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1.
Jet milling is a fluid energy impact‐milling technique generally used for the ultrafine reduction of higher value materials. The efficiency of jet milling combined with air classification appears very efficient to separate starch from other wheat flour aggregate components and to produce wheat starch with very low residual protein content. Indeed, residual protein content of the starch‐rich fraction can be reduced to <2% db with a series of successive grinding and air classification operations. Lipid and pentosan contents were also reduced in the starch‐rich fraction. Nevertheless, jet milling cannot eliminate grinding differences observed between different types of wheat. Wheat hardness continues to have an effect on milling and classification yields and on the composition of air classification fractions. To obtain starch‐rich fraction with only 2% protein content, hard wheat flour required a series of at least five grinding steps, whereas only three steps are necessary for soft wheat flour. Under these conditions, hard wheat flours give 24% mass yield with 12% starch damage compared with 39% yield and a low starch damage content (6.4%) for soft wheat flour. These results highlight new prospects for the development of cereal flours, especially soft wheat flours.  相似文献   

2.
The separation efficiency of wheat flour particles based on size, with minimum bran contamination, is important for a flour mill. Separation of flour during fractionation depends on the surface characteristics and shape of flour particles. Wheat flour particle characteristics such as surface lipid content, roughness, and morphology with respect to particle size were studied to better understand the differences between hard and soft wheat flours. Fractal analysis using image analysis was used to ascertain surface roughness. That was in turn verified by atomic force microscopy measurements. Soft wheat flours (soft red winter and soft white) had a higher degree of surface roughness than the hard wheat flours (hard red spring, hard red winter, and hard white). The fractal dimension values ranged from 2.67 to 2.78 and from 2.28 to 2.55 for soft and hard wheat flours, respectively. The surface lipid content increased with particle size in hard wheat but decreased in soft wheat flours. The surface lipid levels ranged from 1.02 to 1.18 and from 2.55 to 2.58% (% of total area) for 45 μm particles in hard wheat flours (hard red spring, hard red winter, and hard white) and soft wheat flours (soft red winter and soft white), respectively. For the 90 μm particles the lipid levels ranged from 1.54 to 1.62 and from 1.70 to 1.83% (% of total area) for flour particles in hard wheat flours (hard red spring, hard red winter, and hard white) and soft wheat flours (soft red winter and soft white), respectively. Surface lipid content and roughness values showed that soft wheat flours will be more cohesive than hard wheat flours. The morphology values revealed the irregularity in flour particles, irrespective of wheat class and particle size, owing to nonuniform fragmentation of protein and starch matrix of the wheat endosperm.  相似文献   

3.
Time-lapse photography showed that, during baking, the diameter of sugar-snap cookies increased linearly then suddenly became fixed. Therefore, cookie diameter was a function of spread rate and set time. Cookies made with soft wheat flour were significantly larger in diameter (184 mm) than those made with hard wheat flour (161 mm). Cookies made with soft wheat flour set later (5.8 min) during baking than those made with hard wheat flour (5.1 min). The differences in set time within cookies made with various hard wheat flours or within cookies made with various soft wheat flours appeared to be affected by flour protein content. However, other factors also affected the difference in set time between cookies made with hard wheat and soft wheat flours. Cookies made with soft wheat flour spread at a faster rate (7.8 mm/min) than those made with hard wheat flour (4.6 mm/min). The level of soluble starch in the flour appeared to cause the difference in spread rate between cookies made with hard wheat and soft wheat flour. The higher level of soluble starch in hard wheat flour (0.352 ± 0.008%) than in soft wheat flour (0.152 ± 0.030%) increased dough viscosity, thus the spread rate was slower. However, soluble starch content did not explain the differences in spread rate within cookies made with various hard wheat flours or within cookies made with various soft wheat flours.  相似文献   

4.
Wheat flour tortillas were made from flour streams of three wheat cultivars: Jagger hard red winter wheat, 4AT-9900 hard white winter wheat, and Ernie soft red winter wheat. Wheat samples were milled on a Miag experimental mill. Twelve flour streams and one straight-grade flour were obtained. Tortillas were made from each flour stream and the straightgrade flour by the hot-press method. Tortilla stretchability and foldability were evaluated by a texture analyzer and six panelists, respectively. Flour protein and water absorption affected tortilla texture. The foldability evaluated by panelists was positively correlated with flour protein content, farinograph water absorption, and damaged starch (P < 0.05). The 2BK and 3BK streams of hard wheat produced tortillas with strong stretchability and good foldability. Middling streams of hard wheat yielded tortillas with lighter color and less stretchability. Under the conditions tested in this study, soft wheat flours were not good for producing flour tortillas.  相似文献   

5.
Prime starch was extracted from soft and hard wheat flours and ballmilled to produce 100% damaged starch. Small amounts of the ball-milled starch or a pregelatinized starch were added to sugar-snap cookie formulations. Other cookie doughs were produced from prime starch only (no flour) with small amounts of the ball-milled starch added. Starch damages of the resulting substituted soft and hard wheat flours and soft and hard wheat prime starches were determined and compared to diameters of sugarsnap cookies produced from the control and treatments. Soft wheat flour and starches produced larger diameter cookies than their hard wheat counterpart at all levels of damaged starch. Both sources of damaged starch (ball-milled or pregelatinized starch) had similar effects on cookie diameter. Cookies produced from all starch (no flour) were similar to their respective flour controls at ≈8% damaged starch. To produce the same size cookie as that produced by soft wheat flour and starch, hard wheat flour and starch cookie formulations required less damaged starch and had lower alkaline water retention than did the soft wheat flour and starch cookie formulations. Other flours were treated with chlorine gas to pH 4.8. Pregelatinized starch (≈5%) was required to reduce the cookie diameter as much as chlorine treatment did. Results suggest unique quality differences between soft and hard wheat starch as they function in sugar-snap cookie baking. The functional results of those differences are not adequately quantified by the estimation of damaged starch level.  相似文献   

6.
An attempt was made to evaluate gluten structural changes in refined and whole wheat pasta from hard white winter wheat to elucidate the impact of whole wheat components on the formation and structure of the gluten network in pasta. Attenuated total reflectance–FTIR spectroscopy was used to track gluten secondary structure through most of the major steps in pasta processing: raw material, mixing, drying, and cooking. Protein solubility, accessible thiols, and SDS‐PAGE data were also collected to provide additional information on the nature of protein interactions and network composition. Few secondary structural differences were observed between refined and whole wheat flours from hard white wheat. However, mixing induced a significant shift to β‐sheet structures in refined dough that was not equally matched by whole wheat dough. Drying under both high temperature, short time (HT) and low temperature, long time (LT) conditions resulted in a reversion to structural distributions similar to those for flour in both pastas. However, greater protein denaturation in HT samples was indicated by lower protein solubility also in the presence of denaturants and disulfide reducing agents. Cooking generated a substantial increase in β‐sheet structures for both pasta systems. This structure was greatest in refined and LT samples. Thiol accessibility data indicate the presence of a highly aggregated, compact gluten network in refined pasta, mostly driven by hydrophobic association. Conversely, the network in whole wheat pasta was more loosely associated and dependent on disulfide bonding, both of which fit well with the secondary structural data.  相似文献   

7.
Physicochemical properties of 34 wheat flours with various classes and different protein contents were related to optimum water absorption of noodle dough. Club and soft wheat flours generally exhibited higher water absorption (34–37%) of noodle dough than hard wheat flours (31–35%). Optimum water absorption of noodle dough in three hard wheat flours with five different protein contents was 33–37%. Optimum water absorption was negatively correlated with flour protein content and SDS sedimentation volume. Physical properties of flour, damaged starch content, NIRS hardness and water retention capacity, influenced optimum water absorption of noodle dough from club, soft and hard wheat flours. A prediction equation developed using protein content, water retention capacity and SDS sedimentation volume of flour provides a reliable estimation of the optimum absorption of noodle dough for making noodles.  相似文献   

8.
The structure of pasta is largely governed by the presence of a structured protein network. This work analyzed the protein network textures of various cooked pasta products through textural image analysis. Six different pasta types were investigated: reference pasta made from durum semolina; pasta enriched with gluten proteins from soft wheat flour at 10 and 20%; autoclaved pasta; soft wheat flour pasta; and pasta made from reconstituted flour fractions. Pasta samples were sectioned, and each crosssection consisted of three distinct zones (central, intermediate, and external) based on the state of swelling of starch granules for each pasta product. Digital images of the protein network in each zone were acquired using confocal laser scanning microscopy. Textural image analysis was then performed. Similarities and differences in protein network texture were assessed by principal component, stepwise discriminant, and variance analyses. With the exception of autoclaved pasta, protein network structure differed greatly with the position in the pasta. Furthermore the effect of technological treatments was greatly influenced by the position in pasta. The most significant differences in protein network structure were obtained with the autoclaved and 20% protein-enriched samples.  相似文献   

9.
Front-face emission spectra of powders can be recorded with a commercial spectrofluorometer. By combining the emissions of a scatterer powder and of a wheat flour sample, the scattering contribution to the front-face emission spectra of flour is removed, and the fluorescence of the flour is isolated. The fluorescence depends on the concentration of the fluorophores. By choosing convenient measurement parameters and by measuring the emission spectra of flour samples suitably enriched with riboflavin, the fluorescence of riboflavin could be isolated from that of other substances present in flours and the concentration of vitamin B(2) in native substrates could be determined. This method is particularly apt for the measurement of vitamin B(2) in low riboflavin-containing powders such as wheat flours, which are usually analyzed through complex chemical and microbiological methods. The method is essentially phenomenological, in view of the interpretation difficulties connected to the origin of the fluorescence resulting from the absorption of multiply scattered photons.  相似文献   

10.
A commercial gluten and glutens isolated from four soft and four hard wheat flours were incorporated into a hard and a soft white flour by replacement to directly determine the quantitative and qualitative role of gluten proteins in making noodles. Gluten incorporation (6%) decreased water absorption of noodle dough by 3%, shortened the length of the dough sheet by 15 and 18%, and increased the thickness of the dough sheet by 18 and 20% in soft and hard wheat flour, respectively. Noodles imbibed less water and imbibed water more slowly during cooking with gluten incorporation, which resulted in a 3‐min increase in cooking time for both soft and hard wheat noodles. Despite the extended cooking time of 3 min, noodles incorporated with 6% gluten exhibited decreases in cooking loss by 15% in soft wheat. In hard wheat flour, cooking loss of noodles was lowest with 2% incorporation of gluten. Tensile strength of fresh and cooked noodles, as well as hardness of cooked noodles, increased linearly with increase in gluten incorporation, regardless of cooking time and storage time after cooking. While hardness of cooked noodles either increased or showed no changes during storage for 4 hr, tensile strength of noodles decreased. There were large variations in hardness and tensile strength of cooked noodles incorporated with glutens isolated from eight different flours. Noodles incorporated with soft wheat glutens exhibited greater hardness and tensile strength than noodles with hard wheat glutens. Tensile strength of cooked noodles incorporated with eight different glutens negatively correlated with SDS sedimentation volume of wheat flours from which the glutens were isolated.  相似文献   

11.
Starches from the endosperm of three types of total‐waxy cereals (bread wheat, maize, and barley) were used in reconstitution studies of durum wheat semolinas to investigate the effect of waxy starch on pasta cooking quality. The chemical composition and the pasting and gelatinization properties of the starches used in this study were evaluated to define the functional properties of each waxy starch. The rheological properties of dough semolinas were evaluated by small‐scale mixograph. Spaghetti was prepared using a small‐scale pasta extruder and its cooking quality was assessed using a texture analyzer. Cooked pasta firmness, resilience, and stickiness were measured. The substitution of semolina starch with waxy starches from different sources changed the functional properties of dough and their pasta quality. A decrease in firmness was detected in all the semolinas reconstituted with waxy starches. An increase in stickiness was found when semolinas with waxy starch from wheat were evaluated. No improvement in pasta quality should be expected if the waxy character is introduced in durum wheat.  相似文献   

12.
Front-surface absorbance spectra of wheat flours in the 250-650 nm region can be obtained by measuring reflectance spectra with a conventional spectrofluorometer suitably set to detect light scattered from powder samples. The spectra recorded on flour samples, obtained from seeds of four bread and five durum wheats, show high-intensity absorption bands due to aromatic amino acids of wheat proteins and low-intensity bands due to chromophores bound to low-molecular-weight compounds. The intensity of these last bands is proportional to the concentration of the corresponding chromophores present in the flour; thus, it can be used to measure the content of the compounds containing the chromophore(s). In particular, a quantitative determination of the carotenoids actually present in the flours is made, obtaining information on the original content of the seeds. This determination is important, as, for example, xanthophylls are well-known antioxidants and free-radical scavengers involved in aging processes of seeds. Reflectance measurements on powder samples are far more economic in terms of time and materials consumption than methods such as extraction and HPLC analysis of extracts and, in addition, give an evaluation of the overall content of carotenoids with absorption bands in the spectral range 450-500 nm. Application of the technique to other food powders with low-intensity absorption bands in the near-UV and vis region is possible.  相似文献   

13.
The highly variable environmental conditions across the Pacific Northwest (PNW) influence the milling and baking quality of wheat grain produced in this region. This study was conducted to compare the flour composition, dough rheology, and baking quality of soft and hard spring wheat grain produced in diverse environments. Thirteen soft and five hard spring wheat cultivars were grown at Lind, WA (semiarid) and Fairfield, WA (high precipitation) for three years. Grain was evaluated for flour composition, rheology, and experimental baked product quality. Flour composition, rheological properties, and baking qualities were primarily influenced by the environment. Protein contents, microSDS values, and water absorption levels were significantly (P < 0.0001) higher for all cultivars grown at Lind compared with those from Fairfield. Cookie diameters were larger (P < 0.0001) for soft flours from Fairfield, whereas loaf volumes were higher (P < 0.0001) for hard wheat flours from Lind. Results indicate that producing soft or hard wheat outside of its optimal climatic zone reduces experimental baked product quality.  相似文献   

14.
Double‐null partial waxy wheat (Triticum aestivum L.) flours were used for isolation of starch and preparation of white salted noodles and pan bread. Starch characteristics, textural properties of cooked noodles, and staling properties of bread during storage were determined and compared with those of wheat flours with regular amylose content. Starches isolated from double‐null partial waxy wheat flours contained 15.4–18.9% amylose and exhibited higher peak viscosity than starches of single‐null partial waxy and regular wheat flours, which contained 22.7–25.8% amylose. Despite higher protein content, double‐null partial waxy wheat flours, produced softer, more cohesive and less adhesive noodles than soft white wheat flours. With incorporation of partial waxy prime starches, noodles produced from reconstituted soft white wheat flours became softer, less adhesive, and more cohesive, indicating that partial waxy starches of low amylose content are responsible for the improvement of cooked white salted noodle texture. Partial waxy wheat flours with >15.1% protein produced bread of larger loaf volume and softer bread crumb even after storage than did the hard red spring wheat flour of 15.3% protein. Regardless of whether malt was used, bread baked from double‐null partial waxy wheat flours exhibited a slower firming rate during storage than bread baked from HRS wheat flour.  相似文献   

15.
Different kinds of cereal flours submitted to various technological treatments were classified on the basis of their mid-infrared spectra by pattern recognition techniques. Classification in the wavelet domain was achieved by using the wavelet packet transform for efficient pattern recognition (WPTER) algorithm, which allowed singling out the most discriminant spectral regions. Principal component analysis (PCA) on the selected features showed an effective clustering of the analyzed flours. Satisfactory classification models were obtained both on training and test samples. Furthermore, mixtures of varying composition of the studied flours were distributed in the PCA space according to their composition.  相似文献   

16.
《Cereal Chemistry》2017,94(2):215-222
Durum wheat (Triticum turgidum subsp. durum ) production worldwide is substantially less than that of common wheat (T. aestivum ). Durum kernels are extremely hard; thus, most durum wheat is milled into semolina, which has limited utilization. Soft kernel durum wheat was created by introgression of the puroindoline genes via homoeologous recombination. The objective of this study was to determine the effects of the puroindoline genes and soft kernel texture on flour, water absorption, rheology, and baking quality of durum wheat. Soft Svevo and Soft Alzada, back‐cross derivatives of the durum varieties Svevo and Alzada, were compared with Svevo, a hard durum wheat, Xerpha, a soft white winter wheat, and Expresso, a hard red spring wheat. Soft Svevo and Soft Alzada exhibited soft kernel texture; low water, sodium carbonate, and sucrose solvent retention capacities (SRCs); and reduced dough water absorptions similar to soft wheat. These results indicate a pronounced effect of the puroindolines. Conversely, SDS flour sedimentation volume and lactic acid SRC of the soft durum samples were more similar to the Svevo hard durum and Expresso samples, indicating much less effect of kernel softness on protein strength measurements. Alveograph results were influenced by the inherent differences in water absorption properties of the different flours and their genetic background (e.g., W and P were markedly reduced in the Soft Svevo samples compared with Svevo, whereas the puroindolines appeared to have little effect on L ). However, Soft Svevo and Soft Alzada differed markedly for W and L . Soft durum samples produced bread loaf volumes between the soft and hard common wheat samples but larger sugar‐snap cookie diameters than all comparison samples. The soft durum varieties exhibited new and unique flour and baking attributes as well as retaining the color and protein characteristics of their durum parents.  相似文献   

17.
《Cereal Chemistry》2017,94(2):199-206
A set of 32 winter wheat lines and varieties was selected to benchmark Ontario winter wheat as a first step toward improving quality. Protein secondary structure, total and accessible thiols, rheological properties, gluten aggregation kinetics, and network forming capabilities of different polymers were determined for each wheat line. Results revealed that there were statistically significant differences among the lines selected (P < 0.05). The differences between hard and soft wheat classes were not as large as would be expected, however, despite the range of quality parameters measured. Benchmarks revealed that several soft wheat lines outperformed hard wheat lines in standard breadmaking quality measures. Protein conformation changed significantly as the moisture content of the samples increased to mimic different model product systems: flour, dough, and batter. The conformation of the flour samples exhibited different patterns between hard and soft wheat classes, although these differences became narrower in the dough and batter states. Principal component analysis (PCA) factors included most quality parameters measured, with the notable exceptions of solvent retention capacity tests and total thiols. Protein conformation and accessible thiols were significant PCA factors that tended to override the rheological measures of quality they represented, suggesting that protein secondary structure and disulfide bonding patterns are fundamental aspects of rheological quality measures.  相似文献   

18.
The compositions and physical properties of Japanese salt and alkaline noodle flours were contrasted and compared to those of flours from U.S. hard white and soft white wheats (HWW and SWW) and from Australian SWW wheats often segregated for salt noodles. The alkaline noodle flours averaged 11.5% protein, which was 3% higher than the salt noodle flours, and they had lower ash content (0.35 vs. 0.41%). Granulation of the salt noodle flours showed the same proportion of small particles (<38 μm) as in soft wheat flours but different levels of intermediate and large particles. The level of small particles was ≈10% greater in salt noodle flours than in the alkaline noodle flours. The alkaline noodle flours had ≈8% more fine particles and 2.5% more damaged starch than the HWW flours, which is consistent with fine grinding of hard wheat flour in the noodle flour. Starch damage also was higher in the salt noodle flours (5.3%) than in the SWW flours. The salt noodle flours had a higher sodium dodecyl sulfate (SDS) sedimentation volume and a higher gluten index than the SWW flours from the United States. The SDS volume and gluten index were lower for the alkaline noodle flours than for the HWW flours, showing the preference for a mellow gluten of low-intermediate strength in alkaline noodle flour. Mixograph data also supported the conclusions of mellow gluten in alkaline noodle flour. The swelling powers (1.7% at 92.5°C) for Australian SWW, salt noodle, U.S. HWW, U.S. SWW, and alkaline noodle flours, were 19.4, 18.1, 17.0, 16.1, and 15.8 g/g, respectively, showing the preferences for high- and low-swelling starch, respectively, in the salt noodle and the alkaline noodle flour. A similar order of flour swelling was indicated by peak viscosity of flours heated at 12% solids in starch paste viscosity analysis. Water holding capacity of flour was correlated highly (r = 0.95, P < 0.01) with swelling power, both measured at 1.7% flour solids at 92.5°C.  相似文献   

19.
Lignans are of increasing interest because of their potential anticarcinogenic, antioxidant, estrogenic, and antiestrogenic activities. In this work, mixed‐cereal pastas manufactured by adding 60% whole‐grain flours of different cereals (wheat, oat, rye, barley, and rice) to durum wheat semolina, a multigrain pasta with different grains (cereals, legumes, and flaxseed), and a traditional industrial durum wheat semolina were analyzed for their lignans content both in the raw and in the cooked state, ready for consumption. For raw mixed‐cereal pastas, total lignans were within the range 94.91–485.62 μg/100 g d.w. After cooking, total lignans losses of about 35.5, 18.31, and 5.46% were observed respectively in oat‐, rye‐, and rice‐added pastas, whereas increases of 5.74 and 13.62% were observed in barley‐added and whole durum wheat pastas. Interesting results were obtained for the multigrain pasta: the raw product exhibited a total lignans content of 9,686.17 ± 287.03 μg/100 g d.w., and the major contribution was given by secoisolariciresinol. This highest total lignans value resulted from its rich and varied composition in seeds of different origin, legumes, and flaxseed in particular. Our findings showed that mixed‐cereal and multigrain pastas can be considered a good source of lignans. The effect of cooking was not the same for each product, and it depended on the different lignans profile of each grain, on the different chemical structure of each lignan, and on the nature of the food matrix.  相似文献   

20.
Worldwide, nearly 20 times more common wheat (Triticum aestivum) is produced than durum wheat (T. turgidum subsp. durum). Durum wheat is predominately milled into coarse semolina owing to the extreme hardness of the kernels. Semolina, lacking the versatility of traditional flour, is used primarily in the production of pasta. The puroindoline genes, responsible for kernel softness in wheat, have been introduced into durum via homoeologous recombination. The objective of this study was to determine what impact the introgression of the puroindoline genes, and subsequent expression of the soft kernel phenotype, had on the milling properties and flour characteristics of durum wheat. Three grain lots of Soft Svevo and one of Soft Alzada, two soft‐kernel back‐cross derived durum varieties, were milled into flour on the modified Quadrumat Senior laboratory mill at 13, 14, and 16% temper levels. Samples of Svevo (a durum wheat and recurrent parent of Soft Svevo), Xerpha (a soft white winter wheat), and Expresso (a hard red spring wheat) were included as comparisons. Soft Svevo and Soft Alzada exhibited dramatically lower single‐kernel characterization system kernel hardness than the other samples. Soft Svevo and Soft Alzada had high break flour yields, similar to the common wheat samples, especially the soft hexaploid wheat, and markedly greater than the durum samples. Overall, Soft Svevo and Soft Alzada exhibited milling properties and flour quality comparable, if not superior, to those of common wheat.  相似文献   

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