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Highlights • The interaction between flavonoids and zein was investigated by spectrofluorimetry. • The effect of flavonoid structure on the interaction was clarified by 3D-QSAR model. • The flavonoids with glucosyl groups at ring A have the excellent binding capacity. Abstract Zein has the potential application of establishing the delivery systems for flavonoids. But there are few reports about the effect of the molecular structures of flavonoids on their interaction with zein. In this study, the binding behaviour of 21 flavonoids and zein was investigated by spectrofluorimetry. The corresponding 3D-QSAR model was also established by Topomer CoMFA method, whose steric and electrostatic field analysis could explain the binding performance of the tested flavonoids with zein. The fluorescence analysis suggested that the flavonoids could interact with zein by forming the complex at the molar ratio of 1. The flavonoids with glucosyl groups at ring A exhibited the outstanding binding capacity with zein, and their binding process with zein was driven by hydrophobic force. The synchronous and 3D fluorescence spectra showed that there was no apparent change in the microenvironment surrounding the tyrosine residues of zein during the interaction. [ABSTRACT FROM AUTHOR]

In this study, bovine serum albumin (BSA)-caffeic acid (CA) conjugate was prepared with free radical-induced grafting method. The CA to BSA ratio of the conjugate was 115.7 mg/g. In vitro antioxidant activity assays suggested that BSA-CA conjugates had stronger antioxidant activity than BSA. Resveratrol-loaded zein encapsulated with BSA and BSA-CA conjugate core-shell nanoparticles were prepared with antisolvent method. Particle sizes were 206.3 nm, and 217.2 nm for BSA and BSA-CA, respectively. The encapsulation efficiencies (EEs) were 85.3% and 86.5% for zein-BSA and zein-BSA-CA nanoparticles, respectively. SEM results indicated that both nanoparticles were spherical with mean diameter approximately 200 nm and smooth surfaces. Both thermal and UV light stability of resveratrol was significantly improved after nanoencapsulation. BSA-CA conjugate showed remarkably greater protection than BSA against resveratrol degradation. Cellular antioxidant activity (CAA) study confirmed that resveratrol in both zein-BSA and zein-BSA-CA nanoparticles had significant higher antioxidant activities than resveratrol alone. [ABSTRACT FROM AUTHOR]

The quality of zein (Z)- and zein-tannic acid (ZTA)-coated guavas was monitored throughout 12 days of storage. Coated fruit showed lower changes in terms of visual appearance, chlorophyll contents and color. Weight loss, softening, and changes in soluble solids were also decreased by the coatings. The respiration peak as well as H 2 O 2 and superoxide dismutase activity peaks were delayed by the coatings, and the ethylene production was reduced. So, the results were consistent with a slowed down ripening of guavas by the coatings, which was probably related to lowered oxygen permeability of guava skin. ZTA coating was more effective than Z to reduce weight loss, softening, color changes, ethylene production, and oxidative stress. The higher efficiency of ZTA coating was ascribed to zein crosslinking, which probably resulted in decreased gas permeability, promoting lower respiration rates and lower ROS production, slowing down the ripening process, and extending guava stability. [ABSTRACT FROM AUTHOR]

A novel ethanol-induced composite hydrogel was prepared by two edible biopolymers: propylene glycol alginate (PGA) and zein. The effect of pH and different mass ratios of PGA and zein on the properties of the composite hydrogel was investigated. PGA and zein could form a gel induced by ethanol at pH ≥ 3.5, the stability, springiness, hardness and water holding capacity were decreased from pH 3.5 to 5.0. The hydrogen-bonding association was enhanced at pH 3.5 and porous structure was observed. The strength and springiness of the composite hydrogel decreased with increasing concentration of zein until the PGA/zein mass ratio was 5:1. At PGA/zein mass ratio of 5:1, the composite hydrogel exhibited a more elastic and tougher structure than other mass ratios at pH 3.5. Meanwhile, compared with the PGA hydrogel, the PGA-zein composite hydrogel showed great ability to sustain the release of curcumin in simulated gastrointestinal tract conditions. [ABSTRACT FROM AUTHOR]

Zeins of differing sub-class composition much more readily formed visco-elastic masses in water or acetic acid solutions than equivalent kafirin preparations. Visco-elastic masses could be formed from both zein and kafirin preparations by coacervation from glacial acetic acid. Dissolving the prolamins in glacial acetic acid apparently enabled protonation and complete solvation. Stress-relaxation analysis of coacervated zein and kafirin visco-elastic masses showed they were initially soft. With storage, they became much firmer. Zein masses exhibited predominantly viscous flow properties, whereas kafirin masses were more elastic. The γ-sub-class is apparently necessary for the retention of visco-elastic mass softness with kafirin and zein, and for elastic recovery of kafirin. Generally, regardless of water or acetic acid treatment, all the zein preparations had similar FTIR spectra, with greater α-helical conformation, than the kafirin preparations which were also similar to each other. Kafirin visco-elastic masses have a much higher elastic character than zein masses. [ABSTRACT FROM AUTHOR]

Curcumin (Cur) exhibits a range of bioactive properties, but its application is restrained due to its poor water solubility and sensitivity to environmental stresses. In this study, zein-lecithin composite nanoparticles were fabricated by antisolvent co-precipitation technique for delivery of Cur. The result showed that the encapsulation efficiency of Cur was significantly enhanced from 42.03% in zein nanoparticles to 99.83% in zein-lecithin composite nanoparticles. The Cur entrapped in the nanoparticles was in an amorphous state confirmed by differential scanning calorimetry and X-ray diffraction. Fourier transform infrared analysis revealed that hydrogen bonding, electrostatic interaction and hydrophobic attraction were the main interactions among zein, lecithin, and Cur. Compared with single zein and lecithin nanoparticles, zein-lecithin composite nanoparticles significantly improved the stability of Cur against thermal treatment, UV irradiation and high ionic strength. Therefore, zein-lecithin composite nanoparticles could be a potential delivery system for water-insoluble bioactive compounds with enhanced encapsulation efficiency and chemical stability. [ABSTRACT FROM AUTHOR]

γ-Zein was modified by SDS or alkali combined with heating treatments in water and in 70% ethanol to change its amphipathic properties and explore the relationship between amphipathic characteristic and structure. γ-Zein water-dispersibility was dramatically increased via alkali or SDS combined with heating treatments, but their ethanol-dispersibilities were significantly different during ethanol evaporation. High both water-dispersibility and ethanol-dispersibility were found from alkali modified γ-zein while high water-dispersibility but low ethanol-dispersibility were obtained from SDS modified γ-zein, indicating that alkali modified γ-zein had better amphipathic characteristic compared with SDS modified γ-zein. Alkali modified γ-zein with higher amphipathic characteristic possessed higher structural inversion ability since it was easy to recover its native state as solvent changing from water to ethanol, contrary to SDS modified γ-zeins whose amphipathic characteristic was not improved. Moreover, the higher structural inversion ability of alkali modified γ-zein depended on the recovery capability of α-helix structure as solvent altering. [ABSTRACT FROM AUTHOR]

Curcumin-loaded zein-shellac composite particles were prepared by the antisolvent co-precipitation method. The encapsulation efficiency of curcumin was significantly improved from 82.7% in zein particles to 93.2% in zein-shellac complex particles. The result of differential scanning calorimetry suggested that curcumin in the polymeric matrix was in an amorphous state. Fourier transform infrared spectroscopy analysis revealed that curcumin had non-covalently interacted with zein and shellac, mainly through hydrogen bonding and hydrophobic interaction. Aggregates in irregular shapes, with large sizes, were found by atomic force microscopy, and conglutination, integration or fusion of different entities into network structures occurred at a high level of shellac. At the mass ratio of zein to shellac of 1:1, curcumin in the complex particles exhibited improved photochemical and thermal stability. Curcumin-loaded zein-shellac complex particles allowed the controlled release of curcumin in both PBS medium and simulated gastrointestinal fluids. [ABSTRACT FROM AUTHOR]

The focus of the present work was to investigate the glycosylation of zein, partial properties of the glycosylated zein (GZ) and its retarding effect on lipid oxidation of ground pork. Zein was glycosylated with chitosan (MW 1500 Da) by microbial transglutaminase, the reaction was verified by FT-IR. Under the optimized conditions, 97.48 mg of glucosamine was covalently conjugated to 1 g of zein, determined by HPLC. The solubility and the surface hydrophobicity of GZ were significantly improved. In vitro studies of GZ showed a dose-dependent scavenging activity against free radicals of DPPH, superoxide and hydroxyl radical, and the EC 50 value for DPPH radical was 1.99 μg TE/mg protein. In addition, reducing power and Fe 2+ -chelating capacity of it were 16.60 and 12.96 μg TE/mg protein, respectively. GZ resulted in low levels of thiobarbituric acid-reactive substances and peroxide value of ground pork. These results suggest that GZ is a potential natural antioxidant. [ABSTRACT FROM AUTHOR]

This study investigated the cooperative antioxidative effects of sage extract (SE) and zein hydrolysates (ZH). The combination of 3 mg/ml ZH and 10 μg/ml SE exhibited a significant synergism in inhibition of the formation of thiobarbituric acid-reactive substances and provided superior protection of liposomes against oxidation. Zeta-potential results revealed that the interactions between liposomes and ZH were electrostatic interactions. Particle size determination further proved that ZH and SE added to oxidized liposomes significantly decreased the mean particle size. Confocal laser scanning microscopy revealed that when ZH was present in the liposome oxidizing system, the droplet sizes were obviously decreased compared to oxidized samples. ZH dispersed more uniformly and the interfacial membrane was more compact in the ZH-SE liposome. Transmission electron microscopy conveyed that the ZH-SE complex around the liposome particles could form a denser network structure, preventing radicals and oxidants from the approach of the liposomes. [ABSTRACT FROM AUTHOR]

Rice flour-zein composites in a hydrated viscoelastic state were utilized to compensate for the role of wheat gluten in gluten-free sheeted dough. The use of zein above its glass transition temperature was able to form a viscoelastic protein network of non-wheat dough with rice flour. The mixing stability and development time of the rice dough were positively increased with increasing levels of zein. The protein secondary structural analysis by FTIR spectroscopy demonstrated that the rice doughs with high levels of zein showed significant increases in β-sheet structures whose intensity was almost doubled by the use of 10% zein. The use of zein at more than 5% (w/w) successfully produced gluten-free dough sheets that could be slit into thin and long noodle strands. In addition, the composites were effective in improving the rheological characteristics of gluten-free noodle strands by increasing their maximum force to extension, compared to wheat-based noodles. [ABSTRACT FROM AUTHOR]

• Improve natamycin dispersibility by encapsulation for postharvest treatment. • A novel pH mixing-induced nanoprecipitation approach was developed. • Nata-Z/C NPs mainly interact via hydrophobic stacking and hydrogen bonds. • NPs improve the control of peach brown rot caused by Monilinia fructicola. This work fabricated natamycin-loaded zein-casein nanoparticles (N-Z/C NPs) by a pH-driven approach and applied to control postharvest peach brown rot caused by Monilinia fructicola. When casein and phosphoric acid were used as a stabilizer and neutralizing acid, respectively, NPs with mean particle sizes < 100 nm and zeta-potentials < −30 mV could be obtained. The NPs could increase the aqueous dispersibility of natamycin and showed high stability against environmental changes, which could be attributed to both hydrophobic stacking and hydrogen bonds between natamycin and zein. Besides, the effects of N-Z/C NPs on the storage of peach were assessed in vitro and in vivo. Nanoencapsulation did not affect the antifungal activities of natamycin. The NPs with 20 and 80 µg/mL of natamycin could basically inhibit the spore germination and mycelial growth of M. fructicola , respectively. The N-Z/C NPs coatings exhibited better results than natamycin in controlling of peach brown rot. [ABSTRACT FROM AUTHOR]

[Display omitted] • Water-insolubility of bixin in acidic water was overcome by nanoemulsion. • 9′- cis -bixin can be dissolved in water at pH 3 to form transparent dispersion. • Caco-2 cells fast absorb nanoemulsion droplets within 15 min. • Low nanoemulsion droplet concentration provides no significant effects on cells. • High nanoemulsion droplet concentration affected cell substructures. Nonionic oil-in-water (O/W) nanoemulsion provides potential to stabilize hydrophobic bio-functional components in aqueous medium. Understanding safety of nanoemulsion droplets via investigating in vitro cell uptake and cellular substructural changes is important to achieve their practical applications. Herein, we developed a nonionic O/W nanoemulsion to stabilize representative bio-functional hydrophobic component of 9′- cis -bixin at pH 3–7 and ultraviolet (UV)-induced degradation at 365, 302, and 254 nm. In vitro cell uptake demonstrated that Caco-2 cells adequately enriched 9′- cis -bixin through fast uptake of nanoemulsion droplets within 15 min. However, excessive nanoemulsion droplets greatly decreased cell survival rate, which was due to the potential destruction of cellular substructures of mitochondria, nuclear membrane, and cell membrane. Lower nanoemulsion concentration provided no significant effects on Caco-2 cell survival. This work provided objective understanding on bio-functional component stability by nanoemulsion with in vitro safety evaluation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stable selenium complex nanoparticle was synthesized under two different methods. • Zein-Se NPs showed an amorphous crystal structure with 0 valence state. • Zein-Se NPs had extremely low toxicity to L-02 cells in vitro. • Zein-Se NPs could be absorbed by mice in vivo and had potential targeting. In this study, novel bioavailable selenium nanoparticles with controllable particle size and low toxicity were developed. With selenium modified zein nanoparticles (zein NPs) in-situ , dispersed nano-selenium particles with different structure were formed simultaneously. The particle size, zeta potential, morphology and binding mechanism of synthesized zein-selenium nanoparticles (zein-Se NPs) were systematically discussed. Selenium was considered to be combined with O H and –CO-NH- groups of zein. The selenium in the complex particles presented an amorphous structure with zero valence. The cytotoxicity of zein-Se NPs was significantly lower than that of sodium selenite, even exhibited a growth-promoting effect on normal liver cells (L-02), and were proven to be orally absorbed by organisms in vivo experiments. The difference in particle structure had certain effects on cytotoxicity and oral targeting. The complex particles obtained by this method were anticipated be further used as food fortifiers or medicines. [ABSTRACT FROM AUTHOR]

Structuring edible oils into solid lipids without saturated and trans fats has attracted increasing interest due to the benefits for human health and promises potential as novel delivery systems for lipophilic bioactive ingredients. The study shows that a zein stabilized high ( ϕ = 0.6) oil-in-glycerol (O/G) emulgels enriched with β -carotene was performed, by a facile one-step homogenization. Rheological measurements and morphologies observations indicated that increasing β -carotene resulted in a progressive strengthening of gel-like network and improving their spreadability in the O/G emulgels stabilized by zein, which was closely related to the hydrophobic interaction of zein and β -carotene. The formation of emulgels significantly enhanced the UV photo-stability of β -carotene, and more than 88% of β -carotene was retained in 64 h storage under UV exposure, and consequently retarded oil oxidation while storage. Further, cakes prepared using zein-based O/G emulgels as a margarine alternative showed comparable functionalities (texture and sensory attributes) to the standard cake. [ABSTRACT FROM AUTHOR]

Dynamic high pressure microfluidization (DHPM) treatment at the pressures of 25, 50, 75, 100, 125 and 150 MPa was performed to explore its effects on the characteristics of zein in aqueous ethanol solution. The results showed that after DHPM treatment at 125 MPa, the volume percentage of zein nanoparticles (d < 100 nm) was increased from 68.8% to 94.7%, and the fluorescence intensity approached to the maximum. DHPM treatment at the pressure of 25 MPa led to the increase of α-helix and β-sheet of zein from 57.1% to 59.4% and from 16.8% to 17.9%, respectively. The partial denaturation of zein was induced after DHPM process at pressures from 50 to 150 MPa. The morphology of zein was modified from nanosphere to the needle-like shapes after DHPM treatment at 75 MPa, and the deduction was proposed that the morphological change at 75 MPa was ascribed to the existence of the intermediate transition state. [ABSTRACT FROM AUTHOR]

Several health benefits have been ascribed to consumption of resveratrol, a polyphenol that can be extracted from grape skins. However, its use as a nutraceutical ingredient is compromised by its low water solubility, chemical stability, and bioavailability. Encapsulation of resveratrol in protein nanoparticles can be used to overcome these issues. Fluorescence quenching experiments were used to study the interaction of resveratrol with gliadin and zein. Resveratrol interacted with both proteins, but the binding constant was higher for zein than for gliadin at 35 °C. Furthermore, binding between resveratrol and gliadin increased at higher temperatures, which was not observed for zein. Analysis of the thermodynamic parameters suggested that resveratrol–gliadin binding mainly occurs through hydrophobic interactions while the binding with zein is predominantly mediated through hydrogen bonds. These results help rationalise ingredient selection and production of protein nanoparticles and microparticles for encapsulation, protection and release of resveratrol and potentially other bioactive compounds. [ABSTRACT FROM AUTHOR]

Biopolymer core–shell nanoparticles were fabricated using a hydrophobic protein (zein) as the core and a hydrophilic polysaccharide (pectin) as the shell. Particles were prepared by coating cationic zein nanoparticles with anionic pectin molecules using electrostatic deposition (pH 4). The core–shell nanoparticles were fortified with curcumin (a hydrophobic bioactive molecule) at a high loading efficiency (>86%). The resulting nanoparticles were spherical, relatively small (diameter ≈ 250 nm), and had a narrow size distribution (polydispersity index ≈ 0.24). The encapsulated curcumin was in an amorphous (rather than crystalline form) as detected by differential scanning calorimetry (DSC). Fourier transform infrared (FTIR) and Raman spectra indicated that the encapsulated curcumin interacted with zein mainly through hydrophobic interactions. The nanoparticles were converted into a powdered form that had good water-dispersibility. These core–shell biopolymer nanoparticles could be useful for incorporating curcumin into functional foods and beverages, as well as dietary supplements and pharmaceutical products. [ABSTRACT FROM AUTHOR]

Highlights: [•] The role of bonding interactions in zein functionality was investigated. [•] Zein forms a visco-elastic material through different means than wheat gluten. [•] Zein is able to form a visco-elastic material with monomeric proteins. [•] Non-covalent interactions are vital to formation of visco-elastic material from zein. [•] Salts can be used to alter the functionality of zein. [ABSTRACT FROM AUTHOR]

Highlights: [•] Thymol was successfully loaded into zein nanoparticles using a low energy method. [•] Sodium caseinate and chitosan hydrochloride were used as the stabilizer layers. [•] Stabilized zein nanoparticles had a desirable redispersibility in water. [•] Improved encapsulation efficiency was achieved with double stabilizer layers. [•] Encapsulated thymol showed stronger antimicrobial activity for a longer time period. [ABSTRACT FROM AUTHOR]

Highlights: [•] Gallic acid loaded zein (Ze-GA) electrospun fibre mats are not cytotoxic. [•] The Ze-GA electrospun fibre mats had exhibited antimicrobial properties. [•] Gallic acid was mainly located on the fibre surface. [•] Gallic acid diffuses from the electrospun fibres in a Fickian diffusion manner. [Copyright &y& Elsevier]

Abstract: Quercetin loaded biopolymeric colloidal particles were prepared by precipitating quercetin (water insoluble polyphenol) and zein (hydrophobic protein), simultaneously, by adding their hydro-alcoholic solution to aqueous solution in presence of sodium caseinate as an electrosteric stabiliser. The presence of protein resulted in altering the shape of quercetin precipitates from needle-like to spherical shape at higher zein proportions, as confirmed by transmission electron microscopy. The average particle size of zein:quercetin composite particles was below 200nm (130–161nm) with negative surface charge (−30 to −41mV), as confirmed by dynamic light scattering and electrophoretic mobility data. Solid state characterisation (X-ray diffraction) and spectroscopic measurements (UV–Vis and IR spectroscopy) confirmed characteristic changes in quercetin due to the entrapment in the biopolymeric matrix of colloidal particles. Results from anti-oxidant study demonstrated the advantage of entrapping quercetin in the colloidal particles in terms of the chemical stability in the alkaline pH and against photodegradation under UV-light irradiation. [Copyright &y& Elsevier]

• Combining the in vitro digestion and Caco-2 cell monolayer mimicked human digestion. • Oral bioavailability of quercetin in Pickering emulsions was investigated. • The effect of quercetin positions in Pickering emulsions on oral bioavailability was established. • Pickering emulsions with shell quercetin were more effective in promoting its oral bioavailability. Protein-based Pickering emulsions have received considerable attention as nutraceutical vehicles. However, the oral bioavailability of nutraceuticals encapsulated in Pickering emulsions was not well established. In this work, a simulated gastrointestinal tract/Caco-2 cell culture model was applied to investigate the oral bioavailability of quercetin encapsulated in zein-based Pickering emulsions with quercetin in zein particles as the control. Pickering emulsions with shell (ZCP-QE) and core quercetin (ZCPE-Q) were constructed, and quercetin bioaccessibility, cell uptake and secretion, and the overall bioavailability were evaluated and compared. The overall oral bioavailability of quercetin was increased from 2.71% (bulk oil) to 38.18% (ZCPs-Q) and 18.97% (ZCPE-Q), particularly reached 41.22% for ZCP-QE. This work took new insights into the contributions of bioaccessibility and absorption (cell uptake plus secretion) to the overall oral bioavailability of quercetin. A schematic representation is proposed to relate the types of colloidal nanostructures in the digesta to the uptake, cell absorption, and overall oral bioavailability of quercetin. This study provided an attractive basis for identifying effective strategies to improve the oral bioavailability of hydrophobic nutraceuticals. [ABSTRACT FROM AUTHOR]