Comparison of xylo-oligosaccharides production by autohydrolysis of fibers separated from ground corn flour and DDGS

Xylo-oligosaccharides (XOS) are known to have beneficial health properties, and are considered to be functional food ingredients. The objective of this study is to compare corn fibers separated from ground corn flour and distillers dried grains with solubles (DDGS) for XOS yield and optimum autohydrolysis conditions. Based on the initial xylan content, the fiber separated from ground corn flour (FC) resulted in higher XOS yield (71.5%) than the fiber separated from DDGS (FD) (54.6%) at the maximum XOS production conditions. XOS produced were mainly xylobiose and xylotriose. Based on total initial material also, FC resulted in higher XOS yield (8.9%) than FD (8.0%), based on total original masses. Thus, fiber separated from ground corn flour would be a better feedstock for production of XOS than fiber separated from DDGS. The conditions for maximum XOS production from FD and FC were 180 °C with 20 min hold-time and 190 °C with 10 min hold-time, respectively.     

木寡糖的研究进展

木寡糖可以从多种多样含木聚糖的原材料中通过化学法或酶法制得，然后再利用物理化学方法精制。作为食物配料，木寡糖具有许多有利的技术特性，并且具有调节肠功能的能力，能导致生物前效应。除了对肠功能的作用外，其他关于木寡糖的生物活性也作了相关综述，包括木寡糖在生物合成配置方面的作用以及他们的技术特性和市场前景。     

甘蔗叶低聚木糖的分离纯化

研究低聚木糖水解液分别经过酸析脱色和活性炭脱色,旋转蒸发仪浓缩纯化处理,得到纯度较高的低聚木糖产品。通过对酸析和改性活性炭脱色条件优化,得到的优化脱色条件是:酸析脱色pH3.0,脱色温度50℃;活性炭用量是10%(w/v,活性炭/溶液),初始pH值是3.0,脱色温度是80℃,脱色时间是100min,此时的脱色了为55.06%。两种方法结合脱色率是68.96%。用旋转蒸发仪将经过脱色处理的低聚木糖水解液进行浓缩,并辅以乙醇继续浓缩得到浓缩糖浆,其中的低聚木糖含量达到32.08%(w/w,低聚木糖对固形物)。     

Structural characterisation and determination of prebiotic activity of purified xylo-oligosaccharides obtained from Bengal gram husk (Cicer arietinum L.) and wheat bran (Triticum aestivum)

Water extractable polysaccharides (WEPs) were isolated from Bengal gram husk and wheat bran. These WEP were subjected to driselase enzyme hydrolysis to obtain oligosaccharide mixtures, which were purified successively on Biogel P-2 and high performance liquid chromatographies. The molecular weight and structural features of the purified oligosaccharides were deduced using ESI-MS and ¹H NMR, respectively. The prebiotic properties of these purified oligosaccharides were studied by using Bifidobacterium adolescentis NDRI 236. Increase in dry cell mass (0.7–0.9 mg/ml) and decrease in pH (<5.8) due to production of short chain fatty acid (SCFA) indicated oligosaccharide fermentation. Acetate was the chief SCFA produced and its amount varied from 97.2% to 100%. The activities of xylanase (257–470 mU/ml), xylopyranosidase (53–60 mU/ml) and arabinofuranosidase (60–70 mU/ml) in the culture broth indicated the breakdown of xylo-oligosaccharides and their subsequent utilisation by the bacterium for its growth.     

Bioactive xylo-oligosaccharides from wheat bran soluble polysaccharides

Soluble polysaccharides (SP, 35 g) isolated from wheat bran (100 g) consisted mainly of arabinose and xylose with minor quantities of rhamnose, mannose, galactose and glucose. Wheat bran SP was subjected to purified endoxylanase (from 96 h ragi malt) treatment to obtain xylo-oligosaccharides (0.3 g/1 g wheat bran). The oligosaccharide mixture was purified on Biogel P-2 column into four major peaks designated as WO-1, WO-2, WO-3 and WO-4. Individual oligosaccharide purity was ascertained by HPLC and their composition was determined by GLC. The purified oligosaccharides were characterized by ESI-MS and ¹H NMR analysis. WO-1 and WO-2 were identified as arabinose containing xylotetraose and xylotriose, respectively, whereas WO-3 and WO-4 were identified as unsubstituted xylotriose and xylobiose, respectively. In vitro studies carried out using Bifidobacterium spp and Lactobacillus spp suggested the prebiotic nature of the crude as well as purified xylo-oligosaccharides as revealed by growth characteristics such as high O.D. of the culture broth, decrease in its pH, increase in cell mass and the resultant fermentation products. β-xylanase, β-xylosidase, α-arabinofuranosidase, α/β-galactosidases and acetyl esterase activities were determined in 24 h old culture broth and xylanase activity (440-830 μU/ml) was found to be the most preponderant among all of them.     

低聚木糖在保健食品中的应用

该文概述了低聚木糖的化学结构和加工特性,对低聚木糖的保健功能进行了重点阐述,并简要说明了低聚木糖的工业制备和在保健食品领域的应用前景。     

微波—酶法提取低聚木糖的研究

利用微波—酶法在玉米芯中提取低聚木糖,根据实验确定最佳工艺条件为：微波压力为1.5 MPa、微波处理时间为6 min、加酶量为1.5%和酶解时间为8 h,可制备含木二糖和木三糖的低聚木糖,提取率为43.8%。     

Characterization of purified xylanase from finger millet (<Emphasis Type="Italic">Eleusine coracana-</Emphasis>Indaf 15) malt

Xylanase (E.C. 3.2.1.8) was purified to apparent homogeneity from 96 h finger millet (Eleusine coracana, Indaf-15) malt by a three step purification procedure via ammonium sulphate fractionation, DEAE-cellulose ion exchange and Sephadex G-75 gel permeation chromatographies with a recovery of 4.0% and fold purification of 60. Xylanase, having a molecular weight of 29 ± 2 kDa was found to be monomeric on SDS-PAGE. pH optimum of the enzyme was found to be in the range of 5.0–5.5. The activation energy was 25 kJmol⁻¹. Xylanase showed maximum stability at 35 °C in a pH range of 5.0–6.0. K _m and V _max of purified xylanase were found to be 0.2% and 4.5 μmol min⁻¹, respectively. Metal ions such as Ca²⁺, Mg²⁺, Mn²⁺, Cu²⁺, Fe²⁺, Ag²⁺ and Ni²⁺ enhanced xylanase activity at 5 mM concentration. p-chloromercuribenzoate, citric, oxalic and boric acids inhibited the enzyme in concentration dependent manner. The mode of action of xylanase was found to be “endo” as determined by the analysis of products liberated from larchwood xylan by ESI-MS and H¹NMR. In vitro studies using Bifidobacterium and Lactobacillus sp. confirmed the prebiotic activity of the xylo-oligosaccharides.     

In vitro fermentation of selected xylo-oligosaccharides by piglet intestinal microbiota

The objective of this study was to compare the in vitro fermentability of xylo-oligosaccharides (XOS) with different degrees of polymerisation (DP) by the intestinal digesta collected in three distinct intestinal sections of the porcine intestinal tract: ileum, caecum, and distal colon. The studied oligosaccharides included commercial short-chain XOS (DP 2-5), and medium-chain (DP 2-14) and long-chain (DP 2-25) XOS obtained by autohydrolysis of brewery's spent grain (BSG), corn cobs (CC) and Eucalyptus globulus wood (EUC). The oligosaccharide and monosaccharide consumption, lactate and short-chain fatty acids concentrations were correlated with shifts on PCR titres of Bacteroides/Prevotella, Bifidobacterium and Lactobacillus/Pediococcus populations, by using group- and genus-specific primers.All tested XOS were extensively fermented by the piglet ileal, caecal and colonic microbiota. The rate of consumption of medium- and long-chain XOS was notably reduced in the fermentations by the ileal inoculum as compared to commercial XOS. EUC XOS, CC XOS and commercial XOS supported an enhancement of bifidobacteria and lactobacilli replication in a first stage of the fermentations. Apparently this stimulation was not selective, because Bacteroides/Prevotella replication increased in a second stage of the fermentations, coincident in time with the highest consumption rates of some XOS mixtures tested. Mostly due to the slow fermentability by the ileal microbiota, medium-chain and long-chain XOS mixtures can be regarded as promising functional candidates suitable to act as distally fermentable substrates.     

木寡糖的研究进展

木寡糖可以从多种多样含木聚糖的原材料中通过化学法或酶法制得,然后再利用物理化学方法精制。作为食物配料,木寡糖具有许多有利的技术特性,并且具有调节肠功能的能力,能导致生物前效应。除了对肠功能的作用外,其他关于木寡糖的生物活性也作了相关综述,包括木寡糖在生物合成配置方面的作用以及他们的技术特性和市场前景。