小麦制粉不同组分中铁锌含量的影响因素探析

提高小麦籽粒有益微量元素含量,特别是对人体影响较大的Fe、Zn含量,是解决中国广大居民微量元素营养匮乏的重要途径之一。2012-2015年将3个不同基因型小麦品种(邯6172、衡5229和周麦16),种植于河北石家庄赵县、陕西杨凌区和河南省新乡辉县。每个地域3个小区,每小区面积10 m²,试验田按照当地小麦品种区域试验管理。共采集36份小麦样品,小麦籽粒粉碎制得全麦粉;同时将小麦籽粒加工制粉,得到粗麸、细麸和面粉。采用电感耦合等离子体质谱法(ICP-MS)测定全麦粉及制粉产品(粗麸、细麸和面粉)中的Fe、Zn含量。结合单因素方差分析及Duncan多重比较分析不同地域、不同基因型、不同年际获得的小麦不同制粉产品间的Fe、Zn含量差异。结果表明,基因型对本研究全麦粉Fe含量影响最为显著,地域是影响全麦粉Zn含量的最重要因素。Fe、Zn含量在小麦制粉不同组分中的变化趋势为:粗麸>细麸>面粉。Fe含量在各组分中受基因型影响最大。Zn含量在全麦粉和粗麸中受地域影响最大,细麸中受年际影响最大,面粉中分别受年际×地域的交互作用、基因型和年际3个因素的影响最大。综上所述,全麦粉相对面粉的Fe、Zn含量更高,且更容易通过选种和选择合适地域耕种提高其Fe、Zn含量。本研究为从小麦的种植及加工角度改善主食中铁锌含量较低这一现状提供了理论参考。     

麸皮面粉面团的粉质和拉伸特性

为了探讨麸皮对小麦面粉品质的影响,将微粉碎后的燕麦麸细粉、小麦麸细粉与小麦粉按混料配方均匀设计制备麸皮面粉,用粉质仪和拉伸仪测定了麸皮面粉的面团流变学特性,并对麸皮面粉各组分含量与流变学参数间的相关性进行分析。结果表明,随着麸皮含量的增加,麸皮面粉面团的吸水率增大,形成时间变化不大,稳定时间不断减少;弱化度和粉质指数在不同样品变化较大,以样品3粉质特性(即小麦粉88.5%,燕麦麸细粉10.20%,小麦麸1.39%)最优;相同醒发时间下,随着麸皮总含量的增加,面团的拉伸曲线面积、延伸度、拉伸阻力及最大拉伸阻力均呈下降趋势;拉伸参数均随醒发时间而呈上升趋势。与面团粉质特性相关性最显著的是小麦粉含量,其次是小麦麸和燕麦麸细粉含量;小麦粉含量与拉伸特性呈显著正相关,与燕麦麸含量呈显著负相关,与小麦麸含量的相关性不显著。这些研究表明麸皮添加比例能够显著影响面团的流变学特性。     

追氮量对黑小麦品种(系)籽粒产量和品质的影响

为探究追氮量对不同黑小麦品种(系)籽粒产量和品质的影响,本研究采用大田裂区试验设计,主区为11个黑小麦品种(系),副区为追施氮量0(N0,对照)、34.5(N1)、51.8(N2)、69.0(N3)kg·hm²,于小麦灌浆期测定旗叶叶绿素含量(SPAD值),成熟期测定籽粒产量及产量构成要素、籽粒氮素含量和品质指标。结果表明,旗叶SPAD值在追氮处理下均增加,除B145-2、L10056、L10058的旗叶SPAD值在N1最高,其余8个品种(系)的旗叶SPAD值均随追氮量增加而升高。追施氮肥均有利于增加黑小麦产量,与N0相比,N1、N2和N3的产量增幅分别为15.2%~99.7%、17.5%~80.9%和0.7%~69.9%。11个品种(系)获得最高产量的适宜追氮量因品种而异,其中L10056、B120-2、运黑14207籽粒产量随追氮量增加而增加,B145-2、L10058籽粒产量在N2最高,其余6个品种(系)籽粒产量在N1最高。追氮量、品种及二者交互均对产量及构成因素存在极显著影响。追施氮肥能够提高多数黑小麦品种籽粒氮素含量,其中B145-2、L10058和运黑14207在N2最高,18鉴46、临黑131、冬黑1号、临黑187、2002-4、运黑161在N1最高。追氮量与籽粒产量、氮含量、蛋白含量呈正相关(相关性不显著),而产量与籽粒蛋白含量及多数品质指标存在极显著负相关关系。综合考虑黑小麦产量及品质的提高,追氮量在34.5~51.8 kg·hm²之间较为适宜。本研究结果可为黑小麦合理施用氮肥提供参考。     

追氮量对黑小麦品种(系)籽粒产量和品质的影响

为探究追氮量对不同黑小麦品种(系)籽粒产量和品质的影响,本研究采用大田裂区试验设计,主区为11个黑小麦品种(系),副区为追施氮量0(N0,对照)、34.5(N1)、51.8(N2)、69.0(N3)kg·hm²,于小麦灌浆期测定旗叶叶绿素含量(SPAD值),成熟期测定籽粒产量及产量构成要素、籽粒氮素含量和品质指标。结果表明,旗叶SPAD值在追氮处理下均增加,除B145-2、L10056、L10058的旗叶SPAD值在N1最高,其余8个品种(系)的旗叶SPAD值均随追氮量增加而升高。追施氮肥均有利于增加黑小麦产量,与N0相比,N1、N2和N3的产量增幅分别为15.2%~99.7%、17.5%~80.9%和0.7%~69.9%。11个品种(系)获得最高产量的适宜追氮量因品种而异,其中L10056、B120-2、运黑14207籽粒产量随追氮量增加而增加,B145-2、L10058籽粒产量在N2最高,其余6个品种(系)籽粒产量在N1最高。追氮量、品种及二者交互均对产量及构成因素存在极显著影响。追施氮肥能够提高多数黑小麦品种籽粒氮素含量,其中B145-2、L10058和运黑14207在N2最高,18鉴46、临黑131、冬黑1号、临黑187、2002-4、运黑161在N1最高。追氮量与籽粒产量、氮含量、蛋白含量呈正相关(相关性不显著),而产量与籽粒蛋白含量及多数品质指标存在极显著负相关关系。综合考虑黑小麦产量及品质的提高,追氮量在34.5~51.8 kg·hm²之间较为适宜。本研究结果可为黑小麦合理施用氮肥提供参考。     

研磨条件对小麦样品粉碎制备效果的影响研究

为了考察不同研磨条件对小麦样品的粉碎效果,有效制备实验室分析样品,本研究使用自主研发的平行研磨仪设定不同研磨时间、循环次数、研磨重量,考察不同条件处理小麦样品通过20、 40、 60目标准筛的过筛率,并基于QuEChERS-超高效液相色谱-串联质谱法,采用不同细度样品中26种农药的添加回收率辅助评价研磨效果。结果表明,过20目筛样品的添加回收效果最好,除甲胺磷外25种农药的回收率为74.7%~114.9%(RSD<13.5%),以此为依据筛选出50 g小麦研磨30 s且循环2次效果最好,过20目筛率达93.7%,未过筛直接添加26种农药回收率为62.9%~120.1%(RSD<7.5%),其次为100 g小麦研磨30 s循环2次效果较好,过20目筛率为54.3%。     

花后土壤干旱和渍水对不同专用小麦籽粒品质的影响

在温室盆栽条件下,以4个籽粒蛋白质含量不同的小麦基因型为材料,研究了花后土壤干旱(SRWC=45%～50%)、渍水和适宜水分条件(SRWC=75%～80%)下小麦籽粒主要品质特性。干旱显著提高各品种籽粒蛋白质含量、谷蛋白含量及谷蛋白/醇溶蛋白比值,并显著提高面粉干/湿面筋含量。渍水显著降低了籽粒谷蛋白含量及谷蛋白/醇溶蛋白比值。干旱和渍水均显著降低籽粒淀粉产量和支链淀粉含量,直链淀粉含量提高,从而不同程度地降低籽粒直/支链淀粉比。干旱和渍水对各品种籽粒面筋指数、沉降值和降落值的影响因品种而异。与对照相比,干旱和渍水下小麦籽粒各品质性状间的相关性降低,表明土壤水分逆境下各籽粒品质特征值与正常水分条件下差异明显,从而改变了专用小麦的籽粒品质特性。     

适量燕麦β-葡聚糖改善面团流变学特性

为探讨燕麦β-葡聚糖在强化面粉中应用的可行性,该文利用粉质仪、拉伸仪和糊化仪分析质量分数为0.5%~5.0%燕麦β-葡聚糖的添加对低筋面粉、中筋面粉、高筋面粉及馒头专用粉的流变学特性的影响。结果表明,随着β-葡聚糖添加量的增加,4种面粉面团的的吸水率、形成时间和稳定时间均增大;0.5%~2.0%添加量增强了4种面粉面团的最大拉伸阻力,0.5%~1.0%添加量能够使低筋面粉的拉伸特性接近馒头专用面粉的拉伸特性;燕麦β-葡聚糖能够使中筋面粉的糊化温度稍有升高,但亦能降低馒头专用粉的糊化温度及4种面粉(2.0%~4.0%添加量的低筋面粉及4.0%添加量的高筋面粉除外)的最高黏度、保持黏度、最终黏度、衰减值和回生值。研究表明适量的燕麦β-葡聚糖能够改善面团的流变学特性,研究结果为燕麦β-葡聚糖在强化面粉中的应用提供参考。     

储藏时间影响小麦蛋白质理化特性的灌溉效应

灌溉对小麦蛋白质理化特性的影响规律报道不完全一致,这可能与检测蛋白质理化特性时籽粒储藏时间长短有关。为明确灌溉效应受籽粒储藏时间的影响,进一步明确灌溉对小麦蛋白质理化特性的影响,本试验将3种灌溉处理水平的衡4399小麦籽粒在室温条件下储藏120 d,每30 d取样一次,用布勒磨磨制小麦粉(出粉率为66%~71%),检测面粉的蛋白质数量属性、质量属性和面团流变学特性。结果表明,灌溉和储藏时间以及二者的交互作用均显著影响小麦蛋白质理化特性。配对T检验显示,面粉粗蛋白含量和湿面筋含量随灌溉量及频次的增加分别相对降低6%和14%;沉降指数、面团稳定时间和面团最大拉伸阻力随灌溉量及频次的增加分别相对增加15%、33%和95%。进一步多重比较表明,储藏时间影响了麦谷蛋白大聚体含量及其储能模量值、面团吸水率和拉伸长度的灌溉效应。储藏2~3个月后小麦蛋白质理化特性指标逐渐趋于稳定。籽粒储藏时间影响小麦蛋白质理化特性的灌溉效应,籽粒收获后至少储藏90 d再检测才能客观反映灌溉效应。本研究为进一步揭示灌溉对小麦品质的影响规律提供了参考。     

糯小麦淀粉结构特征和理化品质研究

为解析糯小麦淀粉结构特征和理化品质，以4个糯小麦为试验材料，3个不同筋力的非糯小麦为对照，测定其淀粉组分及含量、X射线衍射特性、结晶度、粒度分布、链长分布和热力学特性。结果表明，糯小麦的总淀粉、直链淀粉含量分别为66.04%～67.84%、0.07%～1.73%，显著低于非糯小麦，而支链淀粉含量则相反。糯小麦A型淀粉颗粒的表面积比、体积比和数量比分别为26.17%～35.16%、52.45%～62.89%、2.11%～3.19%，显著低于非糯小麦；B型淀粉除数量比外，表面积比和体积比都显著高于非糯小麦；C型淀粉的表面积比、体积比和数量比均显著高于非糯小麦，其中中科糯麦1号的C型淀粉数量比和表面积比最高。X射线衍射图表明，衍射角2θ在15°、17°、18°、23°附近出现了较强的波谱峰，在20°处非糯小麦有较弱波谱峰，但糯小麦几乎没有。糯小麦结晶度在25.16%～26.78%之间，显著高于非糯小麦，其中中科糯麦1号结晶度最高。糯小麦与非糯小麦在链长分布上整体无显著差异，除扬糯麦1号外，糯小麦较长的B3链和平均链长略高于非糯小麦。糯小麦的起始温度、峰值温度、终止温度、热焓值分别为58.62...     

振动磨机磨介特征对小麦麸皮超微粉碎效果的影响

为研究振动磨机磨介的密度、尺寸、形状等特征对小麦麸皮超微粉碎效果的影响,构建具有控温功能的振动粉碎试验平台,基于振动磨机振动特性相同原则设计试验方案,开展小麦麸皮振动冲击粉碎试验。结果表明：磨介密度在麸皮超微粉体产量方面引起的差异率为50.05%;磨介尺寸引起的最大差异率为49.64%;磨介形状引起的最大差异率为70.07%。当磨介质量相同时,低密度氧化锆磨介的麸皮超微粉产量高于高密度不锈钢磨介,且氧化锆磨介的麸皮微粉品质优于不锈钢磨介。随着磨介尺寸的增大,麸皮超微粉体产量呈现出先减小后增大的非线性特征,而麸皮微粉品质却一直下降。随着粉碎时间的增加,圆柱形磨介和球形磨介的麸皮微粉品质先提升后下降,而麸皮超微粉产量却近似呈线性增加,且圆柱形磨介的超微粉产量始终大于球形磨介。球形磨介微粉品质劣化速度大于柱形磨介,但当粉碎时间为1.0 h时,两种磨介的麸皮微粉品质差异率仅为2.26%。磨介特征明显改变了小麦麸皮超微粉碎效果,研究结果在振动磨机超微粉碎性能调控方面具有潜在应用前景。     

Cooking,Roasting, and Fermentation of Chickpeas,Lentils, Peas,and Soybeans for Fortification of Leavened Bread

The effects of cooking, roasting, and fermentation on the composition and protein properties of grain legumes and the characteristics of dough and bread incorporated with legume flours were determined to identify an appropriate pretreatment. Oligosaccharide content of legumes was reduced by 76.2–96.9% by fermentation, 44.0–64.0% by roasting, and 28.4–70.1% by cooking. Cooking and roasting decreased protein solubility but improved in vitro protein digestibility. Mixograph absorption of wheat and legume flour blends increased from 50–52% for raw legumes to 68–76, 62–64, and 74–80% for cooked, roasted, and fermented ones, respectively. Bread dough with cooked or roasted legume flour was less sticky than that with raw or fermented legume flour. Loaf volume of bread baked from wheat and raw or roasted legume flour blends with or without gluten addition was consistently highest for chickpeas, less for peas and lentils, and lowest for soybeans. Roasted legume flour exhibited more appealing aroma and greater loaf volume of bread than cooked legume flour, and it appears to be the most appropriate preprocessing method for incorporation into bread.     

Fermentation Reduces Free Asparagine in Dough and Acrylamide Content in Bread

Free asparagine is an important precursor for acrylamide in cereal products. The content of free asparagine was determined in 11 milling fractions from wheat and rye. Whole grain wheat flour contained 0.5 g/kg and whole grain rye flour 1.1 g/kg. The lowest content was found in sifted wheat flour (0.2 g/kg). Wheat germ had the highest content (4.9 g/kg). Fermentation (baker's yeast or baker's yeast and sourdough) of doughs made with the different milling fractions was performed to investigate whether the content of free asparagine was reduced by this process. In general, most of the asparagine was utilized after 2 hr of fermentation with yeast. Sourdough fermentation, on the other hand, did not reduce the content of free asparagineas efficiently but had a strong negative impact on asparagine utilization by yeast. This indicates that this type of fermentation may result in breads with higher acrylamide content than in breads fermented with yeast only. The effect of fermentation time on acrylamide formation inyeast‐leavened bread was studied in a model system. Doughs (sifted wheat flour with whole grain wheat flour or rye bran) were fermented for a short (15+15 min) or a long time (180+180 min). Compared with short fermentation time, longer fermentation reduced acrylamide content in bread made with whole grain wheat 87%. For breads made with rye bran, the corresponding reduction was 77%. Hence, extensive fermentation with yeast may be one possible way to reduce acrylamide content in bread.     

南方馒头专用小麦粉原料选择研究

为生产高品质南方馒头,确定优质南方馒头专用小麦粉原料特性的取值范围,本研究以20种小麦粉为原料制备南方馒头,探究小麦粉的理化特性、糊化特性、拉伸特性、粉质特性对南方馒头品质的影响,通过逐步回归分析法筛选出影响南方馒头综合品质的小麦粉关联性指标,结合聚类分析得到适宜加工南方馒头的小麦粉原料关联性指标范围。结果表明,小麦粉原料的灰分、降落数值、峰值黏度、形成时间、稳定时间、弱化值、延伸度、拉伸面积、拉伸比、最大拉伸比与南方馒头品质综合得分存在显著(P < 0.05)相关性。影响南方馒头综合品质的关键指标为延伸度、形成时间和峰值黏度,适宜加工南方馒头的小麦粉参考关键指标范围为:延伸度126.00~158.00 mm、形成时间1.70~5.00 min、峰值黏度 1 027.00~1 326.00 Pa·s。小麦粉原料选择模型的建立和关键性指标范围的确定可预测南方馒头品质。本研究为南方馒头原料选择提供了依据,并可用于进一步改善南方馒头的综合品质。     

Antioxidant contents and antioxidative properties of traditional rye breads

The purpose of this research was to find out the effect of flour extraction rate on the antioxidative properties of traditional rye bread and then to compare the bioactive compounds content and antioxidant properties of rye breads with commercial wheat roll. Four types of rye flour with different extraction rates of 100 (whole meal dark flour), 95 (brown flour), 90 (brown flour), and 70% (light flour) originated from Warko rye cultivar were used for traditional bread baking with sourdough fermentation. Four types of the respective rye breads were analyzed for their potentially beneficial components, including tocopherols and tocotrienols, total phenolics and flavonoids, reduced glutathione, and inositol hexaphosphates. Moreover, the phenolic acids profile was provided. The Trolox equivalent antioxidant capacity (TEAC) of the breads was evaluated using free radical scavenging activities of 80% methanol extracts against ABTS*+ radical cation (ABTS radical cation decolorization method) whereas radical scavenging activity (RSA) was determined against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*). The superoxide dismutase-like activity (SOD-like activity) was evaluated as free radical scavenging activities of PBS extracts against superoxide anion radicals (O2*-). The results were compared to whole meal rye bread as well as to wheat roll taken as representative example of wheat based bakery product. The studies showed that flour extraction rates strongly affected the content of bioactive compounds and antioxidative properties of traditionally baked rye breads. The incorporation of the rye flours with extraction rates from 100 down to 70% in the formulation caused decrease in tocopherol (T), tocotrienol (T3), inositol hexaphosphate (IP6), and phenolic compound (TPC) contents in rye breads. No changes in reduced glutathione (GSH) contents were noted between each type of rye bread. A significant decrease in Trolox equivalent antioxidant capacity and radical DDPH scavenging activity was also found in bread formulated on flour with an extraction rate of 70% in comparison to the breads formulated on flour with extraction rates from 100 to 90%. The highest SOD-like activity was noted for rye bread formulated on flour with an extraction rate of 70%. The four types of rye breads showed better antioxidative properties and higher antioxidant contents when compared to wheat roll with one exception made to tocopherols and tocotrienols.     

Quality of Flours from Waxy and Nonwaxy Barley for Production of Baked Products

One nonwaxy (covered) and two waxy (hull-less) barleys, whole grain and commercially abraded, were milled to break flour, reduction flour, and the bran fraction with a roller mill under optimized conditions. The flour yield range was 55.3–61.8% in whole grain and increased by 9–11% by abrasion before milling. Break flours contained the highest starch content (≤85.8%) independent of type of barley and abrasion level. Reduction flours contained less starch, but more protein, ash, free lipids, and total β-glucans than break flours. The bran fraction contained the highest content of ash, free lipids, protein, and total β-glucans but the lowest content of starch. Break flours milled from whole grain contained 82–91% particles <106 μm, and reduction flours contained ≈80% particles <106 μm. Abrasion significantly increased the amount of particles <38 μm in break and reduction flours in both types of barley. Viscosity of hot paste prepared with barley flour or bran at 8% concentration was strongly affected by barley type and abrasion level. In cv. Waxbar, the viscosity in bran fractions increased from 428 to 1,770 BU, and in break flours viscosity increased from 408 to 725 BU due to abrasion. Sugar snap cookies made from nonwaxy barley had larger diameter than cookies prepared from waxy barley. Cookies made from break flours were larger than those made from reduction flours, independent of type of barley. Quick bread baked from nonwaxy barley had a loaf volume similar to that of wheat bread, whereas waxy barley bread had a smaller loaf volume. Replacement of 20% of wheat flour by both waxy and nonwaxy barley flour or bran did not significantly affect the loaf volume but did decrease the hardness of quick bread crumb.     

Contribution of Sourdough Lactobacilli,Yeast, and Cereal Enzymes to the Generation of Amino Acids in Dough Relevant for Bread Flavor

The amino acid release was determined in wheat doughs supplied with salt, acid, dithiothreitol, or starter cultures to evaluate the relevance of the amino acid concentration on bread flavor. Wheat flour proteinases almost linearly released amino acids and the highest activity of wheat flour proteinases was found in acidified and reduced doughs. The effects of starter cultures on amino acid concentrations depended on their composition. Yeasts exhibited a high demand for amino acids, however, the total amino acid concentrations were not markedly affected by lactic acid bacteria. The individual amino acid contents were determined by the pH during fermentation and microbial metabolism. The formation of proline was favored by values higher than pH 5.5, whereas release of phenylalanine, leucine and cysteine mainly occurred at lower pH. Ornithine was found only in doughs fermented with Lactobacillus pontis. To determine effects of the amino acid concentration on bread aroma, fermented doughs were evaluated in baking experiments. An increased intensity of bread flavor was obtained by preferments prepared with lactic acid bacteria. The roasty note of wheat bread crust could be markedly enhanced by L. pontis. This results support the assumption that flavor of wheat bread is enhanced by increasing the concentration of free amino acids and especially ornithine in dough.     

Variations in Amino Acid and Protein Contents of Wheat During Milling and Northern‐Style Steamed Breadmaking

To determine the variations of amino acid and protein during milling and steamed breadmaking, two types of wheat cultivars belonging to soft and hard wheat types were used. The results showed that losses occurred in 17 amino acids during milling. The mean loss of threonine (18.0%) was the highest, which was followed by proline (15.5%), methionine (15.1%), and histidine (15.1%). The losses of tyrosine and lysine were the lowest (8.1 and 9.7%, respectively). Losses were also found for 17 amino acids during steamed breadmaking. The highest loss was observed in alanine (17.1%), with tyrosine (12.5%) close behind, and leucine (4.3%) exhibiting the lowest loss. The mean protein contents for whole‐wheat meal, flour, and steamed bread prepared from the test materials were 15.25, 14.27, and 14.33%, respectively. This meant that protein content decreased during milling; however, a slight increase was observed during steamed breadmaking. Amino acid scores of lysine in whole‐wheat meal, flour, and steamed bread prepared from the test materials were 45.4, 41.0, and 38.2, respectively. The general trend in the variations of protein and amino acids was similar in the two wheat cultivars tested.     

Changes in Phytate Content in Whole Meal Wheat Dough and Bread Fermented with Phytase‐Active Yeasts

The degradation of inositol hexakisphosphate (IP6) was evaluated in whole meal wheat dough fermented with baker's yeast without phytase activity, different strains of Saccharomyces cerevisiae (L1.12 or L6.06), or Pichia kudriavzevii with extracellular phytase activity to see if the degradation of IP6 in whole meal dough and the corresponding bread could be increased by fermentation with phytase‐active yeasts. The IP6 degradation was measured after the dough was mixed for 19 min, after the completion of fermentation, and in bread after baking. Around 60–70% of the initial value of IP6 in the flour (10.02 mg/g) was reduced in the dough already after mixing, and additionally 10–20% was reduced after fermentation. The highest degradation of IP6 was seen in dough fermented with the phytase‐active yeast strains S. cerevisiae L1.12 and P. kudriavzevii L3.04. Activity of wheat phytase in whole meal wheat dough seems to be the primary source of phytate degradation, and the degradation is considerably higher in this study with a mixing time of 19 min compared with earlier studies. The additional degradation of IP6 by phytase‐active yeasts was not related to their extracellular phytase activities, suggesting that phytases from the yeasts are inhibited differently. Therefore, the highest degradation of IP6 and expected highest mineral bioavailability in whole meal wheat bread can be achieved by use of a phytase‐active yeast strain with less inhibition. The strain S. cerevisiae L1.12 is suitable for this because it was the most effective yeast strain in reducing the amount of IP6 in dough during a short fermentation time.     

Moderate decrease of pH by sourdough fermentation is sufficient to reduce phytate content of whole wheat flour through endogenous phytase activity

Whole wheat bread is an important source of minerals but also contains considerable amounts of phytic acid, which is known to impair their absorption. An in vitro trial was performed to assess the effect of a moderate drop of the dough pH (around 5.5) by way of sourdough fermentation or by exogenous organic acid addition on phytate hydrolysis. It was shown that a slight acidification of the dough (pH 5.5) with either sourdough or lactic acid addition allowed a significant phytate breakdown (70% of the initial flour content compared to 40% without any leavening agent or acidification). This result highlights the predominance of wheat phytase activity over sourdough microflora phytase activity during moderate sourdough fermentation and shows that a slight drop of the pH (pH value around 5.5) is sufficient to reduce significantly the phytate content of a wholemeal flour. Mg "bioaccessibility"of whole wheat dough was improved by direct solubilization of the cation and by phytate hydrolysis.     

Effect of spelt wheat flour and kernel on bread composition and nutritional characteristics

Spelt wheat seeds (Triticum aestivum subsp. spelta cv. Ostro) were used to obtain white spelt flour (64.5% yield), wholemeal spelt flour (100% yield), and scalded spelt wheat kernels. From these materials, white spelt wheat bread (WSB), wholemeal spelt wheat bread (WMSB), and spelt wheat bread with scalded spelt wheat kernels (SSKB) were made and were compared to the reference white wheat bread (WWB). The spelt wheat flours and breads contained more proteins in comparison to wheat flour and bread. Among the samples the highest rate of starch hydrolysis was noticed in WSB. During the first 30 min of incubation this particular bread was shown to have significantly more (P < 0.05) rapidly digestible starch than the WMSB and later on also more starch than in WWB and SSKB, respectively. The WMSB had the lowest hydrolysis index (HI = 95.7). However, the result did not differ significantly from that in the reference common wheat bread. On the other hand, the most refined spelt wheat flour resulted in a bread product (WSB) that was statistically withdrawn (P < 0.05) as one with the highest HI (112.6).