小麦麸皮结构层干法分离的初步研究

研究了干法分离麦麸结构层。首先对小麦麸皮进行微粉碎,通过粒径分析出麦麸粉体的粒径分散性最好的粉碎时间,利用旋振筛对此时的麦麸进行筛分,得到粒径不同的4种麦麸粉体,然后对各个麦麸粉体进行荧光定性和生化标示物定量研究。结果表明,筛分后,外皮层和中间层集中在200目筛上物的麦麸中,约占78.9%,麦麸糊粉层的细胞壁主要集中在200目筛下物和325目筛上物中,比例达41.7%,而小颗粒的麦麸糊粉层细胞内容物则集中在325目筛下物。研究初步表明,通过微粉碎和筛分的方法可以对不同麦麸结构层进行富集,为麦麸的深加工提供了一种简单的干法分离途径。     

小麦麸皮结构层中抗氧化物质的研究

采用酶法与化学法,分别对麦麸的外皮层、中间层及糊粉层进行水解,对提取物中酚酸的种类和含量进行了测定。对比了酶解与碱解所得提取物中总酚的含量和清除自由基的能力。结果表明：碱解处理后,外皮层申阿魏酸脱氢聚体含量最高,达4．34mg／g,而糊粉层中阿魏酸单体的含量最高,达5．90mg/g;酶解后,外皮层、中间层和糊粉层的水解液中阿魏酸脱氢聚体含量分别为碱解释放量的71．0％、52．6％和51．1％,而阿魏酸单体的释放量为碱解释放量的46．9％、51．0％和56．3％。同时,碱解和酶解提取物中的总酚含量和抗氧化能力与酚酸含量直接相关。     

高纤维麦粉——新型营养食品添加剂

高纤维麦粉是加工小麦时从分离出来的麦麸中获取的,麦麸由小麦的种皮和附着在种皮上的少量胚乳组成的,而种皮上的糊粉层及胚乳中含有人体不可缺少的微量元素和矿物质。经测定,每100g高纤维麦粉中含蛋白质13.4g、脂肪3.3g、碳水化含物50.6g、钙83mg、铁8mg、V_(B1)0.64mg、V_(B2)0.28mg、100g小麦粉中     

裸燕麦米和燕麦粉加工所得麸皮中β-葡聚糖和酚酸的分布

选取具有代表性的裸燕麦品种,分析燕麦麸皮和胚乳所占的比例和微观结构特征;同时分析β-葡聚糖和酚酸在燕麦麸皮（果皮、种皮＋糊粉层）和胚乳中的分布,并验证了现有燕麦米和燕麦粉主流加工方式的适宜程度。结果表明,在所选裸燕麦品种中,β-葡聚糖均富集在麸皮中,质量分数达8.57%,约是胚乳中含量的4.5?倍;麸皮中p-香豆酸和阿魏酸的含量分别达0.099?mg/g和1.00?mg/g,分别是胚乳中相应含量的24?倍和48?倍;在麸皮中,果皮中p-香豆酸和阿魏酸含量分别约为种皮＋糊粉层中的13?倍和2.7?倍。研磨制燕麦米所得第2道麸皮中,β-葡聚糖质量分数平均为1.7%,远小于麸皮中的平均含量,加工程度适宜;而燕麦制粉所得第4道和第5道麸皮,β-葡聚糖质量分数达6.73%和7.80%,接近糊粉层中β-葡聚糖含量,加工过度。综上可知,利用分析燕麦加工所得麸皮中葡聚糖和酚酸含量,可初步判定燕麦米和燕麦粉的加工程度,为其加工提供技术支撑。     

机械分离富集小麦麸皮中糊粉层的研究

小麦麸皮是小麦加工中重要的副产物,其中糊粉层含有大量对人体健康有益的功能物质。本试验研究了干法机械分离麸皮中糊粉层的工艺。首先对小麦麸皮进行预粉碎及筛分分离处理,降低尺寸并去除部分胚乳,再将大于425μm(40目)的小麦麸皮投入分级式冲击磨进行粉碎。粉碎后的小麦麸皮被筛分分离成B1(425μm)、B2(180~425μm)、B3(100~180μm)、B4(100μm)组分。选定总磷含量作为糊粉层标识物,考察该工艺下分级式冲击磨刀片线速度、分级轮转速及进料速度对各分离组分总磷含量的影响。结果表明:当刀片线速度36 m/s、分级轮转速2 800 r/min、进料速度900 g/h条件下,B3组分的总磷含量高达(18.46±0.51)mg/g,糊粉细胞结构完整,糊粉层含量高达65.30%,小麦麸皮各结构层分离效果明显。     

高纤维麦粉——新型营养食品添加剂

高纤维麦粉是加工小麦时分离出来的副产品——麦麸中获取的。麦麸是由小麦的种皮和附着在种皮上的少量胚乳组成的,而种皮上的糊粉层及胚乳中含有人体不可缺少的微量元素和矿物质。经测定,每100g高纤维麦     

植物乳杆菌发酵对小麦糊粉层粉营养组分的影响

该研究为提高小麦副产品的加工利用率、提升小麦糊粉层粉的营养品质,以小麦糊粉层粉为原料,以植物乳杆菌JCM1149为发酵剂,通过单因素试验结合响应面方差分析优化得到最佳发酵条件,并在最佳发酵条件下对比发酵前后小麦糊粉层粉蛋白质、膳食纤维、矿物质、B族维生素和游离氨基酸含量的变化。研究结果表明,各因素对样品中多酚含量的影响顺序为发酵时间>发酵温度>JCM1149接种量,最佳发酵条件为发酵时间22 h、JCM1149接种量1.4×10⁷CFU/g、发酵温度38℃,在该条件下发酵得到的小麦糊粉层粉酸面团多酚含量为(2.31±0.01)mg/g。发酵后小麦糊粉层粉酸面团蛋白含量和不溶性膳食纤维含量下降,可溶性膳食纤维含量升高,膳食纤维比例得到改善;镁、铁、钙、锰等微量元素和B族维生素含量明显提升,必需氨基酸含量较发酵前提升18.19%,芳香族氨基酸含量上升。     

改良的Folin-Ciocalteu比色法测定核桃外果皮中总多酚含量

目的:建立核桃外果皮中总多酚含量的比色测定方法。方法:以没食子酸为对照品,对测定核桃外果皮中总多酚含量的比色条件,包括检测波长、碳酸钠溶液用量、Folin-Ciocalteu试剂用量、反应温度及时间对吸光值的影响进行了研究。结果:对照品标准曲线在1～7μg/mL范围内为y=0.1031x+0.0793,R2=0.9996,线性关系良好,测定方法为采用核桃外果皮中总多酚提取液1.0mL,Folin-Ciocalteu试剂1.0mL、15%的碳酸钠溶液4.0mL、30℃显色1.5h,平均回收率为100.2%(RSD=0.91%)。此条件下测得核桃外果皮中总多酚含量为3.306mg/g。结论:该方法简便快速、结果准确、重现性和稳定性好,可用于核桃外果皮中总多酚含量的测定。     

麦芽根营养成分分析及其应用前景

对麦芽根的营养成分、活性成分、消化率等指标进行测定与分析,并与麦麸的营养成分进行对比,结果表明：麦芽根中蛋白质（34.3%）、膳食纤维（39.4%）含量高于麦麸,必需氨基酸含量（8.37 g/100 g）为麦麸（4.03 g/100 g）的2倍,赖氨酸、苏氨酸、缬氨酸含量相对较高,粗蛋白消化率为80.04%,高于麦麸（74.08%）。麦芽根中维生素B2、B6、叶酸、B12、维生素C含量高于麦麸,分别为0.6 mg/100 g、0.46 mg/100 g、0.17 mg/100 g、0.11 μg/100 g、4.35 mg/100 g,并含有维生素E（3.14 mg/100 g）。钠、钾、钙、锌、铜、磷、铁、镁含量丰富,并具有较高含量的总多酚（1.09%）及少量多糖。同时,从饲料、食品、化妆品三个领域分析其法规现状、应用现状及前景,为麦芽根副产物的高值化利用提供依据。     

小麦细胞壁结构的地理差异及水分调控作用

为了探讨小麦糊粉层细胞的细胞壁结构在不同产地的地理差异,以8个不同产区的小麦品种为研究对象,研究了小麦籽粒中糊粉层细胞壁厚度及其组分(阿拉伯木聚糖和β-葡聚糖)的含量和小麦籽粒体内水分子移动性。通过相关性分析和主成分分析研究了不同参数之间的相互关系,结果表明:在8个不同产区中,小麦籽粒糊粉层细胞壁厚度及其组分含量差异显著;小麦籽粒糊粉层细胞壁厚度与籽粒总阿拉伯木聚糖(Total arabinoxylan,TAX)含量呈极显著正相关性(r=0.931,P0.01),可通过测量TAX含量来比较小麦籽粒糊粉层细胞壁厚度;小麦籽粒糊粉层细胞壁厚度和TAX含量与海拔呈显著正相关(r=0.839,P0.01)。通过低场核磁共振分析发现糊粉层细胞壁结构对籽粒内的水分有一定的调控作用:在75%相对湿度下,糊粉层细胞壁越厚的小麦籽粒吸水量越少。     

Aleurone cells are the primary contributor to arabinoxylan oligosaccharide production from wheat bran after treatment with cell wall-degrading enzymes

Arabinoxylans and in particular arabinoxylan oligosaccharides (AXOS) from wheat are recognised for their prebiotic potential. A high-yield, non-chemical production of AXOS is therefore of interest when producing functional foods. This study investigated the enzymatic production of AXOS from wheat bran with the aim of establishing the main fraction contributing to production of AXOS. Fractions of wheat bran, outer pericarp and aleurone with two different purities were treated with the cell wall-degrading enzymes: xylanase, cellulase and β-glucanase. The yield of solubilised arabinoxylans upon treatment was greatest in the most pure aleurone fraction (164 g kg⁻¹) and lowest in the outer pericarp fraction (15 g kg⁻¹). The yield was mainly recovered as AXOS rather than soluble arabinoxylans and was negatively related to the arabinose/xylose ratio found in the raw material. In conclusion, wheat aleurone cell walls are the main contributor to the production of AXOS from wheat bran and this seems to depend on the A/X ratio of the raw material.     

The phenolic acid and polysaccharide composition of cell walls of bran layers of mature wheat (Triticum aestivum L. cv. Avalon) grains

The purpose of this study was to examine the carbohydrate and phenolic‐ester composition of cell walls in wheat bran layers. Four defined layers of wheat bran were separated manually from mature grains of wheat (Triticum aestivum L. cv. Avalon) to give samples of beeswing bran (outer pericarp), cross cells, testa + nucellar epidermis and aleurone cells. The cell‐wall material from each layer, and from a sample of intact bran, was analysed for carbohydrates and wall‐bound esterified phenolic acids. The cell‐wall material of intact bran was rich in arabinose and xylose with significant quantities of glucose and uronic acid and a relatively small amount of galactose and mannose. The varying ratios of arabinose:xylose in cell walls of isolated bran layers indicated that the heteroxylans had tissue‐specific substitution patterns. HPLC analysis of phenolic acids identified significant amounts of esterified ferulic acid and 8‐8′‐ (aryltetralin form), 5‐8′‐, 5‐5′‐, 8‐0‐4′‐ and 5‐8′‐(benzofuran form)‐dehydrodiferulic acids in the isolated cell walls. Ferulic acid was highly concentrated in the aleurone layer, whereas dehydrodiferulates were concentrated in the beeswing bran and cross cells. The role of phenolic cross‐linking is discussed in relation to the architecture of the cell walls of wheat bran and to processing implications. Copyright © 2005 Society of Chemical Industry     

Tribocharging properties of wheat bran fragments in air–solid pipe flow

Triboelectric separation (TS) has been used to separate aleurone particles from wheat bran fragments, but its mechanism remains poorly understood. In this study, the tribocharging properties of different bran tissues in the pipes made of Teflon, Nylon and stainless steel were investigated. The effects of air flow rate and water content on tribocharging were also studied. The results showed that, after tribocharging with Teflon pipe, the total charges of the bran fragments were positive, and decreased with the times of tribocharging, while, in Nylon pipe, the total charges obtained by the bran fragments were negative initially, then increased to be positive. The more aleurone cells in bran fragments, the more their total charges changed. After tribocharging with steel pipe, the total charges of bran fragments were positive and almost constant. The results of TS indicated that the polarities of the charges obtained by aleurone and pericarp particles were reversed by the pipe materials. Based on the results, a mechanism of tribocharging in air–solid pipe flow was built to explain the charging diversity of the wheat bran tissues in TS.     

Influence of water content and negative temperatures on the mechanical properties of wheat bran and its constitutive layers

Wheat bran is currently an undervalued by-product, and could be processed into food ingredients with high nutritional potential. The aim of this study was to determine the influence of bran moisture content, and the influence of sub-zero temperatures on the mechanical properties of whole bran layers and hand isolated bran tissues (outer pericarp, intermediate layer, aleurone layer), to get information on their potential breakage behavior during fractionation processes and determine the most suitable working conditions to develop efficient processes. The mechanical properties of bran strips were assessed by stress–strain tests using a dynamic mechanical thermal analyzer, with temperature control and relative humidity control. This work showed that it is possible to modulate the mechanical properties of bran samples by modifying their moisture content and the temperature. The extensibility (ultimate strain) of bran tissues was positively correlated to their moisture content (from 9% to 21%, w.b.) and to the temperature (from −100 to 25 °C), whereas their stiffness (Young modulus) was negatively correlated to these parameters. In certain conditions, the constitutive layers of whole bran strips broke at different locations, showing that these layers could be dissociated. At temperatures of −50 °C and below, whole bran and intermediate layers seemed to lose their plasticity. This phenomenon could be linked to a small glass transition detected between −40 and −50 °C in the intermediate layer. These results may allow adapting fractionation processes for a better use of bran.     

彩色小麦麸皮的营养分析

彩色小麦麸皮作为小麦加工的主要副产物未被深度利用,通过对彩色小麦与普通小麦麸皮粉的蛋白质含量、氨基酸组成、矿物质元素含量的比较,展现了彩色小麦麸皮独特的营养价值。通过设计合理的工艺条件提取彩色小麦麸皮的糊粉层粉作为具有特色食品的营养添加物具有非常好的市场前景。     

Triboelectric separation of aleurone cell-cluster from wheat bran fragments in nonuniform electric field

Nonuniform electric field (NUEF) was designed to separate aleurone cell-cluster from wheat bran fragments after tribocharging in a polytetrafluoroethylene tube. After triboelectric separation (TS), the ultrastructure, composition and particle size distribution of the bran fragments were studied. The results showed that, the positive-NUEF had a higher efficiency than the negative-NUEF for the enrichment of aleurone cell-cluster. After the first step of TS in positive-NUEF, about 1.5-time more aleurone cell clusters and 1.3-time more testa particles were deflected to the positive electrodes, while the outer pericarp fragments were enriched in the middle fraction. No obvious difference was found between the particle sizes of the electrode-fraction and middle-fraction, suggesting that the difference in particle size was not the main reason for the charging diversity. After two steps of TS in positive-NUEF, the proportion of aleurone cells increased from 51% to 78% with a total yield of 42%, indicating that the nonuniform electric field was effective for the enrichment of aleurone particles.     

黑小麦麸皮酚酸物质的定性分析与阿魏酸含量测定

对黑小麦麸皮中的主要酚酸物质进行制备和定性分析,并测定阿魏酸含量。采用乙醇和氢氧化钠溶液处理黑小麦麸皮,提取样品中的游离态酚酸(free phenolic acids,FPA)和结合态酚酸(conjugated phenolic acids,CPA)。通过液质联用(LC/MS)和紫外光谱(UV)等方法对提取的酚酸物质进行定性分析。紫外光谱显示,游离态和结合态酚酸具有与阿魏酸相似的分子结构。LC/MS检测结果显示,游离态和结合态酚酸的相对分子质量分别为224和194。由此判断黑小麦麸皮中的游离态酚酸FPA主要为芥子酸,结合态酚酸CPA主要为阿魏酸。采用高效液相色谱(HPLC)对黑小麦麸皮中的结合态阿魏酸含量进行测定。结果表明,紫粒黑小麦麸皮的阿魏酸含量为2.07 mg/g,与蓝粒黑小麦麸皮的阿魏酸含量(2.12 mg/g)相近,其含量高于当地种植的普通小麦麸皮的阿魏酸含量(1.17 mg/g)。     

Correlation of microstructure,pore characteristics and hydration properties of wheat bran modified by airflow impact mill

Strategies that could modify the structure of wheat bran by micronization are of great interest to improve its industrial application. The correlation between microstructure, pore characteristics and hydration properties of plant-scale, tissue-scale and cellular-scale wheat bran modified by airflow impact mill (AFIM) was investigated. AFIM treatment mainly caused different structural disruption of micropores in pericarp and aleurone layer, which significantly increased the soluble dietary fiber content, water-soluble index, whiteness and suspension stability of AFIM-treated wheat bran, but had a negative effect on its hydration properties (including water retention capacity, swelling capacity and oil retention capacity). Pearson correlation analysis indicated that the water retention capacity of wheat bran was significantly correlated with the percentage of microporous at the cellular level (r = − 0.99) and the tissue level (r = 0.72). These results could guide the application of different scales wheat bran in food systems.