Binding of 14C-Labeled Food Mutagens (IQ, MeIQ, MeIQx) by Dietary Fiber In Vitro

Binding of three mutagens, known to occur in fried or broiled foods, by thirteen different types of dietary fiber was investigated in vitro. Nonspecific binding by other food polymers was minimized by using protease and amylase treatment. Water-insoluble fiber components were responsible for most of the binding capacity. Generally, a slightly larger proportion of 2-amino-3,4-dimethylimidazo [4,5-f]quinoline (MeIQ) than of 2-amino-3-methylimidazo [4,5-f]quinoline (IQ) and 2-amino-3,8-dimethylimidazo] -4,5-f]quinoxaline (MeIQx) was bound. There was a significant correlation between Klason lignin content and binding of mutagens. Optimum pH for binding was between 4 and 6. Dietary fiber from sorghum had the highest binding capacity, which could be due to the presence of a large Klason lignin fraction.     

Iron, Zinc, Copper and Magnesium Binding by Cooked Pinto Bean (Phaseohs vulgaris) Neutral and Acid Detergent Fiber

Iron, copper and zinc but not magnesium were bound by neutral (NDF) and acid (ADF) detergent fiber obtained from cooked pinto beans. Iron binding increased with higher pH, higher iron concentration, higher fiber concentration and smaller fiber particle size. Maximum binding of iron was at pH 6.5 and minimal binding at pH 4.0 for both NDF and ADF. A 50% decrease in particle size increased iron binding by 8%. Binding of copper and zinc increased with higher copper and zinc concentrations. Both NDF and ADF had a greater affinity for copper than for either iron or zinc. Scatchard plots indicated the presence of two types of binding sites for zinc, one type for iron, and one type for copper.     

In Vitro Binding of Vitamin E to Selected Dietary Fiber Sources

An in vitro method was used to assess interaction between whole fiber (WF) sources and vitamin E under simulated physiological conditions (pH 2, pH 7, pH 2–7; bile salt 5–15 mM; 37°C). Dose-response and binding characteristics (via Scatchard analysis) were examined. Binding of vitamin E by lupin and gum were higher (p≤0.05) at pH 2 and pH 7 than at the sequential treatment. Oat bran, treated at pH 7 or sequentially, showed increased (p≤0.05) binding of vitamin E as fiber level increased (25 - 100 mg). Scatchard plots revealed two specific noninteracting binding sites for sugarbeet and barley bran. Affinities (K_d) and capacities (n) were compared among fibers. Affinities for vitamin E were: sugarbeet>oat>lupin>barley>gum. Capacities were: barley > gum > lupin > sugarbeet > oat. Vitamin E binding to DF is complex, multifactorial, and not due to a single mechanism.     

两种超微粉碎法对西番莲果皮水不溶性膳食纤维改性效果的研究

本实验以西番莲果皮膳食纤维为原料,采用干法超微粉碎和湿法超微粉碎进行改性处理,并对改性后的膳食纤维进行形貌观察和理化性质测定。电镜扫描结果显示经两种方式改性后,膳食纤维的组织结构都有破坏,且湿法更严重;红外光谱分析结果显示改性后的膳食纤维羟基所在峰位均发生一定的蓝移,促进了羟基基团的暴露;X衍射结果显示改性后的膳食纤维晶区并未发生改变;膳食纤维改性后,持水力、膨胀力、水溶性和SDF溶出率都有所增强,尤其是经湿法改性持水力由6.739 g/g提高到20.085 g/g,增加了198.04%;但改性对阳离子交换能力影响不大;膳食纤维改性后,对脂肪酸、胆固醇、亚硝酸根离子和胆酸钠的吸附能力都有提高,且湿法强于干法。整体而言,这两种超微粉碎法对膳食纤维的改性都有效果,并且湿法对多数指标的改性效果均达到显著水平,强于干法。     

发芽对绿豆皮膳食纤维结构及性质的影响

为研究发芽对绿豆皮膳食纤维结构及功能性质的影响,采用X射线衍射分析、红外光谱分析和电子显微镜扫描等方法测定其结构,并对其持水力、持油力、膨胀力、阳离子交换能力、吸附葡萄糖能力、吸附胆固醇能力和吸附NO2 － 能力等功能性质进行对比研究。结果表明：发芽处理后绿豆皮中总膳食纤维含量增加3.40%,可溶性膳食纤维增加13.62%。发芽绿豆皮膳食纤维的持水力、持油力、膨胀力明显提高,分别达到（6.97±0.32）、（4.93±0.10） g/g、（4.79±0.11） mL/g,阳离子交换能力略有降低,为（0.47±0.02） mmol/g,吸附葡萄糖能力增加,为（8.37±0.18） mmol/g,吸附胆固醇能力增加,为（2.23±0.11） mg/（mL·g）,吸附NO2 － 能力有所降低,为（3.92±0.09） mg/g。扫描电子显微镜结果表明,发芽可使绿豆皮膳食纤维表面出现更多孔隙和褶皱,有利于膳食纤维吸附能力的提高;X射线衍射结果表明,发芽没有改变绿豆皮膳食纤维的结晶度,较好地保留了膳食纤维的结晶区和非结晶区;傅里叶红外光谱分析表明,发芽没有破坏绿豆皮膳食纤维的官能团结构。绿豆经发芽处理后改善了绿豆皮膳食纤维的大部分功能性质,较好地保留了其结构,有利于绿豆副产物的开发利用。     

麦麸及麦麸膳食纤维常规粉碎和超微粉碎物化特性比较

为明确普通粉碎和超微粉碎对麦麸和麦麸膳食纤维物化特性影响,对处理后的麦麸和麦麸膳食纤维持水性、持油性、吸水膨胀性、黏度、阳离子交换能力及对油脂、胆固醇、胆酸钠和葡萄糖吸附能力进行了测定。结果表明:麦麸膳食纤维比麦麸具有更高的WHC和OHC,而超微粉碎处理可进一步提升麦麸膳食纤维WHC和OHC,分别为4.99 g/g和6.30 g/g;在胆酸钠浓度为3 mg/mL时,超微粉碎麦麸及麦麸膳食纤维胆酸钠吸附量最高,分别为40.58 mg/g和46.08 mg/g;在葡萄糖浓度为50～100 mmol/L范围内,超微粉碎后麦麸及麦麸膳食纤维葡萄糖吸附量亦明显上升。pH7时,普通粉碎处理后麦麸胆固醇吸附能力低于麦麸膳食纤维,而超微粉碎处理后麦麸胆固醇吸附能力高于麦麸膳食纤维。普通粉碎的麦麸对不饱和脂肪酸和饱和脂肪酸吸附量最高,分别达到1.56 g/g和1.13g/g。研究表明麦麸及麦麸膳食纤维表通过处理后现出不同物化特性,这将为麦麸食品化利用及对食品体系物化特性影响提供理论依据。     

Effects of Dietary Fiber from Shredded and Puffed Wheat Breakfast Cereals on Intestinal Function in Rats

Rats were fed a semi-purified diet containing 63% puffed wheat (PW) or 63% shredded wheat (SW) breakfast cereals for 6 wk. A 16% unprocessed wheat bran (WB) diet was used as control. The neutral detergent fiber (NDF) content was 3.2%, 1.9%, and 1.9% in diets PW, SW, and WB, respectively. Feces were collected during three 96-hr periods: fecal weight and volume were lower (P < 0.001), fecal density was higher (P < 0.001), and intestinal transit time was longer (P < 0.01) in group PW than in groups SW and WB. Results indicate that the dietary fiber content of puffed wheat breakfast cereals is lower than that of shredded wheat breakfast cereals.     

Extraction and fractionation of insoluble fiber from five fiber sources

Commercially processed wheat bran (WB), rice bran (RB), oat fiber (OF), tomato fiber (TF), and apple fiber (AF) were analyzed for proximate composition, soluble fiber (SF), insoluble fiber (IF) and total dietary fiber (TDF). IF was further fractionated into four fractions: cellulose, hemicellulose A and B, and lignin. Protein, IF, and TDF values were significantly different among the samples. Protein content ranged from 4.6% in OF to 24.9% in TF. SF values ranged from 1.5% in OF to 13.9% in AF. IF values varied from 46.7% in RB to 73.6% in OF. TDF ranged from 51.4% in RB to 75.1% in OF. Hemicellulose A to B ratio was high in all the samples except rice bran. WB had the highest total hemicellulose (44.0% of TDF) content followed by AF (38.4%), OF (38.3%), TF (36.5%), and RB (31.6%). Cellulose was 32.2, 26.6, 24.4, 20.8, and 19.7% of TDF in WB, OF, RB, AF, and TF, respectively. Lignin levels ranged from 5.2% in WB to 21.4% in OF.     

Effect of pH and Heat Treatment on the Binding of Calcium, Magnesium, Zinc, and Iron to Wheat Bran and Fractions of Dietary Fiber

The effect of pH and heat treatment on the binding of added food grade sources of calcium, magnesium, zinc, and iron to a standard wheat bran, cellulose, and lignin was investigated. 1% solutions of pectin and guar gum were examined for their ability to bind these metals in aqueous solution. Lignin and pectin was found to have high metal binding capacities. Metal binding to fiber was found to be pH dependent. Toasting had no effect on metal binding by cellulose, but had a significant effect on the binding of metals by lignin and wheat bran. Boiling had a significant effect on the binding of metals by cellulose, lignin, and wheat bran.     

Copper and Zinc Binding to Dietary Fiber Sources: An Ion Exchange Column Method

The ion exchange capacities of dietary fiber sources for copper and zinc were studied via a factorial design: 4 fiber sources X 2 treatments X 3 solutions. The treatments were: (1) neutral detergent and (2) enzymatic. The treated fiber residues were used as the stable matrix in columns and mineral-containing solutions were pumped through the columns. The amount of minerals bound varied with fiber type and treatment type. All fiber residues bound more copper than zinc. Binding of both minerals was reduced when they were applied in combination. The treatment of the fibers produced residues with dissimilar physical properties. These results indicate the variability introduced by methodology.     

羊毛角蛋白改性氧化棉纤维的工艺研究

利用自制的羊毛角蛋白溶液对高碘酸钠选择性氧化的棉纤维进行改性整理,研究了角蛋白溶液对氧化棉纤维的改性工艺。与未经氧化的原棉相比,相同改性条件下经选择性氧化的棉纤维与角蛋白的结合量明显增加。讨论了不同工艺条件对氧化棉纤维增重率和力学性能的影响,得出羊毛角蛋白改性氧化棉纤维的优化工艺,并得出经角蛋白溶液整理后的氧化棉纤维力学性能略有提高。     

Antioxidant Properties of Fresh,Powder, and Fiber Products of Mango (Mangifera Foetida) Fruit

This study was aimed to investigate the antioxidant capacity and antioxidant components in fresh, powder and fiber products prepared from Mangifera foetida fruit, locally known as bacang. The antioxidant capacity and components (reducing, flavonoid, carotenoid, and ascorbic acid contents) were in the order of fresh > fiber > powder, whereas based on β-carotene bleaching method, order of antioxidant activity was fiber > powder > fresh. Pearson correlation coefficient showed that there was positive and significant correlation (r > 0.9) between antioxidant capacity and certain antioxidant components.     

Peanut Hull Flour as Dietary Fiber in Wheat Bread

Peanut hull flour (PHF) at 0, 4, and 8% was added to wheat bread (WB) to increase the dietary fiber content. The bread was tested for textural properties, proximate composition, dietary fiber content, specific volume, color, and some sensory attributes. While addition of PHF caused some changes in the bread, all samples were evaluated by a panel as being acceptable. From the standpoint of bread quality, PHF is an acceptable material which can be added to WB to increase the level of dietary fiber.     

不同品种马铃薯膳食纤维化学组成及理化性质分析

以夏波蒂、白玫瑰、黑玫瑰、克新1号、费乌瑞它、冀张薯8号6个品种的马铃薯为研究对象,自提薯渣并采用中温α-淀粉酶、碱性蛋白酶和糖化酶水解提取膳食纤维,研究了不同品种干马铃薯渣(dried potato residue,DPR)和马铃薯膳食纤维(potato dietary fiber,PDF)的化学组成、微观结构及理化性质。结果表明:不同品种DPR的各化学组分含量差异显著(P0.05),其中夏波蒂、黑玫瑰的总膳食纤维含量较高,分别为43.16%和31.87%。PDF得率最高的是夏波蒂(62.19%),最低的是白玫瑰(42.99%),黑玫瑰为51.27%。与DPR相比,酶解后得到的PDF中淀粉和果胶含量较低,蛋白质、纤维素、半纤维素、木质素含量较高;DPR结构紧密,而酶解得到的PDF结构更疏松,有褶皱和很多空洞,表面积大。黑玫瑰PDF的淀粉含量最低,蛋白质含量为7.69%,显著低于白玫瑰(P0.05),纤维素含量高达21.30%,木质素含量与含量最高的白玫瑰差异不显著(P0.05),果胶含量显著高于其他品种(P0.05)。综合比较,黑玫瑰PDF的持水性、持油性、膨胀性和葡萄糖束缚能力在6个品种中均较大,因此黑玫瑰是一种适合提取PDF的马铃薯资源。     

牛蒡膳食纤维对香肠品质的影响

将牛蒡膳食纤维以0%、0.25%、0.50%、0.75%、1.00%、1.25%添加到香肠中,研究对香肠的色泽、pH值、持水性、蒸煮损失、质构参数的影响,并根据感官评价的结果确定最适的纤维添加量.结果表明:添加纤维后香肠变暗,红色减少而黄色增加.香肠红色的减少与持水性的增加显著相关,黄色增加可能是由于牛蒡纤维带入了类胡萝卜素的缘故.香肠pH值随牛蒡膳食纤维的添加而升高,这是由于纤维本身的高灰分引起的.随牛蒡膳食纤维添加量的增加,香肠的持水性和蒸煮损失分别增大和减小.蒸煮损失的减小不仅与持水性的增大有关,而且还可能与脂肪结合能力的增大相关.香肠的质构参数也显著地受到牛蒡膳食纤维的影响,硬度随纤维量的增加而增加,弹性呈现先增后降的变化趋势.感官评价显示,超过1%的牛蒡膳食纤维添加量会严重影响香肠的感官评分.     

SOLUBLE COMPLEXES OF COPPER AND ZINC IN WHISKEY DISTILLERY SPENT WASH

The capacity of samples of malt whiskey distillery spent wash to complex added ionic copper was examined, and copper binding capacities of up to 3250 mg litre^?1 found. A correlation between the copper binding capacity and the total hexose content of spent wash was demonstrated. Gel filtration studies indicated that the copper was probably bound to an organic fraction containing both carbohydrate and ninhydrin positive material, whereas zinc appeared to be complexed by a lower molecular weight fraction containing both hexose and phenolic moieties.     

竹笋膳食纤维对冷冻面团流变学特性、水分分布和微观结构的影响

本实验比较竹笋膳食纤维、米糠膳食纤维和大豆膳食纤维的功能和理化特性,结果显示竹笋膳食纤维 的持水性、持油性、膨胀性、对NO2－和胆固醇的吸附能力分别为17.85 g/g、10.14 g/g、9.63 mL/g、4.82 μmol/g和 6.88 mg/g,均远高于米糠膳食纤维和大豆膳食纤维。研究不同竹笋膳食纤维添加量对冷冻面团流变学特性、水分分 布以及微观结构的影响,结果发现竹笋膳食纤维的添加使得冷冻面团的弹性模量和黏性模量得到提高;竹笋膳食纤 维改变了冷冻面团的水分分布,显著缩短冷冻面团峰T22的弛豫时间,增强了面团的持水能力;扫描电子显微镜观 察发现,竹笋膳食纤维改变了冷冻面团的微观结构,使其淀粉颗粒与面筋网络排列更加均匀。本研究将为竹笋膳食 纤维对冷冻面团的改良提供理论依据。     

Reductive capacity of natural reductants

Reductive capacities of soil minerals and soil for Cr(VI) and chlorinated ethylenes were measured and characterized to provide basic knowledge for in-situ and ex-situ treatment using these natural reductants. The reductive capacities of iron-bearing sulfide (pyrite), hydroxide (green rust; GR(SO4)), and oxide (magnetite) minerals for Cr(VI) and tetrachloroethylene (PCE) were 1-3 orders of magnitude greater than those of iron-bearing phyllosilicates (biotite, vermiculite, and montmorillonite). The reductive capacities of surface soil collected from the plains of central Texas were similar and slightly greater than those of iron-bearing phyllosilicates. The reductive capacity of iron-bearing soil minerals for Cr(VI) was roughly 3-16 times greater than that for PCE, implying that Cr(VI) is more susceptible to being reduced by soil minerals than is PCE. GR(SO4) has the greatest reductive capacity for both Cr(VI) and PCE followed by magnetite, pyrite, biotite, montmorillonite, and vermiculite. This order was the same for both target compounds, which indicates that the relative reductive capacities of soil minerals are consistent. The reductive capacities of pyrite and GR(SO4) for chlorinated ethylenes decreased in the order: trichloroethylene (TCE) > PCE > cis-dichloroethylene (c-DCE) > vinyl chloride (VC). Fe(II) content in soil minerals was directly proportional to the reductive capacity of soil minerals for Cr(VI) and PCE, suggesting that Fe(II) content is an important factor that significantly affects reductive transformations of target contaminants in natural systems.     

Iron Binding by Fiber is Influenced by Competing Minerals

Iron was bound by neutral (NDF) and acid (ADF) detergent fibers extracted from cooked pinto beans (Phaseolus vulgaris). Soluble iron (total iron minus bound iron) in the presence of NDF was increased from 13.11 ± 5.08 to 35.58 ± 9.20% and from 22.22 ± 164 to 29.98 ± 0.96% when 1.17 and 1.38 ppm (18.4 and 21.4 PM) of copper and zinc were added, respectively. In contrast, 0.93 μm (14.6 PM) of copper decreased the soluble iron from 61.02 ± 5.77 to 17.88 ± 4.5% in the presence of ADF. Neither magnesium or cobalt altered the amount of soluble iron in the presence of fiber. The change in soluble iron was directly proportional to the concentration of copper and zinc. The presence of two types of binding sites is proposed.     

Fiber Constituents and Fibrous Food Residue Effects on the In Vitro Enzymatic Digestion of Protein

In vitro digestibility of casein was significantly (P < 0.05) reduced as the fiber weight-to-protein weight ratio increased from 0.0:1.0 to 1.0:1.0 for isolated fiber constituents and fibrous food residues. For casein digestibility in the presence of fiber constituents, the reduction ranked in the following order: karaya gum > xylan > pectin > lignin > holocellulose. The order of reduction by fibrous food residues ranked as follows: kernel corn > blackeye pea > broccoli > brown rice > wheat bran. Gel filtration profiles of casein hydrolysates were generally not affected by the fiber constituents whereas significant alterations to greater molecular weight peptides occurred in the presence of food residues. The data supported the interaction of dietary fiber components by interference of the enzyme-substrate complex formation in proteolytic digestion.