The molecular weight,solubility and viscosity of oat beta-glucan affect human glycemic response by modifying starch digestibility

The interaction between oat β-glucan and other food components has the potential to influence starch digestibility and consequently affect its bioactivity in reducing glycemic responses. Blood glucose concentrations were measured before and after ingesting wheat and oat granolas, with 0.6 and 6.2 g of β-glucan, respectively, and two starch doses (40 and 60 g). As the in vitro extract viscosity of β-glucan increased, the in vitro starch digestibility was reduced and the glucose responses were lowered. The peak blood glucose response (PBGR) and the incremental area under the curve (iAUC) were lower in the 40 g than in the 60 g starch formulation. β-Glucan was significantly more active in reducing PBGR and iAUC when the β-glucan/starch ratio was 1.6:10 rather than 1.1:10. This information is valuable for new product development and for quality assessment of bioactive foods containing oat β-glucan.     

葡萄酒泥酵母β-葡聚糖提取工艺条件优化

以诱导自溶的葡萄酒泥酵母细胞壁为试材,在料液比、碱液浓度、浸提时间和浸提温度等单因素实验基础上,采用正交实验优化β-葡聚糖提取最优工艺条件。结果表明,葡萄酒泥酵母β-葡聚糖提取优化的最佳工艺条件为:料液比1∶40（g/m L）,Na OH浓度3%,浸提温度80℃,浸提时间1.5 h,在此条件下β-葡聚糖提取率为19.38%。此方法提取率较高且简单易行、成本较低。      

地衣酚——盐酸法测定燕麦β葡聚糖中的戊聚糖含量

目前国内外对从植物提取葡聚糖和戊聚糖的方法较为相似。文章以地衣酚——盐酸法为基础,根据己糖与戊糖混合体系的反应液在吸收光谱670 nm与580 nm处存在最大差谱,进行燕麦β-葡聚糖中戊聚糖的测定。通过精确度和回收率试验验证了该方法进行可行性。     

A ROLE FOR CARBOXYPEPTIDASE IN THE SOLUBILIZATION OF BARLEY β-GLUCAN

An enzyme is described which catalyzes the release of soluble β-glucan from insoluble barley endosperm cell walls. This enzyme increases in activity throughout malting. It has been partially purified and found to behave in the same way as an acidic carboxypeptidase on isoelectric focusing and in its sensitivity to inhibitors and activators and to heating. The importance of the β-glucan solubilizing enzyme in malting and mashing is discussed. An improved method for β-glucan determination is described.     

A comparative study of analytical methods for alkali-soluble β-glucan in medicinal mushroom, Chaga (Inonotus obliquus)

Crude β-glucan content in the medicinal mushroom Chaga (Inonotus obliquus) was measured by different extraction and analytical methods, and the results were compared. The alkali extraction (AE) method or enzymatic digestion (ED) method followed by a gravimetric analysis was employed to determine the crude β-glucan content. The amount of crude β-glucan in Chaga obtained by either AE or ED was 13.7 g/100 g or 15.3 g/100 g of the sample, respectively. Crude β-glucan content of Chaga obtained by the above preparation methods were corrected by chemical composition analysis and HPLC analysis. After composition analysis, the amounts of β-glucan measured in the 100 g Chaga samples were corrected to 10.1 g for ED and 10.7 g for AE method. β-glucan contents calculated by the amount of glucose in the HPLC analysis were 8.3 g/100 g and 8.1 g/100 g for ED and AE preparation methods, respectively. Although extraction method did not affect β-glucan content in Chaga as indicated by no significant difference (P>0.05) between extraction method, significant differences (P<0.05) were noted between the correction methods. The discrepancies of the result indicate a need for standardization of analytical method for β-glucan measurement in Chaga     

Production and characterization of insoluble α-1,3-linked glucan and soluble α-1,6-linked dextran from Leuconostoc pseudomesenteroides G29

Exopolysaccharides can be produced by various bacteria and have important biological roles in bacterial survival depend on molecular weight, linkage, and conformation. In this study, Leuconostoc pseudomesenteroides G29 was identified and found to produce two types of exopolysaccharides from sucrose including soluble and insoluble α-glucans. By regulation of pH above 5.5, soluble α-glucan production was increased to 38.4 g·L^-1 from 101.4 g·L^-1 sucrose with fewer accumulation of lactic acid and acetic acid. Simultaneously, the quantity of thick white precipitate, that is insoluble α-glucan, was also increased. Then, α-glucans were prepared by enzymatic reaction with crude glucansucrases from the supernatant of G29 fermentation broth and purified for structure analysis. Based on the integration analysis of FT-IR and NMR, it was observed that soluble α-glucan is a highly linear dextran with α-1,6 glycosidic bonds while the insoluble α-glucan has 93% of α-1,3 and 7% of α-1,6 glycosidic bond. The results extend our understanding of exopolysaccharides production by L. pseudomesenteroides, and this water insoluble α-1,3-glucan might have potential application as biomaterials and/or biochemicals.     

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. © 1997 SCI.     

A new method for quantitative determination of polysaccharides in the yeast cell wall. Application to the cell wall defective mutants of Saccharomyces cerevisiae

A reliable acid hydrolysis method for quantitative determination of the proportion of β-glucan, mannan and chitin in Saccharomyces cerevisiae cell wall is reported together with a simple extraction procedure to quantify within a standard error of less than 2% the proportion of the wall per gram of cell dry mass. This method is an optimized version of Saeman's procedure based on sulfuric acid hydrolysis of complex polysaccharides. It resulted in an almost complete release of glucose, mannose and glucosamine residues from cell wall polysaccharides. After complete removal of sulfate ions by precipitation with barium hydroxide, the liberated monosaccharides were separated and quantified by high performance anion-exchange chromatography with pulsed amperometric detection. The superiority of this method over the hydrolysis in either trifluoroacetic or hydrochloric acid resides in its higher efficiency regarding the release of glucose from β1,6-glucan and of glucosamine from chitin. The sulfuric acid method was successfully applied to determine the β-glucan, mannan and chitin contents in cell walls of genetically well-characterized yeast mutants defective in cell wall biosynthesis, and in Schizosaccharomyces pombe cell walls. The simplicity and reliability of this procedure make it the method of choice for the characterization of cell walls from S. cerevisiae mutants generated in the EUROFAN programme, as well as for other pharmacological and biotechnological applications. © 1998 John Wiley & Sons, Ltd.     

Physical and Sensory Characteristics of Reduced-Fat Breakfast Sausages Formulated With Barley β-Glucan

ABSTRACT: Barley β-glucan, a soluble fiber component, with health benefits, has the potential to be used as a fat replacer in meat systems. Reduced-fat (12%, w/w) sausages formulated with β-glucan at 0.3% (w/w) (0.3 β-gl) and 0.8% (w/w) (0.8 β-gl) levels were developed and compared to high-and reduced-fat controls both sensorially and instrumentally. Compression tests showed 0.3 β-gl to be similar ( p > 0.05) to controls. A trained panel found 0.8 β-gl to be less firm ( p ≤ 0.05) than all others, while consumer panelists evaluated 0.3 β-gl sausages to be acceptable. Raw and cooked sausages contained the same amount of β-glucan. Findings suggest that reduced-fat sausages formulated with β-glucan gum could be a valuable addition to a meat product line.