Evaluation of mechanical and water barrier properties of transglutaminase cross‐linked zein films incorporated with oleic acid

In this study, four concentrations of transglutaminase were used in zein films incorporated with four oleic acid concentrations, and subsequently, the mechanical and water barrier properties were evaluated. Enzyme concentration significantly affected mechanical and barrier properties of the films. Transglutaminase concentration at 1% improved tensile strength of control sample from 17.5 to 26.9 MPa while solubility decreased from 6.4% to 4.4%. Incorporation of oleic acid into transglutaminase‐treated zein films irrespective of enzyme concentration decreased water vapour permeability and solubility with the 1% transglutaminase‐treated zein films incorporated with 3% oleic acid registering the lowest permeability (0.37 g mm m^?2 h^?1 kPa^?1) and solubility (2.8%) values while elongation at break was not significantly improved. The use of transglutaminase at 1% concentration in cross‐linking zein films coupled with incorporation of controlled concentrations of oleic acid can be an effective approach in improving mechanical and water barrier properties of zein‐based films.     

Edible films produced from agrifood by-products and wastes

This study aims to develop edible films using agrifood by-products (pumpkin seeds, broken rice and orange pectin) and wastes (quince peel, potato peel, potato pulp, orange peel, pumpkin peel). The physicochemical characteristics of the films were investigated, including their mechanical and barrier properties. Higher amounts of plasticizer induced poorer mechanical and barrier properties in the films. The most promising ones were obtained with orange pectin, broken rice and pumpkin peel, with water contact angles (WCA) between 48° and 57°, maximum water vapor transmission rate and water vapor permeability of 575 g.m⁻².d⁻¹ and 108 × 10⁻¹² g.Pa⁻¹.s⁻¹.m⁻¹, respectively, Young's modulus between 350 and 800 MPa, maximum tensile strength between 9.0 and 26.25 MPa, and elongation at break between 2.28 and 9.3%. Orange pectin and broken rice are promising raw materials since they led to higher WCA, better barrier and mechanical properties. Broken rice and quince peel can be good substitutes for commercial starch and glycerol, respectively. Agro-industrial by-products and wastes revealed potential for the production of sustainable edible films.     

Effect of antioxidants in combination of VCO nanoemulsion on gel properties and storage stability of refrigerated sardine surimi gel

Impacts of β-glucan–virgin coconut oil (VCO) nanoemulsion containing epigallocatechin gallate (EGCG) and α-tocopherol at levels of 0–3.0 g kg⁻¹ on properties and storage stability of surimi gel were investigated. Augmented breaking force, deformation and fracture constant were obtained in gels containing 2.0 g kg⁻¹ EGCG or 1.0 g kg⁻¹ α-tocopherol (P < 0.05). Expressible moisture content increased as EGCG levels were more than 2.0 g kg⁻¹. Smoother microstructure was observed in gels containing 2.0 g kg⁻¹ EGCG. Whiter gels were obtained when β-glucan–VCO nanoemulsion was incorporated. No change in protein pattern of gels was observed regardless of antioxidant incorporation. Viscoelastic moduli decreased as β-glucan–VCO nanoemulsion was added; however, incorporation of 2.0 g kg⁻¹ EGCG or 1.0 g kg⁻¹ α-tocopherol lowered the decrease in G'. β-glucan–VCO nanoemulsion containing gels had higher likeness scores than the control (P < 0.05). Gels containing EGCG and α-tocopherol at selected levels had the improved oxidative stability and lowered microbial loads.     

Effects of nisin concentration on properties of gelatin film-forming solutions and their films

The addition of nisin into a gelatin matrix can change properties of the film. The aim of this work was to develop gelatin-based films containing different nisin concentrations in order to study their influence on the film's antimicrobial and physical properties and their rheological properties as a film-forming solution (FFS). The FFS was characterised by rheological assays, and the gelatin-based active films were characterised and assessed by the effects of nisin concentrations on their various properties, including antimicrobial activity. Nisin's concentration affected not only its viscoelastic properties of FFS but also its film solubility in water, film surface roughness and light barrier. The addition of nisin also slightly modified the water contact angle and the mechanical properties of the gelatin films. Finally, the films demonstrated activity against Staphylococcus aureus and Listeria monocytogenes at concentrations above 56 mg of nisin g⁻¹ of gelatin.     

Effects of glycerol,sorbitol, xylitol and fructose plasticisers on mechanical and moisture barrier properties of pullulan–alginate–carboxymethylcellulose blend films

The effects of glycerol, sorbitol, xylitol and fructose plasticisers on water sorption, mechanical properties, water vapour permeability (WVP) and microstructure of pullulan–alginate–carboxymethycellulose (PAC) blend films were investigated. At low plasticiser concentrations (below 7% w/w dry basis), antiplasticisation effect was observed, causing an increase in tensile strength (TS) but a decrease in the equilibrium moisture content. As glycerol concentration increased from 0% to 7%, TS increased from 68.1 to 69.6 MPa, whereas equilibrium moisture contents at 0.84 a_w decreased from 0.37 to 0.3 g H₂O g^?1 dry basis. At higher plasticiser concentrations (14–25% w/w), an opposite trend was observed on the PAC films, resulting in the reduction of TS and elevation of moisture content. Among the four plasticisers tested, the fructose‐plasticised films were the most brittle, showing the highest TS, but had the lowest elongation at break (EAB), WVP and equilibrium moisture content values than films plasticised with other polyols. On the other hand, glycerol resulted in the most flexible film structure, exhibiting opposite materials' properties as compared with the fructose‐plasticised films. For instance, at 25% (w/w) plasticiser concentration, EAB and WVP values of fructose‐plasticised films were 33.5% and 3.48 × 10^?6 g m Pa^?1 h^?1 m^?2, which were significantly lower than that of glycerol‐plasticised films (58.6% and 4.86 × 10^?6 g m Pa^?1 h^?1 m^?2, respectively). Scanning electron microscopy showed that the plasticised PCA films were less homogeneous and more porous than the unplasticised counterparts, indicating that plasticisers had an effect on the microstructural morphology of the film matrix.     

The influence of different plasticisers and fatty acids on functional properties of basil seed gum edible film

In this study, the influence of different concentrations of plasticisers and fatty acids on functional properties of basil seed gum (BSG) films was investigated. The results revealed that glycerol and sorbitol were effective plasticisers for BSG films. Glycerol‐plasticised films exhibited hydrophilic nature with high moisture content (27–49%) and water vapour permeability (4.2–6.5 × 10^?11 g Pa^?1 m^?1 s^?1), moisture uptake higher than 100%, solubility ranging 39–50% and moderate mechanical properties. The films containing sorbitol showed lower moisture content, moisture uptake and percentage elongation compared with glycerol‐plasticised samples. Presence of fatty acids promoted an increase in hydrophobicity of samples, characterised by lower moisture uptake, solubility, water vapour permeability and higher contact angles. Among investigated fatty acids, oleic acid efficiency on improving the characteristics of films was higher than saturated fatty acids (palmitic and stearic acid). Concluding, BSG films showed a substantial potential to be incorporated into food packaging applications, especially for those that require less hydrophilic films.     

Mechanical properties and water vapour permeability of hydrolysed collagen–cocoa butter edible films plasticised with sucrose

The aim of this study was to develop and characterise edible films produced from hydrolysed collagen and cocoa butter and plasticised with sucrose. The mechanical properties, water vapour permeability, opacity and morphology of the films were characterised. The film composition that yielded the best results was used to produce a coating for application in chocolate panned products. A water-based coating with desirable barrier properties that could replace shellac is important for the environment as well as health, and also because chocolate products have great appeal among children. The films obtained were easily manageable and flexible. Sucrose reduced tensile strength (TS), while hydrolysed collagen at concentrations above 15% increased it. Cocoa butter resulted in less-resistant films. The elongation at break values (EAB%) were higher for films containing higher sucrose concentrations. The water vapour permeability (WVP) ranged from 0.32 to 0.63 g mm m⁻² h⁻¹ kPa⁻¹. For the same concentration of cocoa butter, the WVP was directly affected by the thickness of the film, i.e., the greater the thickness, the higher the WVP. Cocoa butter increased film opacity, while sucrose decreased it, particularly at concentrations above 17.5%. High concentrations of hydrolysed collagen produced films with more homogeneous surfaces. The brightness of the product with the coating developed in this study was attractive; however the brightness of the product with shellac was considered more intense. The properties of these films indicate that they are promising systems for coating chocolate panned products.     

Structural and physical properties of soybean protein isolate films with ohmic heating treatment: Impacts of electric field

The effects of ohmic heating (OH) and conventional heating (CON) on the structural and physical properties of soybean protein isolate (SPI) and SPI films were studied. When the electric field was varied from 0 to 12 V·cm⁻¹, the fluorescence intensity, average particle size, and polydispersity index (PDI) of the OH-SPI were the least at 9 V·cm⁻¹ and increased thereafter. Meanwhile, the free SH-group content and surface hydrophobicity were the maximum at 9 V·cm⁻¹ and decreased thereafter. Moreover, the α-helix content decreased and the random coil content increased noticeably at 12 V·cm⁻¹. In terms of the properties of the SPI films, the mechanical properties and water resistance of the OH-SPI films were superior to those of the CON-SPI films. When the electric field was 9 V·cm⁻¹, the tensile strength of the OH-SPI film increased from 2.76 MPa to 4.34 MPa, and the elongation at break of the OH-SPI films improved. Moreover, the water resistance of the OH-SPI films was the best at this electric field.     

Unraveling the Potential of Innovative Eco-friendly Thermoplastic Starch/SEBS-g-MA/Graphene Oxide Bionanocomposites

The increasing focus on bionanocomposites as environmentally friendly solutions for sustainable applications forms the crux of this study. This study explores the influence of incorporating 2% graphene oxide (GO) on the mechanical and thermal characteristics of blends containing glycerol plasticized thermoplastic starch (TPS) and polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene-graft-maleic anhydride (SEBS-g-MA), based matrix films through a solution casting method. Starch is successfully obtained from three varied sources: corn, cassava, and potato, with confirmation via fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. The authors formulate and examine varying proportions of TPS/SEBS-g-MA (ranging from 10 to 50 wt.%), focusing on their biodegradability, and find that a 10 wt.% SEBS-g-MA concentration yields optimal degradation rates, thus this is kept constant. The bionanocomposite films are probed using techniques such as FTIR, XRD, mechanical strength testing, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), water absorption, and biodegradability studies. These results indicate that GO incorporation results in a robust hydrogen bonding network within the cassava starch-based bionanocomposite films, enhancing their mechanical strength while decreasing their moisture absorption. Upgraded thermal properties of these films are also evident from the results. Consequently, these materials show promising utility, particularly in the realm of food packaging.     

Colour and flavour of potato protein preparations,depending on the antioxidants and coagulants used

The colour and profile of the aromatic compounds of potato juice (PJ) protein preparations were investigated following various process modifications. Several antioxidants (sodium bisulphate, tartaric acid, ascorbic acid), acidulants (tartaric, ascorbic and hydrochloric acids) and chelating agents (chloride, lactate and calcium hydrogen phosphate salts) used for pectin removal during the coagulation of the PJ proteins were evaluated. The combination of sodium bisulphate or ascorbic acid as antioxidants, with calcium chloride or lactate, and ascorbic acid as the protein coagulant, increased the brightness of the protein preparations. Forty-one aromatic compounds, including aldehydes, alcohols and alkanes, were identified. The total concentration of volatiles ranged 59–105 μg g⁻¹. The ascorbate variant contained the lowest n-hexanal concentration. Different treatments did not impact significantly on the 2-methyl-propanal and 2-methyl-butanal concentrations. Interestingly, 2-pentylfuran production was dramatically reduced (16.48 μg g⁻¹) in the lactic variant in comparison to 40.52 μg g⁻¹ with CaHPO₄ addition.     

Antimicrobial, water vapour permeability, mechanical and thermal properties of casein based Zataraia multiflora Boiss. Extract containing film

Hydrophobic sodium caseinate based edible films were prepared by incorporating stearic and oleic acids. Films were produced with a protein/lipid ratio of 1.05. Antimicrobial films were produced based on the hydrophobic films by adding the essential oil of Zataraia multiflora Boiss. Water vapour permeability, microstructure, antimicrobial, mechanical and thermal properties of these films were studied. Water vapour permeability decreased from 2.18 × 10⁻⁹ to 7.81 × 10⁻¹¹ gPa⁻¹s⁻¹ m⁻¹ on the addition of lipid compounds to film. Scanning electron microscopy showed a partial phase separation of lipid compounds and protein. This fact was confirmed by obtaining two endothermic peaks for lipid containing films during Differential scanning calorimeter. The incorporation of fatty acids into the film structure increased the total specific thermal capacity. The presence of lipids and essential oil decreased tensile strength but increased the elongation at break. Films containing essential oil exhibited a large inhibitory effect on Staphylococcus aureus, as compared to Salmonella typhimurium and Escherichia coli O157:H7.     

Comparative study of the phenolics,antioxidant and metagenomic composition of novel soy whey-based beverages produced using three different water kefir microbiota

Water kefir microbiota was used to develop novel soy whey-based beverages that have antioxidant activity. In the present study, comparative phenolics, antioxidant and metagenomic composition of the soy whey beverages fermented using three different water kefir microbiota, named WKFS-A, WKFS-B and WKFS-C were investigated. WKFS-B beverage had the highest concentrations of isoflavone aglycones (208.73 ± 2.78 mg L⁻¹) and phenolic acids (132.33 ± 3.41 mg L⁻¹) compared with WKFS-A (193.88 ± 1.15 mg L⁻¹) and (91.73 ± 2.34 mg L⁻¹) and WKFS-C (160.63 ± 1.76 mg L⁻¹) and (97.13 ± 2.63 mg L⁻¹), respectively. The WKFS-B also showed higher DPPH and ABTS radical scavenging activity and ferric reducing antioxidant power compared with WKFS-A and WKFS-C beverages. Microbial species diversity index analysis showed that a higher concentration of isoflavone aglycones, phenolic acids and increased antioxidant activity in the WKFS-B beverage correlates with the higher relative abundance of Lactobacillus genus. This study thus revealed that Lactobacillus dominated water kefir microbiota produces soy whey beverages with high phenolic acids, isoflavone aglycones and antioxidant activity.     

Performance evaluation of biobased/biodegradable films for in-package thermal pasteurization

This study examined the feasibility of biobased/biodegradable films for in-package thermal pasteurization. Salmon in sauce and beet mixed mashed potato were vacuum packed in polylactic acid (PLA), and polybutylene adipate terephthalate (PBAT)-based pouches (oxygen transmission rate (OTR): 330–619 cm³ m⁻² day⁻¹ and water vapor transmission rate: 38–49 g m⁻² day⁻¹), pasteurized targeting 6-log reduction of L. monocytogenes (P_70°C^7.5°C = 3 min), and stored at 4 °C for 10 days. The gas barrier properties of all films decreased significantly (P < 0.05) after processing, and some haziness developed in PLA films. Although the OTR increased, the microbial, physical, and chemical qualities were maintained at the end of storage. The lipid oxidation, based on TBARS, was within the acceptable limit in salmon in sauce. However, the vitamin C in mashed potato packed in biobased/biodegradable films demonstrated losses 2–3 times higher than in the control (polyethylene) film. Overall findings indicate that selected PLA and PBAT-based films are suitable for in-package pasteurization and can replace polyethylene for ≤10 days of shelf life at 4 °C.Industrial significanceIncreasing consumer awareness about plastic waste disposal and demand for sustainable products has prompted food and polymer companies to develop sustainable solutions for food packaging. The use of biobased and biodegradable packaging could be one solution to address this challenge. However, current applications of biobased/biodegradable films are limited to fresh produce, meat, yogurt, some beverages, and dry products. Our findings extend the application of these films to in-package thermal pasteurization of high-moisture products, such as ready-to-eat meals.     

Impact of lecithin incorporation on gel properties of bigeye snapper (Priacanthus tayenus) surimi

Gelling characteristics of bigeye snapper (Priacanthus tayenus) surimi functionalised by lecithin at different concentrations were investigated. Lecithin at ≤1 g 100 g⁻¹ had no impact on breaking force and deformation (P > 0.05). Expressible drip tended to decrease with increasing lecithin level up to 1 g 100 g⁻¹. Lecithin at 1–3 g 100 g⁻¹ improved the whiteness (P < 0.05). Jointed clusters were formed in the gel microstructure with 1 g 100 g⁻¹ lecithin. Gel without and with 1 g 100 g⁻¹ lecithin had the same texture profile and likeness scores (texture, odour and flavour) (P > 0.05). Peroxide value, TBARS content and rancid odour score of gels were changed considerably during refrigerated storage (4 °C/polyethylene bag) for 15 days but lower values of all indices were noticeable in gel with lecithin. Therefore, lecithin at 1 g 100 g⁻¹ was the optimum concentration for stabilising the texture, improving the water holding capacity, whitening the colour and retarding the lipid oxidation of bigeye snapper surimi gel.     

Physical,mechanical, and antibacterial characteristics of bio-nanocomposite films loaded with Ag-modified SiO2 and TiO2 nanoparticles

In this study, starch-based films incorporating metal oxide (MO₂) nanoparticles (NPs) of TiO₂ and SiO₂ (at a concentration of 1 to 4 wt. %) were produced by solution casting method. In order to exhibit antimicrobial properties, MO₂ NPs were modified by synthesizing silver (Ag) ions over the NPs using cationic adsorption method. Ag ions were then reduced to metallic Ag by sodium borohydride solution. Scanning electron microscopy showed a smooth surface for the pure starch film. Incorporating MO₂@Ag NPs in the films increased surface roughness with agglomerated NPs within starch matrix. Energy dispersive X-ray analysis exhibited a uniform dispersion of Ag-loaded MO₂ NPs, which increases surface contact between these NPs and the biopolymer matrix leading to improved physical and mechanical properties of the resulting films. With increasing in the NPs concentrations, the tensile strength and elongation at break % of the films increased and decreased, respectively. Incorporating MO₂@Ag NPs into starch matrix decreased solubility in water and water vapor permeability of the obtained films, and significantly inhibited the growth of Escherichia coli and Staphylococcus aureus. The most antibacterial effect was obtained for the films containing higher weight concentrations of Ag-loaded SiO₂-NPs.     

Characterisation of composite edible films based on wheat starch and whey‐protein isolate

Composite films prepared by casting wheat starch and whey‐protein isolate at proportions of 100–0%, 75–25%, 50–50%, 25–75% and 0–100% were characterised. Combination of both substances gave continuous and homogeneous films. The more the starch is in a film, the more dull is the appearance. The highest water adsorption was observed for pure whey‐protein films and the lowest for pure wheat starch films with the final water content of 0.264 and 0.324 g water g d.m.^?1, respectively. An exponential equation well fitted the experimental data of water vapour kinetics (R² ≥ 0.99). The highest values of thickness and elongation at break were observed for films obtained by blending of wheat starch and whey protein. With the increasing content of whey‐protein isolate, the values of the swelling index and tensile strength increased from 34.31% to 71.01% and from 2.29 to 8.90 MPa, respectively. The values of water vapour permeability depended on humidity conditions and decreased slightly with the increasing content of whey‐protein isolate.     

Evolution of the physicochemical properties of oil-free sweet potato chips during microwave vacuum drying

The demand for healthy and convenient foods is a worldwide trend. Sweet potato attracted great attention due to its carbohydrates with a low glycemic index. Dehydrated sweet potatoes can be an excellent alternative for using and adding value to this raw material. The objective of this study was to evaluate the physicochemical properties of sliced sweet potato during the microwave vacuum drying (MWVD) for producing crispy oil-free chips. Fresh sweet potato samples were selected, peeled, sliced, blanched, and then dehydrated using a microwave oven adapted with a vacuum chamber and a rotation system to operate under vacuum. It was measured the evolution of moisture, water activity, temperature, color, apparent specific mass, porosity, and acoustic/mechanical analysis of the texture during the MWVD. Crispy sweet potato chips were obtained in <30 min, presenting low moisture (0.028 g g⁻¹ db) and water activity (0.262). The dehydrated samples showed high porosity (67.5%) and a low apparent density (0.456 g cm⁻³). Optical micrographs and acoustic/mechanical properties showed an expanded (puffed) product structure with large pores, which resulted in irregular acoustic/mechanical signals, characteristics of a crispy food matrix. Colorimetric analyses indicated a little change between fresh and dried samples, with an absence of burnt spots. In conclusion, MWVD is a suitable process to produce highly porous sweet potato chips, adding value, and extending the vegetable's shelf life.     

Influence of fermentation parameters on phytochemical profile and volatile properties of mulberry (Morus nigra) wine

In the present study Box–Behnken Design was employed to analyse the effects of fermentation parameters such as temperature (T _F), pH, inoculum size (I _S) and °Brix (B_X) on total phenolic concentration (TPC), total flavonoid concentration (TFC), total anthocyanin concentration (TAC), ethanol concentration (ETHC), total higher alcohol concentration (THAC) and total ester concentration (TESC) for the development of a phytochemical‐rich wine using mulberry as a substrate. The results demonstrated that fermentation parameters significantly alter the wine characteristics. Hence, a wine with excellent consumer preference (overall acceptability of 8.51) and high concentration of phytochemicals (TPC = 6014.03 ± 27.80 mg L⁻¹, TFC = 4791.35 ± 21.22 mg L⁻¹, TAC = 1480.72 ± 5.33 mg L⁻¹) as well as good aromatic properties (ETCH =82.85 ± 0.87 g L⁻¹, THAC =249.91 ± 0.31 mg L⁻¹ and TESC =52.55 ± 0.17 mg L⁻¹) with high antioxidant activity (DPPH =220.18 mmol·l⁻¹) was obtained at optimized fermentation conditions of T _F = 25°C, pH = 4.00, I _S = 10% (v /v) and B_X = 26. The results from the present study might contribute to strengthening the development of wine containing high concentrations of phytochemical compounds with attractive olfactory attributes. Copyright © 2017 The Institute of Brewing & Distilling     

Effect of carp (Cyprinus carpio) oil incorporation on water vapour permeability,mechanical properties and transparency of chitosan films

The effect of carp oil incorporation on properties of chitosan films was evaluated. Chitosan and carp oil were obtained from shrimp wastes and viscera respectively. Tests were performed with different values of chitosan: oil ratios, agitation rates, homogenisation times and pH. The optimum conditions for stability of the film–forming dispersions were of 20,000 rpm at 10 min, and 10:1 ratio of chitosan:oil. The highest values of tensile strength and elongation percentage (%E) of films were obtained at pH 3.5. The addition of carp oil in the chitosan films (10:1 ratio) showed an increase in the resistance to diffusion of water vapour (1.7 g mm m^?2 day^?1 kPa^?1) in relation to pure chitosan films (4.1 g mm m^?2 day^?1 kPa^?1). However, pure chitosan films showed better mechanical properties (38 MPa and%E 18%) and transparency than films of chitosan:oil (20.4 MPa and 8.8%).     

Effects of ultraviolet-C irradiation on the physicochemical properties of polysaccharide films prepared from the stalk base of oyster mushrooms (Pleurotus ostreatus)

The effects of ultraviolet (UV)-C irradiation on the physicochemical properties of oyster mushroom polysaccharide (OMP) films were investigated. The prepared OMP films were subjected to UV-C treatment (5.4 kJ m⁻²). UV-C irradiation increased the tensile strength and decreased the water vapour permeability of the OMP films. In addition, the incorporation of 1.0% Cudrania tricuspidata leaf extract (CTLE) enhanced the antioxidant activity as well as antimicrobial activity of OMP films; however, UV-C treatment did not affect the activities of films containing CTLE. Furthermore, UV-C-irradiated films had higher contact angles than non-irradiated films, indicating increased surface hydrophobicity. Microstructural imaging revealed that UV-C treatment caused the surface of treated films to be smoother than that of untreated films owing to surface degradation. These results indicated that UV-C irradiation can be used for OMP films to improve film properties that are associated with application of films as food packaging material.