Influence of Kernel Maturity,Milling Degree,and Milling Quality on Rice Bran Phytochemical Concentrations

Rice bran is a rich source of phytochemicals including tocopherols (T), tocotrienols (T3), and γ‐oryzanol that have purported positive effects on human health. The screening of germplasm to determine the genetic diversity influencing contents of these compounds requires knowledge of how sample preparation influences concentrations of the phytochemicals in rice bran. Obtaining this knowledge was the objective of this study. Cultivars with different milling qualities were all milled to different degrees. The differences in bran removal among cultivars decreased as the milling time increased. Samples that were milled for 30 and 40 sec (milled to the degree of 0.23–0.44% surface lipid content [SLC]) showed no significant differences in T and T3 concentrations in the bran within cultivars. Bran starch concentration affected the rankings of cultivars based on phytochemical contents. Expression of the γ‐oryanol concentration in bran after subtracting starch reduced the concentration differences resulting from differences in degree of milling (DOM). Bran from the mature thin kernels had phytochemical contents similar to that of the mature thick kernels milled for 30 sec. The immature thin kernels had significantly lower contents of most of the bran phytochemicals than did the mature kernel fractions.     

Effect of Stabilized Rice Bran Fractions on the Formation of Rice Flour Pasting Properties

Rice flour composition played a key role in determining the changes in pasting properties of rice flour. The influence of incorporating defatted rice bran (DFRB), rice bran fiber (RBF), rice bran protein (RBP), and stabilized rice bran (SRB) fractions on the mechanism of rice flour pasting viscosities was investigated. Pasting properties of long‐ and medium‐grain rice flour substituted with 5, 10, 15, 20, and 100% bran fractions resulted in a significant decrease (P < 0.05) in rice flour pasting property values. Flour substituted with RBP had the lowest pasting property measurements compared with other fractions, and the greater the percentage substituted, the lower the pasting property values. DFRB and RBF were least affected properties when used as a replacement. Results were attributed to the contribution of rice starch in the mechanism of rice paste formation, in which decreasing starch in a rice flour sample, as a result of substituting with fractions of SRB, may have resulted in faster swelling of starch granules to the maximum extent and increased their susceptibility to be disrupted by shear, resulting in low paste viscosities. Results also suggested that protein structural integrity and the nature of starch–protein bonding affected rice flour pasting mechanism formation.     

Characterization of Protein Fractions of Rice Bran to Devise Effective Methods of Protein Solubilization

Proteins from the defatted brans of representative rice cultivars were fractionated into albumins, globulins, prolamins, and acid-soluble glutelins, accounting for 34, 15, 6, and 11% of the total bran proteins, respectively. The remaining insoluble residue protein, after treatment with 0.1M sodium hydroxide, resulted in the solubilization of 95% of the residue protein, representing 32% of the total bran protein. The relative molecular mass (M_r) values determined by size-exclusion HPLC were 10–100 kDa, 10–150 kDa, 33–150 kDa, and 25–100 kDa for the fully dissociated polypeptides of albumins, globulins, prolamins, and acid-soluble glutelins, respectively. Despite a breakdown of disulfide bonds of the residue protein during sodium hydroxide solubilization, the M_r of the majority of the fully dissociated polypeptides of this fraction ranged from 45 to 150 kDa. Insolubility of residue protein was due mainly to its strong aggregation and extensive disulfide bond cross-linking. Efficient methods may be developed for solubilizing up to 98% of rice bran protein by the use of dissociating and disulfide breaking agents currently in use in the food industry.     

Effect of Rice Kernel Thickness on Degree of Milling and Associated Optical Measurements

Three cultivars of long-grain rice were milled to three degree of milling (DOM) levels. Inverse linear relationships were established between surface fat concentration (SFC) and Satake milling meter (MM1B) optical DOM measurement values, including whiteness, transparency, and DOM, for the unfractionated head rice within each cultivar. Milled bulk rice for each cultivar was subsequently separated into thickness fractions. Effects of milled rice kernel thickness on SFC and optical DOM measurements were investigated. For a given DOM level, SFC decreased with increasing milled rice kernel thickness up to a thickness of 1.67 mm, after which it remained constant. As the overall DOM level increased, the difference in DOM between thin kernels and thick kernels lessened, implying that thin kernels were milled at a greater bran removal rate than thick kernels. Milled rice kernel thickness significantly (at the 0.05 significance level) affected MM1B whiteness and MM1B transparency in two of the cultivars because of the predominant effects of the thinner kernel fractions. Within each cultivar, MM1B DOM was not significantly influenced by milled rice kernel thickness.     

Growth-Inhibitory Effects of Pigmented Rice Bran Extracts and Three Red Bran Fractions against Human Cancer Cells: Relationships with Composition and Antioxidative Activities

We determined the phenolic, anthocyanin, and proanthocyanidin content of three brown, purple, and red rice brans isolated from different rice varieties using HPLC-PDA with the aid of 27 standards of known structure and matching unknown peaks to a spectral library of known compounds. Antioxidative capacities were determined by DPPH and ORAC and cell-inhibiting effects using an MTT assay. Based on the calculated IC(50) values, the light-brown bran had no effect, the purple bran exhibited a minor effect on leukemia and cervical cancer cells, and the red bran exhibited strong inhibitory effects on leukemia, cervical, and stomach cancer cells. High concentrations of protocatechuic acid and anthocyanins in purple bran and proanthocyanidins in red bran were identified. The red bran was further fractionated on a Sephadex column. Fraction 3 rich in proanthocyanidin oligomers and polymers had the greatest activity. Red bran has the potential to serve as a functional food supplement for human consumption.     

In Vitro Binding of Bile Acids by Rice Bran,Oat Bran,Wheat Bran,and Corn Bran

The in vitro bile acid binding by rice, oat, wheat, and corn brans was determined using a mixture of bile acids normally secreted in human bile at a physiological pH of 6.3. The objective of the study was to relate bile acid binding of cereal brans to health promoting properties. Three experiments were conducted testing substrates on an equal weight (dry matter) basis, an equal total dietary fiber (TDF) basis, and an equal TDF and equal fat basis. Each experiment was repeated to validate the results (for a total of six experiments). The relative in vitro bile acid binding of the cereal brans on an equal TDF basis considering cholestyramine as 100% bound was rice bran 51%, wheat bran 31%, oat bran 26%, and corn bran 5%. The data suggest that cholesterol lowering by rice bran appears to be related to bile acid binding. The primary mechanism of cholesterol lowering by oat bran may not be due to bile acid binding by soluble fiber. Bile acid binding did not appear to be proportional to the soluble fiber content of the cereal brans tested. Bile acid binding by wheat bran may contribute to cancer prevention and other healthful properties.     

Removal of Nickel onto Alkali Treated Rice Bran

Water, Air, & Soil Pollution - Different bases were used for the pretreatment of Rice bran biomass. Pretreatment with bases such as NaOH, Ca(OH)2 and Al(OH)3 were found to improve biosorption...     

Physicochemical Properties of Wheat Fractionated by Wheat Kernel Thickness and Separated by Kernel Specific Density

Two wheat cultivars, soft white winter wheat Yang‐mai 11 and hard white winter wheat Zheng‐mai 9023, were fractionated by kernel thickness into five sections; the fractionated wheat grains in the 2.7–3.0 mm section were separated sequentially into three fractions according to kernel specific density. Physical properties of unfractionated, fractionated, and separated wheat grains and the physicochemical properties of processed wheat flour were determined. Test weight, relative density, and whiteness of flour in the middle kernel thicknesses were maximal and those properties decreased with increasing or decreasing kernel thickness; they also decreased with decreasing kernel specific density. Extensigraph properties showed the same results. Water absorption of flour and kernel hardness increased with increasing kernel thickness and decreasing kernel specific density. The farinograph properties also were related to kernel thickness and specific density. Pasting viscosity increased with increasing kernel thickness for sections from <2.5 mm to 3.0–3.2 mm, except that the >3.2 mm section was lowest; the kernels with the lightest specific density also were lowest. Thus, the quality of wheat grains with the greatest kernel thickness was not the best, and in fact may be the worst. The quality of wheat grains with small kernel thickness and light kernel specific density generally were worst. Most physicochemical properties of unfractionated and unseparated wheat grains were accurately predicted by the weighted‐average of the different kernel thickness sections and different kernel specific density fractions, except relative density, falling number, dough development time, and pasting temperature.     

Characterization of Indigestible Carbohydrates in Various Fractions from Wheat Processing

Fractions rich in indigestible carbohydrates, such as fructan and arabinoxylan, are obtained as by‐products when ethanol, starch, and gluten are produced from wheat flour. Today, these fractions are used as animal feed. However, these components may have positive physiological effects in humans. In this study, the content of indigestible carbohydrates in distillers' grains and process streams from the wet fractionation of wheat flour was determined. The fractions were further characterized by ethanol extractability analysis, anion‐exchange chromatography, NMR, and size‐exclusion chromatography. One fraction from wet fractionation contained (g/100 g, db) 6.0 ± 1.0 fructan and 10.3 ± 1.1 dietary fiber (66 ± 4% arabinoxylan), while distillers' grains contained 20.7 g/100 g (db) dietary fiber (30% arabinoxylan). In addition to indigestible carbohydrates from wheat, distillers' grains contained β‐(1→3) and β‐(1→6) glucans and mannoproteins from the yeast and low molecular weight carbohydrates mainly composed of arabinose. The use of endoxylanase in wet fractionation decreased the molecular weight of the arabinoxylans and increased the arabinose to xylose ratio but had no effect on the fructans. In conclusion, waste streams from industrial wheat processing were enriched in fructan, arabinoxylan, and other indigestible carbohydrates. However, the physiological effects of these fractions require further investigation.     

Effects of Commercial Processing on Antioxidants in Rice Bran

Rice bran contains high amounts of beneficial antioxidants including tocopherols, tocotrienols, and oryzanols. Current rice milling technology produces rice bran from different layers of the kernel caryopsis. Under current practices, these layers are combined and then steam‐extruded to form a stabilized rice bran pellet that is storage‐safe prior to oil extraction. Each of these rice bran intermediates can vary in antioxidant content. The objective of this study was to investigate the changes in selected antioxidants in rice bran from both long‐ and medium‐grain rice during commercial milling and bran processing. Rice bran collected from various milling breaks of a commercial system had varying antioxidant levels. Bran collected after milling break 2 had the highest levels of tocopherol and tocotrienol. Oryzanol concentration was significantly higher in outer bran layers. Results also indicate that the long‐grain rice bran averaged ≈15% more antioxidants than the medium‐grain rice bran.     

稻米爆腰机理与碎米率

碾米过程中产生的碎米率与稻谷中的糙米的爆腰率有重要相关关系。米粒的主要成分是淀粉,淀粉以一定的晶体结构排列在米粒的胚乳细胞壁中,当淀粉在受热和受潮时,淀粉粒膨胀,使米粒产生热应力和水分应力差,当此拉应力大于米粒抗拉强度时,米粒内部就产生裂纹而形成爆腰米粒。稻谷在收获后期、收获后的干燥、贮藏中均会受到温度和水分变动而产生爆腰米粒,稻谷在加工过程中受到机械力的作用也会增加米粒的破碎。所以,降低碎米率应该从稻谷的收获后期就引起注意,防止温度和水分过大的波动,在稻谷加工中米粒应避免拉伸和弯曲的作用。     

垩白米粒的计算机图像识别

自行开发研制了计算机图像处理系统，用于优质稻谷国家标准GB/T 17891-1999中质量指标垩白度及垩白粒率的检测。利用该系统对6种粳米和2种籼米进行测定，结果表明，该方法具有客观性、准确性、快速性和可重复性等特点，在收购优质稻米进行快速分等定级中具有良好的应用前景。     

长期秸秆还田对潮土土壤各形态磷的影响

基于黄淮海低平原区潮土上33年长期肥料定位试验,采用蒋柏藩―顾益初的石灰性土壤无机磷分级方法,研究冬小麦―夏玉米轮作中长期不同氮磷用量下秸秆还田对土壤全磷、有效磷(Olsen-P)及各形态无机磷的影响。结果表明:黄淮海低平原区潮土上冬小麦―夏玉米轮作中P2O5用量0~240 kg hm~(-2),随磷肥用量的增加,土壤全磷、Olsen-P、无机磷总量及无机磷中Ca2-P、Ca8-P、Al-P和Fe-P均显著增加,O-P和Ca10-P无显著变化;当土壤输入磷量低于作物输出磷量时,无论秸秆还田与否,土壤全磷、无机磷总量、Olsen-P和无机磷中除Ca8-P外的其他各形态磷均无显著变化;当土壤输入磷量高于作物输出磷量时,随秸秆用量的增加土壤全磷、Olsen-P和无机磷中的Ca2-P、Ca8-P、Al-P均显著增加,其中以Olsen-P增幅最大,无机磷中以Ca2-P增幅最大,其次为Ca8-P,再次为Al-P;土壤磷素盈余和亏缺量与土壤中各磷形态含量均呈显著正相关关系。     

Functional Properties of Rice Bran Protein Isolate at Different pH Levels

The functional properties of proteins from Tarom and Shiroodi cultivars were determined and compared with technological aspects of food and nutraceutical applications. Shiroodi has higher protein content than Tarom, and the yields of protein obtained were 72.88 and 66.36%, respectively. Nitrogen solubilities of rice bran protein of Tarom were more than Shiroodi at all pH levels. In addition, higher solubility was found in acidic or alkaline conditions. Although the rice bran proteins had lower emulsifying properties than bovine serum albumin, they had similar foaming properties in comparison with egg white. Tarom isolates had a significantly higher solubility, emulsifying property, and foaming stability and greater surface properties than Shiroodi isolates. The results showed the surface hydrophobicities of rice bran protein were greater than casein and ovalbumin and lower than other proteins such as bovine serum albumin. Water and oil absorption capacities were 1.03 and 1.66 for Tarom and 87.3 and 75.3 for Shiroodi, respectively. The bulk densities of Tarom and Shiroodi were also 0.55 and 0.53 g/mL, which make them suitable for weaning food and other industrial applications. As a result, these rice bran proteins showed higher hydrophobicity than that of other rice bran protein varieties as well as more functionality. Thus, they have good potential in the food and pharmaceutical industries.     

Observation and Measurement of Residual Bran on Milled Rice Using Hyperspectral Imaging

Residual bran on milled rice is directly related to its quality. This study proposes a method to measure the residual bran patterns on a single rice grain by using hyperspectral imaging (HSI). HSI is a sensing technique that combines both spatial and spectral information and may be used for chemical compound identification and quantification. In this study, HSI was applied to assess rice bran residue nondestructively. In the experiment, rice samples were milled and scanned with an HSI system. Afterward, the rice samples were dyed to enable the residual bran to be identified with optical microscopy and image processing algorithms. Classifiers were then developed to predict the rice bran residue by using the HSI measurements as inputs. The predicted images were compared with the micrograph images for classifier performance evaluation. The proposed approach can estimate the residual bran distribution on milled rice surface with an accuracy of 93.5%.     

稻谷颗粒内部传质及其应用

本文推导了用于分析稻谷颗粒内部水分扩散的三层体模型。并编制了用于分析干燥和缓苏过程中颗粒内部水分扩散和颗粒降水速度的模拟软件。经验证模拟结果与实验结果能很好的逼近。并利用该软件分析了颗粒内部水分的扩散过程及间歇干燥过程中间歇比和循环周期对降水速度的影响。     

米根霉发酵米糠工艺优化及其益生活性研究

为探究米根霉发酵米糠的最佳条件,本研究采用过热蒸汽对米糠作稳定化处理,以米根霉为菌种发酵稳定化米糠,以米糠可溶性膳食纤维(SDF)得率为指标,并对此条件下发酵米糠的体外益生活性进行评价。结果表明,过热蒸汽稳定米糠最佳条件为160℃、2 min,此条件下脂肪酶失活率为88.01%;甜香型米根霉发酵米糠的最佳条件为:以甜香型米根霉为发酵菌种,料液比1∶2.25、接种量0.7%、发酵温度35℃、发酵时间24 h,此条件下SDF得率为5.83%,比未发酵米糠提高了近一半;与未发酵米糠相比,经甜香型米根霉发酵后的米糠,可有效促进双歧杆菌(对数值6.85)和乳酸杆菌(对数值5.23)的增殖;总短链脂肪酸含量提高37.30%,肠道益生活性显著增强(P<0.05)。本研究结果为改善米糠功能特性提供了依据,对今后米糠在发酵方面的应用具有一定的指导意义。     

氮肥运筹对水稻氮素吸收和稻田渗漏液氮素浓度影响

通过大田试验,设计3个不同氮肥水平（0、150、240kgN·hm^-2）和两种不同施肥比例（基肥：分蘖肥：穗粒肥：40％：30％：30％、基肥：分蘖肥：穗粒肥=30％：20％：50％）,研究了氮肥运筹对水稻氮素吸收和稻田渗漏液氮素浓度的影响。结果表明,稻田渗漏液中NH4＋-N、NO3--N和总N浓度在施肥后第3d达到最大、随后降低,在施氮后的第7d,分别降为峰值的5．6％～16．9％、13．8％～22．5％、22．5％～34．5％。施氮水平处于0—240kgN·hm^-2时,水稻产量、氮素积累总量（totalNaccumulation,TNA）和稻田渗漏液Nm—N、N0i—N和总N浓度随着氮素水平的提高而显著增加;在较高氮肥水平（240kgN·hm^-2）下,与氮肥前移相比（基肥：分蘖HE：穗粒肥=40％：30％：30％）,采用氮肥后移（基肥：分蘖肥：穗粒肥=30％：20％：50％）的施肥比例,水稻产量和成熟期TNA分别增加6．2％和16．4％,稻田渗漏液NO3--N及总N浓度分别降低8．9％和4．8％,而对NHZ—N浓度影响不显著,说明适宜的氮肥运筹可以增加水稻的产量和氮素吸收,减少氮素渗漏损失。     

Effects of Nighttime Temperature During Kernel Development on Rice Physicochemical Properties

Rice quality can vary inexplicably from one lot to another and from year to year. One cause could be the variable temperatures experienced during the nighttime hours of rice kernel development. During the fall of 2004, a controlled temperature study was conducted using large growth chambers, testing nighttime temperatures of 18, 22, 26, and 30°C from 12 a.m. until 5 a.m. throughout kernel development, using rice cultivars Cypress, LaGrue, XP710, XL8, M204, and Bengal. As nighttime temperature increased, head rice yields (HRY) significantly decreased for all cultivars except Cypress and Bengal, for which HRY did not vary among nighttime temperature treatments. Kernel mass did not vary among temperature treatments for any cultivar. Grain dimensions generally decreased as nighttime temperature increased. The number of chalky kernels increased with an increase in nighttime temperature for all cultivars but Cypress. The amylose content of Cypress and LaGrue was significantly lower at the nighttime temperature of 30°C, while total brown rice lipid and protein contents did not vary among temperature treatments for all cultivars.