低β-葡聚糖青稞麦芽制备工艺的研究

β-葡聚糖具有良好的保健功效,用于青稞酿造啤酒时,其含量过高会严重影响啤酒的易滤性及成品啤酒的非生物稳定性.通过正交实验研究青稞发芽温度、发芽时间、赤霉素(GA3)添加量以及焙焦温度对青稞麦芽中β-葡聚糖含量的影响.确定最佳青稞制麦工艺为:发芽温度16℃、发芽时间96h,GA3添加量0.1 mg/L,焙焦温度84℃.     

3D Structural Insights into β-Glucans and Their Binding Proteins

β(1,3)-glucans are a component of fungal and plant cell walls. The β-glucan of pathogens is recognized as a non-self-component in the host defense system. Long β-glucan chains are capable of forming a triple helix structure, and the tertiary structure may profoundly affect the interaction with β-glucan-binding proteins. Although the atomic details of β-glucan binding and signaling of cognate receptors remain mostly unclear, X-ray crystallography and NMR analyses have revealed some aspects of β-glucan structure and interaction. Here, we will review three-dimensional (3D) structural characteristics of β-glucans and the modes of interaction with β-glucan-binding proteins.     

Combination of vegetable soup and glucan demonstrates synergistic effects on macrophage-mediated immune responses

Vegetable soup (VS), a plant-based functional food, has been used as a traditional folk medicine and is attracting attention for its ability to enhance the immune response. β-Glucan, a well-established and effective immunomodulator, has synergistic effects when used in combination with some bioactive compounds. In the present study, we aimed to evaluate the synergistic immunomodulatory effects of the combination of VS and β-glucan on macrophage-mediated immune responses. β-Glucan was demonstrated to synergistically enhance the VS-stimulated immune response, including the production of interleukin-6, tumor necrosis factor-α, and nitric oxide, mainly through the mitogen-activated protein kinase pathway in macrophages. In addition, this combination has the potential for further development in functional foods with immune-enhancing activity.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10068-021-00888-x.     

Impact of β-glucan on debittering,bioaccessibility and storage stability of skim milk fortified with shrimp oil nanoliposomes

Shrimp oil was encapsulated in nanoliposomes and fortified into skim milk. Shrimp oil nanoliposomes (SONL) were thermodynamically stable when added into skim milk at 10 mL 100 mL⁻¹. Mild bitterness in fortified skim milk caused by the SONL was masked by adding β-glucan at various levels (0.05–0.2 g 100 mL⁻¹). With the addition of SONL, fortified skim milk appeared more reddish in colour due to the presence of astaxanthin. Addition of β-glucan resulted in the increase in viscosity of the fortified milk by forming network of junction zones. During the storage of skim milk fortified with SONL and 0.1 g 100 mL⁻¹ β-glucan at 4 °C for 15 days, no major quality changes took place. Simulated in vitro digestion studies revealed that 45.41 g 100 g⁻¹ eicosapentaenoic acid (EPA) and 48.86 g 100 g⁻¹ docosahexaenoic acid (DHA) from shrimp oil were bioaccessible for absorption in the gut after digestion.     

ENZYMIC QUANTIFICATION OF (1→3) (1→4)-β-D-GLUCAN IN BARLEY AND MALT

A simple and quantitative method for the determination of (1→3) (1→4)-β-D-glucan in barley flour and malt is described. The method allows direct analysis of β-glucan in flour and malt slurries. Mixed-linkage β-glucan is specifically depolymerized with a highly purified (1→3) (1→4)-β-D-glucanase (lichenase), from Bacillus subtilis, to tri-, tetra- and higher degree of polymerization (d.p.) oligosaccharides. These oligosaccharides are then specifically and quantitatively hydrolysed to glucose using purified β-D-glucosidase. The glucose is then specifically determined using glucose oxidase/peroxidase reagent. Since barley flours contain only low levels of glucose, and maltosaccharides do not interfere with the assay, removal of low d.p. sugars is not necessary. Blank values are determined for each sample allowing the direct measurement of β-glucan in maltsamples.α-Amylasedoes not interfere with the assay. The method issuitable for the routineanalysis of β-glucan in barley samples derived from breeding programs; 50 samples can be analysed by a single operator in a day. Evaluation of the technique on different days has indicated a mean standard error of 0–1 for barley flour samples containing 3–8 and 4–6% (w/w) β-glucan content.     

VARIATION IN THE BIOCHEMICAL COMPOSITION OF ACID EXTRACTS FROM BARLEYS OF CONTRASTING MALTING QUALITY

Acid extracts from barleys of poor malting quality were characterized by high viscosity caused by enhanced concentrations of high molecular weight carbohydrates of which more than 80 per cent was β-glucan. Up to 67 per cent of the β-glucan in these barleys was soluble in the acid extracting solution. In contrast, only about 25 per cent of the β-glucan in good malting barleys was soluble, resulting in extracts having low viscosity. No evidence was found for autolysis in any of the extracts, and extracts from good malting varieties were characterized by high concentrations of fructose and sucrose. Protein concentration in the extracts varied little, although the protein content of the barleys ranged from 9·1 per cent to 15·4 per cent. Soluble protein has no effect on extract viscosity or the gel filtration properties of the carbohydrates. Some quantitative variation in acid-soluble and salt-soluble proteins was seen after electrophoresis on polyacrylamide.     

AN ENZYMIC METHOD FOR THE MEASUREMENT OF TOTAL AND WATER-SOLUBLE β-GLUCAN IN BARLEY

Crude cellulase preparations from Trichoderma reesei, freed of amyloglucosidase by heating, will completely hydrolyse barley β-glucan to glucose. Apparent non-quantitative recovery of glucose is due to its adsorption by the high levels of protein present. Methods are given for the measurement of total and water-soluble β-glucan. Dehusking does not lower the amount of β-glucan which is measured.     

Characterisation of oat bran products with and without supercritical carbon dioxide extraction

Morphology, starch structures and thermal and pasting properties of oat bran concentrate (OBC) and Nutrim‐OB (NOB), a jet‐cooked oat bran product, with or without supercritical carbon dioxide extraction (SCD) were studied. Oil composition was analysed. OBC had three thermal transitions, starch gelatinisation and two amylose–lipid complex transitions. NOB only had amorphous amylose–lipid transition. SCD significantly decreased gelatinisation temperatures of OBC. Pasting properties, showed NOB had significantly higher peak viscosity and breakdown, with significantly lower final viscosity, setback and pasting temperature compared with OBC. SCD increased peak viscosity for NOB and final viscosity for OBC. Thermogravimetric analysis showed NOB had higher water‐holding capacity (WHC) than OBC, while SCD decreased WHC. Amylopectin molecular weight was 3.4 × 10⁸ for OBC and was significantly lower for NOB (1.4 × 10⁸). Predominant fatty acids were oleic (41%), linoleic (38%) and palmitic (16%). Study showed NOB had different properties from OBC thereby expanding industrial applications.     

Effect of extrusion process on antioxidant activity, total phenolics and β-glucan content of extrudates developed from barley-fruit and vegetable by-products

The aim of this study was to determine the effects of extrusion processing variables on antioxidant activity (AA), total phenolic content (TP) and β-glucan content (BG) of extrudates. Products were prepared by extrusion cooking of barley flour, barley flour–tomato pomace and barley flour–grape pomace blends. Antioxidant activity as measured by the DPPH method was 43.17 ± 0.362, 27.57 ± 0.120 and 82.23 ± 0.785% while TPs, expressed as ferulic acid equivalents, were 5.29 ± 0.126, 4.66 ± 0.023 and 9.15 ± 0.015 mg g⁻¹ dry sample in the extracts obtained from barley flour, tomato and grape pomaces, respectively. Extrusion cooking decreased AA and TP of barley, barley–tomato pomace and barley–grape pomace extrudates. Temperature and screw speed had significant ( P  <   0.05) effect on BGs of barley flour and barley–grape pomace extrudates. However, BG of tomato pomace blend extrudates had significantly ( P  <   0.05) influenced from pomace level only. Results indicated that the content of β-glucan is higher in barley flour than in extrudates of barley flour and pomace blends.     

燕麦-葡聚糖辅助降血糖功能的研究

目的研究燕麦β-葡聚糖对大鼠辅助降血糖功能的作用。方法以0.375、0.75和1.5 g/(kg·bw)剂量的燕麦β-葡聚糖对大鼠灌胃,分别进行空腹血糖(fasting blood glucose, FBG)、糖耐量、胰岛素抵抗指数测定。结果胰岛素抵抗糖/脂代谢紊乱模型成立。与模型组比较,各受试样品剂量组空腹血糖下降百分率及糖耐量血糖曲线下面积无统计学差异(P0.05);中、高剂量组糖耐量0 h(空腹血糖)血糖值有统计学差异(P0.05);中剂量组糖耐量0.5h血糖值及高剂量组糖耐量2h血糖值有统计学差异(P0.05)。结论燕麦β-葡聚糖具有辅助降血糖的保健功能。