Influence of modified starches on properties of gluten-free dough and bread. Part I: Rheological and thermal properties of gluten-free dough

The aim of this study was to analyze the influence of chemically modified starches (HDP and ADA) and high amylose corn starch (HACS) on the rheological and thermal properties of gluten-free dough based on corn and potato starches with pectin and guar gum. The results indicate that the dough with the addition of modified starch behaves as weak gel, the value of storage modulus G′ significantly depends on the frequency and the values of tan δ = G″/G′ range from 0.32 to 0.49. Significant influence of hydroxypropylated distarch phosphate (HDP) on the viscoelastic properties of dough was observed. The share of modified starch in the system caused a decrease of the instantaneous and viscoelastic compliance. It also influenced the retardation time and zero shear viscosity. The application of modified starches (HDP and ADA) for dough preparation did not have much impact on the pasting characteristics. However, significant reduction of the onset and end viscosities were found for high amylose starch (HACS). Thermograms obtained for individual dough systems were characterized by the presence of two peaks, associated with the existence of two different starches in the system. No significant effect of modified starch on the onset temperature (T_O) and only a slight effect of HACS starch on gelatinization enthalpy were observed. However, the level of addition of individual starch affected peak and end (T_E) temperatures, depending on the type of preparation.     

Influence of hydrocolloids on dough handling and technological properties of gluten-free breads

BackgroundThe development of gluten-free breads has attracted great attention as a result of better diagnoses of relationship between gluten-free products and health. The market demand for gluten-free products is increasing day by day due to growing number of celiac disease cases. Development of gluten-free bread remains a technological challenge due to the key role of gluten in the breadmaking process and in bread structure, appearance, texture and shelf life.Scope and approachThis review covers recent advances in the application of hydrocolloids in dough handling, technological and nutritional properties of gluten-free breads, which affect its quality and value.Key findings and conclusionsGluten-free breads results from the combination of different ingredients and hydrocolloids required to building up network structures responsible for bread quality. Various gluten-free formulations have applied hydrocolloids to mimic the viscoelastic properties of gluten. In addition, the impact of different hydrocolloids on the characteristics of dough and bread quality is known to be highly dependent on raw materials, the nature and quantity of hydrocolloids. Hydrocolloids improve the texture, increase the moisture content and extend the overall quality of bread. The results of the reviewed studies indicate that some of those products were acceptable and presented similar or better sensory attributes than control formulations and some were even comparable to their wheat-based counterparts. Based on successful applications of hydrocolloids, it is suggested that novel nutritious ingredients, combined with hydrocolloids can be added to gluten-free bread formulations to improve the quality of life.     

Effect of dry- and wet-milled rice flours on the quality attributes of gluten-free dough and noodles

The rheological and cooking properties of gluten-free noodles prepared with dry- and wet-milled rice flours were characterized. Dry-milled rice flour with a higher degree of starch damage exhibited greater water hydration properties than wet-milled rice flour at room temperature. However, the pasting results of rice flour suspensions demonstrated that wet-milled rice flour showed a higher value of peak viscosity due to its great swelling power upon starch gelatinization. The similar thermo-mechanical tendency was observed in a rice dough system by Mixolab. In the planar extensional test, the noodle dough sample prepared with dry-milled rice flour exhibited higher elongational viscosity which could be favorably correlated to more resistance of dry-milled rice noodle strands to extension. When rice noodles were cooked, increased cooking loss was observed in dry-milled rice noodles which was attributed to great water solubility derived from a higher degree of starch damage.     

Comparison of rheological, fermentative and baking properties of gluten-free dough formulations

This paper examines the fundamental rheological properties, capability of CO₂ retention during proofing, and baking behaviour of gluten-free (GF) dough. Maize flour, maize starch, rice flour, and buckwheat flour formulations are compared. Apple pectin is used as the structuring agent. Rheologically, the GF dough formulations can be defined as physical gels of different viscoelasticity and structural networking. The curves of CO₂ retention in the GF dough best fit with the asymmetric transition sigmoidal function. Some correlations between characteristic parameters of the transition sigmoids versus rheological parameters of the GF dough, the spread parameter n of Cole–Cole model and the shear-thinning consistency index k, were found. In baking tests, extending the proofing time improved the taste, aroma, and mouth feel of gluten-free breads, particularly when a sourdough step was applied or flaxseed was added to the formulation.     

The effects of maltodextrins on gluten-free dough and quality of bread

The aim of the study was to check if maltodextrins of various dextrose equivalents (DE) could be used to improve stability and quality of gluten-free bakery products, and effectively reduce starch retrogradation. The maltodextrins, which were used for partial replacement of starch in the recipe for gluten-free dough, were characterised by DE 3.6, 15.3, 18.0 and 21.8. Basing on the obtained results it was concluded, that the addition of applied maltodextrins significantly influences starch gelatinisation, by increasing pasting temperature and reducing viscosity of the obtained pastes. Rheological properties of the obtained dough are also modified by maltodextrins, which weaken its structure and increase deformation sensitivity. The addition of maltodextrins with low DE (3.6) diminishes loaf volume and causes deterioration of bread quality. Maltodextrins with higher DE, especially 18.0 and 21.8, positively influence bread volume and have a beneficial influence on crumb hardening during storage. Maltodextrin with the highest DE is also an effective factor reducing recrystallisation enthalpy of amylopectin.     

The impact of resistant starch on characteristics of gluten-free dough and bread

The study focused on partial replacement in gluten-free breads of corn starch with tapioca and corn resistant starch preparations. The use of resistant starch resulted in the increase of storage and loss moduli of the dough, and the lowering of loss tangent, which indicates its more elastic character. The incorporation of resistant starch reduced creep and recovery compliance and elevated zero shear viscosity. Modified doughs displayed higher starch gelatinization temperatures and lower viscosities that were proportional to the share of RS. It was found that the loaves baked with the share of resistant starch had less hard crumb than bread without RS addition. The crumb hardness diminished with the increasing amount of applied RS preparation. The addition of resistant starch raised total dietary fibre, by up to 89%, as compared to control (bread without RS addition). The most pronounced change was observed for insoluble dietary fibre (increase 137%), while only slight increase was found for its soluble fraction (18%).     

Influence of modified starches on properties of gluten-free dough and bread. Part II: Quality and staling of gluten-free bread

The aim of the study was to check the quality of gluten-free bread produced basing on the recipes, in which part of native starch was replaced with high amylose corn starch (HACS), acetylated distarch adipate (ADA), and hydroxypropyl distarch phosphate (HDP). The application 10 or 15% of chemically modified starches (HDP, ADA) caused the increase in volume of the obtained gluten-free loaves. The changes were accompanied by a decrease of average cell size, and an increase in their number. Due to the addition of modified starch crumb structure became more elastic, which was revealed in the results of stress relaxation. A slight decrease in hardness and chewiness of the crumb was also observed on the day of baking, and its extent depended on the level of modified starch, and was a little more pronounced in case of starch adipate. In comparison to the chemically modified starches, HACS deteriorated structural and mechanical properties of the crumb, which is probably related to their resistance to pasting and divergence in retrogradation pattern, where amylose component is more important than amylopectin.     

Extensional flow,viscoelasticity and baking performance of gluten-free zein-starch doughs supplemented with hydrocolloids

Viscoelastic doughs of zein and starch were prepared at 40 °C, above the glass transition temperature of zein. The effects of hydrocolloid supplementation with hydroxypropyl methylcellulose (HPMC) or oat bran with a high content of β-glucan (28%) were investigated by dynamic measurements in shear, confocal laser scanning microscopy (CLSM) and Hyperbolic Contraction Flow. Zein-starch dough without hydrocolloids exhibited rapid age-related stiffening, believed to be caused by cross-links between peptide chains. A prolonged softness was attributed to doughs containing hydrocolloids, with the oat bran exhibiting the most pronounced reduction in age-related stiffening. Moreover, CLSM-images of dough microstructure revealed that a finer fibre network may be formed by increased shearing through an addition of viscosity-increasing hydrocolloids, a reduction in water content in the dough or the use of appropriate mixing equipment. The Hyperbolic Contraction Flow measurements showed that doughs containing hydrocolloids had high extensional viscosities and strain hardening, suggesting appropriate rheological properties for bread making. Zein-starch dough without hydrocolloids showed poor bread making performance while hydrocolloid additions significantly improved bread volume and height. Although the hydrocolloid supplemented doughs had similar extensional rheological properties and microstructures, a fine crumb structure was attributed only to bread containing HPMC, marking the importance of surface active components in the liquid-gas interface of dough bubble walls. Zein could not mimic the properties of gluten on its own, but hydrocolloids did positively affect the structural and rheological properties of zein, which yielded dough similar to wheat dough and bread with increased volume.     

Effects of oxidase and protease treatments on the breadmaking functionality of a range of gluten-free flours

In this study, the application of glucose oxidase and protease commercial preparations was investigated in order to evaluate their impact on the breadmaking performance of four different gluten-free flours (buckwheat, corn, sorghum and teff). Bread formulas were developed without addition of hydrocolloids in order to avoid synergistic effects. Glucose oxidase improved corn (CR) and sorghum (SG) bread quality by increasing specific volume (P < 0.05) and reducing collapsing at the top. The improvements could be related to protein polymerization which resulted in enhanced continuity of the protein phase and elastic-like behavior of CR and SG batters. No significant effects were detected on buckwheat (BW) and teff breads. On the other hand, protease treatment had detrimental effects on the textural quality of BW and SG breads. The effects were related to protein degradation resulting in increased liquid-like behaviour of BW and SG batters. Overall, the results of this study suggest that protein polymerisation can improve the breadmaking performance of gluten-free flours by enhancing elastic-like behaviour of batters. However, the protein source is a key element determining the impact of the enzymes. In the absence of hydrocolloids, protein structures are important to ensure the textural quality of these types of breads.     

Effects of soy protein isolate and egg white solids on the physicochemical properties of gluten-free bread

Gluten-free formulations are often supplemented with proteins to improve their quality. To determine the effects of alternative proteins on a hydroxypropyl methylcellulose (HPMC)-treated gluten-free dough system, soy protein isolate was added at 1%, 2% and 3% while egg white solids were investigated at 5%, 10% and 15%. The formulated doughs were analysed using thermoanalytic and rheological techniques to determine the role of water and subsequent flow behaviour upon hydrocolloid addition. The baked loaves were measured for specific loaf volume and tensile strength to determine bread quality. The addition of soy protein isolate and egg white solids (5% and 10%) reduced dough stability by suppressing HPMC functionality, reducing available water, weakening HPMC interactions with the starch matrix and reducing foam stability. At 15% addition, egg white solids became the primary protein scaffolding in the dough and overcame negative interactions with HPMC, improving the loaf volume. However, this formulation may need further optimisation to meet full consumer acceptability.     

The role of buckwheat and HPMC on the breadmaking properties of some commercial gluten-free bread mixtures

Although the food industry has risen to the formulation challenges associated with removing gluten from dough, and a number of gluten-free (GF) products are now commercially available, many GF bread formulations are still based on pure starches, resulting in low technological and nutritional quality. The aim of this research was to evaluate the role of buckwheat and HPMC on the breadmaking properties of two commercial GF bread mixtures. A dehulled (DBF) and a puffed (PBF) buckwheat flour were used, and high substitution levels (40%) were tested, with the aim of improving the nutritional value of the final GF breads without decreasing their technological quality. Ten mixtures (2 commercial, 8 experimental) were evaluated. The inclusion of 40% DBF was demonstrated not to reduce but actually improve the baking performances of the commercial GF mixtures. Moreover, the presence of a small amount of PBF, as well as of HPMC, turned out to be useful in limiting both the diffusion and the loss of water from the bread crumb and the interactions between starch and protein macromolecules, resulting in a softer GF bread crumb and reduced staling kinetics during storage.     

Effects of particle size distributions of rice flour on the quality of gluten-free rice cupcakes

The particle size distributions (PSD) of rice flour and milling processes are important in making gluten-free products. The dry rice flour was prepared by grinding dried rice grains after soaking. Effects of PSD on the quality of rice cupcakes were investigated using the newly-developed rice flour. The flour properties passed through 80, 120, 160, and 200 (<180, <125, <95, and <75 μm) meshsieves, and batters and cupcakes prepared from their flours were analyzed. The PSD patterns showed two peaks containing cells and free starch fractions, in which the starch fraction peak intensity increased as a particle size decreased. While damaged starch, water binding capacity, solubility and lightness increased, crude protein and yellowness decreased as a particle size decreased. The final and setback viscosities increased as a particle size decreased. The specific volume of cupcakes was the highest in the cupcakes made with rice flour passed through under 95 μm. Hardness and springiness decreased as a particle size decreased. The air cell sizes decreased as a particle size decreased with homogeneity. Air cell homogeneity, volume, hardness, and softness of cakes determined by the different test, and appearance, texture, and overall quality determined by the preference test were all significantly different (p < 0.05).     

Production of acidic extruded rice flour and its influence on the qualities of gluten-free bread

One of the greatest technological challenges in the production of gluten-free bread (GFB) is to find a low-cost ingredient capable of retaining gas during fermentation and the baking process. The use of gelatinized starch appears to show promise for this purpose. In this study, GFB was made using raw rice flour (100 g) with the addition of 10 g acidic extruded rice flour (AERF). The AERF was produced in a single-screw extruder, varying the extrusion temperature and lactic acid concentration. Response surface methodology (RSM) and the principle components analysis (PCA) were used to analyze the results. The results of RSM showed no significant difference, but the mean volume obtained with the AERF (1.95 mL g⁻¹) was still low when compared with that of wheat bread (6 mL g⁻¹). The crust and crumb colors and the texture (hardness = 173 g; chewiness = 90.5 and fracturability = 178) presented results similar to those of wheat bread and better than other GFB found in the literature. When analyzed by PCA the AERF obtained at 150 °C-0.5 mol L⁻¹ lactic acid, showed the best results for the GFB obtained. IR spectroscopy showed that no bands were found for esters (1740 cm⁻¹) in the AERFs, which could indicate that no new bonds were formed between the rice flour and the lactic acid.     

Effect of low lactose dairy powder addition on the properties of gluten-free batters and bread quality

Different low lactose dairy ingredients including sodium caseinate (SC), milk protein isolate (MPI), whey protein isolates (WPIS and WPIM) and whey protein concentrate (WPC) were tested in a gluten-free bread formulation and compared to controls with the addition of no dairy ingredient (C) and one dairy ingredient containing lactose, skim milk powder. Rheological characterisation (frequency sweep and creep-recovery) of the batters at 90% water level (WL) suggested that the addition of WPIS, WPIM and WPC significantly decreased G′ and G″ values. SC and MPI had the opposite effect with a significant increase in both these parameters being found (p < 0.05). The WL of the batters was adjusted in order to obtain the same consistency of the batter C at 90% WL. A Power Law model was used to predict the new WL based on single frequency measurements of G* for each sample. The baking analysis demonstrated that the correction of the WL did not show a strong impact in the quality of the breads. Nevertheless, whey proteins demonstrated the ability to increase significantly the specific volume of the breads and decrease the hardness over time (p < 0.05). SC had a negative impact on the specific volume, which led to an increase in crumb hardness (p < 0.05).     

Influence of the addition of lupin sourdough with different lactobacilli on dough properties and bread quality

The aim of this research was to study the effects of solid‐state fermentation (SSF) with Lactobacillus sakei, Pediococcus pentosaceus and P. acidilactici on lupine sourdough parameters and lupine sourdough influence on the physical dough properties and wheat bread quality. The results showed that lactic acid bacteria (LAB) significantly reduced the pH and increased total titratable acidity (TTA) of SSF lupine. The highest protease activity in lupine is excreted by L. sakei (187.1 ± 8.6 PU g^?1), and the highest amylase activity, by P. pentosaceus (155.8 ± 7.5 AU g^?1). Lupine sourdough has a significant effect on the rheological properties of doughs, which affect the baking characteristics of the final product. In conclusion, it can be said that L. sakei, P. pentosaceus and P. acidilactici could be used for lupine SSF, and the addition of up to the 10% SSF lupine products increases the wheat–lupine bread quality.     

Rheological study of layer cake batters made with soybean protein isolate and different starch sources

The study of new gluten-free foods suitable for celiac people is necessary since people allergic to wheat proteins are more and more frequent. This study examined the effect of using different starch sources (rice, corn, potato and wheat) and protein types (soy protein isolate, wheat protein) at different percentages (0%, 10%, 20%), on the rheological properties of batters (flow, viscoelastic and stickiness behaviour) and on batter density and cake volume. The highest consistency, viscous and elastic moduli, and adhesive force corresponded to batters made of rice starch and soy protein isolate, which showed the most similar rheological behaviour to wheat flour batters. The batters obtained showed adequate characteristics in processing and in achieving high quality products. However, the percentages of starches and proteins should be experimentally optimized in each case.     

Effects of freezing and frozen storage conditions on the rheological properties of different formulations of non-yeasted wheat and gluten-free bread dough

Empirical and fundamental rheological measurements were made on fresh and frozen dough to study the effects of freezing and frozen storage conditions. Frozen dough was stored at two different temperatures, −18 °C and −30 °C, and for 1, 7 and 28 days. Four dough formulations were tested: a standard wheat dough, a fibre-enriched wheat dough, a standard gluten-free dough and a gluten-free dough containing amaranth flour. No yeast was used in any formulation. The wheat dough is more affected by freezing and by the first days of storage whereas the gluten-free dough is more affected by a longer storage time. A storage temperature of −30 °C alters dough rheological properties more than a storage temperature of −18 °C. The addition of dietary fibres to the wheat dough increases its resistance to freezing and frozen storage. The addition of amaranth flour to gluten-free dough also increases its resistance to freezing but decreases its resistance to storage conditions.     

Influence of inulin on physical characteristics and staling rate of gluten-free bread

Inulin preparations with different degree of polymerization (HSI with a DP < 10, GR − DP ? 10 and HPX − DP > 23) were used for the production of gluten-free bread. It was found that an addition of investigated compounds resulted in an increase of loaf volume and reduction of crumb hardness. However, internal structure of the obtained loaves was less uniform and more open than in control bread. Generally, inulin preparations with lower degree of polymerization had stronger effect on all analyzed parameters than that with higher DP. A decrease in staling was observed (measured as the rate of crumb hardening), which was caused by the presence of inulin. The highest content of retrograded amylopectin was found for crumb with HSI, and the lowest for samples with HPX.     

Effect of amylose content and rice type on dynamic viscoelasticity of a composite rice starch gel

Amylose content is an important indicator to determine the utility of raw milled rice. Indica type rice with high amylose content is usually used for manufacturing rice noodles, while Japonica rice may be mixed partially to adjust the noodle texture. The effect of amylose and rice type on dynamic viscoelasticity of rice starch gel was investigated using a model starch composite in this study. The information will be helpful to control and obtain the required noodle texture by combination of different rice types. The results show that nonwaxy Indica and waxy Japonica rice starches in a composite mixture were incompatible and demonstrated their individual gelatinization behavior during heating. High amylose starch showed higher moduli and lower loss tangent values, as well as higher retrogradation rate. The starch gel made from Japonica rice starch showed a slow retrogradation rate even containing a similar amount of amylose to Indica starch. The storage modulus of the gel made from higher amylose rice was shown to be more independent of frequency. Not only amylose content but also chain length distribution in amylopectin affected the dynamic viscoelasticity of rice gel. Japonica rice starch, with fewer super-long chains in amylopectin, retrograded slower after gelatinization than Indica rice, thus the paste is too sticky for production of rice noodles.     

Effect of modified tapioca starch and xanthan gum on low temperature texture stability and dough viscoelasticity of a starch-based food gel

This work investigated the effect of modified tapioca starch and xanthan gum on dough viscoelasticity and texture stability during storage at 4 °C of starch sheets for Chinese shrimp dumplings. Hydroxypropylated starch and hydroxypropylated-crosslinked starch were used to substitute for tapioca starch in the control formulation, and xanthan gum was added to adjust the formulation. During storage, texture of the control became firmer due to amylopectin retrogradation confirmed by differential scanning calorimetry and X-ray diffraction. Conversely, gel sheets containing modified starches showed less texture change. Dough viscoelasticity of the formulations substituted by hydroxypropylated starch were much softer and easier to deform than that of the control one. Dough with hydroxypropylated-crosslinked starch was, however, stiffer and more strain-resistant. Moreover, the formulation comprising the mixture of both types of modified starches and xanthan gum gave dough viscoelasticity similar to that of the control, and provided gel sheet the least texture change. Consequently, this modified formulation could be beneficial for the application of frozen/chilled dumpling wrappers.