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[Display omitted] Except for chemical composition, surface morphology may endue colloidal nanoparticles with special interfacial behaviors, which is highly desired in certain scenarios, for example, ultra-stable Pickering emulsion for pharmaceutical applications where only limited chemicals are allowed. Herein, silica colloidal nanoparticle was chosen as a demo to illustrate a kinetically-controlled seeded growth strategy for the surface morphology regulation of colloidal nanoparticles. Surface chemical heterogeneity was primarily introduced to the silica seed nanoparticles by a seeded growth process in the presence of mixed silicate moieties with thermodynamical incompatibility. Then a further kinetically-controlled seeded growth step was performed to regulate the surface morphology of silica nanoparticles by promoting the selective condensation of tetraethoxysilane on the hydrophilic microdomains. Upon reducing the growing rate, tetraethoxysilane hydrolysates tend to condensate on silica microdomains, resulting in the formation of raspberry-like nanoparticles. The generality of the kinetically-controlled seeded growth strategy was validated by its success on differently-sized silica seeds modified with a range of silane coupling agents. This established strategy is facile and effective for massive production of raspberry-like silica colloidal nanoparticles with precisely-designed surface morphology and size, offering an ideal platform for the investigation on the exclusive contribution of morphology to the interfacial behaviors of nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract The present study developed a novel approach by using a common solvent to fabricate edible composite films made of whey protein isolate (WPI) and zein. Three types of spray-dried powder with WPI and zein at the ratios of 2:1, 1:1 and 1:2 (w/w, denoted as WPI/zein-2/1, WPI/zein-1/1 and WPI/zein-1/2, respectively) were obtained. With few exceptions, composite films were successfully prepared by using deionized water and 25%, 50%, 75% or 95% ethanol as film forming solvents for the spray-dried powders. Physicochemical properties including thickness, moisture content, color parameters, transparency, mechanical properties, heat sealing properties, and water solubility were determined. Solvent types did not significantly affect the moisture content of composite films. For all three types WPI/zein powder, lower water vapor permeability was detected in films prepared with 75% and 25% ethanol. Composite films prepared with deionized water showed higher transparency. Brightness and white index of films decreased as the ethanol concentration in film forming solution increased. Maximum elongation and break elongation of films increased as the WPI content increased, while higher ethanol concentration exerted lower elongation. All composite films could be heat-sealed and had good hot water solubility. Highlights • Novel whey protein isolate (WPI) and zein composite films were fabricated. • Spray-dried WPI/zein powder was made by an innovative approach. • A single common solvent was used to dissolve WPI/zein and make composite films. • Novel WPI/zein composite films were heat-sealable and dissolved in hot water. [ABSTRACT FROM AUTHOR]

Abstract Kafirin and zein could be used in making wheat-free leavened dough-based products if their functionality can be modified to more closely resemble gluten. Recently, stable viscoelastic masses were produced from isolated kafirin and total zein by dissolution of the prolamins in glacial acetic acid, followed by simple coacervation with rapid water addition. The methodology was, however, not compatible with food systems, as the final acid concentration was too high (33%). This work revealed that coacervation with reduction in the final acetic acid concentration down to 0.1% still enabled formation of kafirin and zein viscoelastic masses, with functionality retained on storage at 4 °C for an extended period; indicating an irreversible molecular change with dissolution in glacial acetic acid. Kafirin masses were much firmer than zein masses but both were softer than gluten. However, kafirin displayed a similarly elastic high component to gluten, whereas zein exhibited more viscous flow characteristics. This was probably due to the presence of more disulphide bonds in kafirin than zein. A model to explain this behaviour is proposed. Regarding the effect of prolamin concentration in glacial acetic acid, a minimum, between 5 and 10% was necessary for viscoelastic mass formation at low final acetic acid concentration (5%). Highlights • Food compatible kafirin and zein viscoelastic masses can be formed by coacervation. • The residual acetic acid concentration in the masses can be as low as 0.1%. • Kafirin and zein viscoelastic masses retain their functionality on storage at 4 °C. • Kafirin viscoelastic masses have a higher elastic component than those of zein. • A minimum protein concentration of 5–10% is needed for viscoelastic mass formation. [ABSTRACT FROM AUTHOR]

Fast, simple laboratory methods were used to analyze 22 maize samples varying in kernel vitreousness from 50.23% to 76.41%. Samples were analyzed in terms of zein content (53.86–86.37 g/kg endosperm DM), amylose content (190.76–259.77 g/kg endosperm DM), amylose to amylopectin ratio in starch (0.28–0.43), as well as starch granule size (10.95–14.89 μm in equivalent diameter) and starch granule shape (circularity, 0.85–0.94). More vitreous samples had higher zein and amylose content, as well as smaller and less circular starch granules. Nearly all grain traits on their own significantly affected vitreousness, and a multiple regression model to account for their combined effects was able to explain 61.8% of variability in kernel vitreousness. Zein content contributed most to the model, followed by starch granule projected area and circularity. In contrast, the amylose content contributed only 5.1% to the model. These results suggest that starch-protein interactions influence maize kernel vitreousness more strongly than starch molecular properties do. [ABSTRACT FROM AUTHOR]

Three food polymers, zein, sodium caseinate (NaCas) and pectin were exploited as the matrix to formulate colloidal complex nanoparticles for encapsulation of eugenol. A heat- and pH-induced complexation process was optimized via polymer concentrations, loading percentage of eugenol, as well as pH conditions, to obtain small, homogeneous, and stable complex nanoparticles. The particulate properties were significantly affected by pH condition during heating process, and the smallest and most homogeneous complex nanoparticles were obtained when heated at pH 6.6, the isoelectric point of zein. NaCas played an important role to achieve desirable stability during storage and spray drying. Fourier transform infrared spectroscopy indicated that hydrophobic and electrostatic interactions were driving forces to form complex structure. The innovative nano spray drying was tested to transform colloidal nanoparticles to fine powder particles, enabling the long-term storage in powder form and thus a greater potential to the applications in food industry. Under optimal preparation condition and formulation, eugenol-loaded complex nanoparticles with a size of 140 nm, spherical shape and uniform size distribution were obtained and their structure was verified by both scanning and transmission electron microscopies. [ABSTRACT FROM AUTHOR]

Fundamental differences exist between the surfaces of hard and soft wheat flours. Ranging from surface roughness, chemical composition to cohesive forces, these differences could affect the flow behaviour of wheat flour. In an attempt to address these differences, we developed a zein film functionalized atomic force microscopy technique to evaluate the surface forces on compacts of hard, soft wheat flour, and its pure components, starch and gluten. Using the pure wheat components as the baseline, we analyzed the chemical compositional differences via Raman spectroscopy coupled with Band–Target Entropy Minimization (BTEM ® ) algorithm. The zein film functionalization distinguishes between wheat starch and gluten with stronger interactions on starch at least twice that of gluten. In general, soft wheat flour has higher adhesion forces than hard wheat flour of the same particle size. Higher starch content at the expense of protein in soft wheat flour seems to suggest the difference. However, the microstructural difference of starch granules on the compacted surface could describe more adequately the effect of particle size on the interaction forces. [ABSTRACT FROM AUTHOR]

To obtain high-elongation flexible packaging, glycerol (GLY) and a series of polyethers (PEs), i.e. poly (ethylene glycol) (PEG), poly (propylene glycol) (PPG), poly (tetramethylene glycol) (PTMG), were chosen as model plasticizers to soften zein films. Different characterizations were conducted to investigate the structure and properties of films in detail. The results indicated that when using a suitable ratio of GLY and PEs, i.e. 1:1 in mass, the plasticized zein films showed excellent elongation at break of 245–350% at 0.45 g plasticizer/g zein. The synergistic plasticizing effects on films were discussed and attributed to the structural change of zein molecules, i.e. the disruption of inter- α -helix packing and the increase of β -sheet content, then the plasticization mechanism was proposed. Films plasticized by GLY and PTMG had higher water vapor permeability because of their unique porous structure. All zein films exhibited excellent UV barrier properties, and PEG improved the transmittance of zein film. [ABSTRACT FROM AUTHOR]

A composite zein nanofibrous mat containing fish oil and ferulic acid was successfully fabricated by electrospinning. The process became more fluent and continuous by adding 30 g/L glycerol into the polymer solutions and using modified coaxial electrospinning. The average diameter of nanofibers was 440 nm. The loading capacity and encapsulation efficiency of fish oil were 20% and 94%, respectively. FTIR data demonstrated that fish oil and ferulic acid were successfully embedded into the nanofibers and there were interactions among the molecules of zein, fish oil and ferulic acid. Addition of ferulic acid into the nanofibers significantly improved the oxidative stability of encapsulated fish oil; moreover, it did not change the release behavior of fish oil. The release of encapsulated fish oil was controlled by a combination of diffusion and macromolecular chain relaxation. This composite nanofibrous mat with favorable oxidation stability and release property is potential in application as nutrition additive. [ABSTRACT FROM AUTHOR]

In this work, a green tea extract (GTE) was encapsulated within electrosprayed protein (i.e. gelatin and zein) microparticles, and the protective ability of both systems on the green tea catechins was assessed. The microparticles (with encapsulation efficiencies ∼90 g/100 g), proved to be very effective in stabilizing the catechins during a thermal treatment at 180 °C (12 min), preserving 85–90 g/100 g of their initial catechins content, while free GTE lost almost 40 g/100 g of its catechins content. In order to assess the impact of microencapsulation in a real food system, the GTE-loaded electrosprayed microparticles were added to biscuits dough. Results showed that microencapsulation did not significantly protect during biscuit processing and emphasized the need of assessing the behaviour of microencapsulation systems in real food processing conditions. The sensorial analysis of the biscuits indicated that addition of the GTE-loaded microparticles did not impact the acceptability of the biscuits, as perceived by consumers. [ABSTRACT FROM AUTHOR]

The aims of this study were to investigate the effect of xanthophylls (Xan) on the colloidal property and interfacial activity of zein hydrolysate (ZH), and the influence of Xan on the colloidal delivery capacity of ZH was also studied by the construction of emulsions and colloidal particles systems. The result indicated that compared with color-free ZH (CF-ZH), ZH was more sensitive to pH and showed obvious aggregation behavior at acidic pH. ZH exhibited lower critical micelle concentration compared with CF-ZH, suggesting the higher amphiphilic characteristic of ZH. The results from interfacial activity investigations showed that ZH exhibited higher interfacial activity compared with CF-ZH, and the thickness and intensity of the interfacial layer constituted by ZH was increased as a result of the existences of Xan. Compared with CF-ZH, the emulsions stabilized by ZH possessing smaller size and higher physical stability, and the curcumin nanoparticles fabricated in ZH solutions showed higher encapsulation efficiency, smaller particle size, better monodispersity and higher zeta potential. In conclusion, the presence of Xan in ZH obviously changed the colloidal property and improved interfacial activity and colloidal delivery capacity of ZH itself, and it endowed ZH with more extensive application prospects. [ABSTRACT FROM AUTHOR]

This study aimed to explore the feasibility of zein as a gluten alternative in preparing sheeted doughs with rice flours containing different amylose contents (12, 19, and 26%) that were successfully slit into noodle strands. Rice-zein mixtures with lower amylose contents exhibited lower pasting parameters and the high amylose paste samples possessed more elastic properties. Higher water absorption was observed in the low amylose rice-zein mixture whereas the use of zein were effective in increasing the stability of rice dough regardless of amylose content. In case of thermal conductivity, the noodle doughs prepared with high amylose rice-zein mixture had low thermal conductivity, probably implying a long cooking time. The structure of the rice-zein noodles had a tendency to become firmer with increasing levels of amylose by showing greater breaking stress and resistance to extension that could be correlated to reduced cooking loss. [ABSTRACT FROM AUTHOR]

Zein films assimilated with 1% monolaurin (ML) and 2 or 3% Zataria multiflora Boiss. essential oil (ZEO) were developed and their antimicrobial effects against Listeria monocytogenes and E. coli O157: H7 in vitro and in minced beef meat were determined. Zein films were developed using casting method. Films containing 1% ML + 3% ZEO had the highest swelling index (52.3%). Only ZEO containing films had a remarkable phenolic (13.53 mg gallic acid/g film) and plain zein films had no phenolic contents. Similar improvement were obtained for antioxidant activity of films containing ZEO. Antimicrobial activity was significantly increased by adding ZEO and ML which influenced by the concentrations of agents as well as type of bacteria, which L. monocytogenes was more susceptible than E. coli . In minced meat, the growth of L. monocytogenes was significantly inhibited by ML and/or ZEO containing films during 3 days of storage at 4 °C, whereas the growth of E. coli was only inhibited by films containing ZEO. The results showed the antimicrobial and antioxidant activity of zein film by addition of ZEO and ML. In the case of combination, ZEO and ML had no additive or synergistic antimicrobial effects. [ABSTRACT FROM AUTHOR]

The addition of nanoentrapped β-carotene in milk is proposed as a valid method to improve stability and enhance antioxidant activity of β-carotene during GI transit. This study focused on two types of delivery systems, nanoparticles and nanoemulsions, and compared their ability to enhance the physicochemical stability and antioxidant activity of β-carotene in the presence of milk under simulated GI conditions. β-Carotene-loaded zein nanoparticles and nanoemulsion, stabilized by pluronic F127 and lecithin, were synthesized and added to liquid milk. Degradation of β-carotene was spectrophotometrically analyzed, and antioxidant activity was measured using ABTS and TBARS assays in simulated gastric fluid (SGF) with pepsin for 2 h and in simulated intestinal fluid (SIF) with pancreatin for 24 h. The initial amount of β-carotene remained at 18.30 ± 1.29% and 4.41 ± 2.51% after a 26 h total time of GI exposure in nanoentrapped and emulsified forms, respectively. In both systems, nanoentrapment proved to be beneficial to beta-carotene stability, but this benefit was decreased in the presence of milk. The improvement in antioxidant activity of nanodelivered β-carotene was confirmed by ABTS and TBARS assays. In conclusion, zein nanoparticles improved chemical stability and antioxidant activity of entrapped beta-carotene versus emulsions in the presence of milk under simulated gastrointestinal environments. [ABSTRACT FROM AUTHOR]

Only predominantly α-type zein (commercial zein) has been shown to form a viscoelastic dough. In maize zein comprises α-, β-, γ- and δ-zein (total zein). Because glacial acetic acid can fully solubilise zein, its effect was investigated. Dissolving total zein (comprising α-, β-, γ- and δ-zein) in glacial acetic acid and casting a film, enabled a viscoelastic dough to be formed with water above zein's T g . The dough was stronger and less extensible than commercial zein dough made without film formation. When residual acetic acid was removed from the total zein film, a dough still formed. CLSM showed that the total zein dough fibrils were shorter and less well-aligned than those of commercial zein dough and appeared as particles. Disulphide bond cross-linking was probably responsible, for total zein dough stiffness. FTIR showed that total zein wet doughs and total zein slurry with water were predominantly β-sheet, indicating that β-sheet conformation was not directly responsible for dough formation. It is suggested that acetic acid brings about chemical changes in zein, enabling it to better interact with water molecules, counteracting disulphide bonding effects, allowing total zein to form a dough. This is the first report of viscoelastic dough formation from total zein. [ABSTRACT FROM AUTHOR]

To improve the rheological properties of zein doughs, α-type zein and zein-starch doughs were prepared with the oxidising agents, hydrogen peroxide and peroxidase, which strengthen gluten-based doughs by cross-linking. Hydrogen peroxide and peroxidase increased zein dough extensibility compared to preparation with water. Hydrogen peroxide prepared zein doughs were extensible and cohesive below zein’s glass transition temperature. The doughs did not exude water and maintained flexibility when stored. Confocal laser scanning microscopy revealed that in zein-starch doughs prepared with hydrogen peroxide a thin continuous zein matrix was formed around the starch granules, whereas doughs prepared with water exhibited clumps of granules. SDS-PAGE of zein doughs and films treated with the oxidising agents showed no evidence of zein polymerisation, nor did Fourier transform infrared spectrometry reveal any significant changes in secondary structure. Further, hydrogen peroxide treatment did not increase zein film glass transition temperature, but it did increase transition enthalpy, and film water uptake increased with hydrogen peroxide concentration. The greatly increased extensibility of hydrogen peroxide prepared zein doughs and their improved water-holding are not due to oxidative cross-linking. It is proposed that the effects are primarily due to hydroxylation of amino acid aliphatic side chains, improving hydration through hydrogen bonding. [ABSTRACT FROM AUTHOR]

This work aims to evaluate the possibility to introduce natural nano-containers for active molecules, such as halloysite nanotubes (HNTs), into an environmentally friendly material: natural zein. Composites were prepared in a wide range of HNTs composition (i.e. 1–10 wt%) and structural and physical properties were analyzed. HNTs were also filled with an active molecule commonly used as preservative in food packaging, such as potassium sorbate (KS), and the diffusion of such molecule was evaluated. The zein thermal degradation resulted significantly improved with the filler content. Mechanical properties showed a reinforcement of zein matrix. HNTs were filled with potassium sorbate and dispersed into the zein matrix. [ABSTRACT FROM AUTHOR]

This study investigates the formation and properties of compatible binary colloidal blends between pre-gelatinized (uncomplexed and complexed with stearic acid) maize starches (hydrophilic component) and commercial zein (hydrophobic component) with the aim of creating a bipolymeric material with unique properties. The blends were formed under alkaline condition (0.1 M NaOH) with 3:1, 1:1 and 1:3 starch: zein (w/w) ratios. The 3:1 starch–zein blends showed best stability or compatibility. Blends made with starch complexed with stearic acid had better stability than those with uncomplexed starch. Most of the blends were not freeze-thaw stable except for 3:1 starch (complexed with stearic acid)-zein blend. The blends with better stability had higher apparent viscosity, and a microstructure showing uniform mix of starch – zein as observed by confocal laser scanning microscopy. The likely reason for the compatibility of starch and zein is the change in surface activity of zein, possibly due to deamidation, in 0.1 M NaOH as shown by the negative zeta potential values. The pre-gelatinized maize starches also show negative zeta potential values. In conclusion, compatible binary colloidal blends can be produced between pre-gelatinized maize starch and commercial zein using 0.1 M NaOH. [ABSTRACT FROM AUTHOR]

Above the zein glass transition temperature (∼40 °C), the viscoelasticity of zein–starch dough is similar to that of gluten. This is of interest because this dough might be used to develop gluten-free products, although it has certain limitations such as workability and aging at room temperature. The most effective way to decrease the dough glass transition temperature is to use a plasticizer, which also influences the viscosity. In this study, viscoelastic zein–starch dough samples were prepared with several concentrations of citric acid as the plasticizer, and the effect of viscoelasticity on crumb structure formation during baking was investigated. Extensional viscosity was correlated with the average bubble size after baking. We found that viscosity could be predicted for this system by measuring the shear viscosity, whereby the Trouton ratio was near-constant for the range of plasticizer concentrations investigated. In addition, our dynamic mechanical analysis (DMA) revealed that bubble growth occurs mainly when the dough reaches 100 °C, due to a combination of steam formation and thermal softening of the matrix. At higher temperatures, hardening occurs due to drying and zein crosslinking. [ABSTRACT FROM AUTHOR]

Abstract: The replacement of gluten in dough products poses a major challenge. Preparing zein doughs in dilute acetic acid and lactic acid, such as produced during sourdough fermentation, was investigated. Increasing acid concentrations (0.7, 1.3 and 5.4% [v/v]) increased zein extensibility and reduced the stress and related parameters. Preparation of zein-maize starch/-rice doughs in dilute organic acids improved dough properties to the extent that the doughs could hold air and be inflated into a bubble by Alveography. Further, they exhibited similar Stability (P), Distensibility and deformation energy (W) to wheat flour dough. Confocal laser scanning microscopy revealed an ordered linear fibril network in zein and zein-rice flour doughs prepared in the dilute acids, which became uniform with increasing acid concentration. SDS-PAGE showed that the acids did not hydrolyse or polymerise the zein. FTIR indicated that the acidic conditions slightly increased the proportion of α-helical conformation in the zein doughs, possibly as a result of deamination. This conformational change may be responsible for the considerably improved zein dough properties. Zein doughs prepared in dilute organic acids show potential as a gluten replacement in gluten-free formulations. [Copyright &y& Elsevier]

Abstract: The aims of the present work are to evaluate zeins as potential clarification agent for red wine and to assess the impact of zeins treatment on the wine “bouquet” through sensory analysis. Zeins have been extracted from commercial corn gluten which is a protein-rich by-product deriving from maize starch industry. Three red wines (cv. Cabernet Sauvignon, Merlot and Valpolicella) have been used for the fining experiments in order to test zein proteins (Z) in comparison with a commercial non-hydrolysed animal gelatins (G1). The new method of zeins extraction gave a good yield of extraction (about 72%). These proteins showed an excellent fining action if compared to wine treatment with G1. In fact, zeins treatment could decrease wine turbidity and remove phenolic compounds, such as anthocyanins and proanthocyanidins, and, at the same time, it did not affect red wine colour. Finally, the sensory analysis indicated that no significant differences were detected between the same wines clarified with Z or with G1. In conclusion, the results show that corn gluten can be used in place of potentially allergenic animal proteins to obtain a low cost fining agent that can be introduced during the wine clarification step. [Copyright &y& Elsevier]

Abstract: In this study, biodegradable hollow zein nanoparticles with diameters less than 100 nm were developed to remove reactive dyes from simulated post-dyeing wastewater with remarkably high efficiency. Reactive dyes are widely used to color cellulosic materials, such as cotton and rayon. Wastewater from reactive dyeing process contains up to 50% dye and electrolytes with concentrations up to 100 g L−1. Current methods to remove reactive dyes from wastewater are suffering from low adsorption capacities or low biodegradability of the sorbents. In this research, biodegradable zein nanoparticles showed high adsorption capacities for dyes. Hollow zein nanoparticles showed higher adsorption for Reactive Blue 19 than solid structures, and the adsorption amount increased as temperature decreased, pH decreased or initial dye concentration increased. At pH 6.5 and pH 9.0, increasing electrolyte concentration could improve dye adsorption significantly. Under simulated post-dyeing condition with 50.0 g L−1 salt and pH 9.0, maximum adsorption of 1016.0 mg dye per gram zein nanoparticles could be obtained. The adsorption capacity was much higher than that of various biodegradable adsorbents developed to remove reactive dye. It is suggested that the hollow zein nanoparticles are good candidates to remove reactive dye immediately after dyeing process. [Copyright &y& Elsevier]

Abstract: Zein, a corn protein, is a mixture of the polypeptides α-, γ-, β-, and δ-zein. α-Zein and γ-zein comprise 70–85% and 10–20% of total zein mass, respectively. Both peptides have similar amino acid composition, except γ-zein is rich in cysteine. The presence of cysteine has been associated with gelation of zein solutions. A common solvent for zein is aqueous ethanol. Preliminary results suggested that pH and ethanol content affect the rheology of zein solutions. Our objective was to investigate the effect of ethanol content (65–90%) and pH of the solvent (2, 6, and 12) on rheological properties of zein solutions (20% w/w) containing γ-zein. Steady shear tests and oscillatory time sweeps were performed to determine flow behavior and gelation time of zein solutions. Results indicated that α-zein solutions were nearly Newtonian while those containing γ-zein showed shear thinning behavior. At high pH, γ-zein increased the consistency index (K) and shortened gelation time. Results were attributed to the cysteine in γ-zein. High pH promoted formation of disulfide bonds leading to higher K values and shorter gelation times. Results of this work are expected to be useful in the design of zein extraction processes and the development of new zein applications. [Copyright &y& Elsevier]

Freezing deteriorates the baking quality of frozen bread dough. This study revealed the protective effects of zein-based ice nucleation films (INFs) on the baking quality of frozen dough. INFs were prepared by immobilizing biogenic ice nucleators on the surface of zein films, which consequently revealed ice nucleation activity and increased the ice nucleation temperature of water from −15 °C to −6.7 °C. By using these films to wrap frozen dough during five freeze/thaw cycles, the specific volume of bread was increased by up to 25% compared to the bread from control frozen dough. The reason was attributed to 40% more viable yeast cells preserved by INFs. In addition, zein-based INFs also reduced the water loss by frozen dough resulting in higher water content in bread crumb. Combining the protective effects on both specific volume and water content from zein-based INFs, the obtained bread showed 68% lower firmness and fracturability and 2.4 times higher resilience compared to the control. The INFs were also superior in that for zein-based INFs, biogenic ice nucleators showed desirable affinity with the surface to sustain at least fifteen repetitive uses on freezing water. [ABSTRACT FROM AUTHOR]

Abstract: Small amplitude and lubricated squeezing flow tests were performed to investigate the effect of high molecular weight glutenin (HMWG) on the rheological properties of gliadin and zein dough composites. It was hypothesized that addition of small amounts of HMWG to zein cause changes in its viscoelastic properties in the same way as its addition to gliadin. Starch (87%, w/w) and protein/protein composites (13%, w/w), and water were mixed into dough. The water content of prepared dough was in the 41.7–45.3% range. Composites were gliadin-HMWG and zein-HMWG. Phase angle and complex modulus (G*) were obtained from frequency sweep tests at 0.5% strain amplitude over a 0.01–100 rad/s frequencies. Lubricated squeezing flow test were carried out at a range of strain rates to determine the sample extensional viscosities. Gliadin and zein samples exhibited high phase angle values that decreased with the addition of HMWG, which was attributed to enhancement of their elastic characteristics. A similar trend was observed in lubricated squeezing flow results. HMWG incorporation increased the extensional viscosities of gliadin and zein samples. This study suggests that rheological properties of zein can be improved with HMWG addition and provides basic information for future investigations on developments for gluten-free products. [Copyright &y& Elsevier]

Abstract: The phase behavior of zein films has been investigated at nano-scale using atomic force microscopy (AFM) and compared to the phase behavior of the bulk using a thermal characterization technique. The local surface properties of the films were evaluated as a function of water activity using AFM. The glass transition temperature (T g) of zein films decreased with increasing water activity. Adhesion forces measured by the AFM force curves increased with increasing water activity. Topography of zein and zein fractions were evaluated both qualitatively and quantitatively by the use of AFM and dedicated software to calculate the surface roughness. It has been found that processing technologies (solvent casting, drop deposition and spin casting) has influence on the surface structures of films. The films which were formed by the alpha zein rich fraction were found to have highest roughness values. Sectional surface profiles revealed that α-zein films have mean roughness (R a) of 1.808 nm and root mean square roughness (RMS) of 2.239 nm while β-zein films have mean roughness (R a) of 1.745 nm and root mean square roughness (RMS) of 3.623 nm. The discussions conducted on the differences/similarities in the observations were based on the hydrophobic/hydrophilic properties and interactions of these zein fractions. [Copyright &y& Elsevier]