Oat Bran Fermentation by Rye Sourdough
ABSTRACT Hydration of oat bran including fermentation by rye sourdough was studied. Three types of oat bran suspensions were prepared (a control, one with whole meal rye flour added, and one with rye starter added). The suspensions were incubated for 1, 2, 3 and 4 hr. beta-Glucan content and solubilities of protein and beta-glucan were analyzed. Viscosity of the supernatants of oat bran suspensions was determined. Neither the rye sourdough nor the rye flour alone had a significant. effect on the total beta-glucan content of oat bran suspensions. However, the addition of rye, either as whole meal rye flour or as sourdough starter, markedly increased the solubility of beta-glucan and proteins and simultaneously decreased the viscosity of the water-soluble fraction of oat bran suspension. This suggests that a hydrolysis of beta-glucan had occurred that could change the rheological properties of oat bran in baking and the physiological potential of oat bran in nutrition.
- SourceAvailable from: Peter R Ellis[Show abstract] [Hide abstract]
ABSTRACT: The water-soluble, mixed-linkage β-glucan, a form of soluble dietary fibre, is considered the main biologically active component responsible for the capacity of many oat products to lower postprandial glycaemia and fasting plasma cholesterol in human subjects. The present review discusses the physical and chemical properties of oat β-glucan that are considered important predictors of these beneficial metabolic effects. In vitro modelling and animal and human studies have provided compelling evidence showing that the ability of oat β-glucan to increase the viscosity of digesta in the gastrointestinal tract (GIT) is a primary determinant of its blood-glucose and cholesterol-lowering properties. Therefore, the chemical structure, molecular weight (MW), the rate and extent of dissolution and solution rheology of oat β-glucan are key factors in determining the physiological function of oat-containing foods. The structure and properties of oat β-glucan vary between species and varieties of oats, and are also affected by the growing and storage conditions and processing of oat grain. In addition, the extraction and analysis methods may also contribute to the variations in the structure, MW, hydration and solution rheology of β-glucan obtained from different laboratories. Recent work has demonstrated that β-glucan solubility in foods depends on the source of the material and processing conditions; solubility may also be subject to changes during food preparation and storage (such as freezing). In conclusion, both the amount and MW of β-glucan that are solubilised in the GIT need to be considered when assessing the blood-glucose and cholesterol-lowering properties of oat-containing foods.British Journal Of Nutrition 10/2014; 112 Suppl 2:S4-S13. DOI:10.1017/S0007114514002256 · 3.34 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Cereal Chem. 82(2):144–151 Flours obtained by a specific polishing process were used to prepare sourdough and bread. Three fractions designated C-1 (100–90%), C-5 (60–50%), and C-8 (30–0%) were studied. The pH, total titratable acidity levels, and buffering capacity of sourdoughs made from polished flours were significantly different from those of the control sourdough with No. 1 Canada Western Red Spring (CW), and they provided sourdough breads with better qualities than that of CW. The growth of lactic acid bacteria and yeast in polished flour sourdoughs were significantly accelerated during fermentation over that in CW sourdough. Higher maturation of polished flour sourdoughs softened the hardness of mixed dough. The intricate network of honeycomb structure gluten and uneven surface of starch granules were distinctly observed in SEM images. Substitutions of C-5 or C-8 sourdoughs for CW significantly increased the loaf volume and softened breadcrumbs more than CW sourdough. Flour qualities of polished flours such as suitable acidity and good buffering capacity caused by the bran fraction were effective for better growth and longer life of yeast in the dough during fermentation. Therefore, application of polished flours in sourdough bread would improve rheological properties of dough and bread as compared with CW sourdough.Cereal Chemistry 03/2005; 82(2). DOI:10.1094/CC-82-0144 · 1.06 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The beneficial role of soluble dietary fiber in human nutrition is well documented and has lead to a growing demand for the incorporation of beta-glucan, particularly from oats and barley, into foods. beta-Glucan with high solubility and high molecular weight distribution results in increased viscosity in the human intestine, which is desirable for increased physiological activity. Molecular weight, level, and solubility of beta-glucan are affected by genotype, environment, agronomic input, and the interactions of these factors and food processing methods. Available literature reveals that the level of beta-glucan in a finished product (e. g. bread, cake, muffins) depends upon several factors in the production chain, whereas food processing operations are major factors affecting molecular weight and solubility of beta-glucans. Therefore, to avail themselves of the natural bioactive compounds, food manufacturers must pay attention not only to ensure sufficient concentration of beta-glucan in the raw material but also to the processing methods and functional properties of beta-glucan, minimizing enzymatic or mechanical breakdown of the beta-glucans in end-product and optimizing processing conditions. This review discusses the different sources of beta-glucan for use in human functional foods and factors affecting the levels and the molecular weight of beta-glucan at various pre- and postharvest operations.Cereal Chemistry 05/2009; 86(3):290-301. DOI:10.1094/CCHEM-86-3-0290 · 1.06 Impact Factor