoenabled delivery systems can also be designed to control the release of active ingredients (such as antimicrobials or antioxidants) into the packaged food over time, which may extend their efficacy. This article reviews the different kinds of nanocarriers available for loading active compounds into these types of packaging materials and then discusses their impact on the optical, mechanical, thermal, barrier, antioxidant, and antimicrobial properties of the packaging materials. Furthermore, it highlights the different kinds of bioactive compounds that can be incorporated into biopolymer-based packaging.

Elaboration of Whey Protein-Based Films in Food Products: Emphasis on the Addition of Natural Edible Bio-nanocomposites With Antioxidant and Antimicrobial Activity

: Food spoilage is one of the major elements of food insecurity that has acquired significant attention over recent decades due to global human population growth. Several studies have investigated increasing shelf life of food products using natural and environmentally friendly compounds. Whey protein (WP) can be an important additive material because it is well-known for its high value of nutrition and well characteristics for the formation of edible films. Furthermore, natural bioactive compounds have been incorporated with WP-based films to confer their antioxidant and antimicrobial activities. Herein, nanotechnology has been effectively potentiated the antimicrobial and antioxidant properties of WP films. A wide range of bioactive agents has been embedded in the WP films, such as essential oils (EOs), TiO2, nano-clay, and even lactic acid bacteria. The current paper reviews the antioxidant and antimicrobial effects of different types of WP films and their applications in food products. This study also discussed the impact of WP films on shelf life, chemical and microbiological quality indices of meats, processed meats, poultry meat products, and fish.

Development of a natamycin-based non-migratory antimicrobial active packaging for extending shelf-life of yogurt drink (Doogh)

A natamycin-based non-migratory antimicrobial packaging for extending shelf-life of yogurt drink (Doogh) was developed. Firstly, the surface of low-density polyethylene film (LDPE) was modified with acrylic acid at different times of UV exposure (0-10 min) to produce carboxylic functional groups. Then, natamycin was applied to the UV-treated films to bind covalently with the pendent functional groups. The maximum grafting efficiency (81.96%) was obtained for the 6 min treated film. Moreover, surface properties of films were evaluated by Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Antifungal activity of different treatments of natamycin grafted film was evaluated against two common spoilage yeasts of Doogh including Rhodotorula mucilaginosa and Candida parapsilosis. Results showed that 6 min treated film provides maximum anti-yeast activity and can be applied to control fungal growth in Doogh. Natamycin-grafted film postponed the yeast spoilage in Doogh and prolonged its shelf-life to 23 days.

Development, Characterization, and Immunomodulatory Evaluation of Carvacrol-loaded Nanoemulsion

Carvacrol (CV) is an essential oil with numerous therapeutic properties, including immunomodulatory activity. However, this effect has not been studied in nanoemulsion systems. The objective of this study was to develop an innovative carvacrol-loaded nanoemulsion (CVNE) for immunomodulatory action. The developed CVNE comprised of 5% w/w oily phase (medium chain triglycerides + CV), 2% w/w surfactants (Tween 80^®/Span 80^®), and 93% w/w water, and was produced by ultrasonication. Dynamic light scattering over 90 days was used to characterize CVNE. Cytotoxic activity and quantification of cytokines were evaluated in peripheral blood mononuclear cell (PBMC) culture supernatants. CVNE achieved a drug loading of 4.29 mg/mL, droplet size of 165.70 ± 0.46 nm, polydispersity index of 0.14 ± 0.03, zeta potential of −10.25 ± 0.52 mV, and good stability for 90 days. CVNE showed no cytotoxicity at concentrations up to 200 µM in PBMCs. CV diminished the production of IL-2 in the PBMC supernatant. However, CVNE reduced the levels of the pro-inflammatory cytokines IL-2, IL-17, and IFN-γ at 50 µM. In conclusion, a stable CVNE was produced, which improved the CV immunomodulatory activity in PBMCs.

Effects of tea polyphenols on physicochemical and antioxidative properties of whey protein coating

Effects of tea polyphenols (TP) incorporation on physicochemical and antioxidative properties of whey protein isolate (WPI) coating were studied. Two WPI coating solutions were prepared by heating WPI solutions (pH 8, 90 °C) for 30 min and then TP was incorporated. TP addition could increase the negative zeta potential of 5% solution. The surface hydrophobicity index of both solutions was increased and intrinsic fluorescence intensity decreased greatly after addition of TP. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis (2 ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging capacities of both solutions increased with increasing TP. Compared with apple pieces coated with whey protein only, those with TP containing whey protein coatings showed lower browning index and slight changes in weight loss during 24 h storage. Data indicated that TP could influence the physicochemical properties and improve the antioxidant activity of WPI coating solutions and can be used to retard the enzymatic browning of fruit during storage.

Protein–TiO2: A Functional Hybrid Composite with Diversified Applications

Functionalization of protein-based materials by incorporation of organic and inorganic compounds has emerged as an active research area due to their improved properties and diversified applications. The present review provides an overview of the functionalization of protein-based materials by incorporating TiO2 nanoparticles. Their effects on technological (mechanical, thermal, adsorptive, gas-barrier, and water-related) and functional (antimicrobial, photodegradation, ultraviolet (UV)-protective, wound-healing, and biocompatibility) properties are also discussed. In general, protein–TiO2 hybrid materials are biodegradable and exhibit improved tensile strength, elasticity, thermal stability, oxygen and water resistance in a TiO2 concentration-dependent response. Nonetheless, they showed enhanced antimicrobial and UV-protective effects with good biocompatibility on different cell lines. The main applications of protein–TiO2 are focused on the development of eco-friendly and active packaging materials, biomedical (tissue engineering, bone regeneration, biosensors, implantable human motion devices, and wound-healing membranes), food preservation (meat, fruits, and fish oil), pharmaceutical (empty capsule shell), environmental remediation (removal and degradation of diverse water pollutants), anti-corrosion, and textiles. According to the evidence, protein–TiO2 hybrid composites exhibited potential applications; however, standardized protocols for their preparation are needed for industrial-scale implementation.

Edible Films of Whey and Cassava Starch: Physical, Thermal, and Microstructural Characterization

The present work aimed to obtain and characterize edible films produced with liquid whey and cassava starch. The films were produced with different proportions of whey (63.75–67.50%) and cassava starch (7.50–11.25%) and characterized in relation to physical, thermal, and microstructural properties. The films showed reduced solubility with increasing concentrations of cassava starch, and those with the highest proportions of whey were more stable to thermal decomposition. The increase in concentration of cassava starch altered the microstructure of the films, making them more irregular and with an accumulation of matter. The production of biodegradable polymer blend films is an important step in the development of films for use in packaging, with the formulation of 67.50/7.50% whey/cassava starch being the best film for continued future work.

Polysaccharide and Protein Films with Antimicrobial/Antioxidant Activity in the Food Industry: A Review

From an economic point of view, the spoilage of food products during processing and distribution has a negative impact on the food industry. Lipid oxidation and deterioration caused by the growth of microorganisms are the main problems during storage of food products. In order to reduce losses and extend the shelf-life of food products, the food industry has designed active packaging as an alternative to the traditional type. In the review, the benefits of active packaging materials containing biopolymers (polysaccharides and/or proteins) and active compounds (plant extracts, essential oils, nanofillers, etc.) are highlighted. The antioxidant and antimicrobial activity of this type of film has also been highlighted. In addition, the impact of active packaging on the quality and durability of food products during storage has been described.