Gluten-free Rice Research Articles

Effects of soy protein isolate interaction with brown rice starch on the multiscale structure of brown rice bread.

Gluten-free bread (GFB) has technical bottlenecks such as hard texture, rough taste and low nutrition in practical production. In order to solve these problems, this study used germinated brown rice starch as the main raw material, and investigated the effects of soybean isolate protein (SPI) on the multiscale structure of germinated brown rice starch and bread quality. A gluten-free rice bread process simulation system was established, and the interaction between SPI and starch in the simulation system was characterized. The result shows that the interaction forces between SPI and germinated brown rice starch were mainly represented by hydrogen bonds, and with the addition of SPI, the crystallinity of starch showed a downward trend. At the same time, when the amount of SPI was 3%, the appearance quality was the best and the specific volume of bread was 1.08 mL g-1. When the amount of SPI was 6%, the texture quality was the best. Compared with the bread without SPI, the hardness of the bread with 6% SPI was reduced by 0.13 times, the springiness was increased by 0.03 times, the color was the most vibrant, the L* value being 1.02 times the original, and the baking loss was reduced to 0.98 times the original. The interaction force between SPI and germinated brown rice starch and its effect on bread quality were clarified, and these results inform choices about providing a theoretical basis for the subsequent development of higher-quality GFB. © 2024 Society of Chemical Industry.

Impact of Sourdough from a Commercial Starter Culture on Quality Characteristics and Shelf Life of Gluten-Free Rice Breads Supplemented with Chickpea Flour.

This study aimed to develop a novel gluten-free bread using a rice/chickpea flour-based sourdough, fermented by a commercial starter culture, to improve the quality characteristics and shelf life of this product. The effects of sourdough incorporation, chickpea flour content (6.5 and 10.0%), and added water level (80-110%) on batter rheology and bread quality were investigated; bread textural characteristics upon storage (0-2 days) were also monitored. The level of added water was the primary factor influencing batter rheology, as evaluated by the back extrusion test. Sourdough incorporation decreased the pH and increased the acidity of batters and breads. The inclusion of sourdough, the water level, and the storage time affected the moisture and texture parameters of the bread crumb. Sourdough incorporation into bread formulations decreased crumb hardness and staling rate and increased loaf specific volume. Moreover, intermediate water (90 and 100%) and high chickpea (10%) levels in the batters increased loaf specific volumes and crust redness, respectively. Sensory analysis revealed that sourdough-enriched breads were preferred by the assessors concerning general appearance and crumb texture. Overall, bread formulations with the incorporation of sourdough, at a 90% level of added water in the batter mixtures, exhibited the most desirable characteristics according to both instrumental and sensory analyses.

Whole Black Rice Flour Improves the Physicochemical, Glycemic, and Sensory Properties of Cracker Snacks.

The present study describes the enhancement of the nutritional values of gluten-free rice crackers by adding whole black rice grain flour. The crackers were prepared by combining whole brown rice flour (WRF) and whole black rice flour (BRF) in ratios of 0% (WRC), 25% (25-BRC), 50% (50-BRC), 75% (75-BRC), and 100% (BRC). The resulting samples underwent in-vivo effects on postprandial blood glucose levels as well as physicochemical and sensory analysis. In comparison to WRC, the samples containing 100% added black rice flour presented higher nutritional qualities in terms of protein, by 16.61%, 8.64% for lipids, 5.61% for ash, 36.94% for crude fiber, 58.04% for total polyphenols, 95.49% for proanthocyanidins, and 88.07% for flavonoids. The addition of BRF had a suppressing effect on lightness (L*) and yellowness (b*), while redness (a*) increased. The results of the glycemic measurements confirmed that consumption of crackers made from brown or black whole-grain rice grain flour does not generate glycemic peaks above the limit of 30 mg/dL in baseline blood glucose levels. The results of developing rice crackers from black and brown flour blends showed promising physicochemical and nutritional properties and could provide a good alternative to wheat flour as a gluten-free product.

Technological quality, bioactive features, and glycemic index of gluten-free cakes formulated with lyophilized wild Prunus spinosa fruit

This study evaluated the effects of rice flour cakes enriched with wild fruit Prunus spinosa powder (PS) on techno-functional, nutrition, and eating quality. PS increases the cakes’ ash, protein, and moisture values. Total phenolic content increased from 35.91±0.25 to 73.39±0.58 mg GAE g-1, and gluten-free cakes’ antioxidant capacity markedly increased with the increasing level of PS powder addition (p<0.05). The increase in PS decreased the glycemic index (eGI), and the lowest eGI was determined as 69.38±1.21 in cake samples containing 4% PS. Except for the 1% PS added sample, the increase in PS caused a decrease in specific volume, % porosity, and increase in hardness, including four days of storage. The addition of PS increased the redness (a*) and decreased the yellow (b*) and brightness (L*) values. The flow behavior index (n) of cake batters containing 1% and 2% PS were similar to the control group. Cakes containing 1% PS received the highest scores in sensory analysis. Although the increase in PS amount negatively affects the textural properties of gluten-free rice flour cakes, it is crucial to increase its bioactive properties and nutritional values and positively contribute to health by reducing the glycemic index.

Physicochemical properties and sensory evaluation of gluten-free rice egg roll with hydrocolloids addition

The growing prevalence of gluten-intolerance disorder causes increasing demand for gluten-free products. This study was carried out to evaluate the quality parameters of gluten-free egg roll in terms of physical, chemical and sensory acceptability. Rice flour was utilized as a gluten-free source to replace wheat flour for the preparation of glutenfree egg roll. Hydrocolloids like carboxymethylcellulose (CMC) and xanthan gum were added at 0.4 g to enhance the quality characteristic of gluten-free egg roll made of rice flour. The results of proximate analyses revealed that the addition of hydrocolloids significantly (p<0.05) increased the moisture content, ash content, crude protein, crude fat, and total carbohydrate content of gluten-free egg roll compared to egg roll made of rice flour without hydrocolloids. The addition of hydrocolloids significantly (p<0.05) increased the lightness (L*) value, but egg roll added with xanthan gum significantly (p<0.05) decreased the a* and b* values. The inclusion of hydrocolloids did not have a significant effect on hardness, but egg roll added with xanthan gum significantly increased the fracture strength as compared to rice flour containing egg roll. Among the hydrocolloids, egg roll added with xanthan gum resulted in a significant improvement in overall acceptability. Thus, rice flour and hydrocolloid (i.e., xanthan gum) could be suitable ingredients in producing the best quality egg roll and could provide benefits to gluten intolerance patients.

Development of Gluten-Free Bread Production Technology with Enhanced Nutritional Value in the Context of Kazakhstan.

This research aims to enhance the nutritional value of gluten-free bread by incorporating a diverse range of components, including additives with beneficial effects on human health, e.g., dietary fibers. The research was focused on improving the texture, taste, and nutritional content of gluten-free products by creating new recipes and including novel biological additives. The goal was to develop gluten-free bread with less than 3 ppm gluten content that can be eaten by people suffering from gluten sensitivity. The physical and chemical properties of gluten-free rice, corn, green buckwheat, chickpea, amaranth, and plantain flours were examined to understand their unique characteristics and the possibility of their mixing combination to achieve the desired results. Initially, nine recipes were prepared, and in survey research, four baking recipes were selected and tested. The composition of amino acids in the prepared gluten-free bread was determined. The variant made of corn, green buckwheat flour with plantain was found to be top-rated. Changes in the nutritional content of the new product were analyzed, and general regulations and nutritional values were identified. Experimental baking processes were carried out, leading to the successful formulation of gluten-free bread containing corn, green buckwheat, and plantain flour in a ratio of 40:40:20, meeting gluten-free requirements and demonstrating improved nutritional properties, as well as consumption properties, confirmed by surveys conducted on a group of consumers.

Glycemic Response in Nonhuman Primates Fed Gluten-Free Rice Cakes Enriched with Soy, Pea, or Rice Protein and Its Correlation with Nutrient Composition.

Celiac disease (CD) is a chronic disease caused by the consumption of gluten foods and is closely related to type 1 diabetes (T1D). Adherence to a gluten-free (GF) diet is the cornerstone of treating CD, and certain plant proteins added to GF foods affect blood glucose to varying degrees. The aim of this study was to analyze and compare the changes in glycemic index (GI) and incremental area under the postprandial glucose tolerance curve (IAUC) of various foods through consumption of GF foods supplemented with certain plant proteins in non-human primates. The test foods were GF rice cakes with 5%, 10%, and 15% added single plant proteins (rice protein, soy protein, and pea protein) mixed with rice flour, as well as 5%, 10%, and 15% gluten rice cakes, and rice flour alone, for a total of 13 food items, and 12 healthy cynomolgus monkeys were examined for their glucose levels in the blood after fasting and after eating each test food (50 g) for 15, 30, 45, 60, 90, and 120 min after fasting and eating each test food. Fingertip blood glucose levels were measured, and the nutrient content of each food, including protein, fat, starch, ash, and amino acids, was examined. All foods tested had a low GI (<50) when analyzed using one-way ANOVA and nonparametric tests. Postprandial IAUC was significantly lower (p < 0.05) for GF rice cakes with 15% pea protein (499.81 ± 34.46) compared to GF rice cakes with 5% pea protein (542.19 ± 38.78), 15% soy protein (572.94 ± 72.74), and 15% rice protein (530.50 ± 14.65), and GF rice cakes with 15% wheat bran protein (533.19 ± 34.89). A multiple regression analysis showed that glycine was negatively associated with IAUC in GF rice cakes with 5%, 10%, and 15% pea protein added (p = 0.0031 < 0.01). Fat was negatively correlated with IAUC in GF rice cakes supplemented with 5%, 10%, and 15% soy protein (p = 0.0024 < 0.01). In this study, GF rice cakes made with added pea protein were superior to other gluten and GF rice cakes and had a small effect on postprandial glucose.

Influence of malted buckwheat, foxtail and proso millet flour incorporation on the physicochemical, protein digestibility and antioxidant properties of gluten-free rice cookies

The gluten-free cookies with improved nutritional value and health promoting qualities were prepared by substituting rice flour with malted buckwheat (BW), foxtail millet (FM) and proso millet (PM) flours at 15 % and 30 % levels. The characteristics of malted BW, FM and PM flours obtained after germination for 1–4 days (GD = 1–4) were first evaluated. The increment in germination days caused a significant improvement in protein content, total dietary fibre (TDF), oil absorption capacity, amylase and protease activity of malted BW, FM and PM flours. Incorporation of 30 % malted (GD=3 and 4) BW, FM and PM flours increased the G', G" and tan δ values of the cookies dough. The protein, ash, fat, TDF content and in vitro protein digestibility (IVPD) of cookies increased while glycaemic and starch hydrolysis index decreased by incorporating malted flours of all three grains. The incorporation of 30 % malted BW flour (GD = 3) increased IVPD, antioxidant capacity, protein, phenolics and flavonoids while incorporation of 30 % malted FM flour (GD = 4) proved useful in improving dietary fibres in gluten-free rice cookies. The 30 % malted BW and FM flour (GD = 3) can be incorporated in rice cookies for the improvement of nutritional and functional properties.

Tomographical, rheological, and structural effects of soy protein concentrate in a gluten-free extruded noodle system.

Global interest in high-protein foods has been rapidly increasing and the gluten-free products are no exceptions. Gluten-free extruded noodles made from rice flour were thus fortified with soy protein concentrate (SPC) (0%, 15%, 30%, and 45% by weight), and the physicochemical properties of the noodles were characterized in terms of tomographical, rheological, and structural features. SPC-rice flour blends showed higher water absorption and swelling power at room temperature with increasing levels of SPC, which were reduced upon heating. The flour blends with high-levels of SPC also had lower pasting viscosities. Thermal analysis showed lower enthalpy values and higher temperatures derived from starch gelatinization. When the SPC-rice flour blends were applied to extruded gluten-free rice noodles, the noodles tomographically showed a dense and compact structure, that could be favorably correlated with their textural changes (increased hardness and reduced extensibility). FTIR analysis presented the structural changes of the noodles containing different levels of SPC by showing higher intensity of protein-related absorption peaks and lower starch peak intensity, which could be associated with the reduced cooking loss. Moreover, there existed two water components with different mobilities in the noodles whose spin-spin relaxation times had a tendency to increase with increasing SPC content. The results obtained from this study provided fundamental insights into the processing performance of protein-rich ingredients in gluten-free extruded noodles, probably promoting the development of a wider variety of protein-fortified gluten-free products.

Physical and Antioxidant Properties of Innovative Gluten-Free Bread with the Addition of Hemp Inflorescence

Hemp inflorescences from byproducts have been proposed as an addition to gluten-free rice bread. The scope of the research was to bake a control loaf of bread as well as bread loaves containing 1%, 2%, 3%, 4%, and 5% dried and crushed hemp inflorescence (HI). The loaves of bread were evaluated in terms of their physical and sensory properties, polyphenol and flavonoid contents, and DPPH and FRAP antioxidant activities. The study’s findings revealed that the addition of HI influenced changes in the physical properties of the bread loaves, such as increased specific volume, decreased bread hardness, increased elasticity, and chewiness of the breadcrumb, especially when the additive concentrations were greater than 3%. The addition of HI significantly increased the total amount of polyphenols, flavonoids, and antioxidant activity in the bread. The sensory evaluation revealed that gluten-free bread can be produced with a maximum of 2% HI without affecting its taste and aroma.

The effect of okra (Abelmoschus esculentus l.) Powder Addition on Qualities of Gluten-free Chiffon Cake.

Rice flour (100%, 97.4%, 94.7%, 89.5% (w/w)) and okra powder (2.6%-10.5%) were used to replace wheat flour to make gluten-free chiffon cakes. The effects of okra powder addition on the physicochemical, color, texture, moisture content, total phenolic content, antioxidant, and sensory scores of cakes were evaluated. The batter viscosity, chewiness, ash, protein, fat, total phenolics, and antioxidant activities (1,1-diphenyl-z-picrylhydrazyl hydrate and reducing power) of cakes showed an increasing trend with okra powder addition. Gluten-free chiffon cake containing 5.3% okra powder showed significantly (p < 0.05) higher protein and ash contents as compared to their control and chiffon cake made with wheat flour. Nevertheless, center height, volume index, L*, a*, and b* values, and white index of gluten-free cake decreased with increased okra powder levels. The sensory characteristics of wheat and gluten-free chiffon cakes substituted with 2.6%-5.3% okra powder showed no difference (p > 0.05). Nevertheless, the sensory scores of the 5.3% okra powder addition cake obtained a higher preference than other gluten-free cakes. Although the overall acceptability of gluten-free chiffon cake supplemented with 10.5% okra flour had a lower (p < 0.05) overall acceptability (2.84) than all cake samples, it was still shown acceptable to consumers. Gluten-free rice chiffon cakes with high nutrient contents and antioxidant activities can be processed by the incorporation of okra powder of less than 10.5% to increase the diversification of gluten-free foods. Gluten-free cakes with high amounts of okra powder addition would produce cake having high water content, total phenol content, 1,1-diphenyl-z-picrylhydrazyl hydrate radical scavenging activity, reducing power, hardness, chewiness, cohesiveness, batter viscosity, ash, and crude protein content through principal component analysis.

Proximate Compositions, Texture, and Sensory Profiles of Gluten-Free Bario Rice Bread Supplemented with Potato Starch.

Current gluten-free food development trends tend to favour pigmented rice flour. Bario Merah Sederhana is a type of red-pigmented rice that is indigenous to Sarawak, Malaysia. This research investigates the nutritional, texture, and sensory properties of gluten-free rice bread produced from a composite of BMS rice flour and potato starch, producing samples referred to as F1 (100:0), F2 (90:10), F3 (80:20), and F4 (70:30). The gluten-free rice bread formulations demonstrated higher ash and crude fibre content and lower carbohydrate content than wheat bread. However, the crude protein content of the bread decreased significantly (p < 0.05) with a decreased amount of rice flour, owing to wheat flour containing greater protein. The crumb of rice bread appeared to be darker due to the red pigment of rice flour; in contrast, the crust was lighter than the control sample, possibly due to a lower Maillard reaction. Among rice bread formulations, F4 demonstrated the lowest hardness in dough and bread, as well as the highest stickiness and springiness in dough and bread, respectively. The wheat bread received the highest rating (p < 0.05) in the sensory test; nonetheless, among the rice breads, F4 was considered to be an acceptable formulation owing to its high score in colour (7.03), flavour (5.73), texture (6.03), and overall acceptability (6.18). BMS has potential in gluten-free rice breads; the formulation of 70% rice flour combined with 30% potato starch was indicated to be acceptable.

ENHANCING THE QUALITY ATTRIBUTES OF RICE BREAD FORTIFIED WITH OKRA MUCILAGE VIA SWEET POTATO (Ipomoea batatas) FLOUR

Functional foods (e.g., gluten-free (GF)) products need continuous improvements in quality characteristics. Generally, GF foods like rice bread (RB) are found to be nutritionally poor when compared to gluten-containing ones. Moreover, due to the absence of gluten, technological properties of RB are different from those of wheat bread (WB). This study was conducted on gluten free rice bread (GFRB) for improving its chemical, physical, textural, sensorial properties, as well as staling rate (SR) with adding of sweet potato flour (SPF) and okra mucilage (OM) used as novel hydrocolloid. Hence, the results revealed that as the replacement levels of rice flour (RF) by orange sweet potato flour (OSPF) and/or white sweet potato flour (WSPF) increased, the RB content from ash (0.82-2.13%) and crude fibers (CF) (1.43-5.17%) increased, while the values for crude protein (CP) (5.97-4.20%), total carbohydrates (TC) (86.42-81.43%), and total calories (412-381kcal/100g) decreased comparing to RB prepared from 100% RF. Concerning physical properties, the bread volume (BV) and specific volume (SV) increased, while the baking loss (BL) and bread density (BD) decreased when replacement levels were up to 30% for both types of SPF and vice versa when the ratios were more than 30% for BV,SV, and BD. In terms of texture profile analysis (TPA), the RB samples made from RF replaced by OSPF and/or WSPF at 30% exhibited minimum values of hardness (2.97 and 3.66 N), chewiness (10.95 and 11.22 mJ), and gumminess (2.94 and 3.05 N), and the maximum values of resilience (0.96 and 0.91) and springiness (3.72 and 3.67 mm) for OSPF and WSPF, respectively. However, the superiority was in favor of OSPF. Regarding bread SR, it is clear that increasing substitution levels of RF with OSPF and/or WSPF caused a decreasing trend in the SR until it reached the best ratio at 30% (0.080 and 0.087, respectively). Accordingly, the current study suggested that the substitution of RF by OSPF at 30% was the ideal ratio to produce a high-quality GFRB, where the produced loaves had the same sensory qualities as wheat bread.

Investigation of some bioactive compounds, in vitro bioaccessibility, and sensory acceptability of couscous produced by pre-gelatinized rice flour.

The purpose of this study was to investigate the sensory properties, antioxidant capacities, total phenolic content, and their bioaccessibility in gluten-free rice couscous that is produced without additives. Since rice does not contain gluten, pre-gelatinized rice flour (GRF) was added instead of gum and enzymes in order to provide the desired structure in the couscous samples. According to the results, the total phenolic content of couscous samples was increased with GRF addition. The highest extractable and hydrolyzable antioxidant capacity values were observed in the couscous samples supplemented with 30% GRF using the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation, cupric-reducing antioxidant capacity, and ferric reducing antioxidant capacity methods. The bioaccessibility of antioxidant capacity was found to be significantly higher (P < 0.05) than the control sample in all methods except the 1,1-diphenyl-2-picrylhydrazyl free radical method in the couscous samples. According to the data obtained, it has been determined that couscous, which has a very small round shape, can be produced with GRF without additives. In this context, gluten-free rice couscous could be used as an alternative valuable food in terms of nutrition and can be an alternative traditional food for celiac diseases as well as for individuals preferring the consumption of gluten-free products. © 2022 Society of Chemical Industry.

Evaluation of chemical composition and cooking properties of Turkish type gluten-free rice couscous

In this study, the aim was to produce traditional couscous in gluten-free form. For this purpose, rice flour (RF) and pre-treated (gelatinized) rice flour (GRF) were added in varying proportions (15, 20, 25, and 30%) to the recipe instead of gums and enzymes in order to provide the desired structure. The control sample without GRF was also produced. With the addition of GRF, the total dietary fibre (TDF) content in the couscous samples increased, and reversely the carbohydrate and energy values decreased. The GRF reduced the level of total soluble organic material (TSOM) as well as the cooking loss of the couscous samples, which resulted in lower deformability. According to the results, the gluten-free rice couscous was successfully produced with GRF, especially at a 30% ratio. Good cooking properties were observed in these couscous samples. In this context, in the addition of 30% GRF, higher water absorption and swelling volume with lower cooking loss were observed compared with the control sample. In addition, the couscous samples had higher ash, dietary fibre and fat content as well as a lower phytic acid ratio (P &amp;lt; 0.05). It was determined that there was significant correlation between the cooking time of the samples with the cooking loss and total soluble organic material. According to the results, the PCA showed that there were clear correlations between cooking trials (water absorption and swelling volume) and chemical composition (moisture, ash, crude fat, and TDF).

Bioactive, Mineral and Antioxidative Properties of Gluten-Free Chicory Supplemented Snack: Impact of Processing Conditions.

This study aimed to investigate the impact of chicory root addition (20-40%) and extrusion conditions (moisture content from 16.3 to 22.5%, and screw speed from 500 to 900 rpm) on bioactive compounds content (inulin, sesquiterpene lactones, and polyphenols) of gluten-free rice snacks. Chicory root is considered a potential carrier of food bioactives, while extrusion may produce a wide range of functional snack products. The mineral profiles were determined in all of the obtained extrudates in terms of Na, K, Ca, Mg, Fe, Mn, Zn, and Cu contents, while antioxidative activity was established through reducing capacity, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) tests. Chicory root addition contributed to the improvement of bioactive compounds and mineral contents, as well as antioxidative activities in all of the investigated extrudates in comparison to the pure-rice control sample. An increase in moisture content raised sesquiterpene lactones and minerals, while high screw speeds positively affected polyphenols content. The achieved results showed the important impact of the extrusion conditions on the investigated parameters and promoted chicory root as an attractive food ingredient in gluten-free snack products with high bioactive value.

Factors affecting the properties of rice flour: a review

Rice (Oryza sativa L.) is a global essential food. Rice flour production had a significant upsurge, leading to various development in rice-based food products. The properties of starch within rice flour are generally affected by different factors, resulting in rice flour with various physicochemical and functional properties. This article summarized the several factors that affect rice flour properties, including environmental conditions in terms of temperature extreme and soil conditions, milling methods, amylose and amylopectin composition, and endogenous protein and lipid. Overall, environmental conditions in extreme temperatures can influence the amylose content, altering the amylopectin chain length and functional and thermal properties, to be specific gelatinization temperature and pasting properties. As for soil conditions like water deficiency and salinity stress could affect the pasting properties, reduce amylose content, increase the swelling rate, and pasting properties due to the alteration of protein endosperm level in rice flour, respectively. Factors such as the milling method are capable of influencing the starch characteristics within rice flour, and wet-milled rice flour is more applicable in the development of gluten-free rice bread than dry-milled rice flour. Amylose and amylopectin composition were found to affect the texture of final products and the physicochemical properties of rice flour, such as swelling capacity, gelatinization temperature and pasting properties. Whereas endogenous protein and lipid can influence the swelling properties, water solubility index, gelatinization temperature and retrogradation rate by the formation of complexes with amylose, called amylose-protein and amylose-lipid. In general, different factors could lead to vast properties of rice flour that can affect its performance of flour.

Effects of the addition of high‐temperature water on the bubble structure, rheological properties, and sensory characteristics of gluten‐free rice flour bread

This study investigated the effect of hot water on the rheological properties of the batter, bubble structure, and sensory properties of the bread. We focused on the thickening effect of starch gelatinization and developed a method to produce gluten-free rice flour bread without additives by increasing the temperature of the water used in the production of gluten-free rice flour bread. Hot water at 50–80°C was more effective than 5°C in improving bubble number and bubble size. In batters prepared using water at 68 and 70°C, which had excellent bubble structure, the frequency-dependent fluctuations of the storage and loss moduli were smaller, while the loss coefficient values were larger. The batters showed more favorable sensory qualities at higher temperatures than the cold-water batters. Appropriate temperature control of the water added during batter preparation can enable easier and cost-effective preparation of high-quality gluten-free rice flour bread. Novelty impact statement Appropriate temperature control of the water added during batter preparation improved the quality of gluten-free rice flour bread. Batter prepared with water at 68 and 70°C improved rheological properties, bubble structure, and sensory properties significantly.

Insight into the regulations of rice protein on the gluten-free bread matrix properties

Gluten-free bread (GFB) crumb was still crisp despite the structure of hydrocolloids. Rice protein (RP), the endogenous protein of gluten-free rice flour, could potentially eliminate the GFB textural disadvantages. Here, RP (0 g/100 g–5.0 g/100 g) replaced the rice flour to investigate their effect on GFB matrix properties by evaluating the dough rheology, crumb texture, bread physicochemical properties and microstructure, respectively. Results of rheological properties indicated the appropriate concentrations of RP enhanced the stored energy and viscoelastic properties of dough, but the excessive one would weaken the structural strength, which was evidenced by the remarkably decreased maximum development height of dough under stress (Hm) and advanced rupture time (Tx) of dough. As a result, the addition of RP positively improved the crumb matrix properties with an increase in springiness, resilience and hardness. Meanwhile, RP made the GFB matrix more moistening with reduced moisture loss and provided crust with pleasant color due to the Millard reaction. However, corresponding to the rheo-fermentation properties, RP had little effect on bread specific volume and even remarkedly decreased it when the RP concentrations exceeded 3.0 g/100 g. As revealed by the microstructure and protein profiles, the addition of RP formed a compacted structure and interacted with hydroxypropyl methylcellulose (HPMC) to enhance the matrix properties, but superfluous RP led to the RP aggregation and interfered with the network of HPMC to deteriorate the GFB structure. • Rice protein (RP) improved the gluten-free bread (GFB) matrix properties. • RP provided the GFB a moist, spring and resilience crumb matrix. • Excessive RP led to protein aggregation interfering with the network of hydroxypropyl methylcellulose (HPMC). • Excessive RP caused a drastic decrease in specific volume. • Synergism of 3% RP and 2% HPMC improved the overall quality of GFB.

Quality improvement of gluten-free rice flour bread through the addition of high-temperature water during processing.

Recently, there has been an increase in the demand for gluten-free bread due to health reasons. One of the flours used to produce gluten-free bread is rice flour; flour characteristics are very important for breadmaking. Although a study has shown that the addition of high-temperature water can improve the quality of rice flour bread, studies are yet to consider different rice properties. Therefore, the aim of this study was to investigate the effect of adding high-temperature water and rice flour characteristics on the quality of rice flour bread using six commercially available rice flours. The rice flours used in the sample had amylose content from 12.1% to 24.5%, damaged starch content from 2.4% to 5.5%, mode diameter from 16.3 to 63.3µm, protein content from 5.4% to 6.1%, and moisture content in the range of 12.0%-15.0%. The results showed that regardless of the rice characteristics, breads prepared at the optimum watering temperature were puffier and softer than those prepared using cold water (5°C). For rice flours with similar particle size, the optimal water temperature and degree of gelatinization for breadmaking increased with rice flours with lower amylose content. Furthermore, the rheological properties of dough prepared at the optimum water addition temperature were stable, with loss modulus (G″) being dominant over the entire frequency range in the frequency sweep test. Since the water temperature added to the dough affects breadmaking properties more than the characteristics of the rice flour, adjusting the water temperature may enable the production of high-quality bread even with rice flour unsuitable for making. PRACTICAL APPLICATION: Presently, the addition of high-temperature water to rice flour has been shown to improve the bread quality. In this study, we investigated the effects of high-temperature water addition on the quality of rice flour bread using rice flour varieties with different flour characteristics. Even in rice flour with small particle size and low amylose content, which is not suitable for breadmaking, bread quality can be improved by adding hot water at around 70°C. This is a simple and practical method to improve the quality of gluten-free rice flour bread without adding thickeners.