Hard Wheat Samples Research Articles

Determination of the effect of high energy ultrasound application in tempering on flour quality of wheat.

This research has been carried out under laboratory conditions. To determine the effect of soaking with ultrasound application to dampen hard wheat samples at one stage in tempering process was the prior goal. In the experiments, Bezostaya-1 wheat samples in different hardness levels (45, 65 and 75%) are used as material. The milling quality and qualitative properties of the flour were investigated. Results compared with the classic tempering process which has two stages tempering for hard and semi-hard wheat at the industrial applications. Ultrasonication of the samples has been applied by a probe-type ultrasound device. Because of experimental deviations, inevitable positive effect of ultrasonic tempering had not seen in the quality parameters of milling experiments like flour yield and energy consumption. But tempering with ultrasound application increased the speed of water intake and diffusion into the grain center. In the study, the wet gluten rates of the flour obtained by classical tempering process were 24.52% and the gluten index rate was 87.17%, while the results obtained by ultrasonic tempering were 22.70% and 93.33%, respectively. Thus it raised flour quality a little, possibly, due to low amount but better quality gluten coming from central endosperm in the flour obtained. Other analysis results in flour showed significant differences in some values of classical and ultrasonic tempering processes. As a result of ultrasonic tempering, the fineness rate (granulation) increased from 73.27% to 79.77%, ash content decreased from 0.61% to 0.55%, Zeleny sedimentation value decreased from 25.0mL to 23.67mL, flour stability increased from 9.76min to 12.06min, water absorption 59.1% decreased from 61.28%, softening resistance increased from 400.33 BU to 504.50 BU, maximum resistance increased from 420.50 BU to 536.16 BU. In bread trials, bread volume increased from 328.3mL to 347.3mL, and specific volume increased from 2.39mL / g to 2.57mL / g. These issues have been confirmed by some analysis such as fine granulation, low ash content, high gluten index, some farinogram, and extensigram properties, and finally better performance in bread making was observed.

Prediction of wheat tortilla quality using multivariate modeling of kernel, flour, and dough properties

Abstract Traditional wheat quality methods for bread have poor predictive power for flatbread quality, which impedes genetic improvement of wheat for the growing market. We used a multivariate discriminant analysis to predict tortilla quality using a set of 16 variables derived from kernel properties, flour composition, and dough rheological properties of 187 experimental hard wheat samples grown across Texas. A discriminant rule (suitability for tortillas = diameter > 165 mm + day 16 flexibility score > 3.0) was used to classify samples. Multivariate normal distribution of the data was established (Shapiro–Wilk p > 0.05). Logistic regression and stepwise variable selection identified an optimum model comprising kernel weight, glutenin–gliadin ratio, insoluble polymeric proteins, and dough extensibility and stress relaxation parameters, as the most important variables. Cross-validation indicated 83% model prediction efficiency. This work provides important insight on potential targets for wheat quality genetic improvement for tortillas and specialty product market. Industrial relevance Tortillas and other flatbread manufacturers currently use wheat developed for other commodities and rely on trial and error, and use of various additives to optimize product quality. Genetic development of wheat for these markets is impeded by lack of knowledge of specific grain quality parameters to target. With the growing demand for clean label and healthy offerings by consumers, the industry is looking for natural ingredients with improved functionality. This work provides the first insight into the specific wheat composition and functional parameters that can predict tortilla quality.

Antioxidant properties of commercial soft and hard winter wheats (Triticum aestivum L.) and their milling fractions

AbstractThe total phenolic content (TPC), total antioxidant activity (TAA), 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) scavenging capacity, inhibition of coupled oxidation in a β‐carotene–linoleate model system, iron(II) chelation activity and inhibition of copper‐induced oxidation of human low‐density lipoprotein (hLDL) cholesterol of 80% ethanolic extracts of soft and hard winter wheat samples and their milling fractions, namely flour, germ, bran and shorts, were investigated. Soft wheat extracts examined demonstrated higher TPC and TAA compared to those of hard wheat extracts. The germ fraction possessed the highest TPC, followed by bran, shorts, whole grain and flour for both wheat types examined. The TAA of both wheat types showed similar results except that shorts performed better than bran in this assay. Free radical scavenging properties of whole grain and milling fractions of both soft and hard wheat samples were examined against DPPH radical. The germ and flour fractions demonstrated the highest and lowest DPPH radical scavenging activity, respectively, among wheat fractions. Wheat extracts were also efficient in preventing bleaching of β‐carotene, which is also known to be free radical mediated. In the iron(II) chelation assay the flour extracts demonstrated excellent activity, while the germ extracts showed a weak activity. The trends were similar in both soft and hard wheat for the iron(II) chelation assay. Wheat extracts also inhibited copper‐induced oxidation of hLDL. In LDL oxidation assay, wheat extracts performed better than the reference antioxidant, ferulic acid. Thus wheat phenolics may serve as effective antioxidative components as measured by in vitro techniques. Copyright © 2005 Society of Chemical Industry

Effect of wheat pearling on flour quality

Debranning or cereal kernel pearling is increasingly recognised by the milling and baking industry as an important stage in cereal processing because it lowers the capital investment costs, giving as well, the benefit of better quality products. Pearling is the process, prior to milling that with the application of abrasion and friction removes effectively only the bran layers from the cereal grains, allowing nutritious parts, such as the aleurone layer to remain in the intact kernels. This pre-treatment potentially could also improve milling yields of superior flour quality. However, so far, there is no satisfactory explanation as to why pearled flour performs better than the unpearled. The effect of the wheat pearling prior to milling was investigated and the results showed that pearling affects flour quality characteristics. Using a laboratory scale Bühler mill, two samples of hard wheat were used, one with (pearled) and the other without the debranning pre-treatment (unpearled) to test whether pearling affects flour milling and hence flour quality. It was found that the flour obtained from pearled wheat had differences from the unpearled wheat flour in the composition, structural properties; particle size distribution and starch damage and starch gelatinisation temperature.

Effect of wheat pearling on flour quality

Debranning or cereal kernel pearling is increasingly recognised by the milling and baking industry as an important stage in cereal processing because it lowers the capital investment costs, giving as well, the benefit of better quality products. Pearling is the process, prior to milling that with the application of abrasion and friction removes effectively only the bran layers from the cereal grains, allowing nutritious parts, such as the aleurone layer to remain in the intact kernels. This pre-treatment potentially could also improve milling yields of superior flour quality. However, so far, there is no satisfactory explanation as to why pearled flour performs better than the unpearled. The effect of the wheat pearling prior to milling was investigated and the results showed that pearling affects flour quality characteristics. Using a laboratory scale Bühler mill, two samples of hard wheat were used, one with (pearled) and the other without the debranning pre-treatment (unpearled) to test whether pearling affects flour milling and hence flour quality. It was found that the flour obtained from pearled wheat had differences from the unpearled wheat flour in the composition, structural properties; particle size distribution and starch damage and starch gelatinisation temperature.

Wheat washing with ozonated water: effects on selected flour properties

Soft and hard wheat samples were washed using ozonated water (1.5 mg L−1). Milling (rate of extraction), rheological (farinograph and extensograph characteristics), chemical (protein, falling number, sedimentation volume), colour (Hunter Laboratory values) and microbiological (total bacterial and yeast/moulds) properties of flours milled from the washed wheat were evaluated. Results indicated that washing with ozonated water did not significantly alter the chemical, physical or rheological properties of the flours from hard wheat samples. However, small but statistically significant (P=0.05) differences were observed on extensograph values of flours milled from the soft wheat washed with ozonated water. A significant reduction (P=0.05) in the total bacterial and yeast/mould counts was obtained after washing with ozonated water for both soft and hard wheat samples. Results suggest that ozonated water can be successfully used to wash hard wheat without affecting flour quality.

Influence of tempering with ozonated water on the selected properties of wheat flour

Soft and hard wheat samples were tempered using ozonated water (1.5 and 11.5 mg ozone/l). Milling (rate of extraction), rheological (farinograph and extensograph characteristics), chemical (protein, falling number, sedimentation volume), colour (Hunter Lab values) and microbiological (total bacterial and yeast/moulds) properties of the parent flours were evaluated. Results indicated that tempering with ozonated water did not significantly alter the chemical, physical and rheological properties of the flours. A statistically significant reduction in the total bacterial and yeast/mould counts were obtained after tempering with ozonated water ( P⩽0.05). Results suggest that the water ozonated up to 11.5 mg ozone/l can be successfully used in the tempering of soft and hard wheat without deterioration in the flour quality.

Relationships Among Grain Hardness, Pentosan Fractions, and End‐Use Quality of Wheat

ABSTRACTGrain texture (hardness) in wheat (Triticum aestivum L.) is a major determinant of end‐usage. Variation in grain texture can be conceptually assigned to the two major hardness classes that result from the action of one major gene (Hardness) or to as‐yet undetermined factors contributing to residual variation within hardness classes. Identifying the physicochemical basis of both sources of texture variation could provide a means of better controlling or manipulating this quality trait. Pursuant to this objective, the role of pentosans was examined. Pentosan fractions (membrane‐associated, total, and soluble) were isolated from 13 hard and 13 soft wheat samples and their flours. Among the hard wheat samples, pentosans had a minimal role in modifying grain hardness. However, among the soft wheat samples, pentosans appeared to have a significant hardness‐modifying effect that carried over into end‐use quality. Among the soft wheat samples, pentosan fractions, along with wheat protein, accounted for 53–76% of the variation in grain texture, depending on the method used to quantify texture. Membrane‐associated pentosans were the most influential single parameter in modeling grain texture for the soft wheat samples. Membrane‐associated pentosans were most influential in accounting for variation (69%) in alkaline water retention capacity. Total pentosans, together with flour protein, accounted for 87% of the variation in cookie diameter for soft wheat samples, with the total pentosan fraction being the more influential.

WHEAT ENDOSPERM COMPRESSIVE STRENGTH PROPERTIES AS AFFECTED BY MOISTURE

Tempering, the addition of water to wheat before milling, is routinely performed to toughen the pericarp of thekernel and thus improve the efficiency of flour extraction. In an effort to better understand how tempering affects thekernels internal structure, the effect of moisture on the physical strength properties of wheat kernel endosperm on an insitu basis was studied. Five soft and five hard wheat samples, available from the U.S. National Institute of Standards andTechnologys Standard Reference Materials Program for the purpose of standardizing wheat hardness instruments, wereexamined. Geometrically precise cylinders of wheat endosperm (1 mm diameter 3 mm height) were conditioned underone of five relative humidities (~0 to 93% RH, producing moisture contents of 3 to 28%, dry basis), then tested for thefollowing compressive strength properties: maximum compressive stress (S max ), modulus of elasticity (E), work tomaximum stress [W(S max )], and strain at maximum stress [e(S max )]. Large variations in strength properties occurredwithin the same sample and humidity, as seen by coefficients of variation reaching as high as 56%. Mean values of S max ,E, W(S max ), and e(S max ), based on 8 to 13 endosperm cylinders per sample humidity setting, were normalized to areference moisture content of 13% d.b. Normalized values of the first three properties were linearly fitted to moisturecontent and statistically tested to determine the similarity in response among samples. S max was most linearly related tomoisture content. When samples within a hardness class were pooled, the slopes of the normalized S max regressionequations were significantly different (P < 0.01) for hard and soft wheats. A similar pooling procedure for normalized Erevealed a moderately significant (P < 0.05) difference between slopes of soft and hard classes. For W(S max ), mostsamples did not exhibit a sensitivity to moisture; however, when pooled into soft and hard classes, the difference betweenthese classes was highly significant (P < 0.01). The response of e(S max ) to moisture was constant except at the highestmoisture content (24 to 28% d.b.), where the values were approximately twice as large.

Block-surface staining for differentiation of starch and cell walls in wheat endosperm.

A staining technique for differentiating starch granules and cell walls was developed for computer-assisted studies of starch granule distribution in cells of wheat (Triticum aestivum L.) caryopses. Blocks of embedded caryopses were sectioned, exposing the endosperm tissue, and stained with iodine potassium iodide (IKI) and Calcofluor White. Excessive tissue hydration during staining was avoided by using stains prepared in 80% ethanol and using short staining times. The IKI quenched background fluorescence which facilitated the use of higher concentrations of Calcofluor White. Cell wall definition was improved with the IKI-Calcofluor staining combination compared to Calcofluor alone. The high contrast between darkly stained starch granules and fluorescent cell walls permitted computer assisted analysis of data from selected hard and soft wheat varieties. The ratio of starch granule area to cell area was similar for both wheat classes. The starch granule sizes ranged from 2.1 microns 3 to 22,000 microns 3 with approximately 90% of the granules measuring less than 752 microns 3 (ca. 11 microns in diameter). Hard wheat samples had a greater number of small starch granules and a lower mean starch granule area compared to the soft wheat varieties tested. The starch size distribution curve was bimodal for both the hard and soft wheat varieties. Three-dimensional starch size distribution was measured for four cells near the central cheek region of a single caryopsis. The percentage of small granules was higher at the ends than at the mid-section of the cells.

Seasonal changes in wheat-grain quality associated with high temperatures during grain filling

Wheat plants exposed to higher than usual temperatures during ripening produced grain with weaker dough properties in glasshouse, field experiments and crop samples. In a review of Prime Hard wheat samples from 1960/61 to 1988/89, those seasons when the dough properties were particularly weak coincided with the years when the number of hours over 35�C during the grain filling period (October to December) was greatest. A five-day period of heat stress in 1988 provided an opportunity to directly investigate the effects of heat stress in the field. A weakening of dough properties was shown, for four varieties, by longer dough development times and faster breakdown in the Farinograph and also by shorter resistance to extension (at 5 cm) in the Extensograph. These (and similar changes for glasshouse grown grain) were accompanied by an increase in the proportion of gliadin (monomeric) proteins. That this increase was associated with the heat stress was shown by demonstrating increased accumulation of 14C amino acids into the gliadin fraction for heat-stressed heads in culture. These results support the hypothesis that episodes of high temperature during grain filling activate the heat shock elements of gliadin genes in wheat causing the mature grain to contain more gliadin and thus to produce weaker doughs.