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1.
为了研究小麦粉混配过程中品质性状的变化，分析了陕西省13个推广小麦品种及其23种混配粉的蛋白质品质和面团流变学特性。结果表明，强筋小麦不同批次制粉品质变化较大，中筋和弱筋小麦品质变化相对较小，不同方式配粉面团流变学特性变化规律不同。强筋 中筋和强筋 弱筋两种方式配粉稳定时间测定值比理论值减少，延伸性有增有减。同时，强筋 中筋=强筋的配粉延伸性以减小为主，而强筋 中筋=中筋的配粉延伸性增加，2个中筋粉或中筋与弱筋粉混配延伸性明显增加。混配粉面筋含量、沉淀值、稳定时间和延伸性测定值与由基础品种估算的理论值无显著差异，而且呈极显著正相关，相关系数分别为0．9818^**、0．9776^**、0．8594^**和0．7189^**。文中还提出了根据配粉需要估算基础品种混配比例的方法。 相似文献
2.
The water adsorption properties of hard and soft wheat flours and flour components (starch, damaged starch, gluten, soluble pentosans, and insoluble pentosans) were determined at 25 °C using a controlled atmosphere microbalance. At different levels of relative humidity (from 10% to 95%), changes in sample mass (i.e., water gain) were continuously measured versus time and described using exponential models (R2≥0·994). Water adsorption isotherms were constructed for wheat flours and flour components and described using Guggenheim-Anderson-de Boer models (R2≥0·997). It was not possible to distinguish between the selected hard and soft wheat flours by their isotherms. The water-soluble pentosans had the highest water adsorption capacity. The theoretical distribution of water between the flour components (calculated using the Guggenheim-Anderson-de Boer parameters) was starch, 88%; gluten, 10%; and pentosans, 2%. 相似文献
3.
The objective of this study was to examine the influence of flour quality on the properties of bread made from pre-fermented frozen dough. The physicochemical parameters of 8 different wheat flours were determined, especially the protein quality was analysed in detail by a RP-HPLC procedure. A standardized baking experiment was performed with frozen storage periods from 1 to 168 days. Baked bread was characterised for specific loaf volume, crumb firmness and crumb elasticity. The results were compared to none frozen control breads. Duration of frozen storage significantly affected specific loaf volume and crumb firmness. The reduction of specific loaf volume was different among the used flours and its behaviour and intensity was highly influenced by flour properties. For control breads wet gluten, flourgraph E7 maximum resistance and RVA peak viscosity were positively correlated with specific loaf volume. However, after 1–28 days of frozen storage, wet gluten content was not significantly influencing specific loaf volume, while other parameters were still significantly correlated with the final bread properties. After 168 days of frozen storage all breads showed low volume and high crumb firmness, thus no significant correlations between flour properties and bread quality were found. Findings suggest that flours with strong gluten networks, which show high resistance to extension, are most suitable for frozen dough production. Furthermore, starch pasting characteristics were also affecting bread quality in pre-fermented frozen dough. 相似文献
4.
The effects of addition of whole barley and barley components (starch, β-glucans and arabinoxylans) on rheological properties of dough prepared from wheat flours with variable gluten quality (cv. Glenlea, extra-strong; cv. Katepwa, very strong; cv. AC Karma, strong; and cv. AC Reed, weak) were investigated in these studies using Mixograph and dynamic rheological measurements. Whole barley meal, starch and non-starch polysaccharides from hulless barley with variable starch characteristics (normal, high amylose, waxy, and zero amylose waxy) were tested. Upon addition of either β-glucans or arabinoxylans, significant increases in peak dough resistance, mixing stability, and work input were recorded in all flours. The addition of starch to various wheat flours reduced the strength of the respective flour-water doughs. The improvement of dough strength upon addition of waxy or zero amylose waxy barley meal was associated with the high content of total and soluble β-glucans present in barley samples. The addition of arabinoxylans or β-glucans increased the G′ of wheat doughs; arabinoxylans had a greater effect than β-glucans. Starch substantially decreased the elastic modulus of dough prepared from cv. Glenlea but waxy and high amylose starches increased the G′ of dough prepared from cv. AC Karma. A combination of the high amounts of non-starch polysaccharides and unusual starch characteristics in barley seems to balance the negative effects associated with gluten dilution brought about by addition of barley into wheat flour. 相似文献
5.
The aim of this study was to identify the biochemical parameters that alter the soft wheat flour functionality for biscuit-making quality. A 9-point simplex centroid was used to investigate the effect of varying the ratios of gluten, water-solubles and starch-fractions isolated from three different flour grades (patent, middle-cut and clear flours) which exhibited a wide range of compositional and functionality characteristics on the dough rheological behaviour and the semi-sweet biscuit quality parameters. The amounts of soluble and insoluble proteins and pentosans as well as the endogenous lipids in each flour fraction were quantified. Dough consistency, elongational viscosity, hardness, half-relaxation time, relaxation rate constant, cohesiveness and springiness as well as biscuit density, firmness, tearing force and spatial frequency for the different flour fraction combinations were also assessed. Regression models have been developed to predict the responses of the rheological attributes of the dough as well as the biscuit quality characteristics to the compositional changes of the flour blends; in addition to the main linear terms (concentration of starch, gluten and water-solubles isolated from the different flour grades), significant interaction terms were identified which cannot be neglected in any prediction scheme for the dough and biscuit properties. Contour plots were drawn in an effort to better understand the overall property responses of the dough and biscuits. Significant relationships among certain dough rheological parameters and biscuit characteristics were found, implying a functional role for the total, soluble and insoluble proteins, pentosans and lipids in biscuit making. 相似文献
6.
Shivananda K. Garimella PurnaRebecca A. Miller Paul A. SeibRobert A. Graybosch Yong-Cheng Shi 《Journal of Cereal Science》2011,54(1):37-43
Physico-chemical properties of bread baked by partially replacing normal wheat (Triticum aestivum L.) flour (15, 30, and 45%) with two hard waxy wheat flours were investigated. Substitution with waxy wheat flour resulted in higher loaf volume and softer loaves. However, substitution at >30% resulted in excessive post-bake shrinkage and a ‘key-hole’ shape with an open crumb structure. Bread crumb microstructure indicated a loss of starch granule rigidity and fusing of starch granules. The cells in the interior of the bread did not become gas-continuous and as a result, shrunk as the loaf cooled. Soluble starch content was significantly higher in bread crumb containing waxy wheat flour than in control bread. Debranching studies indicated that the soluble starch in bread made with 30-45% hard waxy wheat flour was mostly amylopectin. Incorporation of waxy wheat flour resulted in softer bread immediately after baking but did not retard staling upon storage. 相似文献
7.
Comparison of quality of refined and whole wheat tortillas 总被引：1，自引：0，他引：1
The use of whole wheat flour instead of refined flour significantly improves the nutritional profile of flour tortillas. However, whole and refined flours differ in properties and in how they process, thus needing process modifications to get the desired product quality. To understand these differences, refined and whole wheat flours, dough and tortillas were evaluated and compared for physical and rheological properties. Overall, whole wheat flour required more water (59% of flour weight) than refined wheat (53%) to make machineable dough. Refined flour doughs were more extensible and softer than whole wheat flour doughs, thus easier to process. Whole wheat flour tortillas were larger, thinner and less opaque than refined flour tortillas. In general, refined wheat tortillas were more shelf-stable than whole wheat tortillas. Smaller particle size and less fiber in the refined wheat flour mainly contributed to the observed differences. Among the whole wheat samples, tortillas from strong flours had excellent shelf-stability, which must be considered when whole wheat tortillas are processed. This will minimize the need to add vital wheat gluten or other dough strengtheners. 相似文献
8.
Secondary field emission scanning electron microscopy (FE SEM), atomic force microscopy (AFM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to investigate native near-isogenic soft and hard wheat kernels and their roller milled flours. FE SEM images of flat-polished interior endosperm indicated distinct differences between soft and hard wheats with less internal continuity in the soft wheat, whereas individual starch granules were much less evident in the hard kernel due to a more continuous matrix. AFM images revealed two different microstructures. The interior of the hard kernel had a granular texture with distinct individual spheroid features of 10–50 nm while the images obtained for the soft kernel revealed less distinct small grains and more larger features, possibly micro-structural features of starch granules. Raman spectra resolved identical distinct frequencies for both kernel types with slightly different intensities between types. Finally, the chemical surface compositions of flour for these two types of kernels obtained by XPS provided subtle insight into the differences between soft and hard wheat kernels. These combined advanced microscopic and spectroscopic analyses provide additional insight into the differences between the soft and hard wheat kernels. 相似文献
9.
Quality characteristics of northern-style Chinese steamed bread (CSB) prepared from two soft red winter (SRW) wheat flours blended with 0–30% waxy wheat flour (WWF) were analyzed to estimate the influence of starch amylose content. The increased proportion of WWF in blends raised mixograph absorption with insignificant changes in protein content and dough strength-related parameters. WWF incorporation generally increased specific volume and crumb softness of CSB. The analysis of covariance revealed that CSB quality attributes were little affected by protein content and dough strength-related parameters, indicating that starch amylose content was largely responsible for the changes in CSB quality. Flour blends with 5–10% WWF, of which starch amylose content was 22.4–24.7%, produced CSB with superior crumb structure compared to other blends, but insignificant changes in surface smoothness, stress relaxation and total score compared to the respective control wheat flours. Flour blends with 15% WWF to produce a starch amylose content of 21.4–22.7% exhibited reduced staling of CSB with total scores comparable to the respective control wheat flours. CSB prepared from blends with more than 10% WWF exhibited a higher soluble starch content, indicative of reduced starch retrogradation, than that prepared from wheat flours without WWF during storage for 3 days. 相似文献
10.
The Farinograph time-to-peak is an important wheat flour quality parameter. It is well-established that insoluble glutenins correlate with the strength of the gluten network and dough mixing time. To learn more about the physical changes at the mesoscopic level, dough samples were prepared in the Farinograph for study with diffusion wave spectroscopy. It was confirmed that a space-filling network was formed by wheat gluten proteins (mainly glutenin). At peak development (9.0 min) it was shown that the starch granules were confined in the gluten network. After the time-to-peak, dough resistance weakened, showing an increase of the starch granule movement. Kneading disrupts insoluble glutenin particles, the disrupted glutenin becomes part of the Sodium Dodecyl Sulfate (SDS)-extractable proteins. Both soluble and insoluble wheat protein extracts have been characterized by light scattering techniques. The results derived from light scattering of the wheat protein fractions: particle radii, apparent molar mass and geometrical shapes, suggests that the disrupted glutenin aggregate shape and glutenin size heterogeneity could be more important for gluten network bulk consistency, connectivity and resistance at dough peak, than the apparent molar mass of the solubilized glutenins, reaching a maximum after dough peak. 相似文献
11.
The use of pseudocereals and ancient grains for breadmaking applications is receiving particular attention since they involve nutrient dense grains with proven health-promoting attributes. Dilution up to 20% of the basic rye/wheat flour blend by accumulative addition of amaranth, buckwheat, quinoa and teff flours (5% single flour) did positively impact either some dough visco-metric and visco-elastic features, or some techno-functional and nutritional characteristics of mixed bread matrices, and induced concomitant dynamics in lipid binding over mixing and baking steps. A preferential lipid binding to the gluten/non gluten proteins and to the outside part of the starch granules takes place during mixing, in such a way that the higher the accumulation of bound lipids during mixing, the higher the bioaccessible polyphenol content in blended breads. During baking, lipids bind to the gluten/non gluten proteins at the expenses of both a free lipid displacement and a lipid migration from the inside part of the starch granules to the protein active sites. It was observed that the higher the decrease of free lipid content during baking, the higher the pasting temperature and the lower the total setback on cooling and the dynamic moduli, but the higher the specific volume in blended breads. 相似文献
12.
Anneleen Pauly Bram PareytNiels De Brier Ellen FierensJan A. Delcour 《Journal of Cereal Science》2012
Wheat (Triticum aestivum L.) kernel hardness is a major quality characteristic, which has been ascribed to the presence of puroindolines a and b. These proteins occur in higher levels at the surface of water-washed starch granules from soft wheat cultivars than at that of starch from hard wheat cultivars. In the present study, prime starch was isolated from flour from soft wheat (cultivar Claire) using a dough ball or batter based separation method. Starch isolated with the dough ball method contained lower levels of puroindolines, as well as of other starch granule associated proteins and lipids than that isolated with the batter method. Similar patterns of puroindoline and lipid levels after starch isolation can presumably be related to (polar) lipid binding by puroindolines. Both isolated starch fractions showed comparable differential scanning calorimetry thermograms, whereas higher levels of starch surface associated components restricted starch swelling. Necessary controls demonstrated that the observed differences did not arise from artefacts associated with hydration, fractionation or freeze-drying in the experimental protocols. Apparently, proteins and lipids at the starch granule surface impact water absorption and, as such, starch swelling, but they do not affect starch granule internal phenomena such as melting of the crystalline amylopectin chains. 相似文献
13.
施氮水平对小麦籽粒淀粉粒分布与加工品质的影响 总被引：3，自引：0，他引：3
为明确施氮对小麦淀粉粒分布与加工品质的影响,选用强筋小麦藁城8901和弱筋小麦豫麦50为材料,分析了不同施氮水平下小麦籽粒淀粉粒分布特征与部分加工品质指标。结果表明,适量施氮(240kg.hm-2)显著提高籽粒B型淀粉粒体积百分比,过量施氮(360kg.hm-2)时小麦籽粒B型淀粉粒体积百分比降低。施氮水平对两个小麦品种籽粒A、B型淀粉粒数目百分比无显著影响。在施氮0～240kg.hm-2范围内,增施氮肥可以提高籽粒直、支链淀粉积累量,而过量施氮不利于籽粒直、支链淀粉的积累。小麦湿面筋、沉淀值、面团形成时间和稳定时间等参数与A型淀粉粒体积百分比呈显著负相关,与B型淀粉粒体积百分比呈显著正相关。适量施氮能使强筋小麦加工品质变优;增施氮肥导致弱筋小麦加工品质变劣。 相似文献
14.
Sodium chloride (NaCl) is an essential ingredient to control the functional properties of wheat dough and bread quality. This study investigated the effect of NaCl at 0, 1 and 2%, (w/w, flour base) on the gluten network formation during dough development, the dough rheology, and the baking characteristics of two commercial flours containing different levels of protein (9.0 and 13.5%) and with different glutenin-to-gliadin ratios. Examination of the dough structure by confocal microscopy at different stages of mixing show that the gluten network formation was delayed and the formation of elongated fibril protein structure at the end of dough development when NaCl was used. The fibril structure of protein influenced the dough strength, as determined by strain hardening coefficient and hardening index obtained from the large deformation extension measurements. NaCl had a greater effect on enhancing the strength of dough prepared from the low protein flour compared to those from the high protein flour. The effect of NaCl on loaf volume and crumb structure of bread followed a similar trend. These results indicate that the effect of NaCl on dough strength and bread quality may be partially compensated by choosing flour with an appropriate amount and quality of gluten protein. 相似文献
15.
《Journal of Cereal Science》1998,27(1):53-60
For the characterization of wheat quality, micro-extension tests for dough and gluten and a micro-baking test were developed using comparable dough compositions, the same mixing temperature and cultivar-specific mixing times. By means of these methods, the flours of 26 wheat samples were studied for dough development time, maximum resistance and extensibility of dough and gluten and loaf volume of the baked products. Standard methods (rapid-mix-test, gluten index determination) were used for comparison. The results indicated that the rheological properties of dough and gluten as well as the gluten index are correlated higher with the optimised micro-baking test than with the standard baking test. If flour protein or wet gluten content is included in the correlations, the extension test of gluten, which can be performed easily and reproducibly, allows a reliable prediction of the loaf volume obtained by the micro-baking test. 相似文献
16.
Reduced glutathione (GSH) commonly exists in wheat flour and has remarkable influence on gluten properties. In this study, effect of GSH on the gelatinization and retrogradation of wheat flour and wheat starch were investigated to better understand the GSH-gluten-starch interactions in wheat flour. Compared with wheat starch, wheat flour showed significant decreases in peak and final viscosity, and gelatinization onset temperature with increasing GSH concentration. GSH depolymerized gluten and thereby broke down the protein barrier around starch granules to make the starch easily gelatinized. However, the interaction between GSH and wheat starch restrained starch swelling. GSH addition resulted in weakened structure with higher water mobility in freshly gelatinized wheat flour dispersions but decreased water mobility in wheat starch dispersions. After storage at 4 °C for 7 d, GSH increased elasticity and retrogradation degree in wheat flour dispersions but retarded retrogradation in wheat starch dispersions. The results indicated that GSH promoted retrogradation of wheat flour, which mainly attributed to the depolymerized gluten embedding in the leached starch chains, and inhibiting the re-association of amylose, and subsequently promoted the starch intermolecular associations and starch retrogradation. This study could provide valuable information for the control of the quality of wheat flour-based products. 相似文献
17.
Wheat filter flours are by-products obtained from air-classification of wheat flour. Physicochemical and rheological properties of wheat filter flours were investigated in the present study. Average values of crude protein, gluten, lipid and damaged starch content of filter flours were higher than those of standard flours for the same batch. The positive correlation of particles with size <20 μm and damaged starch was found. Moreover, the filter flours had higher water absorption, stability time except head milling filter flour samples. Short peak time and low peak viscosity were also observed. Different composition of wheat filter flours may be an important factor influencing its properties. This study is very useful for exploring the utilization of wheat filter flours in the food industry. 相似文献
18.
Waxy wheat flour (WWF) was substituted for 10% regular wheat flour (RWF) in frozen doughs and the physicochemical properties of starch and protein isolated from the frozen doughs stored for different time intervals (0, 1, 2, 4 and 8 weeks) were determined to establish the underlying reasons leading to the effects observed in WWF addition on frozen dough quality. Using Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimeter (DSC) and X-ray Diffraction (XRD) among others, the gluten content, water molecular state, glutenin macropolymer content, damaged starch content, starch swelling power, gelatinization properties, starch crystallinity and bread specific volume were measured. Compared to RWF dough at the same frozen storage condition, 10% WWF addition decreased dry gluten and glutenin macropolymer contents and T23 proton density of frozen dough, but increased the wet gluten content, T21 and T22 proton density. 10% WWF addition also decreased damaged starch content, but increased starch swelling power, gelatinization temperature and enthalpy, crystallinity of starch and bread specific volume of frozen dough. Results in the present study showed that the improvement observed due to WWF addition in frozen dough bread quality might be attributed to its inhibition of redistribution of water molecules bound to proteins, increase in damaged starch content and decrease in starch swelling power. 相似文献
19.
Three types of wheat: 8901 (hard wheat), Nanyang white wheat, NYWW (medium wheat), and Australian white wheat, AWW (soft wheat) were milled after debranning by abrasion and friction, and by conventional milling. The quality of flours produced by the two procedures and their performance in steamed breadmaking were evaluated. The results showed that debranning affected both the quality of flour and the steamed bread, especially for 8901 and NYWW. Debranning lowered the gluten index, maximum resistance and starch damage; whereas, it increased pericarp content, ash content, L* value, falling number and particle size distribution. The pasting properties such as peak viscosity and final viscosity of NYWWDII and 8901DII were higher than those of NYWWCII and 8901CII. Debranning had positive effects on the quality scores, volume, volume/weight, height and structure of steamed bread from second flour, except for those from soft wheat. For the two other samples, the quality scores for steamed bread were lower than that for the conventional flour. The shape and structure of steamed bread from the top flours of AWWCII and 8901CII were better than from debranned flour. The milling methods did not affect the texture of steamed bread, except in the case of second flour of NYWW. 相似文献
20.
The different gluten subunits, gliadins, LMW glutenins, and HMW glutenins have been reported to play different key roles in different type of wheat products. This paper studied the interaction between gliadin, LMW and HMW glutenins in soft, hard and durum semolina flour doughs during different stages of mixing. In order to see how do the gluten subunits (gliadin, LMW glutenin and HMW glutenin) redistribute during mixing, dough samples were taken at maximum strength and 10 min after maximum strength. The doughs have been mixed with the same level of added water (55%), therefore they all have different strengths values due to their changes in proteins content. Oscillatory rheological measurements were performed on the doughs. It has been found that HMW glutenins are relatively immobile because of their less molecular mobility and do no redistribute themselves especially at high strength for doughs such as hard wheat flour. LMW glutenins and gliadins on the other hand redistribute themselves at even at high dough strengths forming a more stable network. In weaker doughs such as soft wheat, the breakdown of the three proteins subunits is responsible for the decay in dough strength. We have also visualized how the greater amount of LMW glutenins in semolina is in constant interaction with HMW glutenins and gliadins allowing the dough to maintain a stable strength for an extended mixing time. Finally, we have found the ‘in situ’ detection and quantitative analysis techniques to be more sensitive to the changes occurring in the gluten network of the dough than the oscillatory rheological analysis. 相似文献