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1.
低温对小麦麸皮拉伸力学特性参数的影响 总被引：2，自引：2，他引：0
为了揭示温度对小麦麸皮破碎性能的影响规律,选取?80～30℃作为试验温度,利用动态热机械分析仪(DMA)对小麦麸皮试样进行拉伸破坏试验,研究温度对小麦麸皮杨氏模量、极限应力、极限应变等力学特性参数的影响。结果表明:随着试验温度的下降,小麦麸皮逐渐由弹塑性材料转变为脆性材料,玻璃化转变温度为?80℃。杨氏模量随着温度的下降而显著增大,?80℃时的杨氏模量增大了93.14%。极限应力对温度的变化似乎不太敏感,在整个温度变化范围内的增幅较小,约为14.58%。极限应变随着温度的下降而减小,在整个温度变化范围内,极限应变降低了66.68%。液氮消耗量随着温度的下降而呈线性升高,?80℃时的液氮消耗量是?40℃的1.74倍,是?10℃的2.94倍。同时发现,在?10℃附近杨氏模量、极限应力、极限应变、液氮消耗量均出现了一个局部极小值现象。综合考虑小麦麸皮力学特性与冷媒消耗量之间的关系,低温粉碎小麦麸皮的适宜温度可取?40～0℃。基于试验结果,分别给出了杨氏模量、极限应力、极限应变、液氮消耗量关于温差的函数关系式。研究结果初步揭示了低温脆化对小麦麸皮力学特性参数的影响规律,可为小麦麸皮超微粉碎温度的选择提供参考。 相似文献
2.
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。 相似文献
3.
麸皮面粉面团的粉质和拉伸特性 总被引：3，自引：1，他引：2
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。 相似文献
4.
为研究超微粉碎对青稞麸皮表观结构及物化特性的影响,探究青稞麸皮超微粉作为食品辅料的可行性。该研究以青稞麸皮为原料,通过气流超微粉碎处理得到青稞麸皮微粉,并比较青稞麸皮粗粉与微粉的微观结构及功能特性。结果表明,青稞麸皮粗粉经超微粉碎20、40 min后获得了平均粒径为72.52和22.69μm的粉体。随着粉体粒径的减小,粉体更加细腻,分布更均匀,色泽更白亮;且对青稞麸皮的营养成分有较好的保留;但超微粉碎并未对粉体的微观结构产生较大影响。与青稞麸皮粗粉相比,2种微粉的休止角与滑角均变大;水溶性增加,持水力和持油力减小,膨胀力和振实密度、堆积密度显著降低(P<0.05);对阳离子交换能力减小,但胆酸盐的吸附能力增强;显著(P<0.05)增加了青稞麸皮微粉的峰值黏度、谷值黏度、最终黏度、崩解值,降低了其回生值;青稞麸皮微粉(平均粒径72.52μm)的膨胀力、持水力、持油力、阳离子交换能力、胆酸盐吸附能力均优于微粉(平均粒径22.69μm)。研究为青稞麸皮的深加工利用提供一定的理论依据。 相似文献
5.
麦麸结构层粉体的电特性研究 总被引：1，自引：1，他引：0
为了确定麦麸结构层粉体静电场分离的可行性,该文以高纯度麦麸糊粉层和外果皮粉体为原料,研究其介电性、导电性和电晕带电特性的差异。结果表明,麦麸粉体的介电常数随频率的增加而降低,最终趋于一致;当频率较低时,外果皮的相对介电常数明显低于糊粉层;当频率为300 MHz时,两者的介电常数之比最大达5.3;麦麸粉体的导电性差,糊粉层粉体的电阻率为2300MΩ/cm,为外果皮电阻率的5倍;经正电晕带电后,糊粉层粉体所获电荷量约为外果皮的1.7倍,具有明显差异;单位质量麦麸粉体所获电荷量随电晕电压的增加而增加,而随麦麸粉体的含水率和粒径的增大而减小。总之,麦麸结构层粉体的介电性、导电性和电晕带电性均存在明显差异,可以利用介电泳和电晕带电后的静电场分离技术对麦麸结构层进行分离纯化。 相似文献
6.
超微粉碎对苦荞麸功能特性的影响 总被引：5，自引：2，他引：5
为研究超微粉碎处理对苦养麸中功能成分的溶出、清除有毒有害物及抗氧化功能特性的影响。将苦养麸皮原粉进行超微粉碎处理得到苦养麸微粉，比较不同粒度的苦养微粉与麸皮原粉中总黄酮提取率、在体外对胆酸钠、Pb^2＋、Cd^2＋、Hg^2＋的吸附力以及对NO2^-、2，2-联苯-1-三砂基苯肼（DPPH）的清除力。结果表明，与苦养麸皮原粉相比，苦养麸微粉（平均粒径为20．621μm）的总黄酮提取率增加0．36个百分点；对胆酸钠的吸附量降低5．60mg／g；对Pb^2＋、Cd^2＋、Hg^2＋的吸附量增加0．184、0．840、1．341mg／g；对NO2的清除率增加24．25个百分点；对DPPH的清除率增加53．56个百分点。超微粉碎处理适合苦养麸皮的深加工；得到苦养麸微粉具有优良的营养、功能特性，是一种极具开发潜力的功能食品原料。 相似文献
7.
机械超微粉碎与不同粒度常规粉碎对红茶理化特性的影响 总被引：5，自引：3，他引：2
为探究机械超微粉碎对茶叶物性及功能成分浸出特性的影响,该文通过超微粉碎和常规粉碎2种方法制备超微红茶粉和4种粒度的粗粉红茶粉,研究了5种茶粉的粒度分布、微观形貌、比表面积、结晶度、表面氧碳元素比、中红外图谱和功能成分的浸出特性。结果表明:常规粉碎不同粒度茶粉间差异较小,而超微粉碎较大程度地改变了茶叶的物料性质。超微粉碎后,茶粉粒度减小至微米级,比表面积增大,茶粉的结晶度降低,表面暴露的纤维素和半纤维素相对含量增多,而中红外谱图显示超微粉碎茶粉的官能团结构并没有改变。沸水浸提过程中茶多酚、咖啡因、可溶性糖和水浸出物的溶出结果表明:5种茶粉功能成分的浸出量都随时间的增加而增加,经过一段时间后达到平衡。在达到浸出平衡时,不同粒度茶粉的茶多酚和咖啡因含量差异不显著,超微茶粉的可溶性糖含量为4种粗粉的2倍左右,水浸出物比粗粉茶粉提高10%以上。上述研究结果表明:超微粉碎能够有效减小茶粉的粒度,破坏植物的细胞壁结构,使内部成分暴露于表面,此外,组织结构和细胞壁的破坏使不溶的纤维成分转化成可溶性成分,可溶性糖和水浸出物显著增多,超微粉碎能够在一定程度上提高茶粉的有效利用率。 相似文献
8.
气流和机械碾轧超微粉碎香菇柄的效果比较 总被引：1，自引：1，他引：0
为了提高香菇副产物菇柄的附加值,应用气流粉碎和机械碾轧粉碎2种工艺分别对菇柄进行超微处理。对气流粉碎工艺中的分级机转速,机械碾轧粉碎工艺中的主机频率、风机频率等操作参数进行了单因素分析,进一步结合分段线性拟合法对2种工艺的加料速度进行了优化,分别得出了2种工艺的较适工艺条件;并对二者的粉碎效果、处理时间、能耗和出品率进行了比较。结果显示:气流粉碎的较适工艺条件为:分级机转速2 400 r/min,加料速度12 kg/h;机械碾轧粉碎的较适工艺条件为:主机频率44 Hz,风机频率42 Hz,加料速度5 kg/h。2种超微粉碎方式都能获得10μm以下的微粉,与机械碾轧粉碎相比,气流粉碎的分级精度较高,处理时间缩短了56.43%,但出品率较低,能耗为前者的4.77倍。总体来看,机械碾轧粉碎更适合规模化生产,该研究为超微粉碎技术应用于香菇柄深加工利用提供了技术依据。 相似文献
9.
为评价超微粉碎对青稞麸皮多酚、体外抗氧化活性和淀粉消化酶抑制活性的影响。该研究制备了3种粒径分别为335.94、72.52、22.69μm的青稞麸皮粉体,对3种粉体的多酚、黄酮含量及其组成、体外抗氧化活性与淀粉消化酶活性抑制率进行测定。结果表明:与粗粉相比,2种微粉的多酚(游离酚、结合酚)、黄酮和总酚含量均显著高于粗粉(P0.05)且粒径越小,含量越高;青稞麸皮粉共检出19种酚酸,其中游离酚以阿魏酸和藜芦酸为主,结合酚以阿魏酸和苯甲酸为主;随着粒径的减小,粉体多酚提取物的抗氧化活性(DPPH·自由基清除能力、FRAP还原能力、ABTS~+·自由基清除能力)及对α-葡萄糖苷酶、α-淀粉酶抑制率均显著增强(P0.05);粉体多酚组成及含量与体外抗氧化活性及淀粉消化酶活性抑制率存在一定的相关性。相关分析结果表明:青稞麸皮游离酚提取物中2,4-二羟基苯甲酸、藜芦酸是清除DPPH·自由基、抑制α-葡萄糖苷酶活性的主要贡献物质,阿魏酸是抑制α-葡萄糖苷酶及α-淀粉酶活性的主要物质;结合酚提取物中2,4-二羟基苯甲酸是抑制α-淀粉酶活性的主要物质。该结果显示超微粉碎一定程度上可提高青稞麸皮中多酚含量、体外抗氧化活性及淀粉消化酶抑制率,可作为青稞麸皮食品的一种有效前处理加工手段。 相似文献
10.
为探讨不同制粉方式及不同粒度对黑小麦流变学特性及加工品质的影响,将运黑161黑小麦经直接粉碎法和回添法制得的全麦粉分别过80、100、120目筛,以运黑161黑小麦面粉为对照,分析全麦粉淀粉含量、水合特性、发酵特性以及流变学特性。结果表明,直接粉碎且过80目筛的全麦粉支链淀粉含量最高,为80.18%,破损淀粉含量最低,为9.93%,溶解度、膨润力最小,分别为2.5%和3%。回添法制备的全麦粉面团发酵高度、持气率小于直接粉碎法。直接粉碎且过80目筛全麦粉的粉质质量指数最高,为59.5,形成时间和稳定时间分别为3.45和3.2 min,较接近于黑小麦面粉,且该全麦粉的阻力值、最大阻力值在醒发时间135 min时最大,用该全麦粉制作的面包感官得分最高。综上,以直接粉碎且过80目筛制备的全麦粉为原料制作的全麦面包品质较好。本研究结果为黑小麦全麦面包研发提供了理论基础。 相似文献
11.
Individual contribution of grain outer layers and their cell wall structure to the mechanical properties of wheat bran 总被引：1，自引：0，他引：1
Antoine C Peyron S Mabille F Lapierre C Bouchet B Abecassis J Rouau X 《Journal of agricultural and food chemistry》2003,51(7):2026-2033
The mechanical properties of wheat bran and the contribution of each constitutive tissue on overall bran properties were determined on a hard wheat (cv. Baroudeur) and a soft wheat (cv. Scipion). Manual dissection allowed three different layers to be separated from wheat bran, according to radial and longitudinal grain orientations, which were identified by confocal laser scanning microscopy as outer pericarp, an intermediate strip (comprising inner pericarp, testa, and nucellar tissue), and aleurone layer, respectively. Tissue microstructure and cell wall composition were determined. Submitted to traction tests, whole bran, intermediate, and aleurone layers demonstrated elastoplastic behavior, whereas pericarp exhibited elastic behavior. By longitudinal orientation, pericarp governed 50% bran elasticity (elastic strength and rigidity), whereas, in the opposite orientation, bran elastic properties were mostly influenced by the other tissues. Regardless of test orientation, the linear force required to bran rupture corresponded to the sum of intermediate and aleurone layer strengths. According to radial orientation, the intermediate strip governed bran extensibility, but according to longitudinal orientation, all tissues contributed until bran disruption. Tissues from both wheat cultivars behaved similarly. A structural model of wheat bran layers illustrated the detachment of pericarp from intermediate layer within radial bran strips. 相似文献
12.
Mechanical properties of wheat grain outer layers from common wheat (Triticum aestivum L.) cultivars known to display distinct milling behavior were analyzed using uniaxial tension tests. Tensile modulus and strain to rupture of the tissues distinguished between the wheat cultivars. Values of strain to rupture were related to coarse bran size generated by grain milling, a characteristic that distinguishes the two hardness classes. As content of an aleurone marker in total or first break flour was also related to coarse bran size, extensibility of wheat grain outer layers' could be a key parameter to explain the observed tissue mechanical behavior and thus distribution of the aleurone layer content in flours. As tissue mechanical properties are generally linked to the cell wall biochemical composition and structure, analysis of the main wheat outer layers' cell wall compounds was undertaken to establish relationships with the differences observed in mechanical properties. No clear correlation could be found with one of the wheat outer layers' component but involvement of the outer layers' cell wall structure in the tissues behavior at milling was confirmed. 相似文献
13.
The structure of the aleurone layer was considered for many years as a potential factor influencing wheat milling efficiency. Eight durum wheat samples of different milling values, including distinct cultivars and harvesting conditions, were employed to investigate the structural characteristics of the aleurone layer through image analysis of kernel sections. Particular attention was paid to tissue thickness and structural irregularity of its interface with the starchy endosperm. Wheat cultivar, agricultural conditions, and location of measurement within the grain had an influence similar to both thickness and irregularity of the aleurone layer. Conversely, grain weight and morphology showed no effect on these parameters. Statistical investigation demonstrated no correlation between structural characteristics and wheat milling behavior. However, the negative correlation between the extraction rate of semolina and starch content in the bran fraction, which was used as an indicator of the endosperm‐aleurone dissociation extent, demonstrated the relevance of the tissue adhesion on milling efficiency. 相似文献
14.
The crumbliness of starchy endosperm and the resistance of bran are key characteristics that enhance milling behavior of wheat and are dependent on the genetic origin and moisture content of the grain. A method was developed to measure the mechanical properties of bran samples based on the measurement of tensile stress and strain. Tests conducted with this highly reproducible and sensitive method documented cultivar and moisture‐content effects (6.3, 13.8, and 18%, wb) on rheological behavior of wheat seed coats. A moisture‐dependent reduction in stress to fracture (‐15 to ‐30%) and in Young's modulus (‐45 to ‐55%) was quantified. An increase in deformation to fracture of seed coats was also correlated with bran size differences after milling. The energy required to fracture a sample (from 0.4 to 1.3 J/mm3) was considered the most valid of all presented parameters for assessing the milling behavior of wheat seed coats and the size of bran fractions. 相似文献
15.
J. D. C. Figueroa Z. J. E. Hernndez M. J. J. Vles P. Rayas‐Duarte H. E. Martínez‐Flores N. Ponce‐García 《Cereal Chemistry》2011,88(1):12-18
Three samples were selected representing bread, soft, and durum wheat. Uniaxial compression and stress relaxation tests were performed on wheat kernels. Force‐deformation curves from intact wheat grain typically exhibited at least two points of inflection (PI) at ≈0.1 and 0.2 mm displacement. The first PI is related to the mechanical properties of all the bran layers. The second PI (0.2 mm) seems to be the endosperm boundary near the aleurone layer. These structures had higher degree of elasticity (DE) compared to the inner endosperm (0.5–0.6 mm). Besides wheat class and specific structures of the caryopsis, moisture content is a prominent factor affecting the mechanical strength of kernels. Stress relaxation tests show that bread wheat kernels with 69.2% DE at 13% moisture decreased to 31.6% DE with additional 6% moisture content. Soft wheat kernels DE of 61.0% at 13% moisture decreased to 22.7% at 19.7% moisture. Stress relaxation revealed pronounced time‐dependence. However, the differences of stress values at 120–180 sec were not significant in all wheat classes and moisture contents evaluated. The stress values after 120 sec might be attributed to the elastic deformation of the kernels. 相似文献
16.
Nordlund E Aura AM Mattila I Kössö T Rouau X Poutanen K 《Journal of agricultural and food chemistry》2012,60(33):8134-8145
Rye bran and aleurone, wheat bran and aleurone, and oat bran and cell wall concentrate were compared in their in vitro gut fermentation patterns of individual phenolic acids and short-chain fatty acids, preceded by enzymatic in vitro digestion mimicking small intestinal events. The formation of phenolic metabolites was the most pronounced from the wheat aleurone fraction. Phenylpropionic acids, presumably derived from ferulic acid (FA), were the major phenyl metabolites formed from all bran preparations. The processed rye, wheat, and oat bran fractions contained more water-extractable dietary fiber (DF) and had smaller particle sizes and were thus more easily fermentable than the corresponding brans. Rye aleurone and bran had the highest fermentation rate and extent probably due to high fructan and water-extractable arabinoxylan content. Oat samples also had a high content of water-extractable DF, β-glucan, but their fermentation rate was lower. Enzymatic digestion prior to in vitro colon fermentation changed the structure of oat cell walls as visualized by microscopy and increased the particle size, which is suggested to have retarded the fermentability of oat samples. Wheat bran was the most slowly fermentable among the studied samples, presumably due to the high proportion of water-unextractable DF. The in vitro digestion reduced the fructan content of wheat samples, thus also decreasing their fermentability. Among the studied short-chain fatty acids, acetate dominated the profiles. The highest and lowest production of propionate was from the oat and wheat samples, respectively. Interestingly, wheat aleurone generated similar amounts of butyrate as the rye fractions even without rapid gas production. 相似文献
17.
Enzymatic oxidative treatments of wheat bran layers: effects on ferulic acid composition and mechanical properties 总被引：1，自引：0，他引：1
Peyron S Abecassis J Autran JC Rouau X 《Journal of agricultural and food chemistry》2001,49(10):4694-4699
Enzymatic treatments known to induce the gelation of feruloylated arabinoxylans solutions were applied to tissue strips isolated from peripheral layers of wheat grain to tentatively produce in situ arabinoxylan reticulation. The treatments by horseradish peroxidase (HRP) and manganese dependent peroxidase (MnP) induced a dimerization of ferulic acid (FA) in wheat bran with concomitant decrease of arabinoxylan solubility. Similar results were obtained, but to a lesser extent, by simple incubation of bran strips in water, suggesting the action of endogenous peroxidases. The fact that these treatments proved to be ineffective on the isolated aleurone layer and pericarp suggested that dimerization occurred mostly at the aleurone-pericarp interface. In addition, the MnP system generated a consumption of monomer and dimer of ferulic acid in the pericarp, perhaps due to their incorporation into lignin. Micro-mechanical tests using DMTA were performed on isolated tissue strips and showed that oxidation of wheat bran increased their mechanical strength (increase of stress and strain to rupture). 相似文献
18.
Wheat bran contains good quality protein, but given its location inside aleurone cells, this protein has restricted digestibility. The aim of this work was to liberate and solubilize wheat bran proteins via cell wall degradation by using carbohydrate‐hydrolyzing and proteolytic enzymes without causing extensive protein hydrolysis. Bran incubated with water (without added enzymes) for 16 h increased the solubilized organic nitrogen content from 14.0 to 42.8%. Enzymes with solely carbohydrate‐hydrolyzing activity increased the water‐soluble pentosan and reducing sugar contents but did not significantly increase protein solubilization or protein release from the aleurone cells. Enzymes with proteolytic activity significantly increased the solubilization of protein to 58.2% already at 4 h. Significant protein hydrolysis was detected with a high dosage of protease. However, based on light microscopy, the enzymatic treatment mainly modified the proteins in the subaleurone layer, and it was less effective on proteins inside the aleurone cells. With optimized protease treatment (3 h, 35°C, and 550 nkat/g), effective protein solubilization (>48%) without extensive protein hydrolysis (free amino nitrogen content <45 mg/L) was achieved. In conclusion, intensive solubilization of proteins in the subaleurone layer of wheat bran is possible by using exogenous enzymes with proteolytic activities. 相似文献
19.
Wheat grains were germinated in the dark at room temperature (24°C) for 1, 2, 3, 5, and 8 days. Germinated wheat grains were pearled in a Waring blender, and the outer bran layers were separated from the pearled grains. Breadmaking was performed with wheat flour and 10% of the outer bran layer. Breadmaking properties (bread height [mm] and specific volume [cm3/g]) were gradually enhanced by blending the germinated outer bran layers, and maximum specific volume was obtained after 5 days of germination. However, the improvement was lost after 8 days of germination. Rapid ViscoAnalyser (RVA) and Brabender Farinograph profiles of wheat flour and outer bran layers (10%) indicated that the maximum decrease of peak viscosity and increase of angle of tail were obtained after 3 and 5 days of germination, respectively. Those changes are presumed to be due to the action of enzymes found in the outer bran layers. Activities of α‐ and β‐amylase, lipase, protease, and xylanase in the outer bran layers were measured, and correlation coefficients (r) between breadmaking properties and peak viscosity (RVA), angle of tail (farinograph), and enzyme activities were calculated. These data suggest that xylanase and α‐amylase activities in the outer bran layers were highly related to the enhancement of the breadmaking properties. 相似文献