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The exopolysaccharide EPS1190 was isolated with high purity from skim milk fermented by the strain Streptococcus thermophilus CRL1190, the major EPS amount being recovered at stationary growth-phase (70.7 mg/L after 16 h). This polymer revealed moderate antioxidant activity in vitro and useful technological properties such as good emulsifying and flocculating capacity at low concentrations, high aqueous solubility (9.1 mg/mL), water and oil holding capacity (528.5% and 1266%, respectively) as well as thermal behavior. Thermogravimetric, Differential Thermal Analysis and Differential Scanning Calorimetry curves showed that the biopolymer was thermally stable up to 216 °C with a crystalline deformation in an endothermic process (△H = 284.46 J) at a melting temperature of 74.08 °C. Furthermore, a degradation temperature (Td) of 295.4 °C was observed. These results postulate that EPS1190 could be used in the food industry due to its special micro-structure (scanning electron microscopy of EPS1190 demonstrated a homogeneous matrix with micro-porous and rough structure), its good performance and functionality in both aqueous and oil systems, which would remain at high temperatures.

Assembly of spherical nanoparticles after Ca2+-induced cold gelation of aqueous extracts of wheat bran was previously reported. Although nanospheres were suggested to be constituted by proteins and stabilized by calcium bridges, their exact origin was not fully demonstrated because of the complexity of wheat bran extracts. To deepen in this respect, by means of a bottom-up approach, the experiment was reproduced with fractions of wheat bran obtained by size exclusion chromatography. After thermal treatment and addition of CaCl2, fractions were characterized by UV–Vis spectroscopy, FTIR spectroscopy, SDS-PAGE electrophoresis, energy dispersive spectroscopy, differential scanning calorimetry, and electron microscopy. Instead of the expected nanospheres, spheroidal particles with diameters 210 – 330 nm were precipitated from a protein fraction of 21 – 43 kDa, even before the addition of CaCl2. Spectroscopic and SDS-PAGE characterization showed that particles were mainly constituted by proteins. Global evidence indicates that calcium did not participate in the assembly of the particles, but rather the driving force for protein aggregation was the denaturation caused by the heat treatment. According to their characteristics, spheroidal particles were classified as biopolymer particles.

Melanin nanoparticles (MNP) were isolated from the sepia ink using a centrifugation method and used as a functional filler for the preparation of agar-based functional films. The MNP were spherical with an average diameter of 95.6 ± 21.2 nm. Field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR) test results indicated that the MNP were well dispersed in agar polymer to form free-standing composite films. The addition of MNP enhanced the UV-blocking, hydrophobicity, mechanical, and water vapor barrier properties of the agar film. Also, the agar/MNP composite films showed a high antioxidant activity comparable to ascorbic acid. The MNP separated from sepia ink can be used as a functional filler to develop antioxidant biopolymer films for food packaging and biomedical applications.

Zein-pectin core/shell nanoparticles loaded with resveratrol were fabricated using a combination of the antisolvent precipitation and electrostatic deposition methods. These nanoparticles were stable to aggregation from pH 2 to 7 and had good heat stability (80 °C for 1 h). The nanoparticles were exposed to a simulated gastrointestinal tract (GIT) containing stomach and small intestine phases, and their bioaccessibility and antioxidant capacity were then measured. The bioaccessibility of the encapsulated resveratrol was higher than that of free resveratrol. Moreover, the in vitro antioxidant capacity of resveratrol was greatly enhanced when it was encapsulated inside the biopolymer nanoparticles, as shown by more potent ABTS+· radical scavenging and ferric ion reducing power. The gastrointestinal fluids collected after digestion of the encapsulated resveratrol also exhibited strong intracellular reactive oxygen species scavenging activity. Our results suggest that the biopolymer nanoparticles produced in this study may be an effective oral delivery system for resveratrol that could be used in functional foods or nutraceutical supplements.

The aim of this work was to encapsulate native bioactive lactoferrin (Lf) in pectin-based colloidal delivery systems with and without a chitosan (CS) coating, and to explore their fate under digestive conditions. We compared the abilities of low methoxyl (LM) pectin and high methoxyl (HM) pectin to form complexes with Lf at different mass ratios. LM pectin led to a smaller particle size (256 nm) and a higher Lf encapsulation efficiency (>72%) than HM pectin because of its greater negative charge (−43.6 versus −16.4 mV). After validating the retention of the bioactivity of native Lf (antimicrobial activity) in these complexes, we coated the Lf‒LM pectin complex with a layer of CS, which had no significant effect on the Lf encapsulation but improved the colloidal stability under gastric conditions. Both Lf‒pectin complexes and chitosanCS-coated complexes retained >90% of the Lf from release in simulated gastric fluid. This resulted in gastric protection of Lf against pepsin-mediated hydrolysis for at least 60 min, relative to free Lf solution. CS-coated complexes also delayed the degradation of released Lf, possibly because of the interaction between this cationic biopolymer and pepsin.

Metal-doped pectin films have been fabricated and their thermal, mechanical and microstructural properties were examined by means of complementary physicochemical techniques. Films were fabricated at two pH values, 2.0 and 7.0, with inclusions of metals (Na+, K+, Ca2+, Mg2+ and Al3+) and conditioned in a range of relative humidity environments. Glass transition temperatures (Tg) of water-plasticised films ranged between 54 and 95 °C. Treatment of Tg values with Gordon-Taylor empirical model revealed a spectacular increase (∼25 °C) of the Tg of dry films at pH 2.0 and with the addition of metals. Uniaxial extension measurements revealed that, at pH 2.0, films were stronger with lower extensibility in contrast to their counterparts prepared at pH 7.0. All films were microstructurally inspected and revealed a continuous one-phase microstructure at length scales >100 μm with no significant differences in the surface topography. Changes of the physical properties of films have been attributed to the modulation of the intermolecular interactions that are influenced by the degree of ionisation of carboxyl groups (pH), electrostatic interactions (inclusion of cations), and conformational reorientation of pectin chains. Overall, it has been shown that it is possible to engineer biopolymer films for a range of applications depending on the desired operating environment.

Electrospinning is a versatile technique to fabricate non-woven fiber mats with an average fiber diameter ranging from nanometers to micrometers. Fibers produced by electrospinning have potential application in numerous fields owing to their light weight, high surface area, and high porosity. In certain applications, anisotropic properties are desired, which may also improve mechanical strength. This study comprehensively documented the feasibility of directed fiber deposition in wet-electrospinning and offers an inexpensive setup for laboratory investigation. Aligned starch fiber mats were produced and the effects of three operational parameters, i.e., rotational speed, drum location, and coagulation bath composition, were evaluated. The alignment of starch fibers was affected by the ethanol concentration in the coagulation bath and drum rotational speed. Coherent fibers could be obtained in all trials except for the one at the lowest ethanol concentration (60% v/v) and highest rotational speed (500 rpm) when the drum was below the liquid. The tensile strength was influenced by the interaction of location and ethanol concentration, and that of rotational speed and ethanol concentration. This study set a promising example of making aligned biopolymer fiber mats and investigating fiber deposition in wet-electrospinning. Aligned starch fiber mats have potential applications in areas such as tissue engineering and as wound dressings.

Application of alginates and carrageenans in food usually include one or the other biopolymer. The combination of the two polymers in gel applications is focus of the present study. Findings not only enhance gel structural understanding, but also enhance biopolymers' fields of application. Structural and rheological properties of mixed alginate/κ-carrageenan, alginate/ι-carrageenan and alginate/furcellaran gels were investigated. Ionic concentration in the gels was set to 50mM K+ and 15mM Ca2+. Based on rheological characterisation, models were utilised to draw conclusions about the gel structure. Mixed gels show phase separation behaviour. The speed of phase separation is dependent on the polysaccharide's sulphate ester content. The fewer sulphate groups present in the carrageenans, the slower phase separation is observed. Alginate/furcellaran gels can be described by an interpenetrating biphasic model, having lower than isostress stability. Alginate/κ-carrageenan gels show phase separation behaviour with counter dilution of the phases and can best be described by a quadratic model. For alginate/ι-carrageenan, a biphasic gel with discrete phase borders, a new model is presented. It is based on a sigmoid function and models the transition from an isostress to an isostrain description.

β-carotene was encapsulated in Pickering emulsions stabilized by biopolymer particles formed by wheat gluten nanoparticles (WGN) or wheat gluten nanoparticle-xanthan gum (WGN-XG) complexes. The WGN-XG emulsions had larger initial mean particle diameters (23.9 μm) than the WGN ones (9.4 μm), but they were still stable to aggregation over a wide range of pH values (4–8) and salt levels (0–1000 mM NaCl). They were also effective at protecting β-carotene from chemical degradation during storage, with around 94.3% and 70.1% of the carotenoids being retained after one-month storage at 25 and 37 °C, respectively. WGN-XG and WGN emulsions were both stable to thermal sterilization. An in vitro digestion experiment showed that β-carotene had a higher bioaccessibility in the WGN-XG emulsions than in the WGN ones. These results may facilitate the design of Pickering emulsions with high stability for nutraceutical delivery in food and supplement products.

Fat-replacers can be applied to enhance creaminess as they often possess a high ability to bind water. Especially for mixed biopolymer complexes, such as whey protein–pectin complexes (WPPC), the viscosity measurement can show non-linear behaviour, impairing exact calculations of bound water or elucidating the structure from the intrinsic viscosity. By means of mass balance based on ultra-centrifugation and capillary viscosimetry, an alteration in biopolymer ratio during thermal stabilisation was determined. The initial ratio of 5:1 (w/w) shifted in favour of the protein component in the complex. 98% of the pectin were not incorporated in the complex but remained in the outer phase increasing its viscosity. By considering this alteration, the voluminosity of WPPC was calculated to be 18.3 ±0.5 mL g−1. Supplementary scanning electron micrographs showed a porous complex structure dominated by denatured whey proteins, which were linked by few pectin molecules. A model of the thermally induced complex formation from whey protein isolate and low-methoxyl pectin was postulated in which the unbound pectin plays a catalyst-like role.

Poor stability in gastrointestinal (GI) tract is a major challenge for applications of natural biopolymer-based nanoparticles as oral delivery vehicles. In this study, chitosan was modified by grafting stearic acid on its backbone to improve its amphiphilicity. The polymeric nanoparticles were prepared using stearic acid-conjugated chitosan and sodium caseinate via ionic gelation and chemical crosslinking by glutaraldehyde and periodate oxidized dextran. The physicochemical properties and stability in simulated GI fluids were systematically studied to obtain the optimal nanoparticles with a diameter of 150 nm and homogeneous size distribution. The electron microscope images suggested the well-maintained nanoparticulate structure in simulated GI fluids. The non-cytotoxicity and internalization of the nanoparticles by Caco-2 cells were confirmed using fluorescence microscope. Successful encapsulation and sustained release of curcumin were demonstrated. The as-prepared polymeric nanoparticles hold promising features to be oral delivery vehicles to carry lipophilic bioactives for future applications in food and pharmaceutical industries.

Hydrophobin II (HFBII) is an amphiphilic biopolymer that could be explored to stabilize oil-in-water nanoemulsions as nutraceutical delivery systems. This study reports the production of HFBII-stabilized nanoemulsions by a spontaneous emulsification process using copaiba oil as a bioactive lipid. HFBII was isolated from a wild-type Trichoderma reesei and characterized. A 23 full factorial design with three central points was used to obtain an optimal nanoemulsion system, whose physical-chemical properties were studied under different ionic strength and pH. The peptide similarity search allowed the identification of a series of 6 ion fragments from the isolated fraction, which can be attributed to the amino acid sequences of the HFBII database. The optimal nanoemulsion system presented a nanoscale droplet size (

The present study aims to develop natural biopolymer bioactive edible films. Particularly, blend (F-Bl) and bilayer (F-Bi) films based on grey triggerfish skin gelatin (G) and agar (A), incorporated or not with vine leaves ethanolic extract (VLE), at 5 and 10 mg/mL, were prepared using the casting method. First, VLE presented an important antioxidant potential evaluated by the iron (Fe2+) chelating activity, ferric (Fe3+) reducing antioxidant power, β-carotene bleaching protection and DPPH•-radical scavenging activity. Furthermore, VLE presented interesting antibacterial and antifungal activities. On the other hand, the composite films were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), physicochemical, and thermal analyses. SEM micrographs showed that agar and gelatin were compatible. Moreover, the mechanical properties results showed that F-Bl and F-Bi were mechanically stronger and more deformable than control films. This change in mechanical properties can be explained by the formation of a dense network after agar addition, due to the interactions with the gelatin matrix. After their incorporation into polymer network, VLE increased slightly the thermal stability, while it improved greatly the antioxidant activity of the composite films (gelatin and agar) in a dose dependent manner. Thus, results encourage the further use of gelatin/agar/VLE films as active food packaging material.

In this study, the soluble fraction of almond gum (SFAG) as a sustainable biopolymer source and whey protein isolate (WPI) were used for self-assembly preparation of SFAG-WPI nano-complexes through electrostatic interaction. The SFAG was characterized using 1H and 13C NMR. The influence of total biopolymer concentration (0.2–0.4 %w/v) and ratios (1:3–3:1) as well as of the pH (2–6) on the formation of complexes was established by visual, light scattering, surface charge, and spectrometric observations. The outcomes proved the formation of negatively charged soluble complexes in the range of pH 4–5 and insoluble complexes at pH values 3 to 4. The soluble coacervate particles at pH 4.5 and total concentration of 0.4 %w/v were selected to induce Pickering stabilization of thymol. The static light scattering with microscopy studies (CLSM and Cryo-SEM) showed the formation of thymol oil-in-water emulsions by adsorption of nano-complexes on the surface of the droplets. Thymol emulsions stabilized using complexes had no size variation under storage (40 days) with an opaque and homogenous appearance. On the other hand, the emulsions containing solely WPI at pH 4.5 showed a substantial droplet size increase with severe creaming. Droplet size analysis together with coalescence and flocculation indices presented that coalescence was mainly responsible for droplet size coarsening of the emulsions stabilized by native WPI at pH 4.5. Overall, our outcomes indicated the improvement of WPI in the stabilization of emulsions through complexation.

There is a wide demand for new biodegradable materials with innovations to improve the basic functions of traditional food packaging and prolong the shelf life of food, enhancing its security and sensorial properties. Poly(L-lactic acid) (PLLA) is a biodegradable biopolymer used in traditional packaging of food because of its non-toxicity, biodegradability, biocompatibility and transparency. The aim of this work is to modify PLLA films in order to prepare an improved material for food active packaging. For this, PLLA was internally blended with zinc oxide (ZnO) nanoparticles and, it was also superficially modified by the deposition of chitosan (CHI) and β-cyclodextrins (β-CD) by layer-by-layer (LbL). These prepared multilayers were characterized by confocal fluorescence microscopy, contact angle measurements, transmission electron microscopy and UV-Vis spectroscopy. On one hand, the proposed multiple modification inhibits polymer-bacterial interactions and improves the biological properties of the PLLA due to the bactericide effect of ZnO nanoparticles and the contact killing capacity of chitosan. On the other hand, the release of the carvacrol incorporated in β-CDs improves the antibacterial and antioxidant properties of prepared films (more than 95 wt% of totally released carvacrol was released within 14 days). This investigation demonstrates that here specifically modified PLLA films could be promising materials in the new trends of biodegradable and active food packaging.

Delivery of techno- and bio-functionality in all-natural processed foods is an area of steadily increasing fundamental and technological interest. One of the main aspects in this field is based on the diffusion of natural bioactive compounds that have been incorporated in high-solid biopolymers matrices. Organoleptic considerations dictate that the delivery vehicles are characterised by a highly amorphous fraction in the biopolymer network. Molecular diffusion in the amorphous state is a complex process associated with the effect of the glass transition temperature (Tg) on the mobility of low molecular-weight bioactives. This work will review the molecular dynamics of high-solid biopolymer systems, and model food preparations in the presence of co-solute, in relation to the diffusion kinetics of natural bioactive compounds. Literature indicates that the metastable properties of condensed biopolymer networks traversing the rubber-to-glass transition region affect significantly the diffusion kinetics of bioactive compounds. These have been modelled using concepts from the classical and improved diffusion theory to unveil a relationship between apparent diffusion coefficient of bioactives and free volume characteristics of the condensed biopolymer network. Further work is required in added value foods, sourcing inspiration from the “sophisticated pharmaceutical research”, to develop food systems that control transport phenomena for targeted release from a specific dosage form.

Bambara groundnut is a protein-rich legume of African origin. This study investigated the influence of fractionation pH on degree of complexation of bambara protein isolate (BPI) with gum arabic (GA). BPI extracted at pH 2, pH 7, pH 9 and by the traditional salt solubilisation method were complexed with GA. BPI-GA complexes appeared as spherical particles (average size: 100–200 nm) that were aggregated. Optimal pHs of biopolymer interactions decreased (pHopt: 4.8 to 2.9) as protein extraction pH became more acidic. pH 2 fraction had the lowest coacervates yield (41%). ζ-potential profiles of protein fractions displayed similar pH dependent patterns, but with different pHs of net neutrality. The pH 2 fraction showed a high molecular weight protein (100 kDa), which was absent in other fractions. It also contained the highest content of basic amino acids. Protein extraction pH could be manipulated to produce better acid-stable structures on complexation with polysaccharides.

The rheological behavior of mucilage dispersions obtained from Hyptis suaveolens L. seeds was characterized. The apparent viscosity showed a non-Newtonian shear-thinning behavior in a range of shear rate 0.1–300 s−1 at 25 °C and pH 6.5. The Cross and Herschel-Bulkley parameters (r2 > 0.9923) indicated that more physical entanglements arise with increasing concentration (0.1–0.75% w/v). Mechanical spectra were obtained by frequency sweep measurement (0.01–10 Hz) at 0.1% deformation and 25 °C. A G´-G´´ cross-over point was observed (1 Hz) for a 0.1% mucilage dispersion, suggesting a molecular transition from random coil to an entangled conformation. The tan(δ) performance for mucilage dispersion with 0.25–0.75% (w/v) concentrations, with values between 0.2 and 0.3, classified into an intermediate behavior between weak and elastic gel. The G´ values were well characterized by power-law frequency dependence ( r 2 ≥ 0.9628 ) . The mucilage dispersion exhibited temperature stability between 20 and 60 °C, and activation energies with values between 7.20 and 12.85 kJmol-1 indicated that more energy was required to disrupt the formed entanglements and to induce viscous flow. For 0.5% mucilage dispersion, the NaCl addition (0–250 mM) generate more aggregates which disruption became more shear dependence as salt concentration growth, and the formed entanglements were less flexible from neutral to alkaline conditions. The sucrose addition (1, 3, 5, 10, and 20% w/v) into 0.5% mucilage dispersion produced a less shear-thinning behavior, giving a stabilizing effect and enhancing the biopolymer gel strength. These results suggest that mucilage could be applied in many food applications, such as stabilizing, thickening and gelling agents.

The aim of this research was to optimise and develop edible films made from zein (ZN), chitosan (CS), poly(vinyl alcohol) (PVOH) and poly(ethylene glycol) (PEG400) using Box Behnken Design (BBD). Four factors viz. ZN:CS ratio (w/w) (1:3, 1:1, 3:1), PVOH wt.% (in dry film) (0, 0.25, and 0.5), PEG400 wt% (0.13, 0.21, 0.31) and ethanol (40–80% v/v in water), were investigated. The effects on tensile strength (TS), Young's modulus of elasticity (EM), elongation at break (%EAB), water vapour permeability (WVP), solubility in water (Ws), and optical properties were evaluated. The films were further characterised using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), x-ray diffraction (XRD) and swelling behaviour. SEM micrographs showed that high levels of ZN and PEG400 resulted in rough surfaces with major film defects, but these were minimised at high levels of CS or PVOH. XRD analysis indicated potential interactions through hydrogen bonding between the polar groups of ZN and hydroxyl moieties of PVOH and CS. Stress-strain curves showed that ZN and CS composite films possessed high TS but were brittle. Incorporation of PVOH increased the ductility of the composite films. Optimum films were obtained using ZN/CS/PVOH/PEG400 ratio of 0.35/0.29/0.13/0.23 (wt.%) and 60% ethanol, giving dry state properties of TS, EM, and EAB as 24.21 MPa, 356.62 MPa and 84.23%. respectively. This study demonstrated the influence of critical interactions between solvent features (polarity) and interfacial properties of ZN, CS, PVOH and PEG400. The observed crosslinking behaviour suggested the effectiveness of blending technique in improving the compatibility of biopolymers and overall functionality of edible films.

Starch is an important biopolymer widely used in the pharmaceutical, food and textile industries. In this study, low-pressure (0.5 atm) cold plasma was used as an novel technique to modify the rheological behaviours of native tapioca starch using four different feeding gases (air, carbon dioxide, argon, and helium). The induced changes in starch samples were studied by rapid visco analyser (RVA), Rheometer, Fourier transform mid-infrared (FTIR) spectroscopy and scanning electron microscope (SEM) images, respectively. The plasma significantly (P

Polysaccharide-based biopolymer particles are known as biocompatible, sustainable and easy to be modified, and widely used in food and biomedical fields. In this study, a novel polysaccharide-based particle as curcumin (Cur) carrier was developed through self-assembly driven by electrostatic interactions between carboxymethylated corn fiber gum (CMCFG) and chitosan (Cs). Firstly, the chemical structure of synthesized CMCFG was characterized to prove successful carboxymethylation. Then Cur-loaded CMCFG/Cs particles (Cur-CMCsPs) with different mass ratios of CMCFG to Cs (1:3, 1:2, 1:1, 2:1 and 3:1) were prepared and their particle size, zeta-potential, crystalline structure and micro-morphology were determined. Smaller particle size was observed when the mass ratio of CMCFG to Cs exceeded 1:1, among which the lowest hydrodynamic diameter was less than 300 nm, as uniform spherical particles. Furthermore, the highest encapsulation efficiency of the resulting Cur-CMCsPs surpassed 93% and the Cur loaded in particles showed the excellent photo/thermal stability. Besides, the particles could significantly improve the bioaccessibility of Cur reaching 74.94%. This study provides strategy support for suitably designing biopolymer particles as delivery vehicles of hydrophobic nutrients in food and biomedical fields.

In this study, biopolymer microparticles were fabricated for the encapsulation and delivery of lutein by electrostatic complexation of sodium caseinate (NaCas) and sodium alginate (ALG) to improve its physicochemical stability and bioaccessibility. The construction conditions of lutein microparticles were determined by analysis of the particle size, zeta-potential, physical stability and microstructure. The formation mechanism of lutein microparticles was examined by Fourier transform infrared spectroscopy (FTIR) analysis. Moreover, the crystalline structure change of lutein was characterized by X-ray diffraction (XRD) and Differential scanning calorimetry (DSC). Bioaccessibility of lutein was also investigated in a simulated gastrointestinal tract (GIT) model. Lutein microparticles were rough irregular structures with larger mean particle size of 1750 ± 2.24 nm, higher physical stability and negative zeta-potential (−54.03 ± 0.38 mV) when the optimized concentration of NaCas and ALG were 2.0 wt%, respectively. FTIR analysis indicated the electrostatic interaction between the amino group of the caseinate and the carboxyl group of the alginate in the formation of microparticles. XRD and DSC analysis confirmed that lutein was encapsulated in microparticles as an amorphous state. Meanwhile, the microparticles effectively reduced the decomposition of lutein during 22 d storage at 37 °C. GIT studies showed that the microparticles presented higher free fatty acid (FFA) release and lutein bioaccessibility (51.27 ± 0.78%) than emulsions (12.83 ± 1.43%). This study provided a broad prospect for the formulation of lutein-fortified functional foods and beverages.

There is great interest in identifying biopolymer-based particles to stabilize Pickering emulsions. Pure zein particles are easy to fabricate but are unsuitable for this purpose because of their high hydrophobicity. In this study, composite zein - propylene glycol alginate particles (ZPGAPs) were prepared using a solvent evaporation method. The potential of using these particles to stabilize oil-in-water emulsions through a Pickering mechanism was also studied. ZPGAPs prepared at a zein-to-PGA mass ratio of 10:1 had considerably smaller particle diameters (346 nm) than those prepared using pure zein (1400 nm) as determined by light scattering and scanning electron microscopy (SEM). The interface wettability of ZPGAPs mainly depended on the zein-to-PGA mass ratio. The three-phase contact angle (θ) of pure zein particles was around 68.1° whereas that of ZPGAPs was around 90°, suggesting that the composite particles had suitable wettability characteristics for stabilizing Pickering emulsions. Confocal laser scanning microscope (CLSM) images showed that ZPGAPs formed a densely packed layer around the surfaces of the oil droplets, further highlighting the potential of the composite particles as emulsion stabilizers. The elastic modulus (G′) was higher than the loss modulus (G″) in all the Pickering emulsions, which was indicative of the formation of an elastic gel-like structure. The rheological properties of the Pickering emulsions could be modulated by altering the composite particle concentration, droplet concentration, ionic strength, pH, and temperature. These results suggest that the ZPGAPs developed in this work may be a promising stabilizer of Pickering emulsions and may extend the application of zein in food products.

The effect of different counterions (Na+, K+ and Ca2+) on the sol-gel transition diagrams of kappa/iota-hybrid carrageenan isolated from Gigartina skottsbergii, together with the thermo-rheological features of the obtained gels are presented. Extraction yield (47.8 ± 3.5 g/100 g), molar fractions of kappa (62 ± 2) and iota (38 ± 2) and polymers with molecular masses between 7.5 104 and 7 103 g/mol were also determined for G. skottsbergii extracts. Gels formed in NaCl exhibited stable and weak gel properties. Gels made in KCl and CaCl2 featured stable and intermediate gel characteristics, except those formulated at the largest carrageenan and salt content that can be considered strong. All gels achieved stability after 15 min of maturation. No water syneresis was identified in tested gels. Gel setting and melting temperatures depended on the biopolymer and ionic contents. Gels formed in CaCl2 at the largest biopolymer content and ionic concentration showed thermo-reversible features.

Biopolymer nanoparticles (NPs) have garnered much interest in the food industry as encapsulating materials for flavors, nutraceuticals and other bioactive compounds. The ability to control and reproduce NP physicochemical properties is a crucial step in the utilization of nanoscale formulations for food based and sustainable packaging applications. Conventional preparations of gelatin NPs involve a range of solution based methods with inconsistent nanoscale properties. Integrating a filtration step prior to gelatin NP formation obtained highly consistent physicochemical properties between two different gelatin types. The average diameter of the entire population was 143 ± 12 nm with a low polydispersity index of 0.07 ± 0.03. Volume distributions revealed a single peak confirming the existence of uniformly sized NPs. Gelatin NPs obtained high chemical crosslinking extents (≥87%) with synonymous chemical bonding determined via FTIR. Rhodamine 110 fluorescent agent incorporation maintained consistent diameters (∼140 nm) with significantly higher fluorescence measurements compared to empty particles. Our results indicate that greater control and reproducibility of gelatin nanoscale properties is dependent on gelatin molecular weight homogeneity prior to NP synthesis. The production of consistent NP properties is anticipated to propel the translation of gelatin NPs as bioactive encapsulators in food and sustainable packaging applications.

Limonene is a kind of widely used flavor oil, susceptible to degradation with the loss of lemon-like odors and the formation of off-flavors. This study aimed to develop a novel structurally well defined zein-based core-shell microencapsules loaded with limonene for limonene protection and controllable release. The microencapsules were fabricated using a two-step heterogeneous precipitation process, with the shell being formed by direct zein precipitation on the oil-water interface and growing along with the water addition driven by hydrophobic interaction. The formation of core-shell microencapsules occurred at the limonene/zein ratio around 2.0 with D4,3 close to 10 μm and shell thickness about 25 nm, while the smaller self-assembled zein particles could be formed at the ratio of 0.1 and 5.0, suggesting that the mass ratio of core to shell affected the formation of encapsulation and the shell thickness could be controlled. An interior rough and porous shell of the microencapsules was also observed. Sodium caseinate (SC) was adsorbed onto hydrophobic zein surface by electrostatic interaction, contributing to a hydrophilic interface and improving the re-dispersibility of the freeze-dried powder in water. The release rate of limonene in the burst release phase from zein-SC microencapsules was significantly lower than that of whey protein isolate (WPI)-stabilized emulsion, and tended to be gradual in the sustained phase, followed the zero order kinetics. The limonene retention rate of the microencapsules was higher than that of the WPI-stabilized emulsion during an acceleration storage condition, attributing to the solid barrier of the zein-SC shell of the microencapsules. High linear relationship (R2 > 0.96) between limonene retention rate and storage time in both microencapsules and WPI-stabilized emulsion was observed, suggesting potential controllability of limonene degradation. The ability to design the natural biopolymer-based colloidal microcapsules with slow-release and oxidation prevention of the unstable flavor oils opens a new opportunity in a stable dispersions in aqueous foods.

Complex coacervation of protein/polysaccharide mixtures has obtained considerable research in the encapsulation of bioactive materials. The rheological properties of the coacervates of rice bran protein/flaxseed gum (RBP/FG) at different pH values including 3.3, 4.0 and 5.3 and varying protein to polysaccharide ratios 3:1, 6:1 and 9:1 were investigated using small amplitude oscillatory shear (SAOS). Moreover, the interrelationship between the ζ-potential, FTIR and viscoelastic properties of the samples was studied. The coacervates showed shear-thinning phenomenon due to the linear reduction of complex viscosity (η*) by increasing frequency. Furthermore, the highest complex modulus (G*) and more compact coacervate structure were obtained at pH = 4.0, revealing less deformability and flow behavior. All the coacervates showed higher storage modulus (G′) than loss modulus (G″) indicating the formation of highly interconnected gel-like structure and were fitted by the Power law model. The maximum fracture stress was obtained at pH 4.0 revealing the highest intermolecular interactions between RBP and FG. The absolute ζ-potential of the coacervate at pH 4.0 and R = 9:1 was close to 0 and less than the other samples in which the highest fracturability and gel strength of the complex coacervate was achieved. It seems this property of the coacervate would be suitable for encapsulation of bioactive materials. The high aggregation of coacervates at pH 4.0 makes them more readily neutralized by protein binding. FTIR results showed that the spectrum of the coacervate was different from each individual biopolymer, related to their compatibility and intermolecular interactions between the functional groups of RBP and FG. Consequently, RBP/FG coacervates can be managed to some extent to achieve proper textural properties in dairy formula through manipulating pH and biopolymer mixing ratio.

Biopolymer-based microgels are increasingly being viewed as promising building blocks for diverse applications, including drug delivery, novel food ingredients, sensing, and cell biology. The formation of microgels with a narrow size distribution is of key importance because the functional properties of these microgels largely rely on their sizes. This study describes the use of protein-polysaccharide segregative phase separation as a facile method to fabricate whey protein-based microgels by heating mixtures of whey protein and anionic polysaccharides. The spherical microgels had a narrow size distribution and their size could be precisely controlled to 1, 3, and 6 μm. The scanning electron microscopic images revealed a core-shell morphology of the individual microgel with an internal structure of densely cross-linked protein network and an outer “hairy” layer of polysaccharide, resembling the hair-like structures of the casein micelles. Compared to the whey protein, the core/shell microgels could produce emulsions that were stable without flocculation and creaming during a 28-day storage test. Considering the size-controllable protein-based microgels can be fabricated in a convenient method without using toxic reagents or high energy input, these microgels will have broad applications in the food, pharmaceutical, and personal care industries.

Protein–polysaccharide biopolymer particles composed of potential acrylamide inhibitors, including zein, chitosan, alginate, and pectin, were used for acrylamide mitigation in this study. The synergistic effect of zein and polysaccharides in complex particles was hypothesized to inhibit acrylamide formation at high temperature. A reaction model utilizing a glucose and asparagine solution heated at 170 °C for 30 min in a heating block was implemented. Zein, zein–polysaccharide complex particles, and a mixture of zein and polysaccharides (non-complex particles) were used as acrylamide inhibitor solutions. The highest acrylamide reduction was observed at a zein concentration of 0.67% (w/v). Because glutamine and asparagine are the major amino acids found in zein, higher zein concentration (>1%, w/v) increased acrylamide formation. An increase in charge or stability was noted after particle formation, such as zein–sodium alginate (−49.07 to −57.20 mV) and zein–pectin (−27.80 to −31.57 mV), coupled with an increase in average size. Zein–polysaccharide complex particles successfully reduced acrylamide concentration in a heating block model. The most effective acrylamide inhibitor was zein–alginate (1:0.50). However, zein–chitosan particles exerted the opposite effect, thereby promoting acrylamide formation. The acrylamide content in fried potato strips dipped in complex particles (11.07–13.22 μg/mL) was lower than that observed in control (16.08 μg/mL). The interfacial rheology of sticky adsorbing particles with food surfaces requires further investigation.

Norbixin is a natural plant-based pigment that can be used to replace synthetic yellow colorants in foods and other products. It is also being explored as a nutraceutical in functional foods and supplements due to its beneficial biological activities. However, the low-solubility and chemical instability of norbixin currently limit its application in many food products. In this study, the potential of biopolymer nanoparticles assembled from food proteins derived from either animal (sodium caseinate (SC) or whey protein isolate (WPI)) or plant (soy protein isolate (SPI)) sources to encapsulate and protect norbixin was examined. The encapsulation efficiency, loading capacity, size, charge, and interactions of the norbixin-loaded nanoparticles were characterized. All protein nanoparticles could successfully encapsulate and protect norbixin, with loading capacities of 26.8%, 31.5% and 17.0% for SC, WPI and SPI, respectively. Fluorescence, infrared spectroscopy, and X-ray diffraction measurements confirmed that norbixin was trapped within the protein nanoparticles in an amorphous form and that hydrogen bonding occurred between the norbixin and protein matrix. The ability of the norbixin-loaded protein nanoparticles to resist environmental stresses (heat, light exposure, and long-term storage) was ranked according as follows: SPI > SC > WPI. The possibility of using norbixin-loaded SPI nanoparticles as plant-based yellow pigments in cheese production to inhibit the leakage of norbixin into whey was also demonstrated. In summary, this study shows that protein nanoparticles can enhance the water-solubility and stability of norbixin, which may extend the application of this natural pigment in foods.

Sustainable multifunctional halochromic nanocomposite films (“smart films”) were prepared using a casting method. Natural pigments (saffron or red barberry anthocyanins) and TiO2 nanoparticles were included in these films as pH-responsive color indicators and for light blocking, respectively, as well as for their other functional attributes. The film matrix was constructed from a network of crosslinked biopolymers consisting of gelatin and κ-carrageenan. The mechanical, morphological, spectroscopic, colorimetric, thermal, barrier, ammonia-sensitivity, antimicrobial, antioxidant, and biodegradable characteristics of the films were investigated. Moreover, the efficacy of the films was demonstrated by using them to monitor changes in the freshness of packaged fish during storage. Incorporation of TiO2 nanoparticles and natural anthocyanins significantly improved the mechanical and moisture resistance of the films. Spectroscopic analysis (ATR-FTIR and XRD) indicated the nanoparticles and pigments were dispersed throughout the biopolymer matrix, and identified the important molecular interactions involved (such as hydrogen and electrostatic bonding). The films changed color in response to alterations in the freshness of the fish samples, which was correlated to ammonia production during fish degradation. The presence of the anthocyanins and TiO2 nanoparticles increased the bacteriostatic properties of the smart films, as well as inhibiting oxidative reactions. The smart films were shown to be biodegradable, decomposing within ∼30 days under simulated environmental conditions. In conclusion, these biodegradable smart/active films may be suitable replacements for plastic packaging materials. Moreover, they are able to detect food deterioration and prolong shelf life, thereby improving quality and reducing waste.

In this paper, the procedure is presented of innovative, biopolymer double-layered film synthesis, based on furcellaran (FUR) (1st layer) and carboxymethyl cellulose (CMC) with a gelatin hydrolysate (HGEL) (2nd layer). The double-layered structure of the films can be clearly observed in SEM images. The water extract from lingonberries was added to FUR to reinforce the antioxidant and antimicrobial activity of the films. The films with the greatest lingonberry extract (LBE) additive demonstrated antimicrobial activity against the tested bacteria and antioxidant activity (from 3.01 to 41.89 mM Trolox/mg - via FRAP method, and from 0 to 20.56% - via DPPH method). The films with 40% of LBE showed the highest thermal stability (improvement by up to ∼92%) in comparison to tested films. They were used as active materials in the storage of cherry tomatoes. In the active films, tomatoes lost weight quickly compared to the synthetic ones. However, they were characterised by lower phenol content, which indicated slow ripening. The obtained double-layered films with LBE are an interesting alternative to plastic materials.

Structured emulsions (40–70% oil) were designed through complexation between nanofibrillated egg white protein (FEWP) and pectin and emulsion properties were then evaluated at different pHs and biopolymer concentrations. While native egg white protein (NEWP) and pectin formed insoluble complexes, TEM observation the FEWP and pectin complexes consisted of unpacked supramolecular network. The rheological properties of these protein-pectin complexes were significantly influenced by pH, protein-to-pectin ratio, and biopolymer concentration. While pectin addition had no significant influence on the rheological properties of emulsions made by NEWP at oil contents between 40 and 50%, pectin significantly improved the viscosity and elastic modulus of the emulsions prepared by FEWP. This effect was optimized at a protein-to-pectin ratio of 10:1 and pH 3.7. Furthermore, the elastic module was enhanced for the FEWP/pectin complex (FEWP/P) emulsions by increasing the total biopolymer concentration. The capability of FEWP-pectin complexes to make emulsions with enhanced elastic modulus and stability could be ascribed to the fibrillar structure of nanofibrils, enabling them to create a solid network at the continuous phase of the emulsions by complexation with pectin. This study demonstrates the potential of nanofibrillar EWP/pectin complexes for fabricating structured O/W emulsions at reduced fat content. This may contribute to formulations for healthier emulsion-based food products with an improved texture such as sauces, mayonnaises, dressings, and dips.

In this study, the possibility of improving the bioavailability of two potent synergistic nutraceuticals, curcumin and resveratrol, using core-shell nanoparticles and its delivery through 3D printed gelatin hydrogel in a customized structure was examined. The co-axial electrospraying technique was adopted for core-shell nanoparticles formation co-encapsulating both the bioactives in zein core protected by polyethylene glycol (PEG) or ethyl cellulose (EC) as a shell. Biopolymer composition and electrospraying conditions were optimized for core-shell nanoparticle formation. Zein-PEG nanoparticles (∼300 nm) provided 68% and 83% and zein-EC nanoparticles (∼344 nm) provided 54% and 71% efficiency for curcumin and resveratrol encapsulation, respectively. Improved antioxidant activity and transition of both bioactives to amorphous form in the obtained nanoparticles were confirmed. The bioaccessibility of both bioactives was significantly improved in zein-PEG core-shell nanoparticles followed by zein-EC core-shell and simple zein nanoparticles, compared to native bioactives. The maximum bioaccessibility of 79% for curcumin and 82% for resveratrol was observed in zein-PEG core-shell nanoparticles, which is 3.6-fold and 1.7-fold higher than its native form. These nanoparticles also supported intestinal permeability enhancement by 3.5-fold and 2.2-fold for encapsulated curcumin and resveratrol, compared to its native form. To deliver these nanoparticles in consumer-preferred customized structures, 3D printing conditions were optimized to fabricate nanoparticle incorporated gelatin hydrogel 3D structures stable at room temperature. Comparatively, zein-PEG core-shell nanoparticles maintained their structural stability and uniform distribution in the hydrogel matrix for the effective protection of encapsulated bioactives. This 3D printed hydrogel model food loaded with nanoparticles will be a potent nutraceutical oral delivery system with the benefits of shape customization.

The current study describes an approach for creating covalently bonded complexes of sodium caseinate (NaCas) and propylene glycol alginate (PGA) without using a cross-linking agent. The principle is based on a transacylation reaction between the esterified carboxylic groups of PGA and amino groups of NaCas during pH shift from alkaline (pH 12.0) to neutral condition (pH 7.0). The increased molecule weight at a higher amount of PGA observed in SDS-PAGE indicated covalent bonding between NaCas and PGA. The hydrodynamic diameter of NaCas-PGA binary complexes increased with an increase in PGA concentration while no significant changes of zeta-potential were observed. Compared to NaCas alone, the complexes with NaCas:PGA mass ratio of 2:1 exhibited the improved thermal stability and was capable of forming gel emulsions with 80% (v/v) oil without macroscopic phase separation. The much greater storage modulus than loss modulus indicated the gel-like structure of the emulsions, which agreed with jammed oil droplets observed in microscopy. The studied NaCas-PGA complexes may be significant to improving the quality of oil-in-water emulsion products such as mayonnaises.