Rice Flour Starch Research Articles

Microwave‐assisted treatment for the improvement of rice flour properties and rice flour bread quality

SummaryModification of rice flour by microwave and its effect on bread making performance was evaluated. Rice flour having two different water content (20% and 30%) were exposed to different level of microwave power (600 W, 700 W and 800 W) with 8 min treatment time to assess its influence on amylose content, thermal properties, morphological structure, functional and crystalline structural that affect bread quality. Microwave‐treated rice flour at 600 W showed notable increment in amylose content of 1.03 folds (for both 20% and 30% water content) as compared to untreated rice flour. The microwave treatment destroyed the amorphous region of the rice flour starch, whereas starch crystal structure was slightly increased after treatment. Rice flour maintained its thermal stability even after exposure to high radiation of microwave. The treated rice flour exhibited starch granules with more voids on its surface, indicating the exudation of amylose at higher temperature. The major effect of microwave treatment was observed on the bread for rice flour treated at 800 W with higher specific volume, increase in gas cells pores, softer crumb, low hardness and delayed staling as compared to untreated rice flour. The microwave‐assisted treatment shows a significant potential in improving the rice flour quality led to increase the quality of bread.

Effects of soaking treatment on water distribution of rice grains, starch characteristics and eating quality of wet rice noodles

Herein, rice was subjected to different soaking processes on water distribution of rice grains, starch characteristics, and eating quality of fresh wet rice noodles. Results demonstrated that, when soaked at temperatures between 10 °C and 40 °C for 120 min, rice grains reached saturation in water absorption, and the hardness gradually stabilized. However, the moisture continued to penetrate the interior of rice grains after 120 min, leading to an increase in moisture content, higher water permeability, and enlarged water migration channels. With extended soaking time periods, the content of damaged starch in rice flour considerably decreased. Although the gelatinization temperature of rice starch decreased after soaking, the enthalpy required for gelatinization increased. The relative crystallinity of rice starch demonstrated an increasing trend, followed by a decreasing trend, and reached its highest value of 18.18 % after 60 min of soaking. To summarize, the texture indices of fresh rice noodles demonstrated an increasing trend, although stretching and cooking quality demonstrated a trend of initially increasing and then decreasing with no considerable changes observed between 120 and 240 min of soaking. In summary, moderate soaking treatment can enhance the edible quality of fresh wet rice noodles.

Higher Grain-Filling Rate in Inferior Spikelets of Tolerant Rice Genotype Offset Grain Yield Loss under Post-Anthesis High Night Temperatures

Increased nighttime respiratory losses decrease the amount of photoassimilates available for plant growth and yield. We hypothesized that the increased respiratory carbon loss under high night temperatures (HNT) could be compensated for by increased photosynthesis during the day following HNT exposure. Two rice genotypes, Vandana (HNT-sensitive) and Nagina 22 (HNT-tolerant), were exposed to HNT (4 °C above the control) from flowering to physiological maturity. They were assessed for alterations in the carbon balance of the source (flag leaf) and its subsequent impact on grain filling dynamics and the quality of spatially differentiated sinks (superior and inferior spikelets). Both genotypes exhibited significantly higher night respiration rates. However, only Nagina 22 compensated for the high respiration rates with an increased photosynthetic rate, resulting in a steady production of total dry matter under HNT. Nagina 22 also recorded a higher grain-filling rate, particularly at 5 and 10 d after flowering, with 1.5- and 4.0-fold increases in the translocation of 14C sugars to the superior and inferior spikelets, respectively. The ratio of photosynthetic rate to respiratory rate on a leaf area basis was negatively correlated with spikelet sterility, resulting in a higher filled spikelet number and grain weight per plant, particularly for inferior grains in Nagina 22. Grain quality parameters such as head rice recovery, high-density grains, and gelatinization temperature were maintained in Nagina 22. An increase in the rheological properties of rice flour starch in Nagina 22 under HNT indicated the stability of starch and its ability to reorganize during the cooling process of product formation. Thus, our study showed that sink adjustments between superior and inferior spikelets favored the growth of inferior spikelets, which helped to offset the reduction in grain weight under HNT in the tolerant genotype Nagina 22.

Physicochemical properties of starch in rice flour with different hardening rates of glutinous rice cake (mochi)

The hardening rate of glutinous rice cake (mochi) made by Kagura-mochi (Kag) was two times higher than that of Hakusanmochi (Hak). Protein in the waxy rice indicated a similar distribution and content; therefore, the textural properties of the rice product were dependent on the physicochemical properties of starch in the rice flour. Urea-induced gelatinization, differential scanning calorimetry, and rapid visco analysis revealed that starch in Kag was less easily gelatinized than that in Hak. The solubility and swelling power at 70 °C of starch in Kag rice flour were slightly lower than that in Hak. Relative crystallinities of starch in Kag and Hak rice flour were 55.1% and 49.3%, respectively. The chain length distribution of the short chain of amylopectin in Kag rice flour was lower than that in Hak. The low short-chain content in Kag may be related to the increase in the hardening rate of the mochi made by Kag.

Structural support of zein network to rice flour gluten-free dough: Rheological, textural and thermal properties

Zein forms viscoelastic network with water to support the weak structure of gluten-free dough, but which requires temperature above 40 °C. A new method preparing zein network at room temperature using food-grade acetic acid was reported in our previous research. The current research explored the influence of zein network containing acetic acid on the rheology, texture, and tensile properties of rice gluten-free dough, as well as the interaction between zein network and rice flour. Results showed that zein network could act as a structural support material by binding rice flour particles to transmit its viscoelasticity and extensibility to rice dough, thus enhancing the ability of rice dough to resist external forces. The structural characteristics of zein-rice dough were both zein network-dependent and rice flour-dependent. α-Zein network could mix with rice flour particles more evenly than total-zein (T-zein, comprising α-, β- and γ-zein) network due to the thinner and denser fiber bundles, so the stretchability and thermal stability of α-zein-rice dough were greater than that of T-zein-rice dough, and the cooking loss of α-zein-rice noodle was less than that of T-zein-rice noodle. Compared with japonica rice dough and indica rice, waxy rice had less amylose, so the elasticity of zein-waxy dough was weaker than that of zein-japonica dough and zein-indica dough. And the gel network formed by amylose in rice during heating increased the elasticity of zein-rice dough. Additionally, the interaction between zein network and rice flour increased the ordered structure of starch in rice flour.

Effect of Shearing and Heat Milling Treatment Temperature on the Crystallinity, Thermal Properties, and Molecular Structure of Rice Starch.

Rice flour is produced by various methods for use in the food industry, but little is known about how the structure of starch is affected during rice flour production. In this study, the crystallinity, thermal properties, and structure of starch in rice flour were investigated after treatment with a shearing and heat milling machine (SHMM) at different temperatures (10-150 °C). Both the crystallinity and gelatinization enthalpy of starch showed an inverse relationship with the treatment temperature; rice flour treated with the SHMM at higher temperatures showed lower crystallinity and gelatinization enthalpy than that treated at lower temperatures. Next, the structure of undegraded starch in the SHMM-treated rice flour was analyzed by gel permeation chromatography. A significant reduction in the molecular weight of amylopectin was observed at high treatment temperatures. Chain length distribution analysis showed that the proportion of long chains (degree of polymerization (DP) > 30) in rice flour decreased at temperatures ≥ 30 °C. By contrast, the molecular weight of amylose did not decrease. In summary, the SHMM treatment of rice flour at high temperatures resulted in starch gelatinization, and the amylopectin molecular weight decreased independently, due to the cleavage of amorphous regions connecting the amylopectin clusters.

Evaluation of temperature and concentration on the development of rice hydrogel and 2D xerogel

The gelification behavior of starch in rice flour was investigated for its application on food structuring to produce rice xerogel. The effect of hydrogel nature in drying was studied for the xerogel surface design. The impact of changes in rice flour was found by the least gelation concentration and pasting properties. It exhibited 4% (w/v) gelatinized rice flour dispersion and can form a 3D polymer network during cooling. Assessment of hydrogel preparation temperature was examined by swelling power, solubility, surface tension, contact angle, and transmittance. An increase in swelling power, solubility, and density is due to the effective binding of starch with water molecules. The decline in absorbance specifies loss of crystallinity and birefringence because of starch granules disruption. Surface tension increased, and contact angle decreased at a higher temperature because of gelling nature. Various concentrations (2%, 4%, and 6%) of rice flour dispersion were exposed to heat at temperatures (60, 70, 80, 90, and 100°C) for developing rice xerogel. It was observed that 4% (w/v) of rice flour suspension gellified at 90°C possesses better structural integrity without deformation and cracks. Novelty Impact Statement The obtained 2D rice xerogel with the addition of flavor could be utilized in complex-shaped foods like chips, pasta, and noodles. As 2D flour-based materials are capable of undergoing shape change into a 3D form during frying/cooking, this is an arising innovation that could encourage diminishing packaging and shipping costs as well as to design user-customized attractive materials.

Quantification of Starch Order in Physically Modified Rice Flours Using Small-Angle X-ray Scattering (SAXS) and Fourier Transform Infrared (FT-IR) Spectroscopy.

The purpose of this study was to understand the ordered structure of starch in rice flour based on a physical modification with non-heating, milling, and water sorption through the structural evaluation of rice flour using small-angle X-ray scattering (SAXS) and infrared spectroscopy within the 4000-100 cm-1 region. The SAXS pattern of the samples with low moisture contents subjected to milling yield a band within the 0.4-0.9 nm-1 of the q range owing to a lamellar repeat of starch with an ordered structure in rice flour. We proposed an order parameter using the intensity of the SAXS band to quantify the order structure of starch in rice flour, and the true density was negatively correlated with the order parameter. Infrared band at 990 cm-1 in COH bending mode applied to the hydroxyl group of C6 shifted to a low wavenumber corresponding to the order parameter. A linear correlation was found between the order parameter and the 990 cm-1 and band at 861 cm-1 owing to COC symmetrical stretching of glycoside bond and CH2 deformation of the glucose unit of starch, 572, 472, and 436 cm-1, owing to the pyranose ring in the glucose unit of starch. The identified infrared bands are effective for quantifying the ordered structure of starch at the lamellar level. When subjected to water sorption, the band position at 990 cm-1 shifted to a higher wavenumber above a water activity of 0.7. This result revealed that the water-induced transition of glass to rubber of starch in rice flour can be clearly evaluated through infrared spectroscopy using the band at 990 cm-1. In addition, the band at 861 cm-1 also shifted to a higher wavenumber, whereas those at 572 and 436 cm-1 did not show a significant shift. These results indicate that water sorption slightly affects the internal structure and may mainly affect the surface of starch.

TOFU DREGS AS A NUTRIENT FOR Saccharomyces cerevisiae IN THE PRODUCTION OF BIOETHANOL FROM RED RICE (Oryza nivara) THROUGH FERMENTATION

Research on the production of bioethanol from red rice flour starch (Oryza nivara) through enzymatic hydrolysis process and fermentation by Saccharomyces cerevisiae with the addition of tofu dregs as a nutrient source of microorganisms has been conducted. The process of bioethanol production consisted of hydrolysis, fermentation, distillation and ethanol content analysis using gas chromatography instrument. This research was conducted to determine the concentration of nutrients and the duration of fermentation to produce optimal ethanol levels. The hydrolysis process is carried out enzymatically through the liquification stage using ?-amylase and gluco-amylase at the saccharification stage. Then the fermentation process continued with a variation of 7, 8 and 9 days using Saccharomyces cerevisiae with the addition of tofu dregs concentration 0.5 %, 1 % and 1.5 % (w/v). The highest ethanol levels obtained from gas chromatography analysis was the addition of tofu dregs 1 % (w/v) and fermentation time for 8 days, with ethanol content obtained at 59.325 %.

INVESTIGATION OF THE EXPEDIENCE OF MODIFICATION OF THE CARBOHYDRATE COMPOSITION OF RICE FLOUR IN THE TECHNOLOGY OF GLUTEN-FREE BREAD

The research considers a possibility of using modification of the carbohydrate composition of rice flour in the technology of bread of the special destination for celiachia. There has been conducted an analysis of the condition of the carbohydrate-amylase complex of rice flour. Revealed regularities have demonstrated that this flour has an unessential amylolytic activity that negatively influences the course of microbiological processes in gluten-free dough and quality parameters of ready products. The aim of the research was to develop arrangements as to accumulation of sugars in dough at the expanse of own reserves of rice bread for providing the necessary intensity of rice dough fermentation by using enzymes of the amylolytic effect. It is a precondition for improving structural-mechanical and organoleptic properties of gluten-free rice bread. At the same time accumulation of products of incomplete hydrolysis of flour starch in the process of its fermentative modification – dextrins will favor deceleration of ready products staling. There has been established the influence of α-amylase of the fungal origin and glucoamylase on accumulation of sugars at hydrolysis of rice flour starch. It has been studied, that dosage of α-amylase in amount 0,005 % and glucoamylase – 0,03 % of a flour mass results in creating sugars in amount 5,5–6 %. There has been proved the effectiveness of using α-amylase by accumulation of dextrins, in which composition the essential raise of the content of low-molecular ones – archo- and maltodextrins has been determined. Based on the conducted studies, it has been determined, that hydrolysis products of rice flour starch are created as a result of its fermentative modification by α-amylase and glycoamylase that is testified by the increase of gas-creation and acid-accumulation. There has been observed the positive influence of using modification of the carbohydrate composition of flour in the technology of rice bread on the specific volume, porosity structure and flexible-elastic properties of crumb of ready products. It has been established, that realization of hydrolysis of flour starch at producing rice bread favors prolongation of its fresh storage term as a result of raising the amount of dextrins, created under the effect of α-amylase.

Studying the possibility of using enzymes, lecithin, and albumen in the technology of gluten-free bread

The comprehensive approach to the technology of bread for people suffering from celiac disease by applying amylolytic enzymes, lecithin, and dry egg albumen was scientifically substantiated. The effect of amylolytic enzymes on sugars accumulation during the hydrolysis of rice flour starch was established. It was proved that the use of enzymes contributes to the formation of mono-and disaccharides in quantity of 5.5–6 %, which are essential for the intensification of microbiological processes in dough. The improvement of gas production in dough during the application of the enzymatic modification of flour starch during fermentation was detected. With the aim of improving the quality of the dough semi-finished and finished products, the expedience of using surfactants was substantiated. The regularities of the influence of sunflower defatted lecithin on properties of dough and quality characteristics of bread with enzymes were determined. It was established that the introduction of phospholipid into dough using the enzymatic modification of starch flour contributes to the improvement of gas formation in it and causes an increase in specific volume and porosity of finished products. To ensure the porous structure of the crumb, the additional use of dry egg albumen in the technology of rice bread was proposed. It was established that the preliminary recovery of albumen when making dough with enzymes and lecithin contributes to its better leavening, which provides high quality indicators of the finished products. It was proved that the use of sunflower defatted lecithin and whipped egg albumens during dough kneading with previously conducted hydrolysis of starch flour by α-amylase and glucoamylase leads to a significant increase in its gas-retaining abilities and contributes to increasing its running. Given the reduction in viscosity of the dough with the addition of selected raw materials, it is recommended to manufacture pan bread. The influence of application of the enzymatic modification of rice flour starch, lecithin, and egg albumen on the process of gelatinization of water-flour suspensions was studied. The identified regularities make it possible to predict an increase in the shelf life of the finished bread.

Influence of fermentative modification of rice flour starch on bread quality for patients with celiac disease

Influence of fermentative modification of rice flour starch on bread quality for patients with celiac disease

In vitro starch digestibility of rice flour is not affected by method of cooking

This study evaluated the effects of different cooking methods on in vitro starch digestibility of three rice varieties. Results from differential scanning calorimetry and X-ray diffraction of cooked rice flours showed that rice starch was completely gelatinized after cooking. The overall paste viscosities of cooked indica hybrid flour (IHF) and japonica flour (JF) were lower than those of their corresponding raw flours. However, cooked waxy flour (WF) showed much higher paste viscosities than raw flours, especially the viscosity at the start of RVA testing. Cooking increased greatly the rate and extent of starch digestion of IHF and JF, but had a small effect on WF. There were small differences in rate and extent of starch digestion of rice after cooking under various conditions. Cooking methods were found to have little effect on in vitro starch digestibility of rice. Viscosity of the gelatinized waxy starch matrix affected in vitro starch digestibility. This study enables us to gain a better understanding of cooking effects on in vitro digestibility of starch in rice flour.

Study on the Change in Powder Properties of Rice Flour by Different Milling Processes.

The aim of this study was to clarify the change in the powder properties of rice flour depending on the milling process. Rice flour samples, which have gradual mechanical shock properties, were prepared using different milling methods. Furthermore, the correlation between the starch damage, owing to mechanical shock, and powder properties of rice flour was investigated. The particle size was changed gradually through each milling process; however, the change did not clearly correlate with starch damage. The results of the X-ray diffraction (XRD) pattern of nongelatinized samples showed the typical A-type structure of starch. The crystal structure of starch in rice flour may change to a disorder state with the progress of milling; thus, in this study, instead of crystallinity, we considered the disorder index (DI) calculated from the XRD intensity of samples. Relationship between DI and starch damage was confirmed with R2 = 0.923. Therefore, the mechanical shock caused by the milling process contributes to the crystal state of starch. The parameter qm calculated from the Guggenheim-Anderson-de Boer (GAB) equation of each sample corresponded to the DI. This result suggested that the sorption site of rice flour decreased, and a positive correlation was observed between the parameter K and DI. Thus, the interaction between the rice flour and water molecules weakened because of the mechanical shock. In addition, the use of a SEM image supports the insight that the change in parameter K may reflect the structural change in the solid phase. These results demonstrated that the change in powder properties of rice flour caused by mechanical shock of the milling could evaluate quantitatively.

Molecular rearrangements in extrusion processes for the production of amaranth-enriched, gluten-free rice pasta

Gluten-free pasta represents a challenge for food technologists and nutritionists since gluten-free materials used in conventional formulations have poor functional and nutritional properties. A novel extrusion-cooking process was set up to improve the textural characteristics of rice-based pasta, and to enrich it with amaranth. Mineral and fiber content, and protein digestibility were improved by amaranth enrichment. Extrusion-cooking of a 75/25 mixture of rice flour and amaranth prior to pasta-making gave the best results as for the textural characteristics of the final product. The firmness of cooked pasta increased due to the extrusion-cooking process, that also decreased protein solubility in the amaranth-enriched pasta. The content in accessible thiols also decreased in amaranth-enriched pastas, indicating that amaranth proteins may be involved in forming disulphide bonds during the pasta-making process. Our results suggest that starch in rice flour interacts best with amaranth proteins when starch gelatinization occurs simultaneously to protein denaturation in the extrusion-cooking process.

Milling of Rice Grains. The Degradation on Three Structural Levels of Starch in Rice Flour Can Be Independently Controlled during Grinding

Whole polished rice grains were ground using cryogenic and hammer milling to understand the mechanisms of degradation of starch granule structure, whole (branched) molecular structure, and individual branches of the molecules during particle size reduction (grinding). Hammer milling caused greater degradation to starch granules than cryogenic milling when the grains were ground to a similar volume-median diameter. Molecular degradation of starch was not evident in the cryogenically milled flours, but it was observed in the hammer-milled flours with preferential cleavage of longer (amylose) branches. This can be attributed to the increased grain brittleness and fracturability at cryogenic temperatures, reducing the mechanical energy required to diminish the grain size and thus reducing the probability of chain scission. The results indicate, for the first time, that branching, whole molecule, and granule structures of starch can be independently altered by varying grinding conditions, such as grinding force and temperature.

Proton NMR relaxation study of swelling and gelatinisation process in rice starch–water samples

Proton transverse magnetization decay curves of rice flour starch–water samples were measured and analysed for the presence of four components in the relaxation curve. T2 values were interpreted on the basis of the diffusive and chemical exchange model that provided evidence for extra granular bulk water and three more water populations whose relaxation rate is governed by diffusive and chemical exchange with starch components. The analysis of relaxation data provided information on dynamics of water molecules as well as on the size and dispersion of diffusive domains. Furthermore, by measuring solid to liquid ratio, transverse and longitudinal relaxation curves of starch–water mixtures at increasing temperatures – from 20 to 77°C – swelling and gelatinisation processes were monitored.

Modification of Gelatinization Properties of Rice Flour by Heat-Treatment

The effects of autoclave and oven treatments on gelatinization properties of rice flour and on crystallite structures of rice starch in rice flour were studied using dynamic oscillatory measurement, differential scanning calorimetry (DSC), X-ray diffractometry, and scanning electron microscopy (SEM). Autoclave-treated rice flour (ATR) and oven-treated rice flour (OTR) were prepared using an autoclave at 120 °C for 60 min and oven at 160 °C for 60 min. Dynamic oscillatory and DSC measurements demonstrated that autoclave treatment modified the gelatinization properties that delayed gelatinization temperature (TG' and To) and decreased in peak storage modulus (G'p). Autoclave treatment caused formation of amylose-lipid complexes and partial gelatinization of starch granules in ATR studied by DSC and X-ray diffractometry. Autoclave-treatment engendered formation of amylose-lipid complexes and partial gelatinization of starch granules in ATR studied by DSC and X-ray diffractometry. Alteration of gelatinization properties of ATR flour is attributed to changes in rigidity of starch granules during treatment. Similarly to ATR, oven treatment was effective for gelatinization properties. Nevertheless, it was insufficient for rearrangement of starch chains in OTR flour.

Hydrogen Breath Test With Low-Dose Rice Flour for Assessment of Exocrine Pancreatic Insufficiency

The hydrogen (H2) breath test is widely used in the assessment of carbohydrate malabsorption. Severe exocrine pancreatic insufficiency markedly diminishes pancreatic amylase production and results in malabsorption of complex carbohydrates. Thus, the H2 breath test with low-dose rice flour starch was tested to determine its value in detecting exocrine pancreatic insufficiency by comparison with a direct measurement of pancreatic function. Ten patients with clinically suspected pancreatic insufficiency confirmed with a duodenal perfusion technique and measurement of trypsin and lipase output after cerulein stimulation were included. An H2-rice flour breath test was performed by orally administering 30 g of rice flour. End-alveolar breath samples were obtained before rice load and at 30-minute intervals thereafter for the next 5 hours. The results are expressed as median (percentile 25-75). Patients included 8 men and 2 women with moderate to severe exocrine pancreatic insufficiency due to chronic pancreatitis, pancreatectomy, or cystic fibrosis. Stimulated duodenal output of lipase and trypsin was abnormally low in all patients (median release, 1.7; range, 0.5-4.5 and 0.8, range, 0.1-11.3 KU/h, respectively). Basal H2 excretion was 9 ppm (range, 7-17) and delta increase over basal H2 excretion was 4 ppm (range, 1-6). Correlation between H2-rice breath test and basal or stimulated duodenal output of lipase and trypsin was not significant. In exocrine pancreatic insufficiency, an oral load of 30 g rice flour slightly raises H2 excretion in breath. This increase is not useful for detecting pancreatic insufficiency due to poor sensitivity and because it is influenced by extrapancreatic factors such as small bowel bacterial overgrowth.

SCREW CONFIGURATION EFFECTS ON STARCH BREAKDOWN DURING TWIN-SCREW EXTRUSION of RICE FLOUR

Screw configuration effects on starch breakdown and ext rudate porosity were investigated during twin-screw extrusion of rice flour. the type, length, position, of mixing elements and spacing between two elements significantly affected molecular breakdown of starch in rice flour and extrudate porosity. Generally, screw profiles with reverse screw element produced more starch breakdown and porous extrudates than those with kneading block. A systematic increase of starch breakdown was observed as the mixing elements were moved fart her from the die, with longer elements, and with increased spacing between elements. Extent of starch breakdown affected porosity of extrudates. Extrudate porosity decreased systematically with increasing distance between die and mixing element, with larger spacing between the elements, and by moving two elements (with same spacing) farther from the die, irrespective of the element type and length. Porosity increased with increasing die temperature.