不同大麦品种来源β-葡聚糖流变学特性

优化大麦β-葡聚糖提取工艺,在提取料水比1∶10,提取液pH=7,提取温度60℃,提取时间4h条件下,可得纯度为96.89%、分子量为1×106大麦β-葡聚糖;利用凝胶过滤色谱法测定5种不同大麦品种来源β-葡聚糖分子特征参数,并使用静态和动态粘弹性测定法研究其流变学特性。结果表明,所得大麦β-葡聚糖分子量在不同大麦品种间差异较大,在0.6×106～1.8×106之间;在浓度0.8%及以上时,江苏啤麦β-葡聚糖具有明显假塑性流体特征;与其它品种相比,1.0%浓度江苏饲麦β-葡聚糖溶液零剪切粘度最低,说明β-葡聚糖分子量越高,分布范围越窄,零剪切粘度越高;浓度为2.0%江苏啤麦具有显著弹性特征,在5个品种中表现出最高增稠能力。     

Structural Characterization,Technological Functionality,and Physiological Aspects of Fungal β-D-glucans: A Review

β-D-glucans are a (1→3)-linked glucose polymer with (1→6)-linked side chains and a major component of fungal cell walls. They exhibit structural integrity to the fungal cell wall. In addition, β-glucans are widely used as food adjuvant in food and pharmaceutical industries because of their physico-chemical properties. Several studies have focused on different isolation processes of (1→3) (1→6)-β-glucan that could affect the physico-chemical and functional properties of β-glucan such as chemical composition, solubility, viscosity, hydration properties, and oil binding capacity. Immunological activity is one of the most important properties of β-glucans. Thus, they are effective in inhibiting growth of cancer cells and metastasis and preventing bacterial infection. In humans, β-glucans reduce blood cholesterol, improve glucose absorption by body cells, and so help wound healing. This review described the prebiotic potentiality of fungal β-D-glucans with the objective to detail the methodologies applied for their extraction, their structure and techno-functional properties, and finally their biological effects.     

Effect of γ-irradiation on structural,functional and antioxidant properties of β-glucan extracted from button mushroom (Agaricus bisporus)

In this study, β-d-glucan extracted from mushroom Agaricus bisporus were irradiated at 5, 10, 20, 30 and 50 kGy. The samples were characterized by ATR-FTIR spectroscopy, gel permeation chromatography (GPC) and quantitative estimation by Megazyme β-d-glucan assay kit. The average molecular weight of non-irradiated β-d-glucan was 181 kDa that decreased to 31.1 kDa at 50 kGy. The functional properties like swelling power and viscosity decreased while fat binding capacity, emulsifying properties, foaming properties, and bile acid binding capacity showed increased trend with the increase in irradiation doses. The antioxidant properties of irradiated β-d-glucan were carried out using six different assays like DPPH, reducing power, inhibition of lipid per oxidation, chelating ability on ferrous ion, FRAP and ABTS assay that also showed increased activity. In conclusion, the present study signifies the importance of irradiated β-d-glucan in various fields of food processing and pharmacy.Industrial RelevanceIn today's scenario, people are having a sedentary life style with increased risk factors of various diseases like hypercholestromia, cancers, obesity, etc. So they are looking for such type of food that has profound health benefits i.e., functional food. β-Glucan is one of the polysaccharide that can be incorporated into the food formulations and make it functional. However its high viscous nature and low solubility pose several restrictions to being applied widely in food industries. Gamma irradiation is one of the useful techniques that can be commercialized to overcome this problem and use irradiated β-glucan in various food formulations as an ingredient with enhanced antioxidant and functional properties.     

Barley: Impact of processing on physicochemical and thermal properties—A review

Barley (Hordeum vulgare L.) is a nutritious cereal but very little (only about 2%) of this grain is used as human food. However, it has attracted the attention of researchers and food processors in the last 15 years for its potential health benefits. It is also recognized as a functional grain because it contains high levels of β-glucan and phytochemicals. Therefore, a number of barley processing research and animal/clinical trials have been performed over the last 15–20 years. Also, health claims have been approved by a number of government agencies including the Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) about consumption of β-glucan, an important component of barley. Barley must undergo various processing steps before human consumption, which greatly affect their composition and physicochemical properties. These properties play an important role in the development of new products. Therefore, the present article reviews the literature on the effect of processing on the physicochemical and thermal properties of barley.     

Pasting,rheological, and dough mixing behavior of rice flour as affected by the addition of native and partially hydrolyzed β-glucan concentrate

This study was aimed at evaluating the potential of barley β-glucan concentrates (native and partially hydrolyzed) in modifying the techno-functionality of rice flour dough. β-Glucan concentrate was partially hydrolyzed to obtain a low molecular weight polymer and their influence on the pasting, rheological, and thermal properties of rice dough were assessed. Hydration, thermal, and pasting properties were significantly modified with the added β-glucans. The rice dough supplemented with β-glucan concentrates showed improved viscoelastic and creep behavior and the effectiveness of β-glucans in imparting strength to rice dough depended on its molecular weight. Hydrolyzed β-glucan concentrates having low molecular weight increased dough elasticity to the greater extent in comparison to native β-glucan concentrates. The micrographs of supplemented dough showed a strong and dense network indicating improved structure and strength.     

燕麦β-葡聚糖复合凝胶制备技术及其凝胶机理研究

为了揭示燕麦β-葡聚糖复合凝胶的形成条件、形成过程,本文对两种不同质量分数的β-葡聚糖(OG和LOG)及其比例对复合凝胶的流变特性、质构特性和微观结构进行分析,筛选制备燕麦β-葡聚糖复合凝胶的参数,并进一步研究β-葡聚糖复合凝胶形成的分子作用力及分子结构。结果表明,当β-葡聚糖总浓度12%,两种葡聚糖质量比(LOG:OG)为1:1时,形成的典型凝胶储能模量(G')和损耗模量(G″)均较大,其硬度为0.838 N,显著高于其他比例制备的凝胶(P<0.05)。通过扫描电镜观察到,在此条件下制备的β-葡聚糖复合凝胶,表面致密,无明显孔洞,并且通过分子作用力实验表明β-葡聚糖复合凝胶形成过程中氢键和静电相互作用起主要作用,且红外光谱分析形成的复合凝胶不改变β-葡聚糖初级结构。因此,燕麦β-葡聚糖复合凝胶其流变特性和质构特性以及表面结构方面的性能均优于其单一组分的β-葡聚糖凝胶。此结论为优化推广燕麦β-葡聚糖复合凝胶在食品工业中的应用提供了理论依据。     

燕麦β-葡聚糖对大豆分离蛋白酸致凝胶物理性质影响的研究

采用乳酸菌发酵法对大豆分离蛋白/燕麦β-葡聚糖混合体系酸致凝胶的物理性质进行研究,将不同分子量燕麦β-葡聚糖添加到大豆分离蛋白中,探讨燕麦β-葡聚糖浓度和分子量对SPI凝胶的脱水收缩作用、质构特性和持水性的影响。结果表明:保加利亚乳杆菌发酵产酸速率较快,并且对混合凝胶性质的影响优于嗜热链球菌和嗜酸乳杆菌,为最佳发酵菌种。较高浓度或高分子量燕麦β-葡聚糖能降低SPI凝胶的脱水收缩作用,即减少乳清的析出;随着燕麦β-葡聚糖浓度的增加,SPI凝胶硬度和持水性呈下降趋势,而弹性和内聚性先增加后降低;高分子量的燕麦β-葡聚糖能够改善SPI凝胶的质构特性,并且增加凝胶的持水性。     

提取方法对产朊假丝酵母β-葡聚糖性质的影响

以产朊假丝酵母（Candida utilis）为原料,采用高压微射流均质法、超声波法及复合酶解生物法对酵母细 胞壁中的β-葡聚糖（yeast β-glucan,YG）进行提取（分别标为H-YG、U-YG和E-YG）。比较了3 种方法提取β-葡 聚糖的得率、纯度、分子质量分布、单糖组成等理化性质,并测定了3 种提取方法对样品抗氧化性和保湿性能的影 响。结果表明：3 种方法提取的β-葡聚糖纯度都在96%以上,高压微射流均质法得到的H-YG得率和含量最高,分 别为19.6%和97.5%;紫外光谱扫描显示多糖样品均不含核酸和蛋白质等杂质;单糖组成分析表明,3 种方法提取 的β-葡聚糖样品均是由葡萄糖组成的均一多糖;采用高效体积排阻色谱与多角度激光光散射联用仪测定了3 种方法 提取的β-葡聚糖的分子质量分布和多糖平均分子半径,表明3 种方法提取的β-葡聚糖的重均分子质量mw存在差异, 分别为1.611×106、4.763×106、2.661×105 g/mol,多分散系数分别为1.025、1.686、1.362,平均分子半径分别为 67.5、33.3、43.7 nm。抗氧化实验表明H-YG、U-YG和E-YG均具有一定的1,1-二苯基-2-三硝基苯肼自由基清除能 力,显示了其抗氧化能力。保湿实验表明：H-YG、U-YG和E-YG都有明显的体外保湿性能,H-YG体外保湿效果在 8～24 h内优于甘油;3 种方法提取的β-葡聚糖样品均对促进内源性天然保湿因子的生成效果显著,其中H-YG的促 进作用最为明显。研究结果表明,不同的提取方法影响酵母β-葡聚糖的理化性质,进而影响其生物活性,可根据其 不同特性应用于相应领域。     

几种主要杂粮的功能特性及其食品应用研究进展

综述了燕麦、荞麦和高梁等杂粮的主要成分及其功能特性,重点是膳食纤维和β-葡聚糖的制取工艺以及近年来国内外以杂粮为原料进行保健食品研究的开发现状、发展趋势。充分利用杂粮特色资源、拓宽杂粮在食品工业中的应用范围,可以改善人类膳食结构,增进人体健康。     

发酵法提取青稞麸皮中β-葡聚糖的工艺优化及其理化性质研究

为提高青稞麸皮β-葡聚糖的产量和纯度,选用发酵法提取制备青稞麸皮β-葡聚糖。运用单因素、正交试验确定最优提取条件,并对该条件下得到的青稞麸皮β-葡聚糖进行了分子量、单糖组成等理化分析。结果表明,发酵法提取青稞麸皮β-葡聚糖最佳工艺参数为:料液比1:6,接种0.05%高活性干酵母,在32℃条件下发酵34 h。在最优条件下生产的β-葡聚糖,得率为5.21%±0.02%,与传统水提法相比提高了60.8%,纯度为91.21%。发酵法提取的青稞麸皮β-葡聚糖理化分析特征为单糖组成主要为D-葡萄糖,其平均相对分子质量为1.366×105,水提法提取的青稞麸皮β-葡聚糖单糖组成有D-阿拉伯糖、D-半乳糖、D-木糖、D-甘露糖、D-葡萄糖,平均分子量为7.759×105。     

三相萃取法提取啤酒废酵母β-葡聚糖及其抗氧化活性研究

β-葡聚糖是重要的食品功能因子,该试验以啤酒生产废弃酵母为原料,采用超声耦合酶法处理废酵母得到粗多糖,通过三相萃取法得到纯化成品。以提取率为考察指标,通过响应面试验优化三相萃取的最佳提取条件,并研究其抗氧化活性功能。结果表明,废酵母经预处理用超声耦合木瓜蛋白酶处理后,在叔丁醇添加量为9.4 mL,（NH4）2SO4含量27.4%,萃取温度35.7 ℃条件下,β-葡聚糖萃取率为90.13%;在β-葡聚糖质量浓度为8 mg/mL时,对1,1-二苯基-2-苦基肼（DPPH）、2,2'-联氮双（3-乙基苯并噻唑啉-6-磺酸）二铵盐（ABTS）自由基清除率可达60.5%和51.5%。     

Influence of homogenisation on the solution properties of oat β-glucan

High pressure and rotor/stator homogenisation are widely used techniques in modifying rheologically interesting polysaccharides such as cereal β-glucan for food purposes. However, the influence of the homogenisation-induced mechanical stress on β-glucan has not been reported. The influence of three different homogenisers (two high-pressure homogenisers and a rotor/stator homogeniser) was examined in terms of the change in flow and molecular properties of oat β-glucan in semi-dilute and concentrated solutions. A clear and irreversible decrease in viscosity and change in flow behaviour were observed after each homogenisation treatment of the semi-dilute solution. The viscosity had a linear relationship with molar mass in the high-pressure homogenised samples and they both decreased in parallel with the mechanical energy input. With the molar mass decrease, the shape of β-glucan became more spherical and dense. In addition, the molecular weight distribution narrowed and storage-related viscosity stabilized. No considerable differences between the influences of the two high-pressure techniques were observed inconsistently with previous studies. Both molecular and technical characteristics were concluded to affect the fragmentation of β-glucan in high-pressure homogenisation. Since homogenisation enhanced the structural stability of the solution and the fragmentation was dependent on the energy input, the techniques were concluded to be relevant methods for controlled fragmentation of β-glucan.     

Extraction and Functional Properties of Barley β-Glucan as Affected by Temperature and pH

Barley is high in β-glucan, a soluble fiber component. Effects of extraction temperature (40 55 C) and pH (7.0 10.0) on recovery, purity and functional properties of β-glucan were investigated on whole Condor barley flour. At pH 7.0, 8.0 and 55°C, 86.5% of the β-glucan in the feed flour was recovered in the gum product with 89.1% (d.w.b.) purity. β-Glucan content increased (p < 0.05) with temperature but not with pH. Apparent viscosity of 1% (w/v) dispersions of β-glucan gum from pH 7.0 increased (p < 0.05) with extraction temperature at constant shear rate and viscosity decreased slightly with increasing shear rate. Whippability and foam stability of gums from pH 8.0 and 45°C were maximum. Emulsions prepared with β-glucan gum from pH 7.0 and 55@c were 63% stable after centrifugation. Barley β-glucan shows great potential as a thickener or stabilizer.     

Physicochemical characteristics and in vitro bile acid binding and starch digestion of β-glucans extracted from different varieties of Jeju barley

Physicochemical properties of six different varieties of barley and their β-glucans were evaluated along with in vitro bile acid binding and starch digestibility for health beneficial effects. β-Glucan concentrations in less-hulled, beer, black, waxy-naked, naked, and blue barley were 3.44, 3.46, 6.08, 6.75, 6.45, and 5.91%, respectively. Viscosity of waxy-naked barley flour was the highest. While the yield of β-glucan from waxy-naked barley after extraction was 95.49%, less-hulled barley was 70.09%. As the increase of β-glucan purification, in vitro bile acid binding was increased when compared with cholestyramine and cellulose. In vitro starch digestibility of barley flour and the mixture of potato starch with β-glucan were increased by heat and β-glucan concentration. Estimated glycemic index (GI) calculated based on in vitro starch digestibility was decreased by increasing β-glucan. These results suggest that the physicochemical properties of barley were dependent on the variety of barley and especially β-glucan was involved.     

酶法合成糖原状α-葡聚糖的研究进展

糖原是一种天然的纳米级树状葡聚糖,可以通过物理或化学方法对其表面和内部进行修饰,从而获得功能性衍生物。但糖原的体内合成环境复杂,体外制备时提取工艺要求严苛,限制了糖原作为功能性成分或纳米载体在食品及生物医学领域的应用。因此,通过体外酶促合成的具有类似糖原结构和性质的糖原状α-葡聚糖成为天然糖原的良好工业替代品。本文综述了4 种体外酶促合成糖原状α-葡聚糖的方法,并比较了不同方法获得的α-葡聚糖结构及理化性质。此外对控制其精细结构的可能性和广泛的应用前景进行了分析讨论,为体外合成的糖原状α-葡聚糖应用于食品、医药和化妆品等领域提供借鉴。     

SELECTIVE DETERMINATION OF β-GLUCAN OF DIFFERING MOLECULAR SIZE,USING THE CALCOFLUOR-FLUORIMETRIC FLOW-INJECTION-ANALYSIS (FIA) METHOD

When using the calcofluor-fluorimetric flow-injection-analysis (FIA) method to determine β-glucan in wort and beer, the actual range of β-glucan molecular weights effectively complexed by the calcofluor, and consequently the total amount detected, is dependent on the ionic strength of the eluent. In the base eluent of very low ionic strength (20 ppm of calcofluor in aqueous 0.1 M TRIS, pH = 11), only β-glucan molecules of molecular weight greater than approximately 200, 000 daltons are fully complexed by calcofluor, and consequently fully detected. As the molecular weight of β-glucan molecules decreases, β-glucan is only partially complexed by calcofluor, and hence partially detected. By increasing the ionic strength of the base eluent through adding successive amounts of NaCl up to a maximum of 1%, the molecular weight of β-glucan which can be detected by the method decreases down to about 65, 000 daltons, whereas the molecular weights below about 10,000 daltons are not significantly complexed nor detected. Different size ranges of β-glucan have been isolated and characterized by enzymatic degradation of high molecular weight standard β-glucan, followed by classical gel permeation chromatography (GPC), using Sephacryl S-400 HR as stationary phase, pure water as eluent, and dextrans as molecular weight markers.     

Pressurized aqueous ethanol extraction of β-glucans and phenolic compounds from waxy barley

Beta-glucans and phenolics were extracted from waxy barley using pressurized aqueous ethanol in a stirred batch reactor at 25 bar and 500 rpm. The effect of temperature (135–175 °C), extraction time (15–55 min) and ethanol content (5–20%) was evaluated. Temperature had an opposite effect on the extraction of both compounds. The higher the temperature, the lower the β-glucan extraction yield due to fragmentation, but a significant increase on the phenolic recovery was observed. Long extraction times favored the extraction of β-glucans at low temperatures and phenolics at any temperature. The ethanol content was not statistically significant on the β-glucan extraction, but helped to maintain the molecular weight of the extracted β-glucan. To obtain liquid extracts rich in high molecular weight β-glucans and phenolics, mild conditions of 151 °C, 21 min and 16% ethanol are needed, leading to 51% β-glucan extraction yield with a molecular weight of 500–600 kDa and 5 mg GAE/g barley.     

Effects of oxidative treatment on the physicochemical,rheological and functional properties of oat β-glucan

The objective of this work was promote oxidation of β-glucan from oat bran with hydrogen peroxide at different concentration levels (0.3%, 0.6% and 0.9% H₂O₂) and reaction times (30 and 60 min), and evaluate the physicochemical and functional properties of isedoxidised β-glucan with in-vitro tests. An increase in carbonyl and carboxyl groups and alterations in swelling power were verified in the oxidised β-glucan. The cholic acid binding capacity increased in the oxidised β-glucan; however, the fat binding capacity was not affected. After chemical digestion, the available glucose of the oxidised β-glucan was increased. Oxidation with hydrogen peroxide decreased the viscosity, hardness, adhesiveness and gumminess of the β-glucan gels. More studies are necessary to determine the effect of the oxidative treatment of β-glucan on its technological properties in food products, and biological properties should be examined with in-vivo studies.     

Probabilistic methodology for assessing changes in the level and molecular weight of barley β-glucan during bread baking

The objective of this study was to create a probabilistic model to assess changes in the levels and molecular weight (Mw) of β-glucan during the bread baking process using Monte Carlo simulation techniques. Three different composite flours were formulated by substituting wheat flour (WF) with barley whole meal flour (BWMF), barley straight grade flour (BSGF) or barley fibre rich fraction (BFRF). The β-glucan level in the flour increased significantly (by approximately 10-fold) when barley was substituted for WF. The baking process resulted in approximately a 47–48% reduction in the β-glucan level in the baked bread (base-line model). The base-line model observed ∼25% and 7% reduction in high molecular weight (HMw) and medium molecular weight (MMw), respectively and a subsequent increase in low molecular weight (LMw). The analysis also showed the importance of various steps involved in bread baking, such as mixing time (Mt), fermentation time (Ft) and baking (BGloss), on the level and Mw of β-glucan in baked breads. A parallel experimental validation study provided confidence in model predictions of β-glucan levels. This study aids in optimising the various unit operations involved in the bread baking process to give a final product with increased nutritional qualities.     

The behaviour and susceptibility to degradation of high and low molecular weight barley β-glucan in wheat bread during baking and in vitro digestion

The behaviour and susceptibility to degradation of a high molecular weight (HMW) and low molecular weight (LMW) barley β-glucan in white bread during manufacture and in vitro digestion were investigated. The incorporation of both HMW and LMW barley β-glucan resulted in stiffer dough, lowered loaf volume and height compared to the control. The HMW barley β-glucan caused the greatest loss of dough and bread quality. Breads with HMW and LMW barley β-glucan exhibited attenuated reducing sugars release (RSR) over a 300 min in vitro digestion compared to the control, with generally no difference between the breads. HMW barley β-glucan was degraded during bread manufacture; however, degradation of the LMW barley β-glucan was not apparent. An in vitro digestion did not result in any further degradation of the molecular weight (MW) of either barley β-glucan.