Article

Effects of Water Soaking on Bread-Making Quality of Brown Rice Flour

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Abstract

We found that brown rice flour produced using a jet mill after soaking for more than 12 h yielded a better formulation of rice/gluten bread, giving an equivalent specific loaf volume (SLV) as bread made with white rice flour. Quality analysis of the brown rice flour showed that soaking for more than 12 h resulted in a lower damaged starch content. There was a significant inverse correlation between damaged starch content and SLV. Substitution of 10% white rice flour with rice bran had little effect on final SLV. Furthermore, endogenous α-amylase activity in brown rice flour produced after soaking was approximately 5 to 12 times higher than that of white rice flour, but there was no correlation with SLV. These results indicate that the improved SLV in brown rice/gluten bread was predominantly due to the decrease in damaged starch content, which depends on soaking time.

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... The rice properties that lead to rice flour with a fine and less damaged starch through pin milling under dry conditions have been investigated (Ashida et al. 2009, Ashida 2014. The properties of rice flour bread made from high-yielding cultivars (Aoki et al. 2010(Aoki et al. , 2012 and the effects of water soaking on the breadmaking quality of brown rice flour (Hamada et al. 2012) were also investigated, in order to ensure a stable supply of rice flour at a low price. ...
... The production of brown rice flour will also contribute to reducing the cost of producing rice flour because no polishing processes are required (Hamada et al. 2012). Brown rice provides more desirable nutritional properties and biofunctional components, such as inositol, dietary fiber, and gamma aminobutyric acid (GABA), as compared with white rice (Ohtsubo et al. 2005). ...
... However, the use of brown rice flour with wheat and/or gluten as an ingredient in bread making remains limited (Okadome et al. 2007) due to tendency of preventing the dough to rise as compared with white rice flour. It was found that brown rice flour produced using a jet mill after soaking for more than 12 h allowed a better formulation of brown rice flour bread with SLV equivalent to that of bread made with white rice flour containing gluten (Hamada et al. 2012). ...
Article
The production of various rice flour-based food products such as bread, noodles, and cakes is expected to increase the consumption of rice and the utilization of rice paddies in Japan. This paper reviews studies conducted on the characteristics of rice flour and the rice cultivars suitable for the production of rice flour bread containing gluten. The challenges of reducing the cost of producing rice bread are also reviewed. The production of rice flour bread containing gluten of a highly specific loaf volume requires the use of rice flour with a low damaged starch content that can be produced by jet milling wet rice after water or enzyme treatment. The amylose content of rice flour affects the quality of bread, including its shape and hardness. Rice flour with an amylose content of 16% to 20% forms a chewy and moderately soft bread. When rice flour with a low damaged starch content (less than 5%) and a desirable amylose content (16% to 20%) is used, the production of rice flour bread containing gluten is easy without being different from how wheat flour bread is made. In order to reduce the cost of producing rice flour, high-yielding cultivars or a pin milling system using floury rice cultivars should be employed; high-yielding cultivars are now being used for the production of rice flour. With the pin milling system, rice flour belonging to the floury rice cultivar has a low damaged starch content. However, there is a need to develop a high-yield floury rice with reduced weight loss during polishing, as well as new polishing processes. Furthermore, the production of brown rice flour contributes to reducing the cost of producing rice flour because no polishing process is required. Brown rice flour with a low damaged starch content can be produced using a jet mill after soaking for more than 12 h. And given its favorable high nutritional properties, bread made from brown rice flour will prove appealing to consumers. Despite expectations of increasing of the consumption of rice through the use of rice flour as in the production of rice flour bread, the cost reduction of rice flour production and the development of delicious rice flour bread desired by consumers are still insufficient. By understanding the requirements of bread-making companies and obtaining a deeper knowledge about the quality characteristics of rice flour, such as amylose content and protein composition, the production of rice flour bread appealing to consumers can be expected.
... Chen et al. (1988) also reported that pre-soaking of 4% apple fibre partly alleviated the negative effect of the untreated fibre on wheat bread loaf volume. Hamada, Aoki, and Suzuki (2012) analyzed the impact of soaking (2 to 48 h) in a flour mixture containing brown rice and vital gluten in the proportion of 80% to 20%. Instead of soaking the pure bran, brown rice grains were soaked and milled afterwards. ...
... During soaking, also time-dependent changes in enzyme activity may occur that have to be taken into consideration. For instance, Hamada et al., (2012) reported that soaking increased α-amylase activity (5 to 12 times higher), but this surprisingly did not correlate with the specific loaf volume. Instead, a strong interrelation between specific loaf volume and the damaged starch content of brown rice flour (r = 0.987) was revealed. ...
... Instead, a strong interrelation between specific loaf volume and the damaged starch content of brown rice flour (r = 0.987) was revealed. The authors concluded that rice bran had little effect on the rising properties of a brown rice/gluten formulation (Hamada et al., 2012). Since GF batters are a neglected issue in this context, further investigations would be valuable to clarify whether soaking of fibers has a positive effect on GF bread quality. ...
Article
Gluten-free (GF) breads often lack proteins, minerals and fibres and have an imbalanced energy value, as they are primarily based on flour or starch. To nutritionally fortify GF bread, dietary fibres from milling and fruit processing by-products can be utilized. However, fibre addition changes sensorial, nutritional and also technological properties, such as dough or batter hydration. This review evaluates and compares different methods for quantifying the hydration properties of GF fibres and the resulting batters. Revelations are that the hydration properties of fibres vary greatly, depending on the utilized measuring technique, thus impeding the calculation of the appropriate water amount for GF batter processing. In addition, bran and fibres increase the loss factor tan δ and delay thermal transformation, compromising the specific loaf volume. Finally, operational strategies, such as enzymatic or extrusion treatments are discussed regarding their efficiency to increase water absorption in order to further improve GF bread quality.
... Renzetti et al. (2009) reported that proteolysis improved the breadmaking performances of brown rice flour by increasing bread specific volume and decreasing crumb hardness and chewiness. Hamada et al. (2012) reported better gluten-free bread formulation using rice batter fermented with proteases from Aspergillus oryzae. Schober et al. (2007) reported that protein hydrolysis in sorghum batter significantly influences flour pasting properties by increasing paste viscosity, thus improving the quality of sorghum bread. ...
Chapter
Proteases represent one of the largest groups of industrial enzymes accounting for about 60% of the total sale of enzymes worldwide. They are degradative enzymes of central importance and possess both degradative as well as synthetic properties. These occur ubiquitously in plants, animals and microbes. Microorganisms are an excellent source of proteases due to their broad biochemical diversity, easy cultivation, rapid growth and their susceptibility to genetic manipulation. These hydrolytic enzymes find application in food industry for enhancing nutritional value, digestibility, palatability and flavor of food and to reduce allergic peptides. They are 54 also used for management of domestic and industrial wastes. Taking into consideration the need for large-scale application of microbial proteases in food industry, the present communication is an overview of proteases produced from microbial sources and their industrial applications, particularly in food industry.
... Proteins, fats, vitamins, and minerals are concentrated in the outer layer of the endosperm and germ (Roy, Orikasa, Okadome, Nakamura, & Shiina, 2011). Presence of the bran and germ in brown rice offers more desirable nutritional properties and contributes to reducing the cost of production compared to white rice because it does not require a polishing step (Hamada, Aoki, & Suzuki, 2012). Brown rice contains about five times more fiber than white rice which can be found in the bran and germ (Kondo et al., 2017). ...
Article
There is a need for acceptable gluten-free foods that provide greater protein. Rice is used in gluten-free products and new higher protein rice varieties now exist. Stores surveyed for products with rice flour as the main ingredient showed 36% snacks and 13% breads, with baked snacks 1.3 g protein/serving. Bread was chosen as the focus for testing higher protein rice flour (HPR). HPR were compared to commercial rice flours (CW) for pasting properties, protein, fat, and fiber content. Gluten-free bread was prepared and tested for color and texture. A consumer sensory study rated appearance, aroma, texture, and taste of the breads. Brown and white HPR were 10.1% and 9.25% protein. There were no differences in acceptance of breads made with any flour. Health benefit information for HPR breads increased purchase intent. Rice flour with greater protein can be used in gluten-free rice flour baked goods without affecting properties.
... Wheat flour is the most commonly used flour type for leavened baked products made up of a mixture of two groups of proteins named gliadins and glutenins [23,24]. During mixing and hydration, these two proteins combine together and form a viscoelastic gluten network that can retain leavened gas during fermentation and baking [23,[25][26][27]. ...
Article
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Quality evaluation of the porous crumb structure of leavened baked goods, especially bread, has become a vast study area of which various research studies have been carried out up to date. Here is a brief review focusing on those studies with six main parts including porous crumb structure development, crumb cellular structure analysis, application of fractal dimension for evaluating crumb cellular structure, mechanical and sensorial properties of crumb structure, changes of porous crumb structure with staling, and modifications to obtain a well-developed porous crumb structure and retard staling. Development of the porous crumb structure mainly depends on dough ingredients and processing conditions. Hence, certain modifications for those factors (incorporating food hydrocolloids, emulsifiers, improvers, etc.) have been conducted by cereal sciences for obtaining well-developed porous crumb structure and retard staling. Several image analysis methods are available for analyzing microstructural features of porous crumb structure, which can directly affect the mechanical and sensorial properties of the final product. A product with a well-developed porous crumb structure may contain the property of higher gas retention capacity which results in a product with increased volume and reduced crumb hardness with appealing sensorial properties.
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Chapter
INTRODUCTION WHEAT FLOUR CONSTITUENTS IN BREADMAKING FUNCTIONALITY OF ENZYMES IN BREADMAKING SYNERGETIC EFFECTS CONCLUSIONS ACKNOWLEDGMENTS
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Development of a novel foodstuff from pre-germinated brown rice by a twin-screw extruder was investigated. The characteristics of the components of the materials and the products are as follows: (1) Pre-germinated brown rice was prepared by soaking in water for 72 h at 30 °C followed by drying to 13–15% moisture content at 15 °C in a low-humidity artificial weather-control room. Total dietary fiber, total ferulic acid and gamma-aminobutyric acid (GABA) contents of the pre-germinated brown rice were higher than those of ordinary brown rice or polished rice. (2) The pre-germinated brown rice was processed with a twin-screw extruder. The puffed pre-germinated brown rice contained more oryzanol, inositol, total ferulic acid and total dietary fibers compared with the un-puffed polished rice. The product prepared by the co-extrusion of pre-germinated brown rice (90%) and beer yeast (10%) contained more free amino acids, such as GABA, glycine, alanine, aspartic acid and glutamic acid, compared with polished rice, brown rice and puffed pre-germinated brown rice. (3) Extrusion cooking was shown to sterilize the germinated brown rice by the incubation test, which would lead to the development of consumer-oriented rice products in terms of food safety. (4) The wheat bread prepared with 30% of the puffed pre-germinated brown rice contained more GABA, free sugars, such as maltose, compared with the ordinary wheat bread. The extrudate bread was shown to be sweeter (P<0.05) and equivalently palatable (P<0.05) as a result of organoleptic test.These results show that novel foodstuff from the extruded pre-germinated brown rice would be acceptable to consumers or the food industry as a promising foodstuff containing more nutritional and bio-functional components than ordinary rice products.
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Gluten is a fundamental component for the overall quality and structure of breads. The replacement of the gluten network in the development of gluten-free cereal products is a challenging task for the cereal technologist. The functionality of proteins from gluten-free flours could be modified in order to improve their baking characteristics by promoting protein networks. Transglutaminase (TGase) has been successfully used in food systems to promote protein cross-linking. In this study, TGase was investigated for network forming potential on flours from six different gluten-free cereals (brown rice, buckwheat, corn, oat, sorghum and teff) used in breadmaking. TGase was added at 0, 1 or 10 U/g of proteins present in the recipe. The effect of TGase on batters and breads was evaluated by fundamental rheological tests, Texture Profile Analysis and standard baking tests. Three-dimensional elaborations of Confocal Laser Scanning Microscopy (CLSM) images were performed on both batters and breads to evaluate the influence of TGase on microstructure. Fundamental rheological tests showed a significant increase in the pseudoplastic behaviour of buckwheat and brown rice batters when 10 U of TGase were used. The resulting buckwheat and brown rice breads showed improved baking characteristics as well as overall macroscopic appearance. Three-dimensional CLSM image elaborations confirmed the formation of protein complexes by TGase action. On the other side, TGase showed negative effects on corn flour as its application was detrimental for the elastic properties of the batters. Nevertheless, the resulting breads showed significant improvements in terms of increased specific volume and decreased crumb hardness and chewiness. Under the conditions of this study, no effects of TGase could be observed on breads from oat, sorghum or teff. Overall, the results of this study show that TGase can be successfully applied to gluten-free flours to improve their breadmaking potentials by promoting network formation. However, the protein source is a key element determining the impact of the enzyme.
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In this study, protease treatment of brown rice (BR) batters was investigated in order to evaluate its impact on the textural and baking properties of BR bread. The enzymatic treatment improved bread quality by significantly increasing specific volume (p < 0.05), while decreasing crumb hardness and chewiness (p < 0.05). Fundamental rheology and viscometry of batters revealed that protein hydrolysis induced lower complex modulus and initial viscosity, while phase angle was unaffected. Flour pasting properties were also affected, with a significant decrease in paste viscosity and breakdown (p < 0.05). Protein analysis of batters revealed that the enzymatic treatment induced the release of low molecular weight proteins from macromolecular protein complexes. In conclusion, a lower resistance to deformation of batters during proofing and in the early stages of baking as well as the preserved batter elasticity and the increased paste stability positively affected the breadmaking performance.
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Rice flour is one of the most valuable cereal flours from a nutritional viewpoint. However, its use is limited to unfermented baked products since rice proteins are unable to hold gas produced during fermentation. Protein functionality can be modified by cross-linking. Rice flour was treated with different concentrations of a microbial transglutaminase (TG). The extent of the modification was evaluated by quantifying amino and thiol groups. The addition of TG improved the dynamic rheological properties of rice flour doughs, resulting in a progressive increase of the viscous (G″) and elastic (G′) moduli with increase in TG concentration. The improvement in rice protein functionality became evident in breadmaking, since it was possible to obtain rice bread with an increased specific volume and softer crumb at 1% TG level in the presence of 2% hydroxypropylmethylcellulose. Analyses showed that rice proteins are polymerised through the TG reaction, providing a protein network necessary for holding the gas produced in fermentation.
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The wide prevalence of celiac disease and wheat allergy has led to a growing demand for gluten-free foods. Rice proteins do not possess the viscoelastic properties typically found in gluten, thus making rice flour unsuitable for the production of yeast-leavened products. In the present study, we found that the addition of glutathione to rice batter improves its gas-retaining properties. Glutathione was found to prevent the formation of the disulfide-linked macromolecular protein barrier, which is reported to confer resistance to the deformation of rice batter in the baking process. Also, glutathione appeared to gelatinize rice starch at lower temperatures. Microstructure analyses of glutathione-added rice bread revealed it to have a perforated structure like wheat bread but with a smoother-looking surface. These data collectively suggest that glutathione facilitates the deformation of rice batter, thus increasing its elasticity in the early stages of bread baking and the volume of the resulting bread.
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Characteristics of the bread prepared from wheat flour blended with the flour of various kinds of newly developed rice cultivars were investigated. Qualities of the bread made from wheat flour blended with rice flour have been reported to be inferior to those from 100% wheat flour bread. To improve its qualities, we searched for the new-characteristic rice flours among the various kinds of newly developed rice cultivars to blend with the wheat flour for the bread preparation. The most suitable new characteristic rices are combination of purple waxy rice, high-amylose rice, and sugary rice. Specific volume of the bread from the combination of wheat and these 3 kinds of rice flours showed higher specific volume (3.93) compared with the traditional wheat/rice bread (3.58). We adopted the novel method, continuous progressive compression test, to measure the physical properties of the dough and the bread in addition to the sensory evaluation. As a result of the selection of the most suitable rice cultivars and blending ratio with the wheat flour, we could develop the novel wheat/rice bread, of which loaf volume, physical properties, and tastes are acceptable and resistant to firming on even 4 d after the bread preparation. To increase the ratio of rice to wheat, we tried to add a part of rice as cooked rice grains. The specific volume and qualities of the bread were maintained well although the rice content of total flour increased from 30% to 40%.
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