Use of Mixolab in Predicting Rice Quality

Mixolab is a new instrument with capability to measure starch pasting properties on actual dough. It characterizes dough rheological behavior using a dual constraints of mixing and temperature. Rice samples (183) collected from 15 provinces across China were tested to determine the possibility of using Mixolab in predicting rice quality. Mixolab measurements, torque (Nm) at different mixing and heating stages (C1 to C5) were compared with rice quality characteristics (gelatinization temperature and consistency, amylose and protein contents), Rapid Visco‐Analyser (RVA) parameters and sensory assessments scores of cooked rice. Our results showed that Mixolab parameters were good indicators of amylose and protein content and quality suggested by significant correlations among Mixolab parameters, and between Mixolab and RVA measurements. Based on a subsample of 30 rice cultivars, correlation coefficients between the Mixolab parameter C4 and sensory assessment characteristics of palatability and total sensory score was negatively significant (P < 0.05). C_b (C3 – C4) was also significantly correlated with flavor (P < 0.05). The rice samples that gave high palatability and total sensory scores had low C4 values and low amylose contents. The cooked rice with high flavor had high values of C_b and GT but low protein content. It is possible to determine physicochemical properties of rice flour and sensory characteristics of cooked rice using Mixolab parameters.     

Variability and Relationships Among Mixolab,Mixograph, and Baking Parameters Based on Multienvironment Spring Wheat Trials

Because of the large number of cultivars that require examination in the development of spring wheat (Triticum aestivum L.) cultivars, breeding programs use predictive methods to test end use quality. The Mixograph is a widely used predictive test with which end use quality of many genotypes can be assessed in a short time. By comparison, the Mixolab is a relatively new device with additional capability that might be used for the same purpose. Our objective was to document variability of, and relationships among, 20 parameters obtained from Mixolab, Mixograph, and bake tests. Tests were performed on flour from 18 genotypes grown in 20 environments. Both genotype and environment had significant effects on quality parameter values. Several Mixograph and Mixolab parameters were highly significantly correlated, particularly when genotype mean values over environments were considered. Correlations between loaf volume and Mixolab parameters within environments were inconsistent and suggest that average genotype values over environments will be most useful. For example, the correlation between Mixolab stability and loaf volume (r = 0.25, P < 0.001) was much higher when genotype averages (r = 0.70, P < 0.001) were considered. Our results show that selection for Mixolab stability and water absorption should help delineate and improve the selection of genotypes with greater loaf volume.     

Physicochemical and Rheological Properties of Chinese Soft Wheat Flours and Their Relationships with Cookie‐Making Quality

The relationship of solvent retention capacity (SRC) values with four solvents, alveograph and farinograph properties, and cookie‐baking performance was evaluated with 20 Chinese soft wheat genotypes, including four cultivars and 16 advanced lines grown in the 2009–2010 season. Significant positive correlations were observed between water SRC (WSRC), sodium carbonate SRC (SOSRC), lactic acid SRC, and sucrose SRC (SUSRC) values. WSRC, SUSRC, and SOSRC showed significant positive correlations with farinograph water absorption (WA), alveograph P (tenacity), and P/L (ratio of tenacity to extensibility). Cookie diameter was significantly correlated with wet gluten (r = –0.491, P < 0.05), WSRC (r = –0.882, P < 0.001), SUSRC (r = –0.620, P < 0.01), SOSRC (r = –0.712, P < 0.001), P (r = –0.787, P < 0.001), L (r = 0.616, P < 0.01), P/L (r = –0.766, P < 0.001) and WA (r = –0.620, P < 0.01), respectively. SRC values were effective predictors of cookie quality in Chinese soft wheat. Alveograph parameters were more closely correlated to cookie quality than were farinograph parameters.     

Relationship Between Solvent Retention Capacity and Protein Molecular Weight Distribution,Quality Characteristics,and Breadmaking Functionality of Hard Red Spring Wheat Flour

This research aims to investigate the relationship between the solvent retention capacity (SRC) test and quality assessment of hard red spring (HRS) wheat flour samples obtained from 10 HRS cultivars grown at six locations in North Dakota. The SRC values were significantly (P < 0.05) correlated with flour chemical components (protein, gluten, starch, and damaged starch contents, except arabinoxylan); with farinograph parameters (stability [FST], water absorption, peak time [FPT], and quality number); and with breadmaking parameters (baking water absorption [BWA], bread loaf volume [BLV], and symmetry). Differences in locations and cultivars contributed significantly to variation in quality parameters and SRC values. Suitability of SRC parameters for discriminatory analysis of HRS wheat flour is greatly influenced by molecular weight distribution (MWD) of SDS‐unextractable proteins. SRC parameters, except for sucrose SRC, showed significant (P < 0.01) and positive correlations with high‐molecular‐weight (HMW) polymeric proteins in SDS‐unextractable fractions, whereas only lactic acid SRC exhibited significant (P < 0.01) correlations with low‐molecular‐weight polymeric proteins. HMW polymeric proteins also exhibited positive associations with FPT, FST, BWA, and BLV. The discrepant variation in association of SRC parameters with respect to MWD of SDS‐unextractable proteins could improve segregation of HRS wheat flour samples for quality.     

Relationships of Free Lipids with Quality Factors in Hard Winter Wheat Flours

Hard winter wheat (Triticum aestivum L.) flours (n = 72) were analyzed for free lipids (FL) and their relationships with quality parameters. The two main glycolipid (GL) classes showed contrary simple linear correlations (r) with quality parameters. Specifically, kernel hardness parameters, flour yields, and water absorptions had significant negative correlations with monogalactosyldiglycerides (MGDG) but positive correlations with digalactosyldiglycerides (DGDG). MGDG showed negative correlations with gluten content but positive correlations with gluten index. The percentages of DGDG in FL had significant positive correlations among cultivars (n = 12) with mixograph and bake mix times (r = 0.71, P < 0.01 and r = 0.67, P < 0.05, respectively), mixing tolerance (r = 0.67, P < 0.05), and bread crumb grain score (r = 0.71, P < 0.01). These results suggest that increasing DGDG in FL could contribute to enhancing wheat quality attributes including milling, dough mixing, and breadmaking quality characteristics. FL content and composition (ratio of MGDG or DGDG to GL) supplement flour protein content to develop prediction equations of mixograph mix time (R² = 0.89), bake mix time (R² = 0.76), and loaf volume (R² = 0.72).     

Pan Bread and Chinese White Salted Noodle Qualities of Chinese Winter Wheat Cultivars and Their Relationship with Gluten Protein Fractions

Improvement of food processing quality has become a major breeding objective in China. Nineteen Chinese leading winter wheat cultivars with improved quality and two Australian cultivars with high bread and noodle-making qualities were sown in four locations for two years to investigate dough properties, pan bread, and Chinese white salted noodle (CWSN) qualities, and their association with the quantity of protein fractions. The results indicated that genotype, environment, and genotype-by-environment interaction significantly affected most of quality traits and amount of protein fractions. Genotype mainly determined the quantity of gluten protein fractions and pan bread quality parameters, while environment was the most important source of variation for the noodle quality parameters. Chinese cultivars were characterized by acceptable protein content (11.1–13.4%), medium to strong dough strength (maximum resistance 176.9–746.5 BU), medium to poor dough extensibility (166.5–216.4 mm), fair to very good pan bread qualities, and good to very good CWSN qualities. Gliadin contributed more in quantity to protein content (r = 0.80, P < 0.001), however, glutenin and its subgroups were more important to dough strength. The quantity of glutenin, HMW-GS, and LMW-GS were highly and significantly correlated with dough strength-related traits such as farinograph development time, stability, extensigraph maximum resistance, and extension area (r = 0.70–0.91, 0.65–0.89, and 0.70–0.91, respectively; P < 0.001). The quantity of LMW-GS could explain 82.8% of the total variation of dough maximum resistance. The quantity of gliadin and the ratio of HMW-GS to LMW-GS determined dough extensibility (r = 0.75 and r = –0.59, respectively; P < 0.001 and P < 0.01, respectively). Higher quantity of glutenin and lower ratio of gliadin to glutenin resulted in higher bread score with r = 0.70 (P < 0.001) and r = –0.74 (P < 0.001), respectively. However, protein content and its fractions have a moderate undesirable effect on CWSN parameters such as color, firmness, and taste. Therefore, both allelic variation and quantity of storage protein fractions should be considered in breeding cultivars with improved pan bread making quality.     

Textural Comparisons of Gluten‐Free and Wheat‐Based Doughs,Batters, and Breads

Studies were conducted with two newly developed gluten‐free bread recipes. One was based on corn starch (relative amount 54), brown rice (25), soya (12.5), and buckwheat flour (8.5), while the other contained brown rice flour (50), skim milk powder (37.5), whole egg (30), potato (25), and corn starch (12.5), and soya flour (12.5). The hydrocolloids used were xanthan gum (1.25) and xanthan (0.9) plus konjac gum (1.5), respectively. Wheat bread and gluten‐free bread made from commercial flour mix were included for comparison. Baking tests showed that wheat and the bread made from the commercial flour mix yielded significantly higher loaf volumes (P < 0.01). All the gluten‐free breads were brittle after two days of storage, detectable by the occurrence of fracture, and the decrease in springiness (P < 0.01), cohesiveness (P < 0.01), and resilience (P < 0.01) derived from texture profile analysis. However, these changes were generally less pronounced for the dairy‐based gluten‐free bread, indicating a better keeping quality. Confocal laser‐scanning microscopy showed that the dairy‐based gluten‐free bread crumb contained network‐like structures resembling the gluten network in wheat bread crumb. It was concluded that the formation of a continuous protein phase is critical for an improved keeping quality of gluten‐free bread.     

Generation of a Mixolab Profile After the Evaluation of the Functionality of Different Commercial Wheat Flours for Hot‐Press Tortilla Production

Refined wheat flours commercially produced by five different U.S. and Mexican wheat blends intended for tortilla production were tested for quality and then processed into tortillas through the hot‐press forming procedure. Tortilla‐making qualities of the flour samples were evaluated during dough handling, hot pressing, baking, and the first five days on the shelf at room temperature. The predominant variables that affected the flour tortilla performance were wet gluten content, alveograph W (220–303) and P/L (0.70–0.94) parameters, farinograph water absorption (57%) and stability (10.8–18.7 min), starch damage (5.43–6.71%), and size distribution curves (uniform particle distribution). Flours produced from a blend of Dark Northern Spring (80%) and Mexican Rayon (20%) wheat had the highest water absorption, and tortillas obtained from this blend showed the highest diameter and lowest thickness. The whitest and best textured tortillas were obtained from the flour milled from three hard types of Mexican wheat blend. A Mixolab profile was generated from the best tortilla flours, those produced by mills 3 and 4. The Mixolab profile showed that a good flour for hot‐press tortillas had a relatively lower absorption and short dough mix time compared with a bread flour and should have a significantly higher gluten compared with an all‐purpose flour. Compared with bread flour, the tortilla flour had higher retrogradation and viscosity values. The Mixolab profile proved to be a good preliminary test to evaluate flours for hot‐press tortillas.     

Rheological Properties of Wheat Flour Dough and the Relationship with Bread Volume. I. Creep‐Recovery Measurements

The rheological properties of 17 pure European wheat cultivars were analyzed and evaluated in relation to the bread volume. Rheological testing included two empirical rheological methods, farinograph and alveograph, and more fundamental creep‐recovery experiments at shear stresses of 100 and 250 Pa. Principal component analysis on the farinograph and alveograph results showed that a wide range of rheological properties was present among the wheat cultivars. Correlation analysis pointed out that creep‐recovery parameters showed significant correlations with protein content, Zeleny sedimentation value, farinograph water absorption, alveograph extensibility, and bread volume. Among the rheological parameters, maximum recovery strain at a shear stress of 250 Pa showed the highest significant correlation with the bread volume (r = 0.790**). Variables were combined to predict the bread volume by multiple linear regression. A combination of protein content, farinograph water absorption, and alveograph P/L showed the best prediction (r² = 0.80). When taking into account the creep‐recovery parameters, the best prediction of the bread volume (r² = 0.74) was obtained for a combination of the maximum recovery strain at a shear stress of 250 Pa with one other quality parameter (Zeleny sedimentation value, farinograph water absorption, or alveograph W).     

Modeling of Dough Mixing Profile Under Thermal and Nonthermal Constraint for Evaluation of Breadmaking Quality of Hard Spring Wheat Flour

This research was initiated to investigate associations between flour breadmaking traits and mixing and empirical dough rheological properties under thermal stress. Thirty hard spring wheat flour samples were analyzed by a Mixolab standard procedure. Mixolab profiles were divided into six different stages, and torque measurements of individual stages were modeled by nonlinear curve fitting using a compound of two solution searching procedures, multidimensional unconstrained nonlinear minimization and genetic algorithm. Mixing patterns followed exponential equations. Dough torque patterns under heat constraint, specifically dough thermal weakening and pasting profiles, were described by a sigmoid logistic equation as a function of time. Dough stability during heating appeared important for bread loaf volume increase from significant correlations between bread loaf volume and parameters generated from models of a dough thermal weakening stage. Multivariate continuum regression was employed to calibrate prediction models of baking traits using Mixolab parameters. Coefficients of determination estimated from prediction models and cross‐validation were greater than 0.98 for bake water absorption, mixing time, and bread loaf volume, indicating that the Mixolab parameters have a potential to enhance evaluation of flour breadmaking quality.     

Application of Response Surface Methodology in the Development of Gluten‐Free Bread

The formulation of gluten‐free (GF) bread of high quality presents a formidable challenge as it is the gluten fraction of flour that is responsible for an extensible dough with good gas‐holding properties and baked bread with good crumb structure. As the use of wheat starch in GF formulations remains a controversial issue, naturally GF ingredients were utilized in this study. Response surface methodology was used to optimize a GF bread formulation primarily based on rice flour, potato starch, and skim milk powder. Hydroxypropylmethylcellulose (HPMC) and water were the predictor variables. Analyses of the treatments from the design were made 24 hr after baking. Specific volume and loaf height increased as water addition increased (P < 0.01). Crumb firmness decreased as water levels increased (P < 0.01). Significant interactions (P < 0.01) between HPMC and water were found for the number of cells/cm². The number of large cells (>4 mm²) decreased with increasing levels of HPMC and water. Optimal ingredient levels were determined from the data obtained. The optimized formulation contained 2.2% HPMC and 79% water flour/starch base (fsb) and measured responses compared favorably to predicted values. Shelf‐life analysis of the optimized formulation over seven days revealed that, as crumb firmness increased, crust firmness and crumb moisture decreased.     

Properties of Starch Noodles as Affected by Sweetpotato Genotype

Starch was extracted from 14 sweetpotato genotypes from the Philippines. The Rapid Visco-Analyzer (RVA) viscoamylographs of the starches showed Type A pasting curves, characterized by a high pasting peak followed by a high degree of shear-thinning. The major difference among genotypes was in the sharpness of the peak, with some showing a very sharp peak while others showed a broad peak. This difference was related to time from onset of pasting to peak viscosity, and to stability ratio (holding viscosity/peak viscosity), which were also highly correlated (r = 0.84, P < 0.01) to each other. Stability ratio was also correlated to noodle firmness (r = 0.95, P < 0.01), rehydration (cooked weight) (r = -0.89, P < 0.01), and swelling volume of the starch (r = -0.62, P < 0.05). The amylose content was correlated significantly only to peak viscosity (r = -0.84, P < 0.01). Significant differences in texture and cooking quality of the starch noodles produced from the different genotypes was found. It was shown that the RVA viscoamylographs could be used to detect differences in pasting characteristics of sweetpotato starch which are related to quality of noodle produced.     

Swelling Index of Glutenin Test. I. Method and Comparison with Sedimentation,Gel‐Protein,and Insoluble Glutenin Tests

Molecular weight distribution of wheat proteins is primarily responsible for the viscoelastic properties of flour dough. Furthermore, the amount of SDS insoluble proteins (mainly high molecular weight glutenin) plays the major role. We have developed a simple test to determine the swelling power of glutenin (swelling index of glutenin or SIG) for predicting dough properties and end‐use quality. Flour samples (40 mg) were hydrated in distilled water and then allowed to swell in nonreducing solvents (SDS, lactic acid, or mixtures of the two) followed by low speed centrifugation. The SIG was calculated as the weight of the residue divided by the original sample weight. The SIG test was compared with the results from other small‐scale tests for 20 flour samples. SIG tests showed highly significant correlations with the gel protein and insoluble glutenin test (r ≥ 0.85, r ≥ 0.93, P < 0.001, respectively) and significant correlations with SDS and Zeleny sedimentation tests (r ≥ 0.74, r ≥ 0.72, P < 0.001, respectively). The swelling capacity of glutenin depended on swelling time and mixing intensity in nonreducing solvents. Swelling curves obtained from SIG values versus different swelling time can be divided into three distinct stages: swelling, swollen, and breakdown. These stages may reflect soluble and insoluble glutenin contents and quality among different cultivars. SIG test values for short swelling time and low mixing intensity were significantly correlated to gel protein content and SDS‐sedimentation values (r = 0.96, r = 0.90, P < 0.001, respectively). SIG test values for long swelling time and high mixing intensity were significantly correlated to insoluble glutenin content (r = 0.96, P < 0.001). The difference of swelling condition (time and mixing intensity) among these small‐scale methods is the reason for their different correlations with insoluble glutenin content. Because large numbers of samples can be analyzed in a short time with excellent reproducibility, the SIG test may be a useful screening test in a breeding program, predicting the quantity and quality of insoluble glutenin.     

Solvent Retention Capacity Values in Relation to Hard Winter Wheat and Flour Properties and Straight‐Dough Breadmaking Quality

Solvent retention capacity (SRC) was investigated in assessing the end use quality of hard winter wheat (HWW). The four SRC values of 116 HWW flours were determined using 5% lactic acid, 50% sucrose, 5% sodium carbonate, and distilled water. The SRC values were greatly affected by wheat and flour protein contents, and showed significant linear correlations with 1,000‐kernel weight and single kernel weight, size, and hardness. The 5% lactic acid SRC value showed the highest correlation (r = 0.83, P < 0.0001) with straight‐dough bread volume, followed by 50% sucrose, and least by distilled water. We found that the 5% lactic acid SRC value differentiated the quality of protein relating to loaf volume. When we selected a set of flours that had a narrow range of protein content of 12–13% (n = 37) from the 116 flours, flour protein content was not significantly correlated with loaf volume. The 5% lactic acid SRC value, however, showed a significant correlation (r = 0.84, P < 0.0001) with loaf volume. The 5% lactic acid SRC value was significantly correlated with SDS‐sedimentation volume (r = 0.83, P < 0.0001). The SDS‐sedimentation test showed a similar capability to 5% lactic acid SRC, correlating significantly with loaf volume for flours with similar protein content (r = 0.72, P < 0.0001). Prediction models for loaf volume were derived from a series of wheat and flour quality parameters. The inclusion of 5% lactic acid SRC values in the prediction model improved R² = 0.778 and root mean square error (RMSE) of 57.2 from R² = 0.609 and RMSE = 75.6, respectively, from the prediction model developed with the single kernel characterization system (SKCS) and near‐infrared reflectance (NIR) spectroscopy data. The prediction models were tested with three validation sets with different protein ranges and confirmed that the 5% lactic acid SRC test is valuable in predicting the loaf volume of bread from a HWW flour, especially for flours with similar protein contents.     

Association of Barley Kernel Hardness with Physical Grain Traits and Food Processing Parameters

Kernel hardness is not a well‐characterized food quality trait in barley. Unlike wheat, not much is known about the effect of barley kernel hardness on food processing. Ten barley genotypes differing in single kernel characterization system hardness index (SKCS‐HI) (30.1–91.2) of dehulled kernels were used to determine the association of barley HI with other physical grain traits and food processing parameters. Thousand kernel weight (TKW) values of 10 genotypes were 29.7–38.1 g. Values for bulk density of grains were 721.1–758.9 kg/m³. Crease width and depth values were 0.9–1.3 mm and 0.4–0.7 mm, respectively. Barley HI showed no significant association with TKW, bulk density, or kernel crease dimensions. Kernel loss due to pearling after 325 sec of abrasion was 28.8–38.4% and showed significant negative correlation with HI (r = –0.87, P < 0.01). Proportion of barley flour particles >106 μm had values of 34.5–42.0%, and starch damage values were 1.8–4.5% among those 10 barley genotypes. HI showed significant positive correlations with both proportion of barley flour particles >106 μm (r = 0.93, P < 0.01) and starch damage (r = 0.93, P < 0.01). Water imbibition of barley kernels and cooked kernel hardness did not show significant correlation with HI.     

Gluten‐Free Bread from Sorghum: Quality Differences Among Hybrids

Gluten‐free breadmaking quality of 10 sorghum flours was compared using (relative basis) decorticated sorghum flour (70), corn starch (30), water (105), salt (1.75), sugar (1), and dried yeast (2). Batter consistency was standardized by varying water levels to achieve the same force during extrusion. Crumb properties were evaluated by digital image analysis and texture profile analysis (TPA). Significant differences (P < 0.001) in crumb grain were found among the hybrids with mean cell area ranging from 1.3 to 3.3 mm² and total number of cells ranging from 13.5 to 27.8/cm². TPA hardness values of the crumb also varied significantly (P < 0.001). Based on significant correlations (P < 0.01), starch damage, influenced by kernel hardness, was identified as a key element for these differences. Breads differed little in volume, height, bake loss, and water activity. Investigation of added ingredients on bread quality was conducted using response surface methodology (RSM) with two sorghum hybrids of opposite quality. Addition of xanthan gum (0.3–1.2% flour weight basis [fwb]) and skim milk powder (1.2–4.8% fwb) and varying water levels (100–115% fwb) were tested using a central composite design. Increasing water levels increased loaf specific volume, while increasing xanthan gum levels decreased the volume. As skim milk powder levels increased, loaf height decreased. Quality differences between the hybrids were maintained throughout the RSM.     

Relationships of High Molecular Weight Glutenin Subunit Composition and Molecular Weight Distribution of Wheat Flour Protein with Water Absorption and Color Characteristics of Noodle Dough

Colors of noodle doughs made from hard white winter wheat flours from Oregon were measured at optimum noodle water absorptions (NWA). Partial correlations, removing effect of protein concentration, indicated that NWA had negative relationships with 0 hr L* and 24 hr b*, and positive relationships with 0 and 24 hr a*. Kernel hardness index had positive simple and partial correlations with NWA without any significant (P < 0.05) correlation with color parameters. High molecular weight glutentin subunits (HMW‐GS) significantly (P < 0.05) affected all measured noodle parameters except for 0 hr L*. Covariance analysis, using protein concentration as a covariate, indicated that HMW‐GS significantly affected NWA and a* (P < 0.01). Wheat cultivars with HMW‐GS 17+18 showed significantly higher mean NWA and a* values than those with alternative Glu‐B1 subunits. Protein molecular weight distributions affected noodles, as shown by significant correlations with absorbance areas and % areas of protein size exclusion (SE) HPLC chromatograms. Protein fractions that had positive correlations with redness had negative correlations with yellowness. Applying multivariate analyses to SE‐HPLC data to derive calibration models to predict fresh noodle dough a* and b* values had R² > 0.91 and cross validations values of R² > 0.75.     

Relationships Between Some Structures and Functionalities of Starches from Wheat Cultivars Grown in East China

Starches separated from 30 wheat cultivars grown in East China were studied for granule size, amylose content, degree of crystallinity, thermal, pasting, and gel textural properties. Average granule size and amylose content of wheat starches were 15.08–20.8 μm and 29.43–34.19%, respectively. The degree of crystallinity and enthalpy of gelatinization of samples was 29.54–42.12% and 5.2–9.95 J/g, respectively. The gelatinization temperature and pasting temperature were 59.45–62.2°C and 75.40–83.95°C, respectively. There was a wide range of gel hardness values (208.5–426 g). Various significant correlations between functionality and structural parameters were observed. Highly positive correlations were found between the gelatinization temperatures. Gelatinization peak temperature was significantly correlated to hardness of starch gels (r = –0.374, P < 0.05). Significant correlations were observed between amylose content and breakdown viscosity (r = –0.483, P < 0.01), hardness (r = 0.373, P < 0.05), and cohesiveness (r = 0.378, P < 0.05). Many significant correlations between the various pasting parameters were observed. The average granule size was positively correlated to peak viscosity, trough viscosity, and final viscosity (r = 0.369, 0.381, and 0.398, respectively, P < 0.05).     

Physicochemical Properties Related to Quality of Rice Noodles

Eleven rice genotypes with diverse Rapid Visco Analyzer (RVA) pasting characteristics were evaluated for their physicochemical and gel textural characteristics relative to their suitability for making rice noodles. Apparent amylose content (AC) was highly correlated with swelling power (r = -0.65, P < 0.05), flour swelling volume (FSV) (r = -0.67, P < 0.05), noodle hardness (r = 0.74, P < 0.01), gumminess (r = 0.82, P < 0.01), chewiness (r = 0.74, P < 0.01), and tensile strength (r = 0.72, P < 0.05). Solubility showed an inverse relationship with the pasting parameters and noodle rehydration, and a positive relationship with cooking loss, noodle hardness, and gumminess. FSV and most of the pasting parameters were negatively correlated with noodle hardness. RVA parameters and textural parameters of gels formed in the RVA canister were well correlated with actual noodle texture and may, therefore, be used for predicting rice noodle quality during early screening of genotypes in breeding programs.     

Preparation and Functional Properties of Gluten Hydrolysates with Wheat‐Bug (Eurygaster spp.) Protease

Suni‐bug (Eurygaster spp.) enzyme was partially purified from bug‐damaged wheat and used to prepare gluten hydrolysates at 3% and 5% degree of hydrolysis (DH). Functional properties of gluten and gluten hydrolysates were determined at 0.2% (w/v) protein concentration and pH 2–10. Gluten solubility after enzymatic hydrolysis increased significantly (P < 0.05) up to 89.1, 89.6, and 95.0% at pH 7, 8, and 10, respectively. Emulsion stability (ES) of gluten hydrolysates improved at neutral and alkaline pH (P < 0.05) and emulsifying capacity (EC) increased significantly (P < 0.05) except at pH 10. Foaming capacity (FC) values of gluten hydrolysates were significantly higher (P < 0.05) at pH 6, 7, 8; foam stability (FS) values of gluten hydrolysates were significantly higher (P < 0.05) at pH 6 and 7. Enzymatic modification of gluten by wheat‐bug enzyme resulted in hydrolysates with higher antioxidant activity compared to gluten. Significant correlations (P < 0.001) were found between solubility and EC, ES, FC, and FS values of gluten and its hydrolysates with 3% and 5% DH.