Influence of Bran Particle Size on Bread‐Baking Quality of Whole Grain Wheat Flour and Starch Retrogradation

The influence of bran particle size on bread‐baking quality of whole grain wheat flour (WWF) and starch retrogradation was studied. Higher water absorption of dough prepared from WWF with added gluten to attain 18% protein was observed for WWFs of fine bran than those of coarse bran, whereas no significant difference in dough mixing time was detected for WWFs of varying bran particle size. The effects of bran particle size on loaf volume of WWF bread and crumb firmness during storage were more evident in hard white wheat than in hard red wheat. A greater degree of starch retrogradation in bread crumb stored for seven days at 4°C was observed in WWFs of fine bran than those of coarse bran. The gels prepared from starch–fine bran blends were harder than those prepared from starch–unground bran blends when stored for one and seven days at 4°C. Furthermore, a greater degree of starch retrogradation was observed in gelatinized starch containing fine bran than that containing unground bran after storage for seven days at 4°C. It is probable that finely ground bran takes away more water from gelatinized starch than coarsely ground bran, increasing the extent of starch retrogradation in bread and gels during storage.     

Effect of Single‐Pass and Multipass Milling Systems on Whole Wheat Durum Flour and Whole Wheat Pasta Quality

Single‐pass and multipass milling systems were evaluated for the quality of whole wheat durum flour (WWF) and the subsequent whole wheat (WW) spaghetti they produced. The multipass system used a roller mill with two purifiers to produce semolina and bran/germ and shorts (bran fraction). The single‐pass system used an ultracentrifugal mill with two configurations (fine grind, 15,000 rpm with 250 μm mill screen aperture; and coarse grind, 12,000 rpm with 1,000 μm mill screen aperture) to direct grind durum wheat grain into WWF or to regrind the bran fraction, which was blended with semolina to produce a reconstituted WWF. Particle size, starch damage, and pasting properties were similar for direct finely ground WWF and multipass reconstituted durum flour/fine bran blend and for direct coarsely ground WWF and multipass reconstituted semolina/coarse bran blend. The semolina/fine bran blend had low starch damage and had desirable pasting properties for pasta cooking. WW spaghetti was better when made with WWF produced using the multipass than single‐pass milling system. Mechanical strength was greatest with spaghetti made from the semolina/fine bran or durum flour/fine bran blends. The semolina/fine bran and semolina/coarse bran blends made spaghetti with high cooked firmness and low cooking loss.     

Effect of Wheat Bran Fiber and Bran Particle Size on Fat and Fiber Digestibility and Gastrointestinal Tract Measurements in the Rat

The effect of wheat bran (AACC hard red) and bran particle size on fat and fiber digestibility and gastrointestinal tract measurements were investigated with diets containing 5.7–10.7% dietary fiber. Fifty‐six male weanling Sprague‐Dawley rats were randomly assigned to four diets containing 5% cellulose (C5); 10.5% cellulose (C10); 21.5% coarse (2 mm) wheat bran (CB); or 22.2% fine (0.5 mm) wheat bran (FB) in a sixweek study. Dietary fiber digestibilities were significantly different (P < 0.05) among treatment diets (CB > FB > C5 > C10) but there was no effect in fat digestibility among treatments. High‐fiber diets fed to rats resulted in significantly greater wet and dry fecal weights than low‐fiber diets. Bran diets resulted in significantly higher fecal moisture than cellulose diets. Cecum lengths increased significantly with bran diets compared with cellulose diets. The CB diet resulted in significantly higher stomach weights than with cellulose diets. Stomachs were heavier and cecal lengths were greater with bran diets than with cellulose diets; however, a high‐cellulose diet resulted in increased colon weight. Except for higher fiber digestibility of coarse bran, bran particle size had no significant effects. Healthful effects of wheat bran may be associated with gastrointestinal morphology and function. Fecal bulking and decreased intestinal transit time can prevent constipation and may dilute or reduce absorption of toxic or carcinogenic metabolites, thus improving gastrointestinal health and lowering the risk of tumor development and cancer.     

Effects of Bran Prehydration on Functional Characteristics and Bread‐Baking Quality of Bran and Flour Blends

The effect of bran prehydration on the composition and bread‐baking quality was determined using bran and flour of two wheat varieties. Bran was hydrated in sodium acetate buffer (50mM, pH 5.3) to 50% moisture at 25 or 55°C for 1.5 or 12 h. The soluble sugar content in bran increased with prehydration. Decreases in phytate and soluble fiber were observed in prehydrated bran, but insoluble fiber was not affected by prehydration. Likewise, free phenolic content decreased, and there was little change in the content of bound phenolics in prehydrated bran. The compositional changes were greater in the bran prehydrated at 55 than at 25°C, and for 12 than for 1.5 h. Addition of prehydrated bran delayed dough development of bran and flour blends and slightly increased water absorption of dough. A higher loaf volume of fresh bread and lower crumb firmness of bread stored for 10 days were observed in bread containing bran prehydrated at 25°C than in bread containing nonhydrated bran or bran prehydrated at 55°C. The prehydration of bran at 25°C before being incorporated into refined flour for dough mixing improved bread quality by altering bran compositional properties, allowing enough water to be absorbed by fibrous materials in the bran and preventing water competition among dough constituents.     

Composition and Distribution of Pentosans in Millstreams of Different Hard Spring Wheats

Six commercially grown samples of hard spring wheat were milled using a tandem Buhler laboratory mill. Individual flour streams and branny by‐products, as well as whole‐grain wheat and straight‐grade flour, were characterized in terms of total (TP), water‐extractable (WEP), and water‐unextractable (WUP) pentosans. One representative cultivar sample was analyzed for its ratio of arabinose to xylose (A/X). TP and WEP of whole grain wheat of the six samples had ranges of 5.45–7.32% and 0.62–0.90% (dm), respectively. Neither TP nor WEP of whole grain was related to ash content variation. There was significant variation in the distribution and composition of pentosans in 16 millstreams of all the wheat samples, including bran and shorts fractions; TP and WEP contents had ranges of 1.69–32.4% and 0.42–1.76% (dm), respectively. When ash contents exceeded ≈0.6% (dm), strong positive correlations were obtained between ash and TP contents, and between ash and WUP contents for all the millstreams. Among bran and shorts fractions, TP and WUP content increased in the order of coarse bran > fine bran > shorts; while WEP, WEP/WUP and A/X showed the opposite pattern of variation of shorts > fine bran > coarse bran. Bran and shorts fractions had pentosan contents several times higher than would be predicted from the relationship between pentosan and ash contents of the flour streams. Pentosans therefore represented a much more sensitive marker of flour refinement compared with ash content. Pentosans of endosperm were substantially different in their extractability and composition from those of bran. On this basis, different functionalities of pentosans of bran and endosperm would be expected. Results demonstrated the importance of milling extraction and millstream blending in the functionality and quality of wheat flour for breadmaking.     

Nutrient Content in Buckwheat Milling Fractions

Buckwheat seeds (Fagopyrum esculentum Moench) were milled into 23 fractions: seven fine flours, three coarse flours, four small semolina, two big semolina, six bran, and one husk fraction. A considerable variation in gross chemical composition was found among the milling fractions. The protein content varied from 4.4 to 11.9% (db) in flours and from 19.2 to 31.3% in bran fractions; starch varied from 91.7 to 70.4% in flours and from 42.6 to 20.3 in bran. The percentage of soluble dietary fiber contained in total dietary fiber was higher in flours than in semolina and bran fractions. Ash, Fe, P, tannin, phytate content, and color were also investigated. A unique distribution of phytate was found in starch. Correlation is significantly positive in husk, bran, and semolina fractions, while correlation is significantly negative in flour fractions. Depending on technological or nutritional demands, appropriate fractions may be chosen to achieve the desired end‐use product.     

Comparison of Yield and Composition of Oil Extracted from Corn Fiber and Corn Bran

We recently reported that corn fiber oil contains high levels of three potential cholesterol-lowering phytosterol components: ferulate-phytosterol esters (FPE) (3–6 wt%), free phytosterols (1–2 wt%), and phytosterol-fatty acyl esters (7–9 wt%). A previous study also indicated that corn bran oil contained less phytosterol components than corn fiber oil. The current study was undertaken to attempt to confirm this preliminary observation using more defined conditions. Accordingly, oil was extracted from corn fiber and corn bran prepared under controlled laboratory conditions, using the same sample of corn hybrid kernels for each, and using recognized bench-scale wet-milling, and dry-milling procedures, respectively. After extraction, the chemical composition of the phytosterol components in the oil were measured. This study confirmed our previous observation—that FPE levels were higher in corn fiber oil than in corn bran oil. During industrial wet-milling, almost all of the FPE are recovered in the fiber fraction (which contains both fine and coarse fiber). During laboratory-scale wet-milling, ≈60–70% of the FPE are recovered in the coarse fiber (pericarp) and 30–40% are recovered in the fine fiber. During laboratory-scale dry-milling, <20% of the FPE are recovered in the bran (pericarp), and the rest in the grits. The recoveries of the other two phytosterol components (free phytosterols and phytosterol-fatty acyl esters) revealed a more complex distribution, with significant levels found in several of the dry- and wet-milled products.     

Calcium-binding capacities of different brans under simulated gastrointestinal pH conditions. In vitro study with (45)Ca

The present study was performed to investigate calcium-binding characteristics of different brans under simulated gastrointestinal pH conditions and to explore the significance of dietary fiber, oxalate, and phytate for calcium binding. Different brans (rice, rye, soy, fine wheat, coarse wheat, and oat) and CaCl(2) solution containing (45)Ca were incubated at 37 degrees C at gastric pH (2.2) followed by buffering steps of 1 degree from pH 3.0 to pH 8.0. Total calcium binding and calcium-binding capacity of the pH 2.2 soluble bran fraction were determined. Additionally, oxalate and phytate contents of brans and solubility profiles of phytic acid were investigated. Calcium-binding capacities of brans showed a clear pH dependence. At gastric pH calcium binding was low in all brans, ranging from 0.022 to 0.040 mmol of calcium/g of bran. Soy bran, nearly phytate-free, showed higher binding values up to pH 4.0 and lower values between pH 5.0 and 8.0. In all other brans, binding values increased strongly with increasing pH in the quantitative order rice bran > coarse wheat bran > fine wheat bran > rye bran > oat bran. The solubility profiles indicate that in the cases of rye, wheat, and rice bran phytate accounts for 70-82% of their total calcium-binding capacities. The results suggest that dietary fiber makes no important contribution to calcium binding, except for soy and oat brans. Oxalate plays only a minor role in calcium binding by brans.     

Bran Characteristics and Bread‐Baking Quality of Whole Grain Wheat Flour

Variations in physical and compositional bran characteristics among different sources and classes of wheat and their association with bread‐baking quality of whole grain wheat flour (WWF) were investigated with bran obtained from Quadrumat milling of 12 U.S. wheat varieties and Bühler milling of six Korean wheat varieties. Bran was characterized for composition including protein, fat, ash, dietary fiber, phenolics, and phytate. U.S. soft and club wheat brans were lower in insoluble dietary fiber (IDF) and phytate content (40.7–44.7% and 10.3–17.1 mg of phytate/g of bran, respectively) compared with U.S. hard wheat bran (46.0–51.3% and 16.5–22.2 mg of phytate/g of bran, respectively). Bran of various wheat varieties was blended with a hard red spring wheat flour at a ratio of 1:4 to prepare WWFs for determination of dough properties and bread‐baking quality. WWFs with U.S. hard wheat bran generally exhibited higher dough water absorption and longer dough mixing time, and they produced smaller loaf volume of bread than WWFs of U.S. soft and club wheat bran. WWFs of two U.S. hard wheat varieties (ID3735 and Scarlet) produced much smaller loaves of bread (<573 mL) than those of other U.S. hard wheat varieties (>625 mL). IDF content, phytate content, and water retention capacity of bran exhibited significant relationships with loaf volume of WWF bread, whereas no relationship was observed between protein content of bran and loaf volume of bread. It appears that U.S. soft and club wheat bran, probably owing to relatively low IDF and phytate contents, has smaller negative effects on mixing properties of WWF dough and loaf volume of bread than U.S. hard wheat bran.     

Restoration Affect Soil Organic Carbon and Nutrients in Different Particle‐size Fractions

Desertification is reversible and can often be prevented by adopting measures to control the causal processes. Desertification has generally decreased in most of the arid and semiarid areas of China during the last few decades because of the restoration of degraded vegetation and soil nutrients. However, little is known about the responses of soil nutrients in different particle‐size fractions to the restoration process and about the importance of this response to the restoration of bulk‐soil nutrients. In this study, we separated bulk‐soil samples in different sieve fractions: coarse‐fine sand (2·0–0·1 mm), very fine sand (0·10–0·05 mm) and silt + clay (<0·05 mm) fractions. Soil organic carbon (SOC), N, P and K contents stored in the silt + clay were greater than the contents of non‐protected nutrients in the coarser fractions. During the restoration of desertified land, the content and stability of bulk‐soil SOC, total N and P and available N, P and K increased with increasing nutrient contents in all fractions. Topsoil nutrients stored in coarse‐fine sand and very fine sand fractions were more sensitive than those stored in the silt + clay fraction to the fixation of mobile sandy lands and vegetation recovery. The changes of bulk‐soil nutrients and their stability were decided by the soil nutrients associated with all particle‐size fractions. Path analysis revealed that SOC and total nutrients in very fine sand and available nutrients in coarse‐fine sand were the key factors driving the soil recovery. These results will help us understand soil recovery mechanisms and evaluate the degree of recovery. Copyright © 2015 John Wiley & Sons, Ltd.     

Fermentability of Oat and Wheat Fractions Enriched in β‐Glucan Using Human Fecal Inoculation

Fermentation by human fecal bacteria of fractions of wheat bran prepared by preprocessing technology were examined and compared with a β‐glucan‐rich oat bran and a purified β‐glucan (OG). The wheat fractions were essentially a beeswing bran (WBA), mainly insoluble dietary fiber, and an aleurone‐rich fraction (WBB) containing more soluble fiber and some β‐glucan (2.7%). The oat bran (OB) had more endosperm and was very rich in β‐glucan (21.8%). Predigestion of WBB and OB to mimic the upper gastrointestinal (GI) tract gave digested wheat bran fraction B (WBBD) and digested oat bran (OBD), respectively. These predigested fractions were fermented in a batch technique using fresh human feces under anaerobic conditions. Changes in pH, total gas and hydrogen production, short chain fatty acids (SCFA), and both soluble and insoluble β‐glucan and other polysaccharide components, as determined from analysis of monosaccharide residues, were monitored. Fractions showed increasing fermentation in the order WBA < WBBD < OBD < OG. Variations in SCFA production indicated that microbial growth and metabolism were different for each substrate. Polysaccharide present in the supernatant of the digests had disappeared after 4 hr of fermentation. Fermentability of oat and wheat β‐glucan reflected solubility differences, and both sources of β‐glucan were completely fermented in 24 hr. Although the overall patterns of fermentation indicated the relative amounts of soluble and insoluble fiber, the anatomical origin of the tissues played a major role, presumably related to the degree of lignification and other association with noncarbohydrate components.     

Composition,Functional Properties,Starch Digestibility,and Cookie‐Baking Performance of Dry Bean Powders from 25 Michigan‐Grown Varieties

The chemical composition, functional properties, starch digestibility, and cookie‐baking performance of bean powders from 25 edible dry bean varieties grown in Michigan were evaluated. The beans were ground into coarse (particle size ≤1.0 mm) or fine (≤0.5 mm) powders. Starch and protein contents of the bean powders varied between 34.4 and 44.5% and between 19.1 and 26.6% (dry basis [db]), respectively. Thermal properties, pasting properties, and water‐holding and oil‐binding capacities of the bean powders differed and were affected by particle size. After blending the bean powders with corn starch (bean/starch = 7:3, db), the blends were used for cookie baking following a standard method ( 1 Approved Method 10‐54.01). Generally, the cookies baked from the fine bean powders had smaller diameters, greater thicknesses, and greater hardness values than those from the coarse counterparts. Differences in the cookie‐baking performances of the bean powders were observed among the 25 varieties. Larger proportions of resistant starch (RS) were retained in the bean‐based cookies (54.7–126.7%) than in the wheat‐flour‐based cookies (10.4–19.7%) after baking. With higher contents of RS and protein, the bean‐based cookies had more desirable nutritional profiles than those baked from wheat flour alone.     

Estimation of clay content from easily measurable water content of air‐dried soil

Soil texture is one of the main factors controlling soil organic carbon (SOC) storage. Accurate soil‐texture analysis is costly and time‐consuming. Therefore, the clay content is frequently not determined within the scope of regional and plot‐scale studies with high sample numbers. Yet it is well known that the clay content strongly affects soil water content. The objective of our study was to evaluate if the clay content can be estimated by a simple and fast measure like the water content of air‐dried soil. The soil samples used for this study originated from four different European regions (Hainich‐Dün, Germany; Schwäbische Alb, Germany; Hesse, France; Bugac, Hungary) and were collected from topsoils and subsoils in forests, grasslands, and croplands. Clay content, water content of air‐dried soil, and SOC content were measured. Clay content was determined either by the Pipette method or by the Sedigraph method. The water content of air‐dried soil samples ranged from 2.8 g kg^–1 to 63.3 g kg^–1 and the corresponding clay contents from 60.0 g kg^–1 to 815.7 g kg^–1. A significant linear relationship was found between clay content and water content. The scaled mean absolute error (SMAE) of the clay estimation from the water content of air‐dried soil was 20% for the dataset using the Pipette method and 28% for the Sedigraph method. The estimation of the clay content was more accurate in fine‐textured than in coarse‐textured soils. In this study, organic‐C content played a subordinate role next to the clay content in explaining the variance of the water content. The water retention of coarse‐textured soils was more sensitive to the amount of organic C than that of fine‐textured soils. The results indicate that in our study the water content of air‐dried soil samples was a good quantitative proxy of clay contents, especially useful for fine‐textured soils.     

Phenolic acids, lipids, and proteins associated with purified corn fiber arabinoxylans

Corn fiber gum (CFG) is a hemicellulose (arabinoxylan)-enriched fraction obtained by the extraction of corn bran/fiber using a proprietary alkaline hydrogen peroxide process. When purified CFG prepared by this process was hydrolyzed with more concentrated base (1.5 N methanolic KOH at 70 degrees C for 1 hour), considerable amounts of hydroxycinnamic acids (up to 0.015% of mainly ferulic acid) and lipids (up to 0.43%) were released. The released phenolic acids and lipids were identified and quantified using high-performance liquid chromatography (HPLC) with detection by both UV and evaporative light-scattering detection (ELSD). During the wet milling of corn, two types of corn fiber are produced: coarse fiber, which is primarily from pericarp, and fine fiber, which is from the endosperm. The total phenolic acid content in CFGs purified from coarse corn fiber (pericarp fiber) is comparatively higher than that purified from fine corn fiber (endosperm fiber). It was also determined that the purified CFG samples contained significant amounts of strongly associated proteins, from 2 to 5% by weight. The presence of these phenolic acids, lipids, and proteins strongly associated or bound to CFG may contribute to its excellent ability to emulsify oil-in-water emulsions.     

Estimation of soil water retention function based on asymmetry between particle‐ and pore‐size distributions

By examining the symmetry between the distributions of particle‐size (PSD) and pore‐size (POD) in a soil, as hypothesized by early pore‐solid fractal (PSF) models, we found significant discrepancies in fractal dimensions between the PSD and the water retention curve (WRC) of a soil. Therefore, we developed an asymmetry‐based PSF model to estimate better the WRC directly from the PSD data of a soil. To do so, we adopted the concept of a microscopic arrangement of different‐sized particles to address such asymmetry, and evaluated the performance of the modified PSF model on five soil textural classes (coarse‐, moderately coarse‐, medium‐, moderately fine‐ and fine‐textured soils) using experimental PSD and WRC data from the UNSODA database (159 undisturbed soils for model calibration and 70 undisturbed soils for model validation). The fit of the symmetry‐based PSF model to the calibration dataset showed that the fractal dimension of the WRC (D_p) was slightly larger than that of cumulative mass distribution of particles (D_s) for most soils. The asymmetry‐based PSF model performed better than the symmetry‐based PSF model. In addition, the asymmetry‐based PSF model reduced the tendency to under estimate soil water content for a given matric head and the performance of the asymmetry‐based model was consistent irrespective of soil texture, indicating that the adoption of asymmetry between the PSD and the POD was adequate in predicting the WRC of a porous, particulate system such as soil.     

The coarse‐soil fraction is the main living space of fungal hyphae in the BhBs horizon of a Podzol

In acidified forest soils, the coarse‐soil fraction is a potential nutrient source. Plant nutrient uptake from the coarse‐soil fraction is aided by ectomycorrhiza. Similarly, (recalcitrant) organic matter (OM) is an important nutrient source largely made plant‐available through (symbiotic) microorganisms, especially in the topsoil. We hypothesized that in a podzol profile, fungal hyphae would concentrate in nutrient hotspots, either OM or the coarse‐soil fraction. Absolute hyphal length, base saturation, and organic‐C content of a Podzol profile were determined in the fine‐earth and coarse‐soil fractions. In the fine‐earth fraction, hyphae were attracted by the organic‐C content and relative high base saturation. In the coarse‐soil fraction of the BhBs horizon, the absolute hyphal length exceeded the hyphal length in the fine earth by factor 3, yet C content and base saturation were lowest. We could not determine to what fungi the hyphae belonged. Most likely ectomycorrhiza, ericoid mycorrhiza and saprotrophic fungi dominate the upper soil layers of this profile and all utilize OM for nutrition. In the deeper mineral horizons and especially in the coarse‐soil fraction, ectomycorrhiza are better adapted than other fungi to harvest nutrients from inorganic sources. Additionally, favorable physical properties may explain the high amount of fungal hyphae in the coarse‐soil fraction of the BhBs horizon. Both the coarse‐soil fraction and deeper mineral soil horizons may play a more active role in microbial nutrient cycling than previously assumed.     

In Vitro Binding of Bile Acids by Rice Bran,Oat Bran,Barley and β‐Glucan Enriched Barley

The in vitro bile acid binding by rice bran, oat bran, dehulled barley, and β‐glucan enriched barley was determined using a mixture of bile acids at a duodenal physiological pH of 6.3. Six treatments and two blank incubations were conducted testing substrates on an equal protein basis. The relative in vitro bile acid binding of the cereal brans on an equal total dietary fiber (TDF) and insoluble dietary fiber (IDF) basis considering cholestyramine as 100% bound was rice bran 45 and 49%; oat bran 23 and 30%; dehulled barley 33 and 57%; and β‐glucan enriched barley 20 and 40%, respectively. Bile acid bindings on equal protein basis for the respective cereals were 68, 26, 41, and 49%. Bile acid binding by rice bran may account to a great extent for its cholesterol‐lowering properties, while bile acid binding by oat bran suggests that the primary mechanism of cholesterol lowering by oat bran is not due to the bile acid binding by its soluble fiber. Bile acid binding was not proportional to the soluble fiber content of the cereal brans tested. Except for dehulled barley, bile acid binding for rice bran, oat bran, and β‐glucan enriched barley appear to be related to their IDF content. Highest relative bile acid binding values for rice bran and β‐glucan enriched barley were observed on an equal protein basis, whereas highest values for dehulled barley were based on IDF. Data suggest that of all four cereals tested, bile acid binding may be related to IDF or protein anionic, cationic, physical and chemical structure, composition, metabolites, or their interaction with active binding sites.     

Effects of weathering state of coarse‐soil fragments on tree‐seedling nutrient uptake

Fine earth accumulated within the weathering fissures of the coarse‐soil fraction (particles > 2 mm), so called “stone‐protected fine earth”, can provide a high short‐term nutrient release by cation exchange. It is thus hypothesized that unweathered gneiss particles cannot provide plants with exchangeable‐cation nutrients and that biological weathering is needed to include silicate‐bound nutrients into biochemical cycles. In a microcosm experiment, ectomycorrhizal Norway spruce (Picea abies) seedlings were grown on either weathered or unweathered paragneiss coarse‐soil fragments under natural hydraulic and climatic boundary conditions. A nutrient solution containing N, P, and K was added, however Mg and Ca could only be taken up from the coarse‐soil substrate. Solutes in drainage were analyzed during the experiment; plant nutrient uptake was determined after the experiment ended. Solute dynamics depended on the weathering state of the substrates: unweathered gneiss showed high initial Mg and Ca fluxes that diminished strongly afterwards, whereas weathered gneiss showed a much more gradual and sustainable release of these cations. Patterns in dissolved organic C and sulfate drainage indicated that the internal pores of weathered gneiss fragments contained organic material most likely as a result of living spaces from microorganisms. Plant biomass did not differ between treatments, however Mg content was higher in seedlings grown on weathered gneiss. Nutrient budgets demonstrated that the “stonesphere” of weathered gneiss can act as a quasi‐constant nutrient source whereas unweathered gneiss only provided high initial nutrients fluxes. In nutrient‐depleted, acidified fine‐earth environments, the coarse‐soil fraction may therefore act as a retreat for nutrient‐adsorbing tissues and as a buffer for nutrient shortages.     

Effect of Corn Milling Practices on Aleurone Layer Cells and Their Unique Phytosterols

Coarse and fine fiber fractions obtained from the corn wet‐milling processes, with and without steeping chemicals (SO₂ and lactic acid), were evaluated microscopically for structure and analytically for recovery of phytosterol compounds from the fiber oil. Microscopic results showed that wet milling, with and without chemicals during steeping, changed the line of fracture between pericarp and endosperm and therefore affected the recovery of the aleurone layer in coarse (pericarp) and fine (endosperm cellular structure) fiber. Analytical results showed that most of the phytosterols and mainly phytostanols in corn fiber are contributed by the aleurone layer. Hand‐dissection studies were performed to separate the two layers that comprise the wet‐milled coarse fiber, the aleurone, and pericarp layer. Analyses revealed that the aleurone contained 8× more phytosterols than the pericarp.     

Milling Performance of North European Hull‐less Barleys and Characterization of Resultant Millstreams

Four hull‐less barley samples were milled on a Bühler MLU 202 laboratory mill and individual and combined milling fractions were characterized. The best milling performance was obtained when the samples were conditioned to 14.3% moisture. Yields were 37–48% for straight‐run flour, 47–56% for shorts, and 5–8% for bran. The β‐glucan contents of the straight‐run white flours were 1.6–2.1%, of which ≈49% was water‐extractable. The arabinoxylan contents were 1.2–1.5%, of which ≈17% was water‐extractable. Shorts and bran fractions contained more β‐glucan (4.2–5.8% and 3.0–4.7%, respectively) and arabinoxylan (6.1–7.7% and 8.1–11.8%, respectively) than the white flours. For those fractions, β‐glucan extractability was high (58.5 and 52.3%, respectively), whereas arabinoxylan extractability was very low (≈6.5 and 2.0%, respectively). The straight‐run white flours had low α‐amylase, β‐glucanase, and endoxylanase activities. The highest α‐amylase activity was found in the shorts fractions and the highest β‐glucanase and endoxylanase activities were generally found in the bran fractions. Endoxylanase inhibitor activities were low in the white flours and highest in the shorts fractions. High flavanoid, tocopherol, and tocotrienol contents were found in bran and shorts fractions.