Vital Wheat Gluten Research Articles

Novel Foams Based on Freeze‐Dried Renewable Vital Wheat Gluten

AbstractA new way of producing rigid or semi‐rigid foams from vital wheat gluten using a freeze‐drying process is reported. Water/gluten‐based mixtures were frozen and freeze‐dried. Different foam structures were obtained by varying the mixing process and wheat gluten concentration, or by adding glycerol or bacterial cellulose nanofibers. MIP revealed that the foams had mainly an open porosity peaking at 93%. The average pore diameter ranged between 20 and 73 µm; the sample with the highest wheat gluten concentration and no plasticizer had the smallest pores. Immersion tests with limonene revealed that the foams rapidly soaked up the liquid. An especially interesting feature of the low‐wheat‐concentration foams was the “in situ” created soft‐top‐rigid‐bottom foams.magnified image

Evaluating the ability of different characterization parameters to describe the surface of fried foods

The objective of this work is to identify surface topography characterization parameters that are capable of discriminating the surfaces of different fried foods. Three fried food model systems with clearly different surfaces were formulated from vital wheat gluten, native wheat starch, and potato flakes. The surfaces were measured with a scanning laser microscope (SLM), and the ability of several parameters to discriminate between them was tested. Two conventional parameters, the root mean square roughness (Sq) and the surface Kurtosis (Sku), were calculated, along with parameters derived from area-scale fractal analysis: smooth-rough crossover (SRC), fractal dimension, and relative area as a function of scale. The coefficient of variation (COV) of Sq, Sku, and SRC and fractal dimension of different sizes of measurement regions were calculated for the surface of the roughest product in order to specify a measurement region that would be sufficiently large to be representative. The size of the representative region was found to be 25 mm². Among the parameters evaluated in this study, the most reliable parameter for discriminating the surfaces of fried foods is the relative area calculated from area-scale fractal analysis.

Effects of glycerol content and film thickness on the properties of vital wheat gluten films cast at pH 4 and 11

AbstractThis study deals with the optical properties and plasticizer migration properties of vital wheat gluten (WG) films cast at pH 4 and 11. The films contained initially 8, 16, and 25 wt % glycerol and were aged at 23°C and 50% relative humidity for at least 17 weeks on a paper support to simulate a situation where a paper packaging is laminated with an oxygen barrier film of WG. The films, having target thicknesses of 50 and 250 μm, were characterized visually and with ultraviolet/visible and infrared spectroscopy; the mass loss was measured by gravimetry or by a glycerol‐specific gas chromatography method. The thin films produced at pH 4 were, in general, more heterogeneous than those produced at pH 11. The thin pH 4 films consisted of transparent regions surrounding beige glycerol‐rich regions, the former probably rich in gliadin and the latter rich in glutenin. This, together with less Maillard browning, meant that the thin pH 4 films, in contrast to the more homogeneous (beige) thin pH 11 films, showed good contact clarity. The variations in glycerol content did not significantly change the optical properties of the films. All the films showed a significant loss of glycerol to the paper support but, after almost 9 months, the thick pH 11 film containing initially 25 wt % glycerol was still very flexible and, despite a better contact to the paper, had a higher residual glycerol content than the pH 4 film, which was also more brittle. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Comparison of quality of refined and whole wheat tortillas

The use of whole wheat flour instead of refined flour significantly improves the nutritional profile of flour tortillas. However, whole and refined flours differ in properties and in how they process, thus needing process modifications to get the desired product quality. To understand these differences, refined and whole wheat flours, dough and tortillas were evaluated and compared for physical and rheological properties. Overall, whole wheat flour required more water (59% of flour weight) than refined wheat (53%) to make machineable dough. Refined flour doughs were more extensible and softer than whole wheat flour doughs, thus easier to process. Whole wheat flour tortillas were larger, thinner and less opaque than refined flour tortillas. In general, refined wheat tortillas were more shelf-stable than whole wheat tortillas. Smaller particle size and less fiber in the refined wheat flour mainly contributed to the observed differences. Among the whole wheat samples, tortillas from strong flours had excellent shelf-stability, which must be considered when whole wheat tortillas are processed. This will minimize the need to add vital wheat gluten or other dough strengtheners.

Properties of Extruded Vital Wheat Gluten Sheets with Sodium Hydroxide and Salicylic Acid

This paper presents a novel approach to improve the barrier and mechanical properties of extruded glycerol-plasticized vital wheat gluten sheets. The sheets were extruded with a single screw extruder at alkaline conditions using 3-5 wt % NaOH. Salicylic acid (SA), known to improve the extrudability of wheat gluten, was also added alone or in combination with NaOH. Oxygen transmission rate and volatile mass measurements, tensile tests, protein solubility, glycerol migration, infrared spectroscopy, and electrophoresis were used to assess the properties of the extrudate. Electrophoresis showed that the gluten/glycerol sheet and the sheet with 3 wt % NaOH and 1 wt % SA contained the same building blocks in terms of proteins and protein subunits, although the protein solubility in these samples was different. The oxygen barrier, at dry conditions, was improved significantly with the addition of NaOH. On the other hand, the addition of salicylic acid yielded poorer barrier properties. The extrudate was placed on a blotting paper and its aging properties were investigated during the first 120 days. It was observed that the extrudate with 3 wt % NaOH had the most suitable combination of properties (low oxygen permeability, large strain at break, and relatively small aging-induced changes in mechanical properties); the reason is probably due to low plasticizer migration and an optimal protein aggregation/polymerization.

White Pan Bread and Sugar‐Snap Cookies Containing Wheat Starch Phosphate, A Cross‐Linked Resistant Starch

ABSTRACTPup‐loaf bread was made with 10, 30, and 50% substitution of flour with wheat starch phosphate, a cross‐linked resistant starch (XL‐RS4), while maintaining flour protein level at 11.0% (14% mb) by adding vital wheat gluten. Bread with 30% replacement of flour with laboratory‐prepared XL‐RS4 gave a specific volume of 5.9 cm3/g compared with 6.3 g/cm3 for negative control bread (no added wheat starch), and its crumb was 53% more firm than the control bread after 1 day at 25°C, but 13% more firm after 7 days. Total dietary fiber (TDF) in one‐day‐old bread made with commercial XL‐RS4 at 30% flour substitution increased 3–4% (db) in the control to 19.2% (db) in the test bread, while the sum of slowly digestible starch (SDS) plus resistant starch (RS), determined by a modified Englyst method, increased from 24.3 to 41.8% (db). The reference amount (50 g, as‐is) of that test bread would provide 5.5 g of dietary fiber with 10% fewer calories than control bread. Sugar‐snap cookies were made at 30 and 50% flour replacement with laboratory‐prepared XL‐RS4, potato starch, high‐amylose (70%) corn starch, and commercial heat‐moisture‐treated high‐amylose (70%) corn starch. The shape of cookies was affected by the added starches except for XL‐RS4. The reference amount (30 g, as‐is) of cookies made with commercial XL‐RS4 at 30% flour replacement contained 4.3 g (db) TDF and 3.4 g (db) RS, whereas the negative control contained 0.4 g TDF and 0.6 g RS. The retention of TDF in the baked foods containing added XL‐RS4 was calculated to be >80% for bread and 100% for cookies, while the retention of RS was 35–54% for bread and 106–113% for cookies.

Analysis of wheat gluten and starch matrices during deep-fat frying

An important quality parameter of fried food is the amount of oil uptake, which is incompatible with recent consumer trends towards healthier food. The oil penetration mechanism is not fully understood but study of formulated products is a good way to elucidate the role of the food matrix in oil absorption. In this context, the oil absorption capacity of a restructured matrix, made with native wheat starch and vital wheat gluten, was examined. Four different product formulations were analysed, using 2 levels of gluten content (8% and 12% d.b.) and 2 levels of water content (38% and 44% w.b.). Dough was sheeted into 2 thicknesses (1 and 2 mm) and cut into discs that were either directly fried or fried after predrying with dry air (2 min at 150 °C). Results showed that gluten had a predominant role in the structure, making the dough more elastic and less permeable to oil absorption. High gluten content resulted in lower oil uptake in products with low moisture content. Overall, predried discs absorbed, on average, half of the oil of undried samples. Interestingly, even though predried products with high gluten content had a higher moisture content before frying, they absorbed a low amount of oil, suggesting that oil uptake is not clearly related to the amount of moisture lost but rather to product microstructure.

Effect of extrusion conditions on physical and chemical properties of high protein glutinous rice-based snack

Abstract Two glutinous rice-based snack formulations were designed using a linear-programming model to minimize total cost to meet the FAO/WHO/UNU. (1985). Energy and protein requirements . Report of a joint FAO/WHO/UNU expert consultation. Technical report series 724. Geneva: WHO requirements for lysine and sulphur amino acids. Effects of protein concentration, feed moisture content and barrel temperature on the chemical and physical properties of the extruded product were investigated. Response surfaces for the parameters were generated using a second-degree polynomial. The high protein nutritious snack was obtained using glutinous rice flour, vital wheat gluten and toasted soy grits. A factorial design was employed to investigate the influence of feed protein content (20 and 30 g/100 g wb), feed moisture (20, 25, and 30 g/100 g wb) and barrel temperature (150 and 180 °C) on the physical and chemical properties of extrudates. Results showed that increasing feed moisture and reducing barrel temperature reduced non-protein nitrogen (NPN) and enhanced lysine retention. The protein and moisture content of raw material and barrel temperature had no significant influence on cysteine and methionine content. The conditions providing high expansion, low bulk density, and low shear strength of extruded snack were feed moisture of 20 g/100 g wb and 180 °C.

Thermal properties of PCL/gluten bioblends characterized by TGA, DSC, SEM, and infrared‐PAS

AbstractComposites of polycaprolactone (PCL) and vital wheat gluten (VG) were extruded, injection‐molded, and analyzed using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscope, and Fourier‐transform infrared (FTIR). Neat PCL sample was cooled down to −70°C and heated to 150°C, where a glass transition (Tg) emerged at −67.0°C [0.20 J/(g °C)] followed by a melting transition at 56.6°C. At the end of the heating cycle, a cooling cycle started, where the same sample exhibited crystallization transition at 30.1°C. VG exhibited a Tg at 63.0°C [0.45 J/(g °C)]. Data analysis of TGA showed a one‐step degradation mechanism of neat PCL versus multiple steps for the composites, indicating similar molecular structure and physical properties of neat PCL unlike the composites. In nitrogen environment versus air, the degradation activation energy (Ea) of the composites has increased at higher VG levels. From the DSC and TGA data, it is apparent that some physical interaction between PCL and VG was present. The FTIR analysis verified the physical nature of this interaction as opposed to chemical interaction. Proteinase degradation activity on the extruded composites was much higher than the injection‐molded as indicated by higher weight loss in the extruded samples. Published 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect on Dough Functional Properties of Partial Fractionation, Redistribution, and In Situ Deposition of Wheat Flour Gluten Proteins Exposed to Water, Ethanol, and Aqueous Ethanol

ABSTRACTThe application of the cold‐ethanol laboratory fractionation method to the bulk separation of wheat starch and gluten is accompanied by incidental dissolution, removal, or redeposition of a small part of the functional gliadin protein. The new distribution resulting from process incidental redeposition of soluble components or by purposeful add‐back of soluble and leached components can lead to differences in functionality and more difficult recovery of native properties. To assess this issue, we exposed several wheat flour types to ethanol and water (50–90% v/v) solutions, water, and absolute ethanol at 22°C and –12°C. The exposure was mass conserving (leached components returned to substrate by evaporation of the solvent without separation of phases) or mass depleting (leached components not returned to substrate). The result of the mass‐conserving contact would be flour with altered protein distributions and intermolecular interactions. The result of the mass‐depleting contact would also include altered protein content. Furthermore, the mass‐conserving contact would model an industrial outcome for a cold‐ethanol process in which leached components would be added back from an alcohol solution. The leaching result was monitored by mixography of the flour, nitrogen analysis, and capillary zone electrophoresis of extracts. Although dough rheology was generally like that of the source flour, there were notable differences. The primary change for mass‐conserving contact was an increase in the time to peak resistance and a decrease in the rate of loss of dough resistance following peak resistance. These changes were in direct proportion to the amount of protein mobilized by the solvent. Leaching at 22°C, prevented dough formation for most aqueous ethanol concentrations and greatly reduced gliadin protein content. Minimal changes were noted for solvent contact at –12°C regardless of the ethanol concentration. The data suggested that 1) the conditions applied in cold‐ethanol enrichment of protein from wheat will generally preserve vital wheat gluten functionality, 2) functionality losses can be recovered by returning the solubilized fractions, and 3) the flour to which the gluten is added may require more mixing.

건식, 습식 및 반습식 쌀가루에 의한 쌀빵의 특성 비교

제분방법을 달리하여 제조한 건식, 습식 및 반습식 쌀가루를 사용하여 제조한 쌀빵의 품질특성을 비교하였다. 습식제분 쌀가루의 제조 시 쌀의 수침온도를 25℃와 55℃로 하였으며 반습식 처리로서 쌀을 살수처리한 후 제분하였다. 쌀가루에 밀가루를 7:3의 비율로 혼합한 복합분에 활성 글루텐을 첨가한 후 mixograph로 반죽의 특성을 측정한 결과 습식제분한 쌀가루에서 반죽시간과 안정성이 증가함을 보여주었다. 습식제분 쌀가루로 제조한 쌀빵이 건식제분과 반습식제분 쌀가루로 제조한 쌀빵에 비해 빵의 체적이 증가했으며, 특히 수침온도에 있어 55℃의 가온 수침처리가 쌀전분에 변화를 초래하여 상온에서 수침한 쌀가루에 비해 쌀빵의 체적을 향상시켰다. 쌀빵의 저장중 경도의 변화에서 습식제분 쌀가루로 제조한 빵이 가장 낮은 증가폭을 보여주었다.

EFFECTS OF CORN MEAL, VITAL WHEAT GLUTEN, HIGH AMYLOSE STARCH AND EXTRUSION PARAMETERS ON TECHNOLOGICAL PROPERTIES OF WHEAT‐BASED EXTRUDED BREADING

ABSTRACT A wheat‐based extruded breading was produced using a Brabender single‐screw laboratory scale extruder (model GNF 1014/2) and applied to chicken nuggets. Response surface methodology was applied to study and optimize the effects of formulation and extrusion parameters on pick up, texture, solid loss, oil absorption and adhesiveness of fried coated nuggets. An optimized extruded breading was produced at 160C, 27% moisture content, 15% vital wheat gluten, 8% high amylose starch and 30% corn meal. The product showed pick up of 29.87%, adhesiveness of 100%, texture of 166.1 g, oil absorption of 2.97% and solid losses of 0.0885 absolute. The product presented similar values of pick up and adhesiveness, better texture, lower oil absorption and higher solid loss during deep‐frying, compared with commercial breadings. Acceptance test showed that the product had better overall appearance and fairly similar texture, compared with the commercial ones.

Aging Properties of Films of Plasticized Vital Wheat Gluten Cast from Acidic and Basic Solutions

In order to understand the mechanisms behind the undesired aging of films based on vital wheat gluten plasticized with glycerol, films cast from water/ethanol solutions were investigated. The effect of pH was studied by casting from solutions at pH 4 and pH 11. The films were aged for 120 days at 50% relative humidity and 23 degrees C, and the tensile properties and oxygen and water vapor permeabilities were measured as a function of aging time. The changes in the protein structure were determined by infrared spectroscopy and size-exclusion and reverse-phase high-performance liquid chromatography, and the film structure was revealed by optical and scanning electron microscopy. The pH 11 film was mechanically more stable with time than the pH 4 film, the latter being initially very ductile but turning brittle toward the end of the aging period. The protein solubility and infrared spectroscopy measurements indicated that the protein structure of the pH 4 film was initially significantly less polymerized/aggregated than that of the pH 11 film. The polymerization of the pH 4 film increased during storage but it did not reach the degree of aggregation of the pH 11 film. Reverse-phase chromatography indicated that the pH 11 films were to some extent deamidated and that this increased with aging. At the same time a large fraction of the aged pH 11 film was unaffected by reducing agents, suggesting that a time-induced isopeptide cross-linking had occurred. This isopeptide formation did not, however, change the overall degree of aggregation and consequently the mechanical properties of the film. During aging, the pH 4 films lost more mass than the pH 11 films mainly due to migration of glycerol but also due to some loss of volatile mass. Scanning electron and optical microscopy showed that the pH 11 film was more uniform in thickness and that the film structure was more homogeneous than that of the pH 4 film. The oxygen permeability was also lower for the pH 11 film. The fact that the pH 4 film experienced a larger and more rapid change in its mechanical properties with time than the pH 11 film, as a consequence of a greater loss of plasticizer, was presumably due to its initial lower degree of protein aggregation/polymerization. Consequently, the cross-link density achieved at pH 4 was too low to effectively retain volatiles and glycerol within the matrix.

Effect of jet-cooked wheat gluten/lecithin blends on maize and rice starch retrogradation

Vital wheat gluten and lecithin (GL) (50:50, w/w) were dry blended in a coffee grinder and a 9.5% (w/v) aqueous slurry was jet-cooked (steam pressures of 65 psi/g inlet and 40 psi/g outlet) to disaggregate wheat gluten and facilitate better dispersion of the two components. The jet-cooked material was freeze-dried and stored at 0 °C for future use. The GL blend was added to pure food grade common maize and rice starch at concentrations of 0 (control), 6, 11, 16, and 21%. Starch gelatinization and retrogradation temperature transitions were determined using Differential Scanning Calorimetry (DSC). From the DSC profiles, the change in the Δ H value was used as an indication of starch retrogradation, where a higher Δ H value indicated higher retrogradation. The Δ H values of the blends at 4 °C had higher values than the −20 °C and the ambient (25 °C) storage temperatures. Overall, the 21% GL/starch blends reduced retrogradation by 50%. The lower amylose content of rice starch relative to maize starch was reflected in Rapid Visco Amylograph (RVA) measurements of peak viscosity, and similarly, Texture Analyzer (TA) measurements indicated that maize starch gel is firmer than rice starch gel. Retrogradation was also evaluated by observing G′, the shear storage modulus, as a function of time after running a standard pasting curve. Using this method, it appears that GL has a significant effect on maize starch retrogradation, since low concentrations (<0.4%, w/w) reduced G′ up to 40%. The opposite behavior was seen in rice starch, where G′ increased directly with added GL. It appears that the amylose level in the rice starch is too low to be affected by the GL, and the increase seen in G′ is most likely due to added solids.

Properties of Aged Montmorillonite−Wheat Gluten Composite Films

The properties of new and aged glycerol-plasticized vital wheat gluten films containing < or =4.5 wt % natural or quaternary ammonium salt modified montmorillonite clay were investigated. The films were cast from pH 4 or pH 11 ethanol/water solutions. The films, aged for < or =120 days, were characterized by tensile testing, X-ray diffraction, and transmission electron microscopy. In addition, water vapor permeability (11% relative humidity) and the content of volatile components were measured. The large reduction in the water vapor permeability with respect to the pristine polymer suggests that the clay platelets were evenly distributed within the films and oriented preferably with the platelet long axis parallel to the film surface. The film prepared from pH 11 solution containing natural clay was, as revealed by transmission electron microscopy and X-ray diffraction, almost completely exfoliated. This film was consequently also the strongest, the stiffest, and the most brittle and, together with the pH 11 film containing modified clay, it also showed the greatest decrease in water vapor permeability. The large blocking effect of the clay had no effect on the aging kinetics of the films. During aging, the pH 4 and pH 11 film strength and the pH 4 film stiffness increased and the pH 4 film ductility decreased at the same rate with or without clay. This suggests that the aging was not diffusion rate limited, that is, that the loss of volatile components or the migration of glycerol or glycerol/wheat gluten phase separation was not limited by diffusion kinetics. The aging rate seemed to be determined by slow structural changes, possibly involving protein denaturation and aggregation processes.

Functional modification of vital wheat gluten with corn syrup using hydrothermal treatment

AbstractFunctional properties of gluten modified using hydrothermal treatment were compared with those of vital wheat gluten (VWG). Gluten slurry was jet cooked under pressure in the presence of corn syrup (CS) at different temperatures (121 and 149 °C) for different times and then spray dried. Foaming properties for all samples (treated and untreated) at different pHs showed that, although the optimum pH was 5, at this pH the treated gluten samples displayed reduced foaming properties as compared with the control, whereas at all other pHs there was an increase in foaming properties. The sample treated with CS at 121 °C (JC121w/cs) showed the highest viscosity and elasticity increase among all treated samples. Emulsifying properties were adversely affected by an increase in temperature of treatment, whilst addition of CS helped to restore emulsion stability (ES). The sample VWG with CS (Cont.w/cs) at pH 3 showed maximum ES. In general, samples after treatment showed increased solubility. The hydrophilic but non‐ionisable sugar hydroxyl groups affected the functionality at lower pH. Molecular changes were followed by size exclusion high‐performance liquid chromatography (SE‐HPLC) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE). Samples subjected to the lower temperature (121 °C) showed a shift of the molecular weight distribution to higher values in the HPLC profile, consistent with higher viscosities for this treatment. For the same samples, SDS‐PAGE of the reduced protein exhibited a decrease in the intensity of bands corresponding to high‐molecular‐weight glutenin subunits, complementing the fact that large‐molecular‐size polymers are involved during protein modification. Copyright © 2005 Society of Chemical Industry

Effect of Amino Acids and Peptides on Mixing and Frozen Dough Properties of Wheat Flour

ABSTRACTFree amino acids, peptides, and vital wheat gluten were investigated to determine their effect on the mixing and frozen dough baking properties of wheat flour. Addition of 1% cysteine and aspartic acid decreased and glutamic acid, histidine, arginine, and lysine increased the mixing tolerance of flour. Cystine, methionine, tryptophan, and phenylalanine increased but isoleucine, histidine, glycine, arginine, glutamic acid, aspartic acid, and lysine decreased loaf volume of nonfrozen dough breads. However cystine, methionine, tryptophan, and phenylalanine did not increase loaf volume of bread prepared from frozen dough. Vital wheat gluten increased mixing tolerance and bread loaf volume only for the nonfrozen dough. However, wheat gluten hydrolysate, corn, and bonito peptides decreased mixing tolerance after optimum mixing time and were effective in increasing loaf volume for both frozen and nonfrozen dough. As the amount of corn and bonito peptide increased, specific loaf volumes also increased. Addition of 2.5% corn peptide was most effective in increasing loaf volume of frozen dough bread. Crust browning and crumb stickiness increased, whereas crumb softness decreased with addition of peptides. Addition of less than 1% peptide did not adversely affect the aftertaste and off‐flavor of bread. These results suggest that addition of peptides are effective for improving the baking quality of frozen dough, whereas amino acids and gluten have no effect.

Intermolecular Interactions and Phase Structures of Plasticized Wheat Proteins Materials

The intermolecular interactions and phase structures of thermally processed wheat proteins with glycerol and water as plasticizers were studied by dynamic mechanical analysis and solid-state high-resolution NMR spectroscopy. The results of phase structures at scales of molecular level to tens of nanometers were correlated with the mechanical properties of the materials. The strong hydrogen bonding intermolecular interactions between the components in wheat proteins and the plasticizers resulted in a significant change in molecular motions of wheat protein materials. The plasticized systems, however, still presented a wide distribution of chain mobility at a scale from the molecular level to 20-30 nm, and the plasticizing effect was different for each wheat protein system. High protein content systems tended to be plasticized relatively easily especially when lipid content is high, but the existence of residual starch would require more plasticizers to reach a similar level of chain mobility. On a scale of 20-30 nm, plasticized vital wheat gluten (WG) and the deamidated wheat proteins (WP-I) were heterogeneous with each component exhibiting its individual mobility, whereas the plasticized insoluble protein system (WP-II) with poor mechanical properties was homogeneous. Both WG and WP-I systems showed excellent mechanical polymeric properties in tensile strength and elasticity despite the heterogeneity. The strong intermolecular hydrogen bonding interactions and soluble protein components in the materials could provide an adhesion among different components and act as a continuous matrix in the systems. Therefore, these materials displayed excellent mechanical properties via coordination effects among different components.

Combining Maltogenic Amylase with CMC or Wheat Gluten to Prevent Amylopectin Recrystallization and Delay Corn Tortilla Staling

ABSTRACTAntistaling properties of a bacterial maltogenic amylase, sodium carboxymethylcellulose (CMC), and vital wheat gluten on quality of corn tortillas were evaluated during 14 days of storage. Amylopectin recrystallization was the driving force behind the staling of corn tortillas. Increasing levels of recrystallized amylopectin measured by differential scanning calorimetry (DSC) correlated significantly with increased tortilla stiffness (r = 0.43) and reduction in tortilla pliability (r = ‐0.42) during storage. Maltogenic amylase (275–1,650 activity units) made tortillas less stiff but did not preserve pliability and extensibility as effectively as CMC (0.25–0.5%). The combination of 825 MANU of maltogenic amylase (to interfere with intragranular amylopectin recrystallization) and 0.25% CMC (to create a more flexible intergranular matrix than retrograded amylose and amylopectin) produced less stiff, equally flexible, and less chewy tortillas than did 0.5% CMC. Vital wheat gluten was not as effective as CMC in preserving tortilla flexibility or as good as the maltogenic amylase in reducing stiffness. Further research is required to optimize the addition of maltogenic amylases in continuous processing lines that use fresh masa instead of nixtamalized corn flour (NCF) and to determine how these amylases interfere with amylopectin recrystallization.

Proteins Extracted by Water or Aqueous Ethanol During Refining of Developed Wheat Dough to Vital Wheat Gluten and Crude Starch as Determined by Capillary‐Zone Electrophoresis (CZE)

ABSTRACTFluids applied to large‐sale, technical separation of wheat starch and protein also extract soluble proteins. The degree and rate of extraction and the specific components extracted depend on the flour, the flour hydration and development, the starch‐displacing fluid composition, the temperature, and the mechanical processing method. This study sought to identify major extracted protein groups using high‐performance capillary zone electrophoresis (CZE) applied directly to fluids obtained during laboratory‐scale technical separations. A dough‐ball or compression separation method was applied using a Glutomatic system and a batter or dispersion method was applied using a a McDuffie mixer and Pharmasep vibratory separator. Process fluids were water at 22°C to model commercial practice and 70 vol% ethanol in water at ‐13°C to model the cold ethanol process being developed here. Data were referenced to use of 70 vol% ethanol in water at 22°C in the Glutomatic compression method. The dough processed by each method was developed by mixing to a separable state. When flooded with excess water, this dough immediately released starch and water‐soluble or albumin proteins. When flooded with excess cold aqueous ethanol, neither the albumin nor gliadin proteins appeared in significant amounts until the bulk of the starch had been displaced, regardless of the mechanical method. Even with extraction and manipulation well beyond that necessary for starch displacement, the net amount of gliadin proteins dissolved was only ≈10% of that available from wet developed dough using 70 vol% ethanol at 22°C. There was more gliadin protein in the fluids at earlier stages of processing when the batter dispersion method was applied using cold ethanol. The most common soluble proteins revealed in the electrophoresis patterns for the batter compression method using cold aqueous ethanol were initially albumins and later γ‐gliadins. Albumins not appearing as soluble in cold 70 vol% ethanol were found in the insoluble crude starch, suggesting their precipitation in the dough fluids during the change from free water to cold aqueous ethanol. These results establish that some protein is dissolved during starch displacement by cold aqueous ethanol, but that the amounts may be limited by control of the mechanical working of the dough in the presence of the displacing fluids.