R. Gary Fulcher

Concentrated oat β-glucan, a fermentable fiber, lowers serum cholesterol in hypercholesterolemic adults in a randomized controlled trial

BackgroundSoluble fibers lower serum lipids, but are difficult to incorporate into products acceptable to consumers. We investigated the physiological effects of a concentrated oat β-glucan on cardiovascular disease (CVD) endpoints in human subjects. We also compared the fermentability of concentrated oat β-glucan with inulin and guar gum in a model intestinal fermentation system.MethodsSeventy-five hypercholesterolemic men and women were randomly assigned to one of two treatments: 6 grams/day concentrated oat β-glucan or 6 grams/day dextrose (control). Fasting blood samples were collected at baseline, week 3, and week 6 and analyzed for total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, glucose, insulin, homocysteine and C-reactive protein (CRP). To estimate colonic fermentability, 0.5 g concentrated oat β-glucan was incubated in a batch model intestinal fermentation system, using human fecal inoculum to provide representative microflora. Fecal donors were not involved with the β-glucan feeding trial. Inulin and guar gum were also incubated in separate serum bottles for comparison.ResultsOat β-glucan produced significant reduction from baseline in total cholesterol (-0.3 ± 0.1 mmol/L) and LDL cholesterol (-0.3 ± 0.1 mmol/L), and the reduction in LDL cholesterol were significantly greater than in the control group (p = 0.03). Concentrated oat β-glucan was a fermentable fiber and produced total SCFA and acetate concentrations similar to inulin and guar gum. Concentrated oat β-glucan produced the highest concentrations of butyrate at 4, 8, and 12 hours.ConclusionSix grams concentrated oat β-glucan per day for six weeks significantly reduced total and LDL cholesterol in subjects with elevated cholesterol, and the LDL cholesterol reduction was greater than the change in the control group. Based on a model intestinal fermentation, this oat β-glucan was fermentable, producing higher amounts of butyrate than other fibers. Thus, a practical dose of β-glucan can significantly lower serum lipids in a high-risk population and may improve colon health.

Physico‐Chemical Properties and the Degradation of Oat Bran Polysaccharides in the Gut of Pigs

Physico-chemical properties and the digestibility of carbohydrates (starch, β-glucan and arabinoxylan (AX)) were studied in the gastrointestinal contents of pigs fed diets based on oat bran. One diet was made of commercially prepared oat bran and another of oat bran milled to pass a 1 mm screen. The pigs were slaughtered and samples were collected quantitatively from 10 sites of the gastrointestinal tract either 1 or 3 h after the morning feeding. The viscosity of the liquid phase (obtained by centrifugation) of the stomach and small intestinal contents varied greatly between animals, and was not significantly different between segments of the upper gastrointestinal tract. The molecular weight of β-glucan was reduced up to 20-fold in the upper gastrointestinal tract but was of a relatively low digestibility until the terminal ileum. The solubility (the fraction of the total content in the liquid phase of digesta after centrifugation) of β-glucan varied from 0·25 to 0·58 in the stomach and small intestine, whereas the solubility of AX was in the range of 0·04–0·16. Microscopic examination of digesta showed that β-glucan was retained in intact endospermic cell wall structures, which remained evident until the distal small intestine but was completely disrupted in the caecum. In spite of a cumulative digestibility of non-starch polysaccharides and AX of ∽0·90 in the large intestine, identifiable fragments of aleurone cell walls resistant to complete microbial degradation remained.

Study of Water in Dough Using Nuclear Magnetic Resonance

ABSTRACT The amount and state of water play an important role in the preparation and properties of wheat flour doughs and their products. A new method for presentation and analysis of relaxation time measurements of protons in dough is described in this article. This new method acknowledges a continuous probability distribution of protons having different relaxation times in heterogeneous systems such as dough, which is dramatically different from the conventional discrete methods that rely on prior assumptions of a number of discrete relaxation components. In the present study, pulsed proton nuclear magnetic resonance was used to study the relaxation characteristics of dough systems at moisture levels of 12–45%. The relaxation curves obtained using a 90-degree pulse (Onepulse) sequence and the Carr-Purcell-Meiboom-Gill pulse sequence were analyzed using a multiexponential discrete model and a continuum model. The discrete model produced three fractions of protons relaxing in three different time domains....

Physiological Effects of Concentrated Barley β-Glucan in Mildly Hypercholesterolemic Adults

Objective: Barley fiber rich in beta-glucans lowers serum lipids, but is difficult to incorporate into products acceptable to consumers. We investigated the physiological effects of two concentrated barley β-glucans on cardiovascular disease (CVD) endpoints and body weight in human subjects. Methods: Hypercholesterolemic men and women (n = 90) were randomly assigned to one of two treatments: low molecular weight (low-MW) or high molecular weight (high-MW) concentrated barley β-glucan consumed as a daily supplement containing 6 grams beta-glucan/day. Fasting blood samples were collected at baseline and week 6 and analyzed for total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, glucose, insulin, homocysteine and C-reactive protein (CRP). Dietary intakes, body weights, blood pressure, hunger ratings, and gastrointestinal symptoms were measured at baseline and 6 weeks. Results: The only difference between treatments in lipid outcomes at week 6 was a reduction of the cholesterol/HDL ratio in the low-MW group and a small increase in the high-MW group. No changes were found in blood pressure, glucose, insulin, and gastrointestinal symptoms. Body weight decreased from baseline to 6 weeks in the high-MW group while body weight increased in the low-MW group. Levels of hunger decreased slightly in the low-MW group and decreased significantly in the high-MW group (P = 0.02) Conclusion: Overall, supplementation with isolated barley β-glucans of different molecular weights had small effects on cardiovascular disease markers. Molecular weight of the barley fiber did alter effects on body weight with the high-MW fiber significantly decreasing body weight.

Light filtering by epidermal flavonoids during the resistant response of cotton to Xanthomonas protects leaf tissue from light-dependent phytoalexin toxicity.

2,7-Dihydroxycadalene and lacinilene C, sesquiterpenoid phytoalexins that accumulate at infection sites during the hypersensitive resistant response of cotton foliage to Xanthomonas campestris pv. malvacearum, have light-dependent toxicity toward host cells, as well as toward the bacterial pathogen. Adaxial epidermal cells surrounding and sometimes covering infection sites turn red. The red cells exhibited 3-4-fold higher absorption at the photoactivating wavelengths of sunlight than nearby colorless epidermal cells. Red epidermal cells protected underlying palisade mesophyll cells from the toxic effects of 2,7-dihydroxycadalene plus sunlight, indicating a role for epidermal pigments in protecting living cells that surround infection sites from toxic effects of the plants own phytoalexins. A semi-quantitative survey of UV-absorbing substances extracted from epidermal strips from inoculated and mock-inoculated cotyledons indicated that the principal increase in capacity to absorb the photoactivating wavelengths was due to a red anthocyanin and a yellow flavonol, which were identified as cyanidin-3-O-beta-glucoside and quercetin-3-O-beta-glucoside, respectively.

SME-arrhenius model for WSI of rice flour in a twin-screw extruder

ABSTRACT We have modeled a rice extrusion process focusing specifically on the starch gelatinization and water solubility index (WSI) as a function of extrusion system and process parameters. Using a twin-screw extruder, we examined in detail the effect of screw speed (350–580 rpm), barrel temperature, different screw configurations, and moisture content of rice flour on both extrusion system parameters (product temperature, specific mechanical energy [SME], and residence time distribution [RTD]) and extrudate characteristics (expansion, density, WSI, and water absorption index [WAI]). Changes in WSI were monitored to reveal a relationship between the reaction kinetics during extrusion and WSI. Reaction kinetics models were developed to predict WSI during extrusion. WSI followed a pseudo first-order reaction kinetics model. It became apparent that the rate constant is a function of both temperature and SME. We have developed an adaptation of the kinetic model based on the Arrhenius equation that shows bet...

Empirical Modeling of Die Pressure, Shaft Torque, SME, and Product Temperature of Rice Flour in a Corotating Twin-Screw Extruder

ABSTRACT Empirical models for predicting die pressure, product temperature, shaft torque, and specific mechanical energy (SME) input based on rice flour extrusion using a DNDL-44/28D Buhler twin-screw extruder are presented. The models incorporate the effects of shear rate, barrel temperature, moisture content, flow rate, and screw geometry. The models were tested using rice flour at various screw configurations and extrusion conditions. Die pressure is a function of moisture content, product temperature, and flow rate. By testing the die pressure model, we found that, within the experimental range tested, die pressure was not significantly affected by barrel temperatures and screw configurations. Product temperature and shaft torque are functions of shear rate, moisture content, flow rate, barrel temperature, and screw configuration. Introducing the effect of screw configuration into the models for temperature and shaft torque resulted in an overall improved model performance. Predictions of various mode...

Evaluation of Soybean Seedcoat Cracking During Drying:PART II. Using MRI

ABSTRACT MRI techniques were developed and employed for non-destructive and noninvasive study of seedcoat cracking in low moisture soybean kernels during heated air drying. Proton density image and transient moisture distribution profile of a single soybean kernel can be obtained using MRI. These MRI techniques proved to be particularly useful for the continuous observation of initiation and propagation of seedcoat cracking during the entire period of drying process without interruption. The proton density images of soybean kernels showed that seedcoat cracking was initiated perpendicular to the long axis of the kernel near the hilum. The transient moisture distribution profiles in soybean kernels during drying indicate that moisture gradient developed during drying was higher in the seedcoat than in the cotyledon. Drying temperature and initial average moisture content were positively correlated with the soyhean seedcoat crackig. The location of the

Evaluation of Soybean Seedcoat Cracking During Drying:PART I. Using Drying Tests

ABSTRACT In this study, seedcoat cracking during heated air drying was investigated in five varieties of Minnesota grown soybeans. Effects of initial moisture contents, drying temperatures and time on cracking levels were evaluated. Digital image analysis (DIA) was employed to measure initial sizes and shapes of soybeans in order to evaluate the influence of physical properties of mature seeds on cracking frequency. Seedcoat cracking rates increased significantly with increase in initial moisture content of the soybeans. drying temperature and time. Rapid water loss at higher initial moisture contents led to greater seedcoat cracking. Variety.growing location. and sizc of soybeans had significant influence on seedcoat cracking. Statistical analysis indicates that interactions between various factors had significant influence on seedcoat cracking.

Quantitative Microscopic Approaches to Carbohydrate Characterization and Distribution in Cereal Grains

Development and utilization of improved cereal varieties for domestic and international use depends upon the ability of both breeders and processors to: (a) identify potential sources of new or improved traits; (b) incorporate these traits into agronomically acceptable cultivars; and (c) exploit these characteristics in improving traditional products or developing new ones. To do so the breeder must identify and measure desirable traits in a large number of potential cultivars in a relatively rapid and simple manner, and the processor must have access to rapid and precise methods for defining grain “quality”, the combination of chemical and structural attributes which defines the utility of grains in processing conditions. In most major cereals, including wheat, rice, barley, oats, maize, and sorghum, our ability to identify and characterize these traits in phytochemical terms is quite variable depending on the history of the crop, but in all cases it is rudimentary and somewhat empirical. This is not surprising in view of the large number of molecular species which interact to contribute to the overall biochemistry of the grains. Consequently, the most important tool for identifying new cereal varieties is pilot or micro-scale processing, (e.g. pilot milling, malting, baking or extrusion) in which relatively large numbers of samples can be analyzed for their suitability for use in food systems. Although the majority of the storage reserves in cereal grains are polysaccharides (e.g. starch, pentosans, β-glucans) or carbohydrate-linked complexes (e.g. phenolic glycosides, lignin), with few exceptions (e.g., β-glucan determination1) individual chemical traits are either too costly or cumbersome to measure routinely in large numbers, or are ill-defined and inappropriate for daily use.