In-vitro mineral binding capacity of five fiber sources and their insoluble components for magnesium and calcium1

In-vitro binding of calcium (Ca) and magnesium (Mg) by total dietary fiber, hemicellulose A (HCL A), lignocellulose (LCL), cellulose (CL), and lignin (L) fractions isolated from rice bran (RB), wheat bran (WB), oat fiber (OF), apple fiber (AF) and tomato fiber (TF) was evaluated. At pH 6.8, significant amounts of Ca were bound by whole fibers, ranging from 800 μg g⁻¹ for RB to 10 097 μg g⁻¹ for TF. Mg bound by whole fibers varied from 496 μg g⁻¹ for OF to 2177 μg g⁻¹ for WB. Re-acid washing (pH<2.0) released 95–99% of the Ca and Mg bound to the fibers. Fibers with the highest endogenous Ca and Mg concentrations bound significantly (P<0.05) the highest amounts of the minerals studied. The Ca bound by HCL A varied from 9753 μg g⁻¹ for RB to 11 337 mg g⁻¹ for TF, whereas Mg bound varied from 1151 μg g⁻¹ for OF to 5626  μg g⁻¹ for TF hemicellulose fractions, respectively. Among the fiber components, Mg binding decreased in the order HCL A>LCL>L>CL, whereas Ca bound was in the order HCL A>LCL>CL>L. A relatively strong correlation was observed between the combined effects of protein content, hemicellulose, and lignin vs total Ca and Mg bound. 1998 Elsevier Science Ltd. All rights reserved     

Distribution of Total and Soluble Fiber in Various Millstreams of Wheat

Twenty-three mill flour streams, four final flours, germ, millfeed and three millfeed fractions from milling hard red wheat were analyzed for soluble fiber (SF) and insoluble fiber (IF). The objective was to identify a fraction(s) that may be a good source of SF. Whole wheat flour and germ each contained about 10% total (IF + SF) fiber; they also matched closely in SF and IF. Excluding the red dog fraction, the bran fraction was highest in SF. SF represented about 5% of the total fiber in the bran. No flour stream was a particularly good source of SF. The sixth middlings stream had about one-fourth of the total fiber as SF. Other streams, as well as “straight” and “patent” flours, contained SF and IF in about equal amounts. Products with straight or patent flour would increase SF in the diet without a disproportionate increase in IF.     

米糖膳食纤维对胆酸钠吸附作用的研究

以酶法和化学法相结合制备出理化性能良好的脱脂米糠不溶性膳食纤维和脱脂米糠可溶性半纤维素B两种膳食纤维,在体外模拟条件下分别采用不同的分析方法测定它们对胆酸钠的吸附作用,发现两对胆酸钠都有显的吸附作用,吸附量分别为0．036－0．042g/g和0.013g/g,并由此就米糠膳食纤维降胆固醇作用的可能机理进行了探讨。     

Precooked bran-enriched wheat flour using extrusion: dietary fiber profile and sensory characteristics

ABSTRACT:  The effect of precooking by extrusion processing on the dietary fiber profile of wheat flour substituted with 0%, 10%, 20%, and 30% wheat bran was evaluated. Depending on the level of bran, total dietary fiber (TDF) and soluble dietary fiber (SDF) in uncooked flours ranged from 4.2% to 17.2% and 1.5% to 2.4%, respectively. Precooking by extrusion significantly increased SDF in flours (by 22% to 73%); although in most cases it also led to a significant decrease in TDF. Cookies and tortillas produced from uncooked and precooked flours with 0% and 20% substituted bran were evaluated for consumer acceptability using a 9-point hedonic scale. With a few exceptions, all cookies had scores ranging from 6 to 7 ("like slightly" to "like moderately") for each attribute, including overall acceptability, appearance, texture, crumbliness, and flavor. Tortillas were rated for the same attributes except for crumbliness, which was replaced with chewiness. In most cases, tortilla scores ranged from 5 to 7 ("neither like nor dislike" to "like moderately"). Consumer acceptability scores of cookies from uncooked flour did not change significantly with increase in bran substitution from 0% to 20%. However, consumer scores for tortillas did decrease significantly with increase in bran level. Extrusion precooking of the flours did not improve the consumer acceptability of cookies and tortillas; however, it did improve their dietary fiber profile by increasing the SDF significantly.     

米糠和麦麸膳食纤维的制备研究

探讨了米糠半纤维素和麦麸膳食纤维的提取工艺。结果表明 :( 1 )料液比 1∶1 0 ,6 0℃浸提 3h ,米糠水溶性半纤维素提取率 1 38% ;( 2 )料液比 1∶1 0 ,0 5mol/L的NaOH 2 5℃浸提 3h ,米糠碱溶性半纤维素提取率 8 86 % ;( 3) 0 6 %的NaOH ,α 淀粉酶加入量 0 4% ,70℃浸提 1 5h ,麦麸膳食纤维提取率达 6 6 2 7%。     

Binding of Zinc to Apple Fiber, Wheat Bran, and Fiber Components

Zinc ion binding to commercial brans, fiber, and fiber components was studied by equilibrium dialysis. Maximum initial concentration of zinc bound by 50 ma of apple fiber (AF) and wheat bran (WB) at pH 7.2 was 220 μg. AF and WB binding capacities were significantly lower for soluble fractions than for unfractionated materials. The water-soluble fraction's binding capacity was 90% lower for AF than for WB. Hemicellulase and phytase slightly increased AF binding capacity but reduced WB capacity. Pectinase increased both AF and WB capacity slightly. Binding capacities of commercially available individual fiber components decreased in the order: lignin > polypectin > pectin > gum > cellulose. Zinc-binding capacities of various dietary fiber types differ, accounting for different zinc bioavailabilties of some foods.     

Binding of four heavy metals to hemicelluloses from rice bran

This paper demonstrates that rice bran hemicellulose A (RBHA), hemicellulose B (RBHB) and hemicellulose C (RBHC) have the potential for binding heavy metal ions. The quantity of metal ions bound varies from one rice bran fibre to another. As it can be inferred from the results of the study, RBHB was characterised by the highest capacity for metal ion (Pb, Cu and Cd) binding, followed by RBHC and RBHA. Binding of heavy metals to insoluble dietary fibre (RBDF) and cellulose from rice bran were found to be poor. Lignin from rice bran was the least active fraction for binding heavy metal ions.     

Effects of rice bran fiber on heat-induced gel prepared with pork salt-soluble meat proteins in model system

The technological effects of rice bran fiber on pork salt-soluble meat proteins in a model system were investigated. Rice bran fiber at levels of 0% (control), 0.1%, 0.5%, 1%, and 2% was added at the same time as salt-soluble meat protein to maintain similar moisture levels in all samples. Samples with increasing amounts of added rice bran fiber had higher pH, yellowness, sarcoplasmic and total protein solubilities. The moisture content, myofibrillar protein solubility and water holding capacity were the highest in the treatments containing with 1% rice bran fiber. However, the lightness and redness, textural properties decreased with increasing rice bran fiber levels. SDS gel electrophoresis did not reveal any changes in proteins regardless different rice bran fiber levels. The apparent viscosity indicated that improvements in water holding capacity and decreased texture due to added rice bran fiber.     

米糠粗蛋白、粗脂肪以及粗纤维含量的近红外预测模型的建立

近红外光谱技术是一种快速无损检测物质含量和鉴别物质的现代分子光谱分析技术.本研究选用分别来自南北方共200个米糠样品(100个粳米米糠、100个籼米米糠),经过理化数据检测、近红外参数优化、光谱信息采集、光谱数据预处理、模型建立及模型优化等步骤,最终建立粳米米糠、籼米米糠及总米糠的粗蛋白、粗脂肪、粗纤维的预测模型,所建...     

Quality characteristics and consumer acceptance of yogurt fortified with date fiber

Yogurt is considered a healthy food and incorporating dietary fiber will make it even healthier. Date fiber (DF), a by-product of date syrup production, is a good source of dietary fiber. The effect of fortification with DF on fresh yogurt quality was investigated. Acidity, pH, color [L* (lightness), a* (redness), and b* (yellowness) values], texture profile, sensory properties, and consumer acceptance were studied. Control yogurt (without fiber), yogurt fortified with 1.5, 3.0, and 4.5% DF, and yogurt with 1.5% wheat bran (WB) were prepared. Fortification with DF did not cause significant changes in yogurt acidity, although pH was increased. Yogurts fortified with DF had firmer texture (higher hardness values) and darker color (lower L* and higher a*) compared with control or WB yogurts. Consumer test results indicated that the appearance, color, and flavor ratings were significantly affected by fiber fortification. Yogurt fortified with up to 3% DF had similar sourness, sweetness, firmness, smoothness, and overall acceptance ratings as the control yogurt. Sensory ratings and acceptability of yogurt decreased significantly when increasing DF to 4.5% or using 1.5% WB. Flavoring yogurt fortified with 4.5% DF with vanilla did not improve flavor or overall acceptance ratings. Thus, fortifying yogurt with 3% DF produced acceptable yogurt with beneficial health effects.     

米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响

以新鲜米糠为原料贮藏0、1、3、5、10 d得到不同酸败程度的米糠,稳定化和脱脂后制备米糠可溶性膳食纤维,研究米糠贮藏时间对米糠可溶性膳食纤维抗氧化性质的影响。结果表明:随着新鲜米糠贮藏时间的延长,米糠可溶性膳食纤维的还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH、O_2~-·能力均先上升后下降;米糠可溶性膳食纤维还原能力、金属离子螯合能力和清除ABTS~+·、DPPH·、·OH在新鲜米糠贮藏5 d时达到最大值,分别为0.943(OD_(700))、35.16%、32.28%、73.51%和13.83%,米糠可溶性膳食纤维清除O_2~-·能力在新鲜米糠贮藏1 d达到最大值,为60.58%。     

米糠半纤维素B的分离和鉴定

由脱脂米糠细胞壁物质碱提分离出半纤维素B，其单糖组成为阿拉伯糖（22．1）、木糖（54．5）、葡萄糖（10.1）和半乳糖（13．4）．结合蛋白的氨基酸组成同游离米糠蛋白有较大差异，半纤维素B主要由50万、3万和1.1万三个分子量组分组成．并发现，碱提浓度和温度过高会对其产生裂解作用．     

Updated profile of aflatoxin and Aspergillus section Flavi contamination in rice and its byproducts from the Philippines.

Our goal was to develop an updated profile of aflatoxin (AF) and AF-producing fungi contamination in rice and its byproducts from the Philippines. The total AF levels in 78 samples of polished and brown rice, determined by an immunoaffinity column clean-up method coupled with HPLC (detection limit: 25 ng/kg), ranged from <0.025-2.7 microg/kg (mean of positive samples: 0.37 microg/kg) and 0.03-8.7 microg/kg (mean of positive samples: 2.7 microg/kg), respectively. The incidence (% of positive samples) of AF in polished and brown rice were 94% and 100%, respectively. The AF levels in polished rice imported from Thailand and Vietnam were approximately 20% of the levels found in locally produced polished rice. AF levels decreased as the rice progressed through the various stages in milling. Fungi recovered include toxigenic Aspergillus flavus and A. parasiticus with an incidence ranging from 14% in rice bran to 78% in rough rice and producing <0.025-6200 microg/kg total AF in in vitro cultures on rice. All samples of rice bran and rice hull contained AF at levels ranging from 0.27-11 microg/kg. The estimated potential daily intake of AFB(1) from rice is between 0.1 and 7.5 ng/kg of body weight/day, the mean of which is 1.0 ng representing 9.1-5.3 times the estimated tolerable daily intake for AFB(1) reported to date for Asia. Thus, Filipinos have a potentially high risk of exposure to AF that can be easily controlled through proper post-harvest handling and storage of rice and its byproducts.     

Characteristics of low-fat meat emulsion systems with pork fat replaced by vegetable oils and rice bran fiber

The effects of vegetable oils prepared from olive, corn, soybean, canola, or grape seed, and rice bran fiber on the composition and rheological properties of meat batters were studied. Pork fat at 30% in the control was partially replaced by one of the vegetable oils at 10% in addition to reducing the pork fat to 10%. The chemical composition, cooking characteristics, texture properties, and viscosity of low-fat meat batters were analyzed. The moisture, protein, ash content, uncooked and cooked pH values, b^∗-value, hardness, cohesiveness, gumminess, chewiness, and viscosity of meat batters with vegetable oil and rice bran fiber were all higher than the control. In addition, batters supplemented with vegetable oil and rice bran fiber had lower cooking loss and better emulsion stability. Low-fat meat batters with reduced pork fat content (10%) and 10% vegetable oil plus rice bran fiber had improved characteristics relative to the regular fat control.     

Optimization of replacing pork back fat with grape seed oil and rice bran fiber for reduced-fat meat emulsion systems

The effects of reducing pork fat levels from 30% to 20% and partially substituting the pork fat with a mix of grape seed oil (0%, 5%, 10% and 15%) and 2% rice bran fiber were investigated based on chemical composition, cooking characteristics, physicochemical and textural properties, and viscosity of reduced-fat meat batters. For reduced-fat meat batters containing grape seed oil and rice bran fiber the moisture and ash contents, uncooked and cooked pH values, yellowness, cohesiveness, gumminess, chewiness, and sarcoplasmic protein solubility were higher than in the control samples. The reduced-fat samples with increasing grape seed oil concentrations had lower cooking loss, emulsion stability, and apparent viscosity. The incorporation of grape seed oil and rice bran fiber successfully reduced the animal fat content in the final products while improving other characteristics.     

Effect of enrichment with hemicellulose from rice bran on chemical and functional properties of bread

This paper examines the use of the defatted rice bran hemicellulose B (RBHB), and insoluble dietary fibre (RBDF), as two functional ingredients added to bakery products. The results show that the RBHB from defatted rice bran had high water-binding and swelling capacity. RBHB exhibited high fat binding capacity. However, RBHB was found to be low viscous. Addition of 1%, 2% and 3% RBHB preparation reduced loaf volume significantly and increased the firmness of the breads. Sensory evaluations revealed that breads with 1%, 2%, 3% RBHB and 2%, 4% RBDF were overall acceptable. This confirms that the RBHB and RBDF preparation from defatted rice bran has great potential in food applications, especially in development of functional foods including functional bakery products.     

Effect of Heat Treatments on Chemical Analysis of Dietary Fiber

Apple fiber, corn fiber, oat bran and soy fiber were analyzed to study the effect of heat processing (autoclaving at 121°C/15 min, 100°C/30 min and microwave heating for 5/10 rain) on dietary fiber fractions. Samples were analyzed for insoluble (IDF), soluble (SDF), and total dietary fiber (TDF) by an enzymatic-gravimetric method. Autoclaving reduced IDF of apple fiber and TDF of apple fiber and oat bran. Microwave heating reduced TDF in apple fiber and oat bran and IDF in oat bran but increased the SDF of apple fiber. All treatments decreased the SDF in corn fiber. Effects on dietary fiber fractions depended on fiber type and processing method.     

Influence of fibre from different cereals on the rheological characteristics of wheat flour dough and on biscuit quality

Demand for health oriented products such as sugar-free, low calorie and high fibre products is increasing. One such recent trend is to increase the fibre content in food products to overcome health problems such as hypertension, diabetes, and colon cancer, among others. Consumption of high fibre products consisting of indigestible cellulose, hemicellulose, lignin and gums have several health benefits. Apart from these benefits, β-glucan-rich fibres have the benefit of reducing the absorption of glucose. Fibre sources from wheat, rice, oat and barley were used to study their influence on rheological characteristics of wheat flour dough and biscuit making quality. Ash, total protein and dietary fibre content of bran samples ranged between 4% and 10%, 12% and 14% and 20.4% and 49.5%, respectively. Farinograph characteristics of the wheat flour-bran blends showed increase in water absorption from 60.3% to 76.3% with increase in the level of bran from 0% to 40%. The resistance to extension values as well as extensibility of the dough decreased with increase in the bran level. The spread ratio of the biscuits prepared from wheat, rice and oat bran blends decreased from 8.38 to 7.52, whereas the same increased to 9.3 for biscuits prepared from barley bran blends. The breaking strength values of biscuits ranged between 1.34 and 3.83 kg. Highly acceptable biscuits could be obtained by incorporating 30% of oat bran or 20% of barley bran in the formulation.     

Mathematical models for maximum improvement of in vitro protein digestibility of high dietary fibre cookies

Via substituting with wheat flour some high dietary fibre cookies were prepared (with 6, 12, 18 and 24%) from cereal industry by-products: corn bran (CB), rice bran (RB) and barley husk (BH). In vitro protein digestibility assay was used to examine the effect of substituting on protein digestibility. The applied nonlinear mathematical models indicated a higher determination coefficient between experimental and predicted data (R2 ≥ 0.999). A maximum in vitro protein digestibility (IVPD) of 88.4, 84.1, 85.2% was obtained when using optimum level substituting with wheat flour (7.9, 9.3 or 5.2%) in the CB, RB or BH respectively for producing cookies. The maximum improvement or minimum reducing IVPD by using fibre sources in producing cookies ranged from ?0.25% in RB to 4.9% in CB.     

米糠膳食纤维的制备与性能研究

将新鲜米糠脱脂后，分别用葡萄糖淀粉酶和木瓜蛋白酶除去淀粉和蛋白质，以4％的NaOH溶液提取半纤维素，得到10％的半纤维素A和2％的半纤维素B粗产品，多糖总量分别为86．38％和92．07％，非碱提物除木质素后，得到7％的纤维素．对它们的性能进行了分析，研究表明，在持水力、膨胀力和粘度方面，半纤维素B均优于半纤维素A及纤维素。