Whole Grain Wheat Flour Research Articles

Whole-Grain and Refined Wheat Flours Show Distinct Metabolic Profiles in Rats as Assessed by a 1H NMR-Based Metabonomic Approach1

The protection against diabetes and cardiovascular disease provided by whole-grain cereal consumption has been attributed to the fiber and micronutrients present in the bran. But exactly how this occurs remains unclear due to both diversity of bran constituents and the complexity of the metabolic responses to each of these constituents. We investigated the metabolic responses of 2 groups of rats (n = 10/group) fed 2 diets, for 2 wk each, in a crossover design. One diet contained 60 g/100 g whole-grain wheat flour (WGF) and the other contained 60 g/100 g refined wheat flour (RF). Markers of oxidative stress [urinary isoprostanes and malondialdehydes (MDA), plasma ferric-reducing ability of plasma, MDA, and vitamins E and C] and lipid status (liver and plasma triglycerides and cholesterol) were measured. Urine samples collected during the feeding periods and plasma and liver samples collected at the end of experiment were analyzed by 1H NMR spectroscopy. Metabonomic analyses showed that each group reached a new metabolic balance within 48 h of changing the diet. Urinary excretion of some tricarboxylic acid cycle intermediates, aromatic amino acids, and hippurate was significantly greater in rats fed the WGF diet. Although the diets did not affect conventional lipid and oxidative stress markers, there were decreases in some liver lipids and increases in liver reduced glutathione and betaine as shown by metabonomic analyses. These suggest that the WGF diet improved the redox and lipid status.

Determination of folate in some cereals and commercial cereal-grain products consumed in Poland using trienzyme extraction and high-performance liquid chromatography methods

A trienzyme treatment (rat plasma conjugase, α-amylase, protease) followed by affinity chromatography (with folate-binding protein from bovine milk) and reversed-phase high-performance liquid chromatography with UV and fluorescence detections was performed for quantification of different folate derivatives in some commercial cereal-grain products and cereals cultivated in Poland. The method described allowed good separation of the main folate vitamins. Of the commercial cereal-grain products analyzed, buckwheat groats (30 μg/100 g) had the highest content of total folate, followed by rye flour (29 μg/100 g), barley groats (21 μg/100 g) and wheat flours (19–20 μg/100 g). Two of the ready-to eat breakfast products were found to be fortified with folic acid with the level slightly exceeding the label declaration. The total folate content of whole-grain wheat flours was more than half as much as in white flours (33–40 μg/100 g), and the highest folate content was found in rye whole grains (123–135 μg/100 g). 5-Formyltetrahydrofolate was the predominating folate form in the cereal products analyzed, above all in rye flour.

In Vitro Iron Availability from Iron-Fortified Whole-Grain Wheat Flour

Iron deficiency is the most common nutritional disorder worldwide. Iron fortification of foods is considered to be the most cost-effective long-term approach to reduce iron deficiency. However, for fortified foods to be effective in reducing iron deficiency, the added iron must be sufficiently bioavailable. In this study, fortification of whole-grain wheat flour with different sources of iron was evaluated in vitro by measuring the amount of dialyzable iron after simulated gastrointestinal digestion of flour baked into chapatis and subsequent intestinal absorption of the released iron using Caco-2 cell layers. The dialyzability of iron from iron-fortified wheat flour was extremely low. Additions of 50 mg/kg iron to the flour in the form of ferrous sulfate, Ferrochel amino acid chelate, ferric amino acid chelate taste free (TF), Lipofer, ferrous lactate, ferrous fumarate, ferric pyrophosphate, carbonyl iron, or electrolytic iron did not significantly increase the amount of in vitro dialyzable iron after simulated gastrointestinal digestion. In contrast, fortification of flour with SunActive Fe or NaFeEDTA resulted in a significant increase in the amount of in vitro dialyzable iron. Relative to iron from ferrous sulfate, iron from SunActive Fe and NaFeEDTA appeared to be 2 and 7 times more available in the in vitro assay, respectively. Caco-2 cell iron absorption from digested chapatis fortified with NaFeEDTA, but not from those fortified with SunActive Fe, was significantly higher than from digested chapatis fortified with ferrous sulfate. On the basis of these results it appears that fortification with NaFeEDTA may result in whole-grain wheat flour that effectively improves the iron status.

Whole-grain rye and wheat foods and markers of bowel health in overweight middle-aged men

Whole-grain cereal foods including rye have been identified as providing significant health benefits that do not occur when refined-cereal foods are ingested. Foods (90 g) containing whole-grain rye flour and whole-grain wheat flour were compared with low-fiber refined-cereal foods for their effects on markers of bowel health and the metabolic markers insulin and glucose. Three 4-wk interventions were undertaken in a randomized crossover design with 28 overweight men aged 40-65 y who had no history of bowel disease. Against a background intake of 14 g dietary fiber (DF), the men were fed low-fiber cereal grain foods providing 5 g DF for a total of 19 g DF/d. High-fiber wheat foods provided 18 g DF, and high-fiber rye foods provided 18 g DF, both giving a total of 32 g DF/d. Fecal samples (48-h) and fasting and postprandial blood samples were collected at the end of each period and assayed. Both high-fiber rye and wheat foods increased fecal output by 33-36% (P = 0.004) and reduced fecal beta-glucuronidase activity by 29% (P = 0.027). Postprandial plasma insulin was decreased by 46-49% (P = 0.0001) and postprandial plasma glucose by 16-19% (P = 0.0005). Rye foods were associated with significantly (P = 0.0001) increased plasma enterolactone (47% and 71%) and fecal butyrate (26% and 36%), relative to wheat and low-fiber options, respectively. High-fiber rye and wheat food consumption improved several markers of bowel and metabolic health relative to that of low-fiber food. Fiber from rye appears more effective than that from wheat in overall improvement of biomarkers of bowel health.

The Effect of Particle Size of Whole-Grain Flour on Plasma Glucose, Insulin, Glucagon and Thyroid-Stimulating Hormone in Humans

Objective: Although it is well known that consumption of whole-grain foods with higher fiber content results in beneficial health effects, most Americans usually prefer bread made with white flour. Changes in bread texture and undesirable intestinal responses have been reported as reasons for avoiding consumption of whole-grain foods or high-fiber menus. The purpose of this study was to determine whether consumption of bread made with ultra-fine-ground whole-grain wheat flour retained beneficial effects while reducing undesirable effects.Methods: Twenty-six men and women, 31 to 55 years of age, consumed glucose solutions or bread made with traditional white, conventional whole-grain wheat (WWF), or ultra-fine whole-grain wheat (UFWF) flour (1 g carbohydrate/kg body weight) in a Latin square design after two days of controlled diet. The effect on glycemic response was determined by comparing blood variables, after a tolerance test with white bread, WWF bread, and UFWF bread, with those after a glucose tolerance test.Results: Men and women had similar responses to all tolerances except postprandial TSH. Glucose and insulin levels one half hour after the glucose load were significantly higher than after any of the bread tolerances. Glucose, but not insulin, areas under the curve were significantly higher after the glucose load than areas after the three breads. Consumption of UFWF resulted in glucose and insulin responses, as well as areas under the curve, similar to those after consumption of conventional whole-wheat bread.Conclusion: The particle size of whole grain wheat flour did not substantially affect glycemic responses.

The effects of various thermal processes on protein quality, vitamins and selenium content in whole-grain wheat and white flour

Whole-grain wheat and white flour from wheat were subjected to various thermal processes - steam flaking, autoclaving, popping, extrusion cooking, and drum-drying - under both mild and severe conditions. The effects of processing on protein quality were evaluated (by comparing biological and chemical methods), and on retention of vitamins (vitamin E, thiamin and folacin) and selenium. Protein quality was affected most by popping and autoclaving. Changes in biological value correlated significantly (P < 0·001) with available lysine measured according to both the fluorodinitrobenzene (FDNB) and the dye-binding procedure. Popping and autoclaving under mild and severe conditions also resulted in the greatest losses of thiamin and folacin. Vitamin E activity, however, was affected most in white flour after extrusion cooking and drum-drying, which destroyed the major part of the vitamin E activity. Selenium retention was practically unaffected by the various thermal processes, except by drum-drying, which caused a 24% loss. No thermal process equally preserved protein quality and process-sensitive vitamins. However, the low-temperature processes, like steam flaking and drum-drying or the high temperature-short time process extrusion cooking, generally, with the exception of Vitamin E, retained the nutrient quality better than popping and autoclaving.

Protein nutritional value of extrusion-cooked wheat flours

The effect of extrusion cooking on the protein nutritional value of wheat flour and whole-grain wheat flour was studied. Amino acid analysis showed lysine retention between 63 and 100%. The retention was positively affected by an increase in feed rate, and negatively by an increase in screw speed. The prominent lysine damage under severe conditions was probably due to formation of reducing carbohydrates through hydrolysis of starch. The loss of other amino acids was small. The BV of extruded wheat flours was significantly reduced in the products showing the most prominent lysine loss. However, no effect was seen in TD. In contrast, a decrease in BV of extruded whole-grain flour was accompanied by a significant reduction in TD. Extrusion cooking of wheat starch did not affect the nitrogen balance in rats given casein/starch diets containing raw or extruded starch.

Effects of processing on availability of starch for digestion in vitro and in vivo; I Extrusion cooking of wheat flours and starch

The effect of extrusion cooking on availability of starch for digestion in wheat products was tested in vitro and in vivo . Hydrolysis in vitro was measured using salivary amylase and the in vivo availability was evaluated by measuring the plasma levels of glucose and insulin after a gastric load in conscious rats. Ther fermentability of starch in human dental plaque in situ was also studied. Extrusion cooking of white flour and whole-grain wheat flour rendered the starch more susceptible to salivary α-amylase than did boiling for 20 min in water. Consequently, the pH drop in dental plaque was more pronounced with extruded materials. The rate of starch absorption in vivo , as judged from the plasma glucose pattern, was similar for boiled samples and for samples extruded under mild conditions. However, under more severe extrusion conditions, there was a significant increase in plasma glucose response. In the case of white flour, this enhanced glucose response was accompanied by an increased insulin response. Thus, processing conditions can influence both the glycaemic response to starch and its cariogenic properties.